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Influence of a Filler on Strength Characteristics of the Properties of a Composite Material Based on Epoxy Resin
Available online at www.sciencedirect.com
ScienceDirect Materials Today: Proceedings 11 (2019) 252–257
www.materialstoday.com/proceedings
ICMTMTE_2018
Influence of a Filler on Strength Characteristics of the Properties of a Composite Material Based on Epoxy Resin Victoria A. Gafarova*, Alexander. Babin, Elvira R. Gareeva, Karina N. Abdrakhmanova, Liliya N. Lomakina Ufa State Petroleum Technological University, Kosmonavtov street, 1, 450062, Ufa, The Russian Federation
Abstract Long-term experience of structural materials study shows that many defects, including fractures, originate as early as at the manufacturing stage. In this regard, we face two main issues. These issues consist in provision of controlled safe development of defects, i.e. safe operation with fractures, and in compulsory containment of damaging, resulting in either residual durability or residual strength. The basic assumption on which the concept of fracture control is based on is that defects always exist, even in new structures, and that they can remain undetected [1-3]. In case of fracture detection, it is necessary to find out how its dimensions correlate with the critical size, by achieving which it starts developing. © 2019 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of International Conference on Modern Trends in Manufacturing Technologies and Equipment 2018: Materials Science. Keywords: Fractures; structural defects; epoxy resins; reinforcing fillers; composition materials
1. Analytical review When making decision to continue operation of the facility with fracture, it should be taken into account that structures in oil and gas industry operate under difficult conditions of high pressures and temperatures, unstable loads and active fire and explosive environment. Destruction of such structures leads to disastrous consequences
* Corresponding author. Tel.: +7-964-954-5131. E-mail address: [email protected] 2214-7853 © 2019 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of International Conference on Modern Trends in Manufacturing Technologies and Equipment 2018: Materials Science.
V.A. Gafarova et al. / Materials Today: Proceedings 11 (2019) 252–257
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associated with human losses, material and environmental damage. For this reason facilities with fractures and fracture-like defects attract researchers and require special attention. Power and energy fracture criteria, which are used to assess fracture resistance, allow us to calculate the critical length. However, studies show that under long-term operation and accumulation of damages, the criterion of fracture resistance also changes. This can affect the value of the critical fracture size [4,5]. Since repair of equipment with fractures is associated with serious economic expenses (for example, pipelines), regulatory documents [6-9] regulating the conditions of operating facilities with fractures are developed in different countries. In this regard, it is necessary to take measures in order to reduce the level of danger and use the economic benefits from operation of fractured facilities. There are different ways for fixing edges of developing fractures, such as application of bandages, devices restricting movement of fracture edges, application of so-called "cold welding", etc. Shut down of equipment for repair works performance causes major economic losses, in this connection the following issues becomes urgent: performance of restriction of fracture edges opening without technological process interruption. Such methods include application of composite material, hardening after filling the fracture cavity, but nowadays this method is used only for explicit fracture-like defects, access to which is unobstructed. Such composite materials are usually of pasty consistency. In order to provide safe fixation of fracture edges, the entire fracture cavity should be filled. For this purpose we developed composite material with high value of fluidity and strength. 2. Experimental part Our composite material is based on epoxy resin, that is due to the fact that epoxy resin possesses high adhesion to various materials, low contraction upon hardening, low thermal expansion coefficient, good mechanical properties, moisture resistance and heat resistance, good electrical insulation properties. To make our composite material (CM) even more strong, we used the following fillers: aluminium powder, graphite, magnetic powder, carbonyl iron (Fig. 1) [10].
a
c
b
d Fig. 1. Composite material fillers (a) al powder; (b) graphite; (c) carbonyl iron; (d) magnetic powder
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In order to determine real mechanical properties of the composite material, flat samples tensile testing was carried out (Fig. 2). Strength properties of composite materials with different fillers for tension, are within close limits of change and correlate with data of other researchers. According to testing results, the tensile strength was about 20 MPa.
Fig. 2. Composite material samples with different fillers: (а) magnetic powder; (b) al powder, (c) graphite; (d) carbonyl iron
To determine the efficiency of using material with such strength characteristics, it is necessary to simulate the tension process [11-15]. At the initial stage, we should check model for adequacy. The Abaqus engineering analysis system is not connected with some particular measurement system, so the entered data should be comparable [16,17]. Due to small size of the studied object, it is more convenient to take measurement units comparable to the length measurement unit of the SI system – millimeter. Modelling results are provided in fig. 3.
