- Email: [email protected]
Finite Element Analysis of 3D Printed Model via Compression Tests
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(SMPM 2019) Procedia Manufacturing 35 (2019) 164–173
Finite Element Analysis of 3D Printed Model via Compression 2nd International Sustainable Materials Processing Manufacturing Finite ElementConference Analysisonof 3D Printed Model viaandCompression Tests (SMPM 2019) 2nd International Sustainable Materials Processing Manufacturing Finite ElementConference Analysisonof 3D Printed Model viaandCompression Tests (SMPM 2019) Tests 2019) Finite Element Analysis of (SMPM 3D Printed Model via Compression D.W. Abbot, D.V.V. Kallon*, C. Anghel, P. Dube Finite Element Analysis of 3D Printed Model via Compression D.W. D.V.V. Kallon*, C. Anghel, P. Dube Tests Department of Mechanical and Abbot, Industrial Engineering Technology, University of Johannesburg,Johannesburg, South Africa Finite Element Analysis of 3D Printed Model via Compression D.W. Abbot, D.V.V. Kallon*, C. Anghel, P. Dube Tests Department of Mechanical and Industrial Engineering Technology, University of Johannesburg,Johannesburg, South Africa Abstract TestsUniversity Department of Mechanical and Abbot, Industrial Engineering of Johannesburg,Johannesburg, South Africa D.W. D.V.V.Technology, Kallon*, C. Anghel, P. Dube
3D Printing has grown tremendously over the past few years and continues to do so as the industry grows with Abstract D.W. Abbot, D.V.V. Anghel, P. Dube new technologies. 3D Printing makes design easierKallon*, and allowsC. engineers to create prototypes and mock-ups of Department Mechanical and Industrial Engineering of Johannesburg,Johannesburg, South Africa with Abstract 3D Printing has ofgrown tremendously over the pastTechnology, few yearsUniversity and continues to do so as the industry grows these designs faster thanD.W. ever before. Edits can be made in hours rather than days and best of all, it can be done Abbot, D.V.V. Kallon*, C. Anghel, P. Dube new technologies. 3D Printing makes over design easier andyears allows engineers to to create and mock-ups of 3D Printing has ofrather grown tremendously the pastThe few and doofsoprototypes as the industry grows Department Mechanical and Engineering Technology, University of Johannesburg,Johannesburg, South Africa with on the desktop, than on Industrial the factory floor. question of continues replaceability conventional manufacturing Abstract these designs faster than ever before. Edits can be made in hours rather than days and best of all, it can be done new technologies. 3D prints, Printing makes design easier andelement allows engineers prototypesmodel and mock-ups of Department of Mechanical and Industrial Engineering Technology, University of Johannesburg,Johannesburg, South technologies with 3D and the accuracy of finite analysis ontoa create 3D printed-like isAfrica the focus on the desktop, rather than the factory floor. question ofrather replaceability manufacturing 3D Printing grown tremendously over past few years and continues to doofand soconventional asbest the of industry grows with these designs faster than everonbefore. can beThe made in hours than days all, can be done Abstract of this study.has This study conducted anEdits FEAthe of some simple structures and compared results of the it simulations to technologies withrather 3D prints, andmakes accuracy of finite element analysis on ato 3D printed-like model is the focus new technologies. 3D design easier and allows engineers create mock-ups of on desktop, than on thethefactory floor. The question of replaceability conventional manufacturing 3D Printing has grown tremendously over the past few years continues doof soprototypes as with thatthe of lab tests on 3DPrinting printed parts. Sample specimens in theand shape of atoblock, 25 mmthex industry 25 and mm xgrows 25 mm in Abstract of this study. with This study conducted FEA ofeasier some simple structures and results ofmodel the simulations to these designs faster3D than ever before. Edits can made in hours rather than days and best of of all, it can be focus done technologies prints, and theanInventor accuracy ofbefinite element analysis oncompared a create 3D printed-like is the new technologies. 3D Printing makes design and allows engineers to prototypes and mock-ups of diameter is designed using Autodesk 2018 and tested in a simulation environment Autodesk Inventor 3D Printing has rather grown tremendously over the pastThe fewquestion years continues to doof25 soconventional as industry with thatthis of study. lab tests on 3D than printed parts. Sample in structures theand shape of acompared block, mmthex of 25the mm xgrows 25 mm in on the desktop, theoffactory floor. of replaceability manufacturing of conducted anthese FEAobjects of specimens some simple and results simulations to these designs faster than everonbefore. Edits can be made in hours rather than days and best of all, it can be done to gain insightThis intostudy the responses under compressive loads. The same designed 3D objects are new technologies. 3D Printing makes design easier and allows engineers to create prototypes and mock-ups of diameter is tests designed using Autodesk Inventor 2018 andelement tested inshape a simulation environment of25Autodesk Inventor technologies with 3D prints, and the accuracy of finite analysis on a 3D printed-like model is the focus that of lab on 3D printed parts. Sample specimens in the of a block, 25 mm x mm x 25 mm in on the desktop, rather than theoffactory floor. question ofrather replaceability of conventional manufacturing then printed using a 3D printer out several different materials and infills. These objects areofexposed to the these faster than everonbefore. Edits can beThe made in hours than days and best all, it can be same done to gaindesigns insight intostudy the responses ofanInventor these objects under compressive loads. The same designed 3D objects are of this study. This conducted FEA of some simple structures and compared results of the simulations to diameter is designed using Autodesk 2018 and tested in a simulation environment of Autodesk Inventor technologies with 3D prints, andthe thefactory accuracy of finite element analysis on athe 3Dresponse printed-like is the focusa external forces applied in the FEA with floor. strain gauges used of to measure andmodel thus providing on the desktop, rather than on The question replaceability of manufacturing then printed using a 3D printer out of several different materials infills. These objects are exposed themm same that of lab tests on printed parts. Sample in the and shape of acompared block, 25conventional mm x of 25 mm xto 25 in to gain insight into the responses these objects under compressive loads. The same designed 3D objects are of this study. This study conducted anaccuracy FEA of specimens some simple structures and results the simulations to comparison with the FEA. The results of these tests are analysed and presented herein. technologies with 3D prints, and the of finite element analysis on a 3D printed-like model is the focus external forces applied in the FEA with strain gauges used to measure the response and thus providing a diameter is designed using Autodesk Inventor 2018 and tested in a simulation environment of Autodesk Inventor then printed using a 3D 3D printer out of several different materials and infills. These objects are exposed to25 themm same that of lab tests on printed parts. Sample specimens in the shape of a block, 25 mm x 25 mm x in of this study. This study conducted anthese FEA of some simple structures and compared results of the3D simulations to comparison with the FEA. The results of these tests are analysed and presented herein. to gain insight into the responses of objects under compressive loads. The same designed objects are external forces applied in the FEA with strain gauges used to measure the response and thus providing a © 2019 The Authors.using Published by Elsevier B.V diameter designed Autodesk Inventor 2018 and tested a simulation environment Autodesk Inventor that of labis tests ona 3D printed parts. Sampledifferent specimens in theinand shape of a These block, 25 mmare xof25 mm xto25 mm in then printed using 3D printer out of several materials infills. objects exposed the same comparison with the FEA. The results of these tests are analysed and presented herein. to gain insight intoresponsibility the responses these objects under compressive loads. The same designed 3D objects are diameter is designed using Inventor 2018gauges and tested into a simulation environment of Autodesk Inventor © 2019 The Authors. Published by B.V Peer-review under ofofElsevier the organizing committee SMPM 2019the external forces applied in Autodesk theout FEA with strain usedof measure response and thus providing a then printed using a 3D printer of several different materials and infills. These objects are exposed to the same to gain insight into the responses these objects under compressive loads. The same designed 3D objects are © 2019 The with Authors. Published byofElsevier B.V comparison the FEA. The results of these tests are analysed and presented herein. Peer-review under ofofthe organizing committee SMPM 2019 external forces applied in the FEA with strain gauges usedof to measure the response and thus providing Keywords: Ansys, Autodesk Inventor, 3D objects, 3Dmaterials Printer, FEM then printed using aresponsibility 3D printer out several different and infills. These objects are exposed to the samea comparison with the FEA. The results of these tests are analysed and presented herein. Peer-review under responsibility of the organizing committee of SMPM 2019 external forces applied in the FEA with strain usedFEM to measure the response and thus providing a © 2019 The Authors. Published by Elsevier B.V gauges Keywords: Ansys, Autodesk Inventor, 3D objects, 3D Printer, comparison with thePublished FEA. The results ofB.V. these tests are analysed and presented herein. © 2019 The Authors. by Elsevier © 2019 TheAnsys, Authors. Published by B.V committee Keywords: Autodesk Inventor, objects, 3D Printer,of FEM Peer-review under responsibility of Elsevier the3D organizing SMPM Peer-review under responsibility of the organizing committee of SMPM 2019. 2019 © 2019 The Authors. Published by Elsevier B.V 1. Introduction Peer-review under responsibility of the3D organizing SMPM 2019 Keywords: Ansys, Autodesk Inventor, objects, committee 3D Printer,of FEM 1. Introduction Peer-review under responsibility of the organizing committee of SMPM 2019 Keywords: Ansys, Autodesk Inventor, 3D objects, 3D Printer, FEM Introduction The 1. 3D printing technology is an additive manufacturing process, which proceeds by making three-dimensional Keywords: Inventor, 3D objects, 3Dprinting Printer, layers FEM of material until the object has been formed solid objectsAnsys, from aAutodesk digital file. This process involves The 1. 3D printing technology is an additive manufacturing process, which proceeds by making three-dimensional with the Introduction use of a 3D printer [1]. 3D printing has enabled the production of complex geometries with minimal solid objects fromtechnology a digital file. This process involves printing layers of material until objectthree-dimensional has been formed The 3D printing is an additive manufacturing process, which proceeds by the making waste1. in Introduction material, when compared to the traditional manufacturing methods, which mostly proceed using with the use from of a 3D printer [1].This 3Dprocess printinginvolves has enabled the layers production of complex geometries with solid objects a digital file. printing of material until the object beenminimal formed subtractive method. This technology offers the flexibility of “embedded” manufacturing-has manufacturing 1. Introduction waste inprinting material, when compared to themanufacturing traditional manufacturing methods, which mostly proceed using The 3D technology is an additive process, which proceeds by making three-dimensional with the use of a 3D printer [1]. 