Fig. 3. Flat plate model tensile diagram
As it could be seen in the diagram, the introduced model of material behavior coincides with the resultant curves of sample deformation, obtained from the final element and recalculated with the applied force by means of the pilot joint. Consequently, the set task can be solved in the selected software package. Further, it is necessary to simulate fractured flat plate tension process (Fig. 4) and plate with fracture filled with composite material with tensile strength of 20 MPa.
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Fig. 4. Fractured sample dimensions
Let us suppose that application of composite material for fracture filling will be more efficient if it has rheological properties, i.e. strength of the material will depend on the deformation rate. While at normal temperature steel mechanical properties do not depend on the deformation rate. Let us test this hypothesis by simulating the tensile testing using model of elastic-plastic behavior steel 09G2S as the main material and mechanical model of elastic-viscoplastic behavior material as a composite material. It was decided to compare mechanical properties dependence on the deformation rate with the pitch of rate change by 10 times. Let us take minimum deformation rate έ as 1·10-5 mm/sec, maximum – 1 mm/sec: έ1 = 1·10-5 mm/sec έ2 = 1·10-4 mm/sec έ3 = 1·10-3 mm/sec έ4 = 1·10-2 mm/sec έ5 = 1·10-1 mm/sec έ6 = 1 mm/sec Let us assume that strength of the composite material (conventionally called CM-1) changes proportionally to the 10 fold change of the deformation rate and in case of rate increase tends to the strength of the plate material. Then tension diagrams under different deformation rates will be as shown in Fig. 5 (a).
Fig. 5. (a) Tension diagrams of the composite material № 1 at different deformation rates; (b) Tension diagrams of filler № 2 at different deformation rates.
Since the deformation rate varies within a wide range of values, dependence of stresses σtr on the composite material deformation rate έ is more conveniently to be represented in logarithmic coordinates.
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V.A. Gafarova et al. / Materials Today: Proceedings 11 (2019) 252–257
In order to be able to compare how rheological properties of the filler affect strength of the plate, let us determine one more filler (conventionally called CM-2) as follows: let us assume that strength of the material in logarithmic coordinates «lgσtr–lgέ » varies linearly. Dependence of composite materials strength on deformation rate is shown in Fig. 6. Tension diagrams of CM-2 at different deformation rates are shown in Fig. 5 (b).
Fig. 6. Rheological properties of selected fillers.
To answer the question whether the rheological properties of the composite material affect the efficiency of its application for fracture filling, let us simulate tension process of fractured flat plate and of a plate with fracture filled with a composite material, filling the fracture with CM-1, CM-2 materials. The results of the experiment are provided in fig. 7.
Fig. 7. Tension diagrams of plate with fracture filled with different fillers.
Based on calculation results it may be concluded that rheological properties of the composite material significantly affect strength of the sample with fracture filled with such material. So, we proved that rheological properties affect the efficiency of composite material application for fracture filling. Now let us check how the deformation rate affects strength of the sample with fracture and filler. And also let us verify the applied model by solving the issue in static, quasistatic and dynamic formulations. For this purpose let us simulate tension testing: of flat plate of fractured flat plate of flat plate with fracture filled with composite material № 2 In quasistatic and dynamic formulations with different deformation rates V and compare the obtained results. Summary results for comparison are provided in Fig. 8.
V.A. Gafarova et al. / Materials Today: Proceedings 11 (2019) 252–257
257
Fig. 8. Tension diagrams Issue modelling in quasistatic and dynamic formulations with different deformation rates.