3D printing has enabled the production of complex geometries with minimal components in place where it is needed, thus reducing transportation cost, and reducing throughput in prototyping. subtractive method. This technology offers the flexibility of “embedded” manufacturingmanufacturing solid objects a when digital file. This process involves printing layers ofassociated material until object has been formed waste in material, compared to themanufacturing traditional manufacturing methods, which mostly proceed using The printing technology isprinter an additive process, which proceeds by the making three-dimensional This 3D is due tofrom mobility of the compared to the massive weights with subtractive machine tools. components in place where ittechnology is needed, thus reducing transportation cost, and reducing throughput in prototyping. with the usemethod. ofanalysis a 3D printer [1]. 3Dprocess printing has the layers production ofengineering complex geometries with minimal subtractive This offers theenabled flexibility of “embedded” manufacturingmanufacturing solid objects from a digital file. This involves printing of material until the object has been formed Finite element (FEA), a technique has provided insight into complex problems over the years The 3D printing technology isprinter an additive process, which proceedswith by making three-dimensional This is due toinof mobility of the compared to the massive weights associated subtractive machine tools. waste in material, when compared to themanufacturing traditional manufacturing methods, which mostly proceed using components place where it is needed, thus reducing transportation cost, and reducing throughput in prototyping. with the use a 3D printer [1]. 3D printing has enabled the production of complex geometries with minimal continuous values of elements calculated across the model from one element to another [2]. It is highly useful solid objectsmethod. from a digital file. process printing layers of material until the problems object has beenthe formed Finite analysis (FEA), aThis technique hasinvolves provided insightweights into complex engineering over years subtractive This technology thethe flexibility of material “embedded” manufacturingmanufacturing This iselement duematerial, to of mobility of the printer compared to massive associated with subtractive machine tools. waste in when compared to the traditional manufacturing methods, which mostlylocal proceed using in estimation mechanical properties ofoffers models with dissimilar properties to obtain effects and with the use of a 3D printer [1]. 3D printing has enabled the production of complex geometries with minimal with continuous values of elements calculated across the model from one element to another [2]. It is highly useful components in place where it is needed, thus reducing transportation cost, and reducing throughput in prototyping. Finite element analysis (FEA), a technique has provided insight into complex engineering problems over the years subtractive method. This technology offers the flexibility of “embedded” manufacturingmanufacturing accurate solution of the whole model via an element-wise approach [3]. waste when compared toofthe traditional manufacturing methods, which mostlylocal proceed using in estimation mechanical properties models with dissimilar material properties to obtain effects and This is in duematerial, toinof mobility of the printer compared to the massive associated with subtractive machine tools. with continuous values elements calculated across the modelweights from one element to another [2]. It isin highly useful components place where ittechnology is needed, thus reducing transportation cost, and reducing throughput prototyping. subtractive method. This offers the flexibility of “embedded” manufacturingmanufacturing accurate solution of the whole model via an element-wise approach [3]. Finite element analysis (FEA), a technique has provided insight into complex engineering problems over the years in estimation of mechanical properties of models with dissimilar material properties to obtain local effects and This is due toinmobility of the printer compared to the massive weights associated with throughput subtractive in machine tools. components place where it is needed, thus reducing transportation cost, and reducing prototyping. with continuous values of elements calculated across the model from one element to another [2]. It is highly useful accurate solution of the whole model via an element-wise approach [3]. Finite analysis (FEA), a technique has provided insightweights into complex engineering problemsmachine over the tools. years This iselement due to of mobility of theproperties printer compared to the massive associated with to subtractive *Corresponding author in estimation mechanical of models with material properties obtain effects and with continuous values of elements calculated across thedissimilar model from one element to another [2]. Itlocal isover highly useful Finite element analysis (FEA), a technique has provided insight into complex engineering problems the years accurate solution of the wholeproperties model viaofanmodels element-wise approachmaterial [3]. *Corresponding author in estimation of mechanical with dissimilar properties to obtain local effects and Email: [email protected] with continuous values of elements calculated across the model from one element to another [2]. It is highly useful accurate solution of the whole model via an element-wise approach [3]. *Corresponding in estimation of author mechanical properties of models with dissimilar material properties to obtain local effects and Email: [email protected] 2351-9789 © 2019 The Authors. Published by Elsevier B.V. accurate solution of the whole model via ancommittee element-wise approach Peer-review under responsibility of the organizing of SMPM 2019. [3]. Email: [email protected] *Corresponding author 10.1016/j.promfg.2019.06.001 *Corresponding author Email: [email protected] *Corresponding author Email: [email protected]
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There has been a tremendous revolution in the 3D printing technology over the past 30 years since the first form of additive manufacturing was developed. In 3D 1981 Dr.Hideo Kodamaover came with a functional prototyping There has been a tremendous revolution in the printing technology theup past 30 years since the first form system usingmanufacturing photopolymerswas to build up a solid printedDr.Hideo model which consisted layersprototyping within the of additive developed. In 1981 Kodama cameofupcross-sectional with a functional model It photopolymers is the build-up to ofbuild theseuplayers that creates the 3D shape of the of object. A few years later in 1984 system [4]. using a solid printed model which consisted cross-sectional layers within the Charles[4]. Hull with aofprocess of using UV laser and a of vatthe of object. resin photopolymer to create 3D model It came is the up build-up these layers thata creates thebeam 3D shape A few years later in 1984 models called Stereolithography (SLA),ofausing process known as beam vat photopolymerization which he then to patented Charles Hull came up with a process a UV laser and a vat of resin photopolymer create [4]. 3D This wascalled doneStereolithography by exposing the photopolymer to the UV laser which would cause the he resin to patented solidify into models (SLA), a process known as vatbeam photopolymerization which then [4]. aThis solid Thethe object is printed tofrom bottom top leaving behindcause a solid material.3D waspiece doneofbyplastic. exposing photopolymer the UV lasertobeam which would thepiece resin of to solidify into printing has numerous of processes which materials that will a solid piece of plastic.amounts The object is printed fromchange bottomintotheir top layering leaving methods behind a and solid piece ofused material.3D play a deciding factoramounts in what of process would bestchange suit the ability to usemethods the FEM ensure reliability and printing has numerous processes which in their layering andtomaterials used that will consistency. play a deciding factor in what process would best suit the ability to use the FEM to ensure reliability and consistency. The FEA is a computer-based method of simulating/analysing the behaviour of engineering structures and components a variety ofmethod conditions, such as structural or behaviour, thermal transport, The FEA is under a computer-based of simulating/analysing thefluid behaviour of engineering structureswave and propagation, theagrowth cellssuch [5]. as Thestructural FEA toolor is primarily concerned with investigating the components and under varietyofofbiological conditions, fluid behaviour, thermal transport, wave response of physical upon specific conditions, thus enhancing strategic and operational propagation, and the system growth models of biological cells [5].imposed The FEA tool is primarily concerned with investigating the decision-making process [6].models The technique is fastimposed becoming a suitablethus alternative to strategic the time-consuming and response of physical system upon specific conditions, enhancing and operational expensive experimental proven toisbe a suitable toola in investigating the behavioural susceptibilityand of decision-making processruns [6].and Thehas technique fast becoming suitable alternative to the time-consuming a model inexperimental almost any runs environmental condition [8]. The has previously been used susceptibility successfully on expensive and has proven to be [7], a suitable toolFEM in investigating the behavioural of years but condition still needs[7], to be[8]. proven be successful on 3Dbeen printed objects. aprototyped model in objects almost for anyseveral environmental The to FEM has previously used successfully on prototyped objects for several years but still needs to be proven to be successful on 3D printed objects. In this paper several 3D printed blocks were printed using a 3D printer with capability printing 3D objects in a wide materials such as blocks ABS, PLA, otherusing materials. Square with blocks were chosen to be3D printed forinthea In thisvariety paper of several 3D printed were and printed a 3D printer capability printing objects use compression testing because evaluatedSquare with higher andtowill distribute wideofvariety of materials such as ABS,these PLA,tests and can otherbematerials. blocks accuracy were chosen be printed for the stresses of the load applied their are accuracy yet to fully trust thedistribute use of FEM use of compression testing equally becauseacross these each tests of can be surfaces. evaluatedEngineers with higher and will the on printed In thisequally paper research is conducted with the use of experimentation and trust software simulations stresses of prototypes. the load applied across each of their surfaces. Engineers are yet to fully the use of FEM andprinted comparison is generated between the experimental the models. on prototypes. In this paper research is conductedand with thesimulated use of experimentation and software simulations and comparison is generated between the experimental and the simulated models. 2. Structural Differences of 3D Printed Parts 2. 2.1Structural Layering Differences of 3D Printed Parts 3D printing 2.1 Layeringtechnique uses a layering process to build up objects with the use of minimal materials. Although this technique its benefits materialtowastage, could a compromise in the strength and rigidity 3D printinghas technique usesofa minimal layering process build upthere objects withbethe use of minimal materials. Although this of the desired solid modelof[9]. 3D printing often leaves there voidscould in-between the layers when could technique has its benefits minimal material wastage, be a compromise in theprinting, strengthwhich and rigidity lead design solid failures, or it[9]. could increase often the objects due to stress distributions, but thiswhich depends on of thetodesired model 3D printing leavesstrengths voids in-between the layers when printing, could whatto processes are followed and materials [9]. strengths due to stress distributions, but this depends on lead design failures, or it could increaseare theused objects what processes are followed and materials are used [9]. 2.2 Anisotropic layering Anisotropic layering occurs in 3D printing when the printed model is stronger along one axis than it is in the other. 2.2 Anisotropic layering This is a challenge 3D printing becausewhen of the affect the printingalong has, one building fromitbottom top. Anisotropic layeringinoccurs in 3D printing thelayering printed model is stronger axis than is in thetoother. Each is layer that is placed top of the next does bond completely the lower evenfrom though the bottom This a challenge in 3Donprinting because of thenot layering affect the to printing has,layer, building bottom to top. layer layer is stillthat partially melted, theofabove layer does adhere completely. in layer, turn creates voids in-between Each is placed on top the next does notnot bond completely to theThis lower even though the bottom each layer andmelted, so, finite (FDM) objectsThis caninonly certain stresses layer is stillprinted partially the deposition above layermethod does not adhereprinted completely. turnwithstand creates voids in-between depending the direction layering. The compression test printed unveils objects the material property of the certain model as either each layer on printed and so, of finite deposition method (FDM) can only withstand stresses isotropic oron anisotropic. depending the direction of layering. The compression test unveils the material property of the model as either isotropic or anisotropic. 3. Materials and Method 3. Materials and Method To compare the 3D printed test specimens to that of the computer-generated results it is necessary to only compare similar materials available on the modelling software the observed experimental of the compression To compare the 3D printed test specimens to that of the and computer-generated results it is results necessary to only compare tests to materials determineavailable whether on thethe testmodelling specimenssoftware are anisotropic isotropic. To this effect, several similar and the or observed experimental results of thethermoplastics compression have to been chosen. whether In this study, wespecimens are aware are thatanisotropic the modelsor from Autodesk areseveral entirelythermoplastics solid objects tests determine the test isotropic. To Inventor this effect, and not porousInobjects as typically seenthat in 3D printing,from however, these two were compared based on have beenthe chosen. this study, we are aware the models Autodesk Inventor are entirely solid objects compressive of same as size. and not the loading porous objects typically seen in 3D printing, however, these two were compared based on compressive loading of same size. The square blocks were printed as sample for the prints using the FDM process on selected thermoplastics. A brief description on eachwere material selected for the testusing specimens used in the on compression tests in Table A 1 [10], The square blocks printed as sample forprinted the prints the FDM process selected thermoplastics. brief [11]. description on each material selected for the printed test specimens used in the compression tests in Table 1 [10], [11].
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D.W.Abbot, D.V.V. Kallon, C. Anghel, P. Dube / Procedia Manufacturing 00 (2019) 000–000 D.W.Abbot, D.V.V. Kallon, C. Anghel, P. Dube / Procedia Manufacturing 00 (2019) 000–000 D.W. Abbot al. / Procedia Manufacturing 35 (2019) 164–173000–000 D.W.Abbot, D.V.V. Kallon, C. Anghel, P. et Dube / Procedia Manufacturing 00 (2019) Table 1. Properties of some 3D printing materials
1. Properties of some 3D printing materials ThermoplasticTableTable 1. Acrylonitrile Properties of some 3D Polyethylene printing materials High Impact Polyurethane Butadiene Terephthalate Polystyrene Thermoplastic Acrylonitrile Polyethylene High Impact (TPU) Styrene (ABS) Polyethylene glycol-modified Thermoplastic Acrylonitrile (HIPS) High Impact Polyurethane Butadiene Terephthalate Polystyrene (PETG) Polyurethane Butadiene Terephthalate Polystyrene (TPU) Styrene glycol-modified (TPU) Styrene (ABS)(ABS) glycol-modified (HIPS) (HIPS) (PETG)(PETG) Impact Strength High High High Durability High High High High Impact Strength High High Impact Strength High High High High Flexibility Very High Low Low Low Durability Durability HighHigh High High High High High High Chemical Resistance Medium-high High High High Flexibility Flexibility VeryVery HighHigh Low Low Low Low Low Low Chemical Resistance High High High High Chemical ResistanceMedium-high Medium-high High High Water Resistance Medium Medium High Medium
Polylactic Acid (PLA) Polylactic Acid Polylactic Acid Onyx (PLA) (PLA)
High Low Low Low Low Medium
High High High
Water Resistance Water Resistance
Nozzle Extruder o Temperature( C) Nozzle Extruder Nozzle Extruder o Closed Chamber o Temperature( C) Temperature( C) Closed Chamber Closed Chamber
High High Low Low
Onyx Onyx
High High High High High High High
Medium Medium
Medium Medium
High High
MediumMedium
Medium Medium
High
220-250 220-250
230-260 230-260
210-250 210-250
230-260230-260
190-210 190-210
230-260 230-260
Not necessary Not necessary
Recommended Recommended Recommended Not necessary Not necessaryRecommended RecommendedNot necessary Not necessary Recommended
220-250
Not necessary
230-260
Recommended
210-250
230-260
Not necessary
190-210
Recommended
Not necessary
High 230-260 Recommended
3.1 Prototypes
3.1For Prototypes a simple object, symmetry in structure leads the force to be divided into equal components. When trying to 3.1 Prototypes Forcalculate a simplethe object, symmetry leads the forcebe to assumed be dividedtointo equal When trying to of in thestructure load, each ‘strut’ share thatcomponents. load equally, as seen in figure 3. to A For a simple distribution object, symmetry in structure leads can the force to be divided into equal components. When trying calculate the distribution of the load, each ‘strut’ can be assumed to share that load equally, as seen in figure 3. Aprint is a prototype, as seen in figure 1 was printed using the UP-3D Printing Systems printer. The quality of the calculateasthe distribution of the load, each ‘strut’ can be assumed to share that load quality equally,ofasthe seen in isfigure 3. A prototype, in figuremakeup 1 was printed theHowever, UP-3D Printing Systems printer.isThe print a in the function ofseen theseen internal of printed the using model. an increase in quality concomitant to an increase prototype, as in figure 1 was using the UP-3D Printing Systems printer. The quality of the print is a function of time. the internal makeuptime of thecould, model. However, qualitytoisprint concomitant in the printing The printing however be an as increase long as in 7 hours a 60 mmtoxan60increase mm x increase 60 mm block. function of the internal makeup of the model. However, an increase in quality is concomitant to an in the printing time. the Theinternal printingblocked time could, however as long asquality 7 hours to print a 60 will mm also x 60increase mm x 60the mmoverall block. The closer thebe higher the intoturn printing time. The printing timestructure, could, as long as 7which hours print 60 mm x 60 mm xstrength 60 mmstrength block. The closer the internal blocked structure, thehowever higher thebequality which in turn will also aincrease the overall of the printed model. closer the internal blocked structure, the higher the quality which in turn will also increase the overall strength of The the printed model.
of the printed model.
Figure 1-Prototype of internal makeup Figure 1-Prototype of internal makeup
Figure 1-Prototype of internal makeup
Prototypes have been printed to visually see observe the internal structures using the FDM printing and to and to Prototypes have been printed to visually see observe the internal structures using the ofFDM of printing observe the different types of densities available with the 3D printers as shown in Fig. 2 to 8. The base of theseof these observe thehave different of densities available with the printers as shown in Fig. to 8. of The base Prototypes beentypes printed to visually see observe the 3D internal structures using the 2FDM printing and to models were illuminated for easy visualizations of theofdifference in the in internal structures. models were illuminated for easy visualizations the difference the internal structures.
observe the different types of densities available with the 3D printers as shown in Fig. 2 to 8. The base of these models were illuminated for easy visualizations of the difference in the internal structures.
Figure 2- 15% quality prototype in ABS
Figure 3 -85% quality prototype in ABS
Figure 2- 15% quality prototype in ABS
Figure 3 -85% quality prototype in ABS
Figure 2- 15% quality prototype in ABS
Figure 3 -85% quality prototype in ABS
D.W.Abbot, D.W.Abbot, D.V.V. D.V.V. Kallon, Kallon, C. C. Anghel, Anghel, P. P. Dube Dube // Procedia Procedia Manufacturing Manufacturing 00 00 (2019) (2019) 000–000 000–000 D.W.Abbot, D.V.V. Kallon, C. Abbot Anghel, P./ Dube / Procedia Manufacturing 00 (2019) 000–000 D.W. et al. Procedia Manufacturing 35 (2019) 164–173
Figure 4- 15% quality prototype in ABS Figure 4- 15% quality prototype in ABS Figure 4- 15% quality prototype in ABS
Figure 5 -85% quality prototype in ABS Figure 5 -85% quality prototype in ABS Figure 5 -85% quality prototype in ABS
3.2 3.2 Compression Compression Test Test This study compression 3.2 ThisCompression study applies applies Test compression tests tests to to the the test test models models both both experimentally experimentally and and computationally. computationally. Results Results obtained obtained using Autodesk Inventor are compared to the experimental test results. The arrow represents the direction in This study applies compression tests to the test models both experimentally and computationally. Results using Autodesk Inventor are compared to the experimental test results. The arrow represents the direction obtained in which which the load has been applied to that of the axes experiencing the load. The horizontal axes, the original axis the using Autodesk Inventor the experiencing experimental the testload. results. The arrow represents direction which the load has been appliedare to compared that of theto axes The horizontal axes, thethe original axisinthat that the objects are printed on, representing an axially distributed load from above, against the grain of the layers. the the loadare hasprinted been applied to that of the experiencing load. Theabove, horizontal axes, original that the objects on, representing an axes axially distributedthe load from against thethe grain of theaxis layers. vertical are axisprinted represents an axial load that would be experienced from the side against of the the test test specimen, with the objects on, an representing load from fromthe above, thespecimen, grain of the the vertical axis represents axial load an thataxially would distributed be experienced side of withlayers. the grain grain of vertical axis represents an axial load that would be experienced from the side of the test specimen, with the grain of the the layers. layers. of the layers.