3. Conclusion Thus, the goal of the studies is achieved, as tension diagrams of defect-free plate and fractured plate coincide in static, quasistatic and dynamic formulations, that shows adequacy of the applied model. The Abaqus software package showed impossibility of deformation of composite material injected into the fracture cavity, correspondingly of deformation of the base material, if their strength is significantly differs. Such analysis turned out to be possible in quasistatic and dynamic formulations of the issue. Computational experiments showed that composite material having certain rheological properties can significantly increase the efficiency of its application in the capacity of an agent for fracture filling. This result shows that one of the key properties of the composite material is its rheological properties, which should correlate with strength characteristics of the metal. Acknowledgements Researches are conducted in Ufa State Petroleum Technological University as a part of developing of initiative fundamental scientific project according to state order to higher education for 2017-2019 (№ 9.7294.2017 / CU of 31.01.2017). References [1] J.A. Collins, Failure of materials in mechanical design, New York, 1981. [2] A.A. Shanyavskaya, Safe fatigue breakdown of aircraft structures elements. Synergy in engineering applications, Ufa, 2003. [3] R.S. Zainullin, E.M. Morozov, A.A. Aleksandrov, Criteria of safe breakdown of pipeline systems fractured elements, Moscow, 2005. [4] N.A. Makhutov, Structural strength, service life period and technogenic safety, Novosibirsk, 2005. [5] V.M. Pestrikov, E.M. Morozov, Solid bodies fracture mechanics: lecture course, Saint Petersburg, 2002. [6] № 07-2011, Midstream operations, ANSI/ASME В31G Manual for Determining the Remaining Strength of Corroded Pipelines. [7] BS 7910:2013+A1:2015. Bsi Standards Publication, Guide to methods for assessing the acceptability of flaws in metallic structures. [8] RD-23.040.00- KTN-386-09, OJC «JC» Transneft, Technology of repair of main oil pipelines and oil product pipelines with pressure up to 6.3 MPa. [9] DNV-RP-F101, Recommended practice, Corroded pipelines. [10] R.R. Tlyasheva, V.A. Gafarova, K.R. Vagazova, A.M. Kuzeev, Composition materials for fracture cavities and fracture-like defects filling, Bashkir chemical journal, Vol. 23 (2016) No 3, 56-62. [11] S.V. Doronin, Strength and engineering systems supporting structures fracture modelling, Novosibirsk, 2005. [12] M.F. Ashly, D.R.H. Jones, Engineering Materials I: An Introduction to Properties, applications and Design. Third Edition, Oxford, 2005. [13] L. Xue, G.E.O. Widera, Z.F. Sang, Influence of pad reinforcement on the limit and burst pressures of a cylinder-cylinder intersection, Journal of Pressure Vessel Technology, Vol. 125 (2003) No. 2, pp. 182-187. [14] J. Rosler, H. Harders, M. Baker, Mechanidchers Verhalten der Werkstoffe, Vieweg+Teubner, GWV Fachverlage GmbH, Wiesbadeb, 2008. [15] GOST 25.506-85 Strength calculations and testing. Methods of metals mechanical testing. Determination of fracture resistance (fracture viscosity) characteristics under condition of static loading. Interstate standard 1986. [16] Y. Murakami, Stress intensity factor handbook (in 2 Volumes), The Society of Materials Science, Japan, 1987.
ScienceDirect Materials Today: Proceedings 11 (2019) 252–257
www.materialstoday.com/proceedings
ICMTMTE_2018
Influence of a Filler on Strength Characteristics of the Properties of a Composite Material Based on Epoxy Resin Victoria A. Gafarova*, Alexander. Babin, Elvira R. Gareeva, Karina N. Abdrakhmanova, Liliya N. Lomakina Ufa State Petroleum Technological University, Kosmonavtov street, 1, 450062, Ufa, The Russian Federation
Abstract Long-term experience of structural materials study shows that many defects, including fractures, originate as early as at the manufacturing stage. In this regard, we face two main issues. These issues consist in provision of controlled safe development of defects, i.e. safe operation with fractures, and in compulsory containment of damaging, resulting in either residual durability or residual strength. The basic assumption on which the concept of fracture control is based on is that defects always exist, even in new structures, and that they can remain undetected [1-3]. In case of fracture detection, it is necessary to find out how its dimensions correlate with the critical size, by achieving which it starts developing. © 2019 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of International Conference on Modern Trends in Manufacturing Technologies and Equipment 2018: Materials Science. Keywords: Fractures; structural defects; epoxy resins; reinforcing fillers; composition materials
1. Analytical review When making decision to continue operation of the facility with fracture, it should be taken into account that structures in oil and gas industry operate under difficult conditions of high pressures and temperatures, unstable loads and active fire and explosive environment. Destruction of such structures leads to disastrous consequences
* Corresponding author. Tel.: +7-964-954-5131. E-mail address: [email protected] 2214-7853 © 2019 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of International Conference on Modern Trends in Manufacturing Technologies and Equipment 2018: Materials Science.