Figure 6. how the loads were applied differently according to the layering axis Figure 6. how the loads were applied differently according to the layering axis Figure 6. how the loads were applied differently according to the layering axis
4. Results 4. Results 4. Results 4.1 Model Testing Testing 4.1 Model Table 2 presents 4.1 Model Testing Table 2 presents the the results results obtained obtained from from the the compression compression test test of of the the test test specimens. specimens. It It also also presents presents the the load load at at which test failure and axes was to Table presents the results experienced obtained from the compression of the the load test specimens. also presents theaxes loadon at which 2these these test specimens specimens experienced failure and on on what whattest axes the load was applied appliedItaccording according to the the axes on which test specimen was printed. which the these specimens failure and on what axes the load was applied according to the axes on the testtest specimen wasexperienced printed. which the test specimen was printed. Table 2: Practical Test Results Material Material Material TPU TPU TPU TPU TPU TPU TPU TPU TPU TPU TPU TPU TPU PETG PETG PETG PETG PETG PETG PETG PETG PETG PLA PLA PLA PLA PLA PLA PLA PLA PLA
% Infill % Infill % Infill 25% 25% 25% 25% 25% 25% 25% 25% 25% 50% 50% 50% 50% 50% 25% 25% 25% 25% 25% 50% 50% 50% 50% 50% 25% 25% 25% 25% 25% 50% 50% 50% 50% 50%
Shape Shape Shape Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube
Table 2: Practical Test Results Dimensions (mm) Direction of force Dimensions (mm) of force Table 2: Practical Direction Test Results Dimensions (mm) Direction 25mm Horizontalof force 25mm Horizontal 25mm Horizontal 25mm Horizontal 25mm Horizontal Parallel (Vertical) 25mm Parallel (Vertical) 25mm Parallel (Vertical) 25mm Parallel (Vertical) 25mm Parallel (Vertical) 25mm Parallel (Vertical) 25mm Parallel (Vertical) Horizontal 25mm Horizontal 25mm Horizontal Parallel (Vertical) 25mm Parallel (Vertical) 25mm Parallel (Vertical) Horizontal 25mm Horizontal 25mm Horizontal Parallel (Vertical) 25mm Parallel (Vertical) 25mm Parallel (Vertical) Horizontal 25mm Horizontal 25mm Horizontal Parallel (Vertical) 25mm Parallel (Vertical) 25mm Parallel (Vertical) Horizontal 25mm Horizontal 25mm Horizontal 25mm Horizontal 25mm Horizontal Parallel (Vertical) 25mm Parallel (Vertical) 25mm Parallel (Vertical)
Colour Colour Colour White White White White White White White White White White White White White White White White White White White White White Black Black Black Black Black Black Black Black Black
Fn (KN) Failure Fn (KN) Failure Fn 1.5 (KN) Failure 1.5 1.5 0.88 0.88 0.88 0.59 0.59 0.59 0.48 0.48 0.48 5.18 5.18 5.18 9.78 9.78 9.78 0 0 0 4.63 4.63 4.63 0 0 0 6.4 6.4 6.4 7.42 7.42 7.42 11.44 11.44 11.44 16.09 16.09 16.09 10.22 10.22 10.22
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168 ABS
15%
Cube
60mm
Parallel (Vertical)
White
8.01
ABS
50%
Cube
50mm
Horizontal
White
12.2
Onyx
50%
Cube
50mm
Horizontal
Black
21
HIPS
50%
Cube
50mm
Horizontal
White
25.05
4.2 Experimental vs Simulated results This section presents the experimental load-displacement results and the simulated of same. Shown in Figure 9 is the experimental result of the load-displacement plot. The parallel force applied was 4.55 kN and the normal force was 12.20 kN. This result follows a near- Hooke’s law of stress-strain curve. It can be deduced that the ABS material used for the printing has a low flexibility as stated in Table 1 of the properties of the printing materials.
Figure 7- Before Applied Load
Figure 8- After Applied Load
Figure 9- Applied load against extension for ABS (50% Infill)
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Figure 10- Before Applied Load
Figure 11- After Applied Load
Figure 12. Applied force against extension for HIPS (50% Infill)
4.3 Simulation Results The ABS material of 25 mm x 25 mm x 25 mm was modelled and simulated for compression loading as presented in Figure 13. The load-compression plot of the simulated results is as presented in Figure 14.
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Load (N)
Figure 13 Maximum displacement at 12200N for ABS Plastic using Autodesk Inventor
13000 12000 11000 10000 9000 8000 7000 6000 5000 4000 3000 2000 1000 0
0
0.08 0.16 0.24 0.32 0.4 0.48 0.56 0.64 0.72 0.8 0.88 0.96 1.04 1.12
Displacement (mm) Figure 14 Applied force VS Displacement using results obtained using FEM using Autodesk Inventor
2018 (ABS Material)
The plot shown in Figure 14 represents a straight line because the load is directionally proportional to that of the displacements. This is because the simulations were run individually at each load, using Autodesk Inventor. This was done to compare the differences of displacements measured as specific loads. A 100%-fill solid block was generated out of the same materials to compare the displacements measured when experiencing the same loads experienced by the mechanically tested specimens. This was done to have a comparison in the differences between the simulated percentage infill displacements. Similarly, a solid HIPS block (25 mm x 25 mm x 25 mm) was modelled and simulated as shown in Figure 15. A linear relationship between the load applied and the displacement observed (Figure 16). This is because the simulations were run individually at each load, using Autodesk Inventor. This was done to compare the differences of displacements measured as specific loads.
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Figure 15 Displacement for HIPS at 25050 N using Autodesk Inventor
30000
Applied Load (N)
25000
20000 15000 10000 5000 0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Displacement (mm) Figure 16 Applied Load VS Displacement using results obtained using FEM using Autodesk Inventor 2018 (HIP Material)
However, a 50% fill simulation and load test were also carried out as shown in Figure 17 using the ABS material. A normal force of same as that used experimentally was subjected to the material (Fn= 12.2 kN).
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Figure 17 ABS 50% infill simulation displacement at a load of 12.2 kN
Figure 18 HIPS 50% infill simulation displacement at a load of 25.05 kN
4.3
Discussion
FEA of 3D printed objects is dependent on what materials and processes are used and the technique of design, which could vary from one simulation software to another. The porosity of the materials and the internal layering effect of the object designed also needs to be considered. There exists a large discrepancy between the experimental result and the simulated result. This is due to the compactness and porosity difference between the modelled design, which has closely packed grains as compared to the experimental model, which has high porosity. The simulated test-pieces are at least 50% more solid than that of the experimental test specimens. In figure 7 we see that the load applied on the different axes according to the way the layering that the 3D specimen was printed. This was done to test whether the test specimens could withstand the same axial loads perpendicular/horizontal to the experienced load, as well as a load applied in parallel/inline to that of the layering. Comparing the results recorded after the loads were applied and tabulated, the test specimens behaved poorly when experiencing loads parallel/inline to that of layering direction in comparison with the load applied perpendicular/Horizontally. This proves that the 3D printed blocks printed using the FDM method are in fact anisotropic and not isotropic. HIPS provided the highest fracture or failure load of 25.05KN, followed closely by that of Onyx at 21KN applied on the horizontal plane and with infills of 50% (Table 2). Comparing the results of that of the ABS test specimens in figure 9, at the point of failure, the experimental specimen reached a maximum load of 12.20 kN and a maximum displacement of about 6.8 – 7mm. The same
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maximum force applied of 12.20 kN, the displacement was measured to be 0.2177 mm was observed on the simulated model (Figure 17). A significant difference in result is observed also at 50% fill density. It is obvious from Figure 9 that the test specimen exceeded its elastic yield point and reached the point of failure. Similarly, for the HIPS Material, the experimental specimen in Figure 12, reached a point of failure at 25.05 kN and had a maximum displacement of 6.6 – 6.8 mm. However, this result compared with the simulated result at an applied load of 25.05 kN, a maximum displacement of 1.098 mm was observed as shown in Figure 18. A significant disparity is also observed between the experimental and the simulated results with this material. A comparison between the displacements at 100% fill density simulations at the failure load (Figure 13 and 15), the displacements seen in the 50% simulations (Figures 17 and 18) are almost exactly double that of the 100%. The 50% infill simulated results differed greatly in the compressive strength from that obtained for 50% infill of the mechanically tested 3D printed. The Autodesk design and simulation cannot replicate the voids created between each layer in the printing process and therefor the simulated file is seen as a solid object and not porous object like that of the 3D generated test specimen. This is observed during the model the simulation process; a simulation error occurs as the object is not seen as a single body but rather a multi-body part. 5. Conclusions and Recommendation Depending on the application of the object being printed, it is essential that one considers the area of application of the printed design, the environment of use, and the operational associated stress at specific axis. 3D printed objects in thermo plastics show a large inconsistency when it comes to compressive strength. The results obtained from this study on different materials at different applied loads across the two different layering axes showed a large variation in compressive strength. This establishes that the design of 3D parts strongly depends on the application of the part. The comparison of the simulated results and the practical test results also showed a large difference as the results were nowhere similar. This was expected due to the infill differences and a simulation test specimen could be constructed/designed to better represent the internal makeup of the 50% infill grid like structure of the practical test specimen to gain better or closer insight. The 50% infill simulations behaved as expected when compared to that of the dimensions of the 100% infill, representing almost double the displacements. The same cannot be said for the 3D printed test specimens that produced significantly different results. This proves the inconsistency of the 3D printed results. A multi-body model can be considered for further studies for simulation to closely illustrate the variation in fill density observed in 3D printed models. References
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ScienceDirect www.elsevier.com/locate/pr ScienceDirect ocedia www.elsevier.com/locate/pr ScienceDirect Procedia Manufacturing 00 (2019) 000–000 ocedia Available online at www.sciencedirect.com www.elsevier.com/locate/pr 2nd International Conference ScienceDirect on Sustainable Materials Processing and Manufacturing ocedia Procedia Manufacturing 00 (2019) 000–000 2nd International Conference on Sustainable Materials Processing and Manufacturing www.elsevier.com/locate/pr (SMPM 2019)000–000 Procedia Manufacturing 00 (2019) ScienceDirect ocedia 2nd International Conference on Sustainable Materials Processing and Manufacturing www.elsevier.com/locate/pr ocedia www.elsevier.com/locate/pr 2nd International Conference on Sustainable Materials Processing and Manufacturing (SMPM 2019) ocedia
(SMPM 2019) Procedia Manufacturing 35 (2019) 164–173
Finite Element Analysis of 3D Printed Model via Compression 2nd International Sustainable Materials Processing Manufacturing Finite ElementConference Analysisonof 3D Printed Model viaandCompression Tests (SMPM 2019) 2nd International Sustainable Materials Processing Manufacturing Finite ElementConference Analysisonof 3D Printed Model viaandCompression Tests (SMPM 2019) Tests 2019) Finite Element Analysis of (SMPM 3D Printed Model via Compression D.W. Abbot, D.V.V. Kallon*, C. Anghel, P. Dube Finite Element Analysis of 3D Printed Model via Compression D.W. D.V.V. Kallon*, C. Anghel, P. Dube Tests Department of Mechanical and Abbot, Industrial Engineering Technology, University of Johannesburg,Johannesburg, South Africa Finite Element Analysis of 3D Printed Model via Compression D.W. Abbot, D.V.V. Kallon*, C. Anghel, P. Dube Tests Department of Mechanical and Industrial Engineering Technology, University of Johannesburg,Johannesburg, South Africa Abstract TestsUniversity Department of Mechanical and Abbot, Industrial Engineering of Johannesburg,Johannesburg, South Africa D.W. D.V.V.Technology, Kallon*, C. Anghel, P. Dube
3D Printing has grown tremendously over the past few years and continues to do so as the industry grows with Abstract D.W. Abbot, D.V.V. Anghel, P. Dube new technologies. 3D Printing makes design easierKallon*, and allowsC. engineers to create prototypes and mock-ups of Department Mechanical and Industrial Engineering of Johannesburg,Johannesburg, South Africa with Abstract 3D Printing has ofgrown tremendously over the pastTechnology, few yearsUniversity and continues to do so as the industry grows these designs faster thanD.W. ever before. Edits can be made in hours rather than days and best of all, it can be done Abbot, D.V.V. Kallon*, C. Anghel, P. Dube new technologies. 3D Printing makes over design easier andyears allows engineers to to create and mock-ups of 3D Printing has ofrather grown tremendously the pastThe few and doofsoprototypes as the industry grows Department Mechanical and Engineering Technology, University of Johannesburg,Johannesburg, South Africa with on the desktop, than on Industrial the factory floor. question of continues replaceability conventional manufacturing Abstract these designs faster than ever before. Edits can be made in hours rather than days and best of all, it can be done new technologies. 3D prints, Printing makes design easier andelement allows engineers prototypesmodel and mock-ups of Department of Mechanical and Industrial Engineering Technology, University of Johannesburg,Johannesburg, South technologies with 3D and the accuracy of finite analysis ontoa create 3D printed-like isAfrica the focus on the desktop, rather than the factory floor. question ofrather replaceability manufacturing 3D Printing grown tremendously over past few years and continues to doofand soconventional asbest the of industry grows with these designs faster than everonbefore. can beThe made in hours than days all, can be done Abstract of this study.has This study conducted anEdits FEAthe of some simple structures and compared results of the it simulations to technologies withrather 3D prints, andmakes accuracy of finite element analysis on ato 3D printed-like model is the focus new technologies. 3D design easier and allows engineers create mock-ups of on desktop, than on thethefactory floor. 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Edits can beThe made in hours than days and best all, it can be same done to gaindesigns insight intostudy the responses ofanInventor these objects under compressive loads. The same designed 3D objects are of this study. This conducted FEA of some simple structures and compared results of the simulations to diameter is designed using Autodesk 2018 and tested in a simulation environment of Autodesk Inventor technologies with 3D prints, andthe thefactory accuracy of finite element analysis on athe 3Dresponse printed-like is the focusa external forces applied in the FEA with floor. strain gauges used of to measure andmodel thus providing on the desktop, rather than on The question replaceability of manufacturing then printed using a 3D printer out of several different materials infills. These objects are exposed themm same that of lab tests on printed parts. 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This study conducted anthese FEA of some simple structures and compared results of the3D simulations to comparison with the FEA. The results of these tests are analysed and presented herein. to gain insight into the responses of objects under compressive loads. The same designed objects are external forces applied in the FEA with strain gauges used to measure the response and thus providing a © 2019 The Authors.using Published by Elsevier B.V diameter designed Autodesk Inventor 2018 and tested a simulation environment Autodesk Inventor that of labis tests ona 3D printed parts. Sampledifferent specimens in theinand shape of a These block, 25 mmare xof25 mm xto25 mm in then printed using 3D printer out of several materials infills. objects exposed the same comparison with the FEA. The results of these tests are analysed and presented herein. to gain insight intoresponsibility the responses these objects under compressive loads. The same designed 3D objects are diameter is designed using Inventor 2018gauges and tested into a simulation environment of Autodesk Inventor © 2019 The Authors. Published by B.V Peer-review under ofofElsevier the organizing committee SMPM 2019the external forces applied in Autodesk theout FEA with strain usedof measure response and thus providing a then printed using a 3D printer of several different materials and infills. These objects are exposed to the same to gain insight into the responses these objects under compressive loads. The same designed 3D objects are © 2019 The with Authors. Published byofElsevier B.V comparison the FEA. The results of these tests are analysed and presented herein. Peer-review under ofofthe organizing committee SMPM 2019 external forces applied in the FEA with strain gauges usedof to measure the response and thus providing Keywords: Ansys, Autodesk Inventor, 3D objects, 3Dmaterials Printer, FEM then printed using aresponsibility 3D printer out several different and infills. These objects are exposed to the samea comparison with the FEA. The results of these tests are analysed and presented herein. Peer-review under responsibility of the organizing committee of SMPM 2019 external forces applied in the FEA with strain usedFEM to measure the response and thus providing a © 2019 The Authors. Published by Elsevier B.V gauges Keywords: Ansys, Autodesk Inventor, 3D objects, 3D Printer, comparison with thePublished FEA. The results ofB.V. these tests are analysed and presented herein. © 2019 The Authors. by Elsevier © 2019 TheAnsys, Authors. Published by B.V committee Keywords: Autodesk Inventor, objects, 3D Printer,of FEM Peer-review under responsibility of Elsevier the3D organizing SMPM Peer-review under responsibility of the organizing committee of SMPM 2019. 2019 © 2019 The Authors. Published by Elsevier B.V 1. Introduction Peer-review under responsibility of the3D organizing SMPM 2019 Keywords: Ansys, Autodesk Inventor, objects, committee 3D Printer,of FEM 1. Introduction Peer-review under responsibility of the organizing committee of SMPM 2019 Keywords: Ansys, Autodesk Inventor, 3D objects, 3D Printer, FEM Introduction The 1. 3D printing technology is an additive manufacturing process, which proceeds by making three-dimensional Keywords: Inventor, 3D objects, 3Dprinting Printer, layers FEM of material until the object has been formed solid objectsAnsys, from aAutodesk digital file. This process involves The 1. 3D printing technology is an additive manufacturing process, which proceeds by making three-dimensional with the Introduction use of a 3D printer [1]. 3D printing has enabled the production of complex geometries with minimal solid objects fromtechnology a digital file. This process involves printing layers of material until objectthree-dimensional has been formed The 3D printing is an additive manufacturing process, which proceeds by the making waste1. in Introduction material, when compared to the traditional manufacturing methods, which mostly proceed using with the use from of a 3D printer [1].This 3Dprocess printinginvolves has enabled the layers production of complex geometries with solid objects a digital file. printing of material until the object beenminimal formed subtractive method. This technology offers the flexibility of “embedded” manufacturing-has manufacturing 1. Introduction waste inprinting material, when compared to themanufacturing traditional manufacturing methods, which mostly proceed using The 3D technology is an additive process, which proceeds by making three-dimensional with the use of a 3D printer [1]. 