V.A. Gafarova et al. / Materials Today: Proceedings 11 (2019) 252–257
253
associated with human losses, material and environmental damage. For this reason facilities with fractures and fracture-like defects attract researchers and require special attention. Power and energy fracture criteria, which are used to assess fracture resistance, allow us to calculate the critical length. However, studies show that under long-term operation and accumulation of damages, the criterion of fracture resistance also changes. This can affect the value of the critical fracture size [4,5]. Since repair of equipment with fractures is associated with serious economic expenses (for example, pipelines), regulatory documents [6-9] regulating the conditions of operating facilities with fractures are developed in different countries. In this regard, it is necessary to take measures in order to reduce the level of danger and use the economic benefits from operation of fractured facilities. There are different ways for fixing edges of developing fractures, such as application of bandages, devices restricting movement of fracture edges, application of so-called "cold welding", etc. Shut down of equipment for repair works performance causes major economic losses, in this connection the following issues becomes urgent: performance of restriction of fracture edges opening without technological process interruption. Such methods include application of composite material, hardening after filling the fracture cavity, but nowadays this method is used only for explicit fracture-like defects, access to which is unobstructed. Such composite materials are usually of pasty consistency. In order to provide safe fixation of fracture edges, the entire fracture cavity should be filled. For this purpose we developed composite material with high value of fluidity and strength. 2. Experimental part Our composite material is based on epoxy resin, that is due to the fact that epoxy resin possesses high adhesion to various materials, low contraction upon hardening, low thermal expansion coefficient, good mechanical properties, moisture resistance and heat resistance, good electrical insulation properties. To make our composite material (CM) even more strong, we used the following fillers: aluminium powder, graphite, magnetic powder, carbonyl iron (Fig. 1) [10].
a
c
b
d Fig. 1. Composite material fillers (a) al powder; (b) graphite; (c) carbonyl iron; (d) magnetic powder
254
V.A. Gafarova et al. / Materials Today: Proceedings 11 (2019) 252–257
In order to determine real mechanical properties of the composite material, flat samples tensile testing was carried out (Fig. 2). Strength properties of composite materials with different fillers for tension, are within close limits of change and correlate with data of other researchers. According to testing results, the tensile strength was about 20 MPa.
Fig. 2. Composite material samples with different fillers: (а) magnetic powder; (b) al powder, (c) graphite; (d) carbonyl iron
To determine the efficiency of using material with such strength characteristics, it is necessary to simulate the tension process [11-15]. At the initial stage, we should check model for adequacy. The Abaqus engineering analysis system is not connected with some particular measurement system, so the entered data should be comparable [16,17]. Due to small size of the studied object, it is more convenient to take measurement units comparable to the length measurement unit of the SI system – millimeter. Modelling results are provided in fig. 3.
Fig. 3. Flat plate model tensile diagram
As it could be seen in the diagram, the introduced model of material behavior coincides with the resultant curves of sample deformation, obtained from the final element and recalculated with the applied force by means of the pilot joint. Consequently, the set task can be solved in the selected software package. Further, it is necessary to simulate fractured flat plate tension process (Fig. 4) and plate with fracture filled with composite material with tensile strength of 20 MPa.
V.A. Gafarova et al. / Materials Today: Proceedings 11 (2019) 252–257
255
Fig. 4. Fractured sample dimensions
Let us suppose that application of composite material for fracture filling will be more efficient if it has rheological properties, i.e. strength of the material will depend on the deformation rate. While at normal temperature steel mechanical properties do not depend on the deformation rate. Let us test this hypothesis by simulating the tensile testing using model of elastic-plastic behavior steel 09G2S as the main material and mechanical model of elastic-viscoplastic behavior material as a composite material. It was decided to compare mechanical properties dependence on the deformation rate with the pitch of rate change by 10 times. Let us take minimum deformation rate έ as 1·10-5 mm/sec, maximum – 1 mm/sec: έ1 = 1·10-5 mm/sec έ2 = 1·10-4 mm/sec έ3 = 1·10-3 mm/sec έ4 = 1·10-2 mm/sec έ5 = 1·10-1 mm/sec έ6 = 1 mm/sec Let us assume that strength of the composite material (conventionally called CM-1) changes proportionally to the 10 fold change of the deformation rate and in case of rate increase tends to the strength of the plate material. Then tension diagrams under different deformation rates will be as shown in Fig. 5 (a).
Fig. 5. (a) Tension diagrams of the composite material № 1 at different deformation rates; (b) Tension diagrams of filler № 2 at different deformation rates.
Since the deformation rate varies within a wide range of values, dependence of stresses σtr on the composite material deformation rate έ is more conveniently to be represented in logarithmic coordinates.
256
V.A. Gafarova et al. / Materials Today: Proceedings 11 (2019) 252–257
In order to be able to compare how rheological properties of the filler affect strength of the plate, let us determine one more filler (conventionally called CM-2) as follows: let us assume that strength of the material in logarithmic coordinates «lgσtr–lgέ » varies linearly. Dependence of composite materials strength on deformation rate is shown in Fig. 6. Tension diagrams of CM-2 at different deformation rates are shown in Fig. 5 (b).