3D printing has enabled the production of complex geometries with minimal components in place where it is needed, thus reducing transportation cost, and reducing throughput in prototyping. subtractive method. This technology offers the flexibility of “embedded” manufacturingmanufacturing solid objects a when digital file. This process involves printing layers ofassociated material until object has been formed waste in material, compared to themanufacturing traditional manufacturing methods, which mostly proceed using The printing technology isprinter an additive process, which proceeds by the making three-dimensional This 3D is due tofrom mobility of the compared to the massive weights with subtractive machine tools. components in place where ittechnology is needed, thus reducing transportation cost, and reducing throughput in prototyping. with the usemethod. ofanalysis a 3D printer [1]. 3Dprocess printing has the layers production ofengineering complex geometries with minimal subtractive This offers theenabled flexibility of “embedded” manufacturingmanufacturing solid objects from a digital file. This involves printing of material until the object has been formed Finite element (FEA), a technique has provided insight into complex problems over the years The 3D printing technology isprinter an additive process, which proceedswith by making three-dimensional This is due toinof mobility of the compared to the massive weights associated subtractive machine tools. waste in material, when compared to themanufacturing traditional manufacturing methods, which mostly proceed using components place where it is needed, thus reducing transportation cost, and reducing throughput in prototyping. with the use a 3D printer [1]. 3D printing has enabled the production of complex geometries with minimal continuous values of elements calculated across the model from one element to another [2]. It is highly useful solid objectsmethod. from a digital file. process printing layers of material until the problems object has beenthe formed Finite analysis (FEA), aThis technique hasinvolves provided insightweights into complex engineering over years subtractive This technology thethe flexibility of material “embedded” manufacturingmanufacturing This iselement duematerial, to of mobility of the printer compared to massive associated with subtractive machine tools. waste in when compared to the traditional manufacturing methods, which mostlylocal proceed using in estimation mechanical properties ofoffers models with dissimilar properties to obtain effects and with the use of a 3D printer [1]. 3D printing has enabled the production of complex geometries with minimal with continuous values of elements calculated across the model from one element to another [2]. It is highly useful components in place where it is needed, thus reducing transportation cost, and reducing throughput in prototyping. Finite element analysis (FEA), a technique has provided insight into complex engineering problems over the years subtractive method. This technology offers the flexibility of “embedded” manufacturingmanufacturing accurate solution of the whole model via an element-wise approach [3]. waste when compared toofthe traditional manufacturing methods, which mostlylocal proceed using in estimation mechanical properties models with dissimilar material properties to obtain effects and This is in duematerial, toinof mobility of the printer compared to the massive associated with subtractive machine tools. with continuous values elements calculated across the modelweights from one element to another [2]. It isin highly useful components place where ittechnology is needed, thus reducing transportation cost, and reducing throughput prototyping. subtractive method. This offers the flexibility of “embedded” manufacturingmanufacturing accurate solution of the whole model via an element-wise approach [3]. Finite element analysis (FEA), a technique has provided insight into complex engineering problems over the years in estimation of mechanical properties of models with dissimilar material properties to obtain local effects and This is due toinmobility of the printer compared to the massive weights associated with throughput subtractive in machine tools. components place where it is needed, thus reducing transportation cost, and reducing prototyping. with continuous values of elements calculated across the model from one element to another [2]. It is highly useful accurate solution of the whole model via an element-wise approach [3]. Finite analysis (FEA), a technique has provided insightweights into complex engineering problemsmachine over the tools. years This iselement due to of mobility of theproperties printer compared to the massive associated with to subtractive *Corresponding author in estimation mechanical of models with material properties obtain effects and with continuous values of elements calculated across thedissimilar model from one element to another [2]. Itlocal isover highly useful Finite element analysis (FEA), a technique has provided insight into complex engineering problems the years accurate solution of the wholeproperties model viaofanmodels element-wise approachmaterial [3]. *Corresponding author in estimation of mechanical with dissimilar properties to obtain local effects and Email: [email protected] with continuous values of elements calculated across the model from one element to another [2]. It is highly useful accurate solution of the whole model via an element-wise approach [3]. *Corresponding in estimation of author mechanical properties of models with dissimilar material properties to obtain local effects and Email: [email protected] 2351-9789 © 2019 The Authors. Published by Elsevier B.V. accurate solution of the whole model via ancommittee element-wise approach Peer-review under responsibility of the organizing of SMPM 2019. [3]. Email: [email protected] *Corresponding author 10.1016/j.promfg.2019.06.001 *Corresponding author Email: [email protected] *Corresponding author Email: [email protected]
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There has been a tremendous revolution in the 3D printing technology over the past 30 years since the first form of additive manufacturing was developed. In 3D 1981 Dr.Hideo Kodamaover came with a functional prototyping There has been a tremendous revolution in the printing technology theup past 30 years since the first form system usingmanufacturing photopolymerswas to build up a solid printedDr.Hideo model which consisted layersprototyping within the of additive developed. In 1981 Kodama cameofupcross-sectional with a functional model It photopolymers is the build-up to ofbuild theseuplayers that creates the 3D shape of the of object. A few years later in 1984 system [4]. using a solid printed model which consisted cross-sectional layers within the Charles[4]. Hull with aofprocess of using UV laser and a of vatthe of object. resin photopolymer to create 3D model It came is the up build-up these layers thata creates thebeam 3D shape A few years later in 1984 models called Stereolithography (SLA),ofausing process known as beam vat photopolymerization which he then to patented Charles Hull came up with a process a UV laser and a vat of resin photopolymer create [4]. 3D This wascalled doneStereolithography by exposing the photopolymer to the UV laser which would cause the he resin to patented solidify into models (SLA), a process known as vatbeam photopolymerization which then [4]. aThis solid Thethe object is printed tofrom bottom top leaving behindcause a solid material.3D waspiece doneofbyplastic. exposing photopolymer the UV lasertobeam which would thepiece resin of to solidify into printing has numerous of processes which materials that will a solid piece of plastic.amounts The object is printed fromchange bottomintotheir top layering leaving methods behind a and solid piece ofused material.3D play a deciding factoramounts in what of process would bestchange suit the ability to usemethods the FEM ensure reliability and printing has numerous processes which in their layering andtomaterials used that will consistency. play a deciding factor in what process would best suit the ability to use the FEM to ensure reliability and consistency. The FEA is a computer-based method of simulating/analysing the behaviour of engineering structures and components a variety ofmethod conditions, such as structural or behaviour, thermal transport, The FEA is under a computer-based of simulating/analysing thefluid behaviour of engineering structureswave and propagation, theagrowth cellssuch [5]. as Thestructural FEA toolor is primarily concerned with investigating the components and under varietyofofbiological conditions, fluid behaviour, thermal transport, wave response of physical upon specific conditions, thus enhancing strategic and operational propagation, and the system growth models of biological cells [5].imposed The FEA tool is primarily concerned with investigating the decision-making process [6].models The technique is fastimposed becoming a suitablethus alternative to strategic the time-consuming and response of physical system upon specific conditions, enhancing and operational expensive experimental proven toisbe a suitable toola in investigating the behavioural susceptibilityand of decision-making processruns [6].and Thehas technique fast becoming suitable alternative to the time-consuming a model inexperimental almost any runs environmental condition [8]. The has previously been used susceptibility successfully on expensive and has proven to be [7], a suitable toolFEM in investigating the behavioural of years but condition still needs[7], to be[8]. proven be successful on 3Dbeen printed objects. aprototyped model in objects almost for anyseveral environmental The to FEM has previously used successfully on prototyped objects for several years but still needs to be proven to be successful on 3D printed objects. In this paper several 3D printed blocks were printed using a 3D printer with capability printing 3D objects in a wide materials such as blocks ABS, PLA, otherusing materials. Square with blocks were chosen to be3D printed forinthea In thisvariety paper of several 3D printed were and printed a 3D printer capability printing objects use compression testing because evaluatedSquare with higher andtowill distribute wideofvariety of materials such as ABS,these PLA,tests and can otherbematerials. blocks accuracy were chosen be printed for the stresses of the load applied their are accuracy yet to fully trust thedistribute use of FEM use of compression testing equally becauseacross these each tests of can be surfaces. evaluatedEngineers with higher and will the on printed In thisequally paper research is conducted with the use of experimentation and trust software simulations stresses of prototypes. the load applied across each of their surfaces. Engineers are yet to fully the use of FEM andprinted comparison is generated between the experimental the models. on prototypes. In this paper research is conductedand with thesimulated use of experimentation and software simulations and comparison is generated between the experimental and the simulated models. 2. Structural Differences of 3D Printed Parts 2. 2.1Structural Layering Differences of 3D Printed Parts 3D printing 2.1 Layeringtechnique uses a layering process to build up objects with the use of minimal materials. Although this technique its benefits materialtowastage, could a compromise in the strength and rigidity 3D printinghas technique usesofa minimal layering process build upthere objects withbethe use of minimal materials. Although this of the desired solid modelof[9]. 3D printing often leaves there voidscould in-between the layers when could technique has its benefits minimal material wastage, be a compromise in theprinting, strengthwhich and rigidity lead design solid failures, or it[9]. could increase often the objects due to stress distributions, but thiswhich depends on of thetodesired model 3D printing leavesstrengths voids in-between the layers when printing, could whatto processes are followed and materials [9]. strengths due to stress distributions, but this depends on lead design failures, or it could increaseare theused objects what processes are followed and materials are used [9]. 2.2 Anisotropic layering Anisotropic layering occurs in 3D printing when the printed model is stronger along one axis than it is in the other. 2.2 Anisotropic layering This is a challenge 3D printing becausewhen of the affect the printingalong has, one building fromitbottom top. Anisotropic layeringinoccurs in 3D printing thelayering printed model is stronger axis than is in thetoother. Each is layer that is placed top of the next does bond completely the lower evenfrom though the bottom This a challenge in 3Donprinting because of thenot layering affect the to printing has,layer, building bottom to top. layer layer is stillthat partially melted, theofabove layer does adhere completely. in layer, turn creates voids in-between Each is placed on top the next does notnot bond completely to theThis lower even though the bottom each layer andmelted, so, finite (FDM) objectsThis caninonly certain stresses layer is stillprinted partially the deposition above layermethod does not adhereprinted completely. turnwithstand creates voids in-between depending the direction layering. The compression test printed unveils objects the material property of the certain model as either each layer on printed and so, of finite deposition method (FDM) can only withstand stresses isotropic oron anisotropic. depending the direction of layering. The compression test unveils the material property of the model as either isotropic or anisotropic. 3. Materials and Method 3. Materials and Method To compare the 3D printed test specimens to that of the computer-generated results it is necessary to only compare similar materials available on the modelling software the observed experimental of the compression To compare the 3D printed test specimens to that of the and computer-generated results it is results necessary to only compare tests to materials determineavailable whether on thethe testmodelling specimenssoftware are anisotropic isotropic. To this effect, several similar and the or observed experimental results of thethermoplastics compression have to been chosen. whether In this study, wespecimens are aware are thatanisotropic the modelsor from Autodesk areseveral entirelythermoplastics solid objects tests determine the test isotropic. To Inventor this effect, and not porousInobjects as typically seenthat in 3D printing,from however, these two were compared based on have beenthe chosen. this study, we are aware the models Autodesk Inventor are entirely solid objects compressive of same as size. and not the loading porous objects typically seen in 3D printing, however, these two were compared based on compressive loading of same size. The square blocks were printed as sample for the prints using the FDM process on selected thermoplastics. A brief description on eachwere material selected for the testusing specimens used in the on compression tests in Table A 1 [10], The square blocks printed as sample forprinted the prints the FDM process selected thermoplastics. brief [11]. description on each material selected for the printed test specimens used in the compression tests in Table 1 [10], [11].
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1. Properties of some 3D printing materials ThermoplasticTableTable 1. Acrylonitrile Properties of some 3D Polyethylene printing materials High Impact Polyurethane Butadiene Terephthalate Polystyrene Thermoplastic Acrylonitrile Polyethylene High Impact (TPU) Styrene (ABS) Polyethylene glycol-modified Thermoplastic Acrylonitrile (HIPS) High Impact Polyurethane Butadiene Terephthalate Polystyrene (PETG) Polyurethane Butadiene Terephthalate Polystyrene (TPU) Styrene glycol-modified (TPU) Styrene (ABS)(ABS) glycol-modified (HIPS) (HIPS) (PETG)(PETG) Impact Strength High High High Durability High High High High Impact Strength High High Impact Strength High High High High Flexibility Very High Low Low Low Durability Durability HighHigh High High High High High High Chemical Resistance Medium-high High High High Flexibility Flexibility VeryVery HighHigh Low Low Low Low Low Low Chemical Resistance High High High High Chemical ResistanceMedium-high Medium-high High High Water Resistance Medium Medium High Medium
Polylactic Acid (PLA) Polylactic Acid Polylactic Acid Onyx (PLA) (PLA)
High Low Low Low Low Medium
High High High
Water Resistance Water Resistance
Nozzle Extruder o Temperature( C) Nozzle Extruder Nozzle Extruder o Closed Chamber o Temperature( C) Temperature( C) Closed Chamber Closed Chamber
High High Low Low
Onyx Onyx
High High High High High High High
Medium Medium
Medium Medium
High High
MediumMedium
Medium Medium
High
220-250 220-250
230-260 230-260
210-250 210-250
230-260230-260
190-210 190-210
230-260 230-260
Not necessary Not necessary
Recommended Recommended Recommended Not necessary Not necessaryRecommended RecommendedNot necessary Not necessary Recommended
220-250
Not necessary
230-260
Recommended
210-250
230-260
Not necessary
190-210
Recommended
Not necessary
High 230-260 Recommended
3.1 Prototypes
3.1For Prototypes a simple object, symmetry in structure leads the force to be divided into equal components. When trying to 3.1 Prototypes Forcalculate a simplethe object, symmetry leads the forcebe to assumed be dividedtointo equal When trying to of in thestructure load, each ‘strut’ share thatcomponents. load equally, as seen in figure 3. to A For a simple distribution object, symmetry in structure leads can the force to be divided into equal components. When trying calculate the distribution of the load, each ‘strut’ can be assumed to share that load equally, as seen in figure 3. Aprint is a prototype, as seen in figure 1 was printed using the UP-3D Printing Systems printer. The quality of the calculateasthe distribution of the load, each ‘strut’ can be assumed to share that load quality equally,ofasthe seen in isfigure 3. A prototype, in figuremakeup 1 was printed theHowever, UP-3D Printing Systems printer.isThe print a in the function ofseen theseen internal of printed the using model. an increase in quality concomitant to an increase prototype, as in figure 1 was using the UP-3D Printing Systems printer. The quality of the print is a function of time. the internal makeuptime of thecould, model. However, qualitytoisprint concomitant in the printing The printing however be an as increase long as in 7 hours a 60 mmtoxan60increase mm x increase 60 mm block. function of the internal makeup of the model. However, an increase in quality is concomitant to an in the printing time. the Theinternal printingblocked time could, however as long asquality 7 hours to print a 60 will mm also x 60increase mm x 60the mmoverall block. The closer thebe higher the intoturn printing time. The printing timestructure, could, as long as 7which hours print 60 mm x 60 mm xstrength 60 mmstrength block. The closer the internal blocked structure, thehowever higher thebequality which in turn will also aincrease the overall of the printed model. closer the internal blocked structure, the higher the quality which in turn will also increase the overall strength of The the printed model.
of the printed model.
Figure 1-Prototype of internal makeup Figure 1-Prototype of internal makeup
Figure 1-Prototype of internal makeup
Prototypes have been printed to visually see observe the internal structures using the FDM printing and to and to Prototypes have been printed to visually see observe the internal structures using the ofFDM of printing observe the different types of densities available with the 3D printers as shown in Fig. 2 to 8. The base of theseof these observe thehave different of densities available with the printers as shown in Fig. to 8. of The base Prototypes beentypes printed to visually see observe the 3D internal structures using the 2FDM printing and to models were illuminated for easy visualizations of theofdifference in the in internal structures. models were illuminated for easy visualizations the difference the internal structures.
observe the different types of densities available with the 3D printers as shown in Fig. 2 to 8. The base of these models were illuminated for easy visualizations of the difference in the internal structures.
Figure 2- 15% quality prototype in ABS
Figure 3 -85% quality prototype in ABS
Figure 2- 15% quality prototype in ABS
Figure 3 -85% quality prototype in ABS
Figure 2- 15% quality prototype in ABS
Figure 3 -85% quality prototype in ABS
D.W.Abbot, D.W.Abbot, D.V.V. D.V.V. Kallon, Kallon, C. C. Anghel, Anghel, P. P. Dube Dube // Procedia Procedia Manufacturing Manufacturing 00 00 (2019) (2019) 000–000 000–000 D.W.Abbot, D.V.V. Kallon, C. Abbot Anghel, P./ Dube / Procedia Manufacturing 00 (2019) 000–000 D.W. et al. Procedia Manufacturing 35 (2019) 164–173
Figure 4- 15% quality prototype in ABS Figure 4- 15% quality prototype in ABS Figure 4- 15% quality prototype in ABS
Figure 5 -85% quality prototype in ABS Figure 5 -85% quality prototype in ABS Figure 5 -85% quality prototype in ABS
3.2 3.2 Compression Compression Test Test This study compression 3.2 ThisCompression study applies applies Test compression tests tests to to the the test test models models both both experimentally experimentally and and computationally. computationally. Results Results obtained obtained using Autodesk Inventor are compared to the experimental test results. The arrow represents the direction in This study applies compression tests to the test models both experimentally and computationally. Results using Autodesk Inventor are compared to the experimental test results. The arrow represents the direction obtained in which which the load has been applied to that of the axes experiencing the load. The horizontal axes, the original axis the using Autodesk Inventor the experiencing experimental the testload. results. The arrow represents direction which the load has been appliedare to compared that of theto axes The horizontal axes, thethe original axisinthat that the objects are printed on, representing an axially distributed load from above, against the grain of the layers. the the loadare hasprinted been applied to that of the experiencing load. Theabove, horizontal axes, original that the objects on, representing an axes axially distributedthe load from against thethe grain of theaxis layers. vertical are axisprinted represents an axial load that would be experienced from the side against of the the test test specimen, with the objects on, an representing load from fromthe above, thespecimen, grain of the the vertical axis represents axial load an thataxially would distributed be experienced side of withlayers. the grain grain of vertical axis represents an axial load that would be experienced from the side of the test specimen, with the grain of the the layers. layers. of the layers.
Figure 6. how the loads were applied differently according to the layering axis Figure 6. how the loads were applied differently according to the layering axis Figure 6. how the loads were applied differently according to the layering axis
4. Results 4. Results 4. Results 4.1 Model Testing Testing 4.1 Model Table 2 presents 4.1 Model Testing Table 2 presents the the results results obtained obtained from from the the compression compression test test of of the the test test specimens. specimens. It It also also presents presents the the load load at at which test failure and axes was to Table presents the results experienced obtained from the compression of the the load test specimens. also presents theaxes loadon at which 2these these test specimens specimens experienced failure and on on what whattest axes the load was applied appliedItaccording according to the the axes on which test specimen was printed. which the these specimens failure and on what axes the load was applied according to the axes on the testtest specimen wasexperienced printed. which the test specimen was printed. Table 2: Practical Test Results Material Material Material TPU TPU TPU TPU TPU TPU TPU TPU TPU TPU TPU TPU TPU PETG PETG PETG PETG PETG PETG PETG PETG PETG PLA PLA PLA PLA PLA PLA PLA PLA PLA
% Infill % Infill % Infill 25% 25% 25% 25% 25% 25% 25% 25% 25% 50% 50% 50% 50% 50% 25% 25% 25% 25% 25% 50% 50% 50% 50% 50% 25% 25% 25% 25% 25% 50% 50% 50% 50% 50%
Shape Shape Shape Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube
Table 2: Practical Test Results Dimensions (mm) Direction of force Dimensions (mm) of force Table 2: Practical Direction Test Results Dimensions (mm) Direction 25mm Horizontalof force 25mm Horizontal 25mm Horizontal 25mm Horizontal 25mm Horizontal Parallel (Vertical) 25mm Parallel (Vertical) 25mm Parallel (Vertical) 25mm Parallel (Vertical) 25mm Parallel (Vertical) 25mm Parallel (Vertical) 25mm Parallel (Vertical) Horizontal 25mm Horizontal 25mm Horizontal Parallel (Vertical) 25mm Parallel (Vertical) 25mm Parallel (Vertical) Horizontal 25mm Horizontal 25mm Horizontal Parallel (Vertical) 25mm Parallel (Vertical) 25mm Parallel (Vertical) Horizontal 25mm Horizontal 25mm Horizontal Parallel (Vertical) 25mm Parallel (Vertical) 25mm Parallel (Vertical) Horizontal 25mm Horizontal 25mm Horizontal 25mm Horizontal 25mm Horizontal Parallel (Vertical) 25mm Parallel (Vertical) 25mm Parallel (Vertical)
Colour Colour Colour White White White White White White White White White White White White White White White White White White White White White Black Black Black Black Black Black Black Black Black
Fn (KN) Failure Fn (KN) Failure Fn 1.5 (KN) Failure 1.5 1.5 0.88 0.88 0.88 0.59 0.59 0.59 0.48 0.48 0.48 5.18 5.18 5.18 9.78 9.78 9.78 0 0 0 4.63 4.63 4.63 0 0 0 6.4 6.4 6.4 7.42 7.42 7.42 11.44 11.44 11.44 16.09 16.09 16.09 10.22 10.22 10.22
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168 ABS
15%
Cube
60mm
Parallel (Vertical)
White
8.01
ABS
50%
Cube
50mm
Horizontal
White
12.2
Onyx
50%
Cube
50mm
Horizontal
Black
21
HIPS
50%
Cube
50mm
Horizontal
White
25.05
4.2 Experimental vs Simulated results This section presents the experimental load-displacement results and the simulated of same. Shown in Figure 9 is the experimental result of the load-displacement plot. The parallel force applied was 4.55 kN and the normal force was 12.20 kN. This result follows a near- Hooke’s law of stress-strain curve. It can be deduced that the ABS material used for the printing has a low flexibility as stated in Table 1 of the properties of the printing materials.
Figure 7- Before Applied Load
Figure 8- After Applied Load
Figure 9- Applied load against extension for ABS (50% Infill)
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Figure 10- Before Applied Load
Figure 11- After Applied Load
Figure 12. Applied force against extension for HIPS (50% Infill)
4.3 Simulation Results The ABS material of 25 mm x 25 mm x 25 mm was modelled and simulated for compression loading as presented in Figure 13. The load-compression plot of the simulated results is as presented in Figure 14.
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Load (N)
Figure 13 Maximum displacement at 12200N for ABS Plastic using Autodesk Inventor
13000 12000 11000 10000 9000 8000 7000 6000 5000 4000 3000 2000 1000 0
0
0.08 0.16 0.24 0.32 0.4 0.48 0.56 0.64 0.72 0.8 0.88 0.96 1.04 1.12
Displacement (mm) Figure 14 Applied force VS Displacement using results obtained using FEM using Autodesk Inventor
2018 (ABS Material)
The plot shown in Figure 14 represents a straight line because the load is directionally proportional to that of the displacements. This is because the simulations were run individually at each load, using Autodesk Inventor. This was done to compare the differences of displacements measured as specific loads. A 100%-fill solid block was generated out of the same materials to compare the displacements measured when experiencing the same loads experienced by the mechanically tested specimens. This was done to have a comparison in the differences between the simulated percentage infill displacements. Similarly, a solid HIPS block (25 mm x 25 mm x 25 mm) was modelled and simulated as shown in Figure 15. A linear relationship between the load applied and the displacement observed (Figure 16). This is because the simulations were run individually at each load, using Autodesk Inventor. This was done to compare the differences of displacements measured as specific loads.
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Figure 15 Displacement for HIPS at 25050 N using Autodesk Inventor
30000
Applied Load (N)
25000
20000 15000 10000 5000 0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Displacement (mm) Figure 16 Applied Load VS Displacement using results obtained using FEM using Autodesk Inventor 2018 (HIP Material)
However, a 50% fill simulation and load test were also carried out as shown in Figure 17 using the ABS material. A normal force of same as that used experimentally was subjected to the material (Fn= 12.2 kN).
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Figure 17 ABS 50% infill simulation displacement at a load of 12.2 kN
Figure 18 HIPS 50% infill simulation displacement at a load of 25.05 kN
4.3
Discussion
FEA of 3D printed objects is dependent on what materials and processes are used and the technique of design, which could vary from one simulation software to another. The porosity of the materials and the internal layering effect of the object designed also needs to be considered. There exists a large discrepancy between the experimental result and the simulated result. This is due to the compactness and porosity difference between the modelled design, which has closely packed grains as compared to the experimental model, which has high porosity. The simulated test-pieces are at least 50% more solid than that of the experimental test specimens. In figure 7 we see that the load applied on the different axes according to the way the layering that the 3D specimen was printed. This was done to test whether the test specimens could withstand the same axial loads perpendicular/horizontal to the experienced load, as well as a load applied in parallel/inline to that of the layering. Comparing the results recorded after the loads were applied and tabulated, the test specimens behaved poorly when experiencing loads parallel/inline to that of layering direction in comparison with the load applied perpendicular/Horizontally. This proves that the 3D printed blocks printed using the FDM method are in fact anisotropic and not isotropic. HIPS provided the highest fracture or failure load of 25.05KN, followed closely by that of Onyx at 21KN applied on the horizontal plane and with infills of 50% (Table 2). Comparing the results of that of the ABS test specimens in figure 9, at the point of failure, the experimental specimen reached a maximum load of 12.20 kN and a maximum displacement of about 6.8 – 7mm. The same
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maximum force applied of 12.20 kN, the displacement was measured to be 0.2177 mm was observed on the simulated model (Figure 17). A significant difference in result is observed also at 50% fill density. It is obvious from Figure 9 that the test specimen exceeded its elastic yield point and reached the point of failure. Similarly, for the HIPS Material, the experimental specimen in Figure 12, reached a point of failure at 25.05 kN and had a maximum displacement of 6.6 – 6.8 mm. However, this result compared with the simulated result at an applied load of 25.05 kN, a maximum displacement of 1.098 mm was observed as shown in Figure 18. A significant disparity is also observed between the experimental and the simulated results with this material. A comparison between the displacements at 100% fill density simulations at the failure load (Figure 13 and 15), the displacements seen in the 50% simulations (Figures 17 and 18) are almost exactly double that of the 100%. The 50% infill simulated results differed greatly in the compressive strength from that obtained for 50% infill of the mechanically tested 3D printed. The Autodesk design and simulation cannot replicate the voids created between each layer in the printing process and therefor the simulated file is seen as a solid object and not porous object like that of the 3D generated test specimen. This is observed during the model the simulation process; a simulation error occurs as the object is not seen as a single body but rather a multi-body part. 5. Conclusions and Recommendation Depending on the application of the object being printed, it is essential that one considers the area of application of the printed design, the environment of use, and the operational associated stress at specific axis. 3D printed objects in thermo plastics show a large inconsistency when it comes to compressive strength. The results obtained from this study on different materials at different applied loads across the two different layering axes showed a large variation in compressive strength. This establishes that the design of 3D parts strongly depends on the application of the part. The comparison of the simulated results and the practical test results also showed a large difference as the results were nowhere similar. This was expected due to the infill differences and a simulation test specimen could be constructed/designed to better represent the internal makeup of the 50% infill grid like structure of the practical test specimen to gain better or closer insight. The 50% infill simulations behaved as expected when compared to that of the dimensions of the 100% infill, representing almost double the displacements. The same cannot be said for the 3D printed test specimens that produced significantly different results. This proves the inconsistency of the 3D printed results. A multi-body model can be considered for further studies for simulation to closely illustrate the variation in fill density observed in 3D printed models. References
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