Fig. 6. Rheological properties of selected fillers.
To answer the question whether the rheological properties of the composite material affect the efficiency of its application for fracture filling, let us simulate tension process of fractured flat plate and of a plate with fracture filled with a composite material, filling the fracture with CM-1, CM-2 materials. The results of the experiment are provided in fig. 7.
Fig. 7. Tension diagrams of plate with fracture filled with different fillers.
Based on calculation results it may be concluded that rheological properties of the composite material significantly affect strength of the sample with fracture filled with such material. So, we proved that rheological properties affect the efficiency of composite material application for fracture filling. Now let us check how the deformation rate affects strength of the sample with fracture and filler. And also let us verify the applied model by solving the issue in static, quasistatic and dynamic formulations. For this purpose let us simulate tension testing: of flat plate of fractured flat plate of flat plate with fracture filled with composite material № 2 In quasistatic and dynamic formulations with different deformation rates V and compare the obtained results. Summary results for comparison are provided in Fig. 8.
V.A. Gafarova et al. / Materials Today: Proceedings 11 (2019) 252–257
257
Fig. 8. Tension diagrams Issue modelling in quasistatic and dynamic formulations with different deformation rates.
3. Conclusion Thus, the goal of the studies is achieved, as tension diagrams of defect-free plate and fractured plate coincide in static, quasistatic and dynamic formulations, that shows adequacy of the applied model. The Abaqus software package showed impossibility of deformation of composite material injected into the fracture cavity, correspondingly of deformation of the base material, if their strength is significantly differs. Such analysis turned out to be possible in quasistatic and dynamic formulations of the issue. Computational experiments showed that composite material having certain rheological properties can significantly increase the efficiency of its application in the capacity of an agent for fracture filling. This result shows that one of the key properties of the composite material is its rheological properties, which should correlate with strength characteristics of the metal. Acknowledgements Researches are conducted in Ufa State Petroleum Technological University as a part of developing of initiative fundamental scientific project according to state order to higher education for 2017-2019 (№ 9.7294.2017 / CU of 31.01.2017). References [1] J.A. Collins, Failure of materials in mechanical design, New York, 1981. [2] A.A. Shanyavskaya, Safe fatigue breakdown of aircraft structures elements. Synergy in engineering applications, Ufa, 2003. [3] R.S. Zainullin, E.M. Morozov, A.A. Aleksandrov, Criteria of safe breakdown of pipeline systems fractured elements, Moscow, 2005. [4] N.A. Makhutov, Structural strength, service life period and technogenic safety, Novosibirsk, 2005. [5] V.M. Pestrikov, E.M. Morozov, Solid bodies fracture mechanics: lecture course, Saint Petersburg, 2002. [6] № 07-2011, Midstream operations, ANSI/ASME В31G Manual for Determining the Remaining Strength of Corroded Pipelines. [7] BS 7910:2013+A1:2015. Bsi Standards Publication, Guide to methods for assessing the acceptability of flaws in metallic structures. [8] RD-23.040.00- KTN-386-09, OJC «JC» Transneft, Technology of repair of main oil pipelines and oil product pipelines with pressure up to 6.3 MPa. [9] DNV-RP-F101, Recommended practice, Corroded pipelines. [10] R.R. Tlyasheva, V.A. Gafarova, K.R. Vagazova, A.M. Kuzeev, Composition materials for fracture cavities and fracture-like defects filling, Bashkir chemical journal, Vol. 23 (2016) No 3, 56-62. [11] S.V. Doronin, Strength and engineering systems supporting structures fracture modelling, Novosibirsk, 2005. [12] M.F. Ashly, D.R.H. Jones, Engineering Materials I: An Introduction to Properties, applications and Design. Third Edition, Oxford, 2005. [13] L. Xue, G.E.O. Widera, Z.F. Sang, Influence of pad reinforcement on the limit and burst pressures of a cylinder-cylinder intersection, Journal of Pressure Vessel Technology, Vol. 125 (2003) No. 2, pp. 182-187. [14] J. Rosler, H. Harders, M. Baker, Mechanidchers Verhalten der Werkstoffe, Vieweg+Teubner, GWV Fachverlage GmbH, Wiesbadeb, 2008. [15] GOST 25.506-85 Strength calculations and testing. Methods of metals mechanical testing. Determination of fracture resistance (fracture viscosity) characteristics under condition of static loading. Interstate standard 1986. [16] Y. Murakami, Stress intensity factor handbook (in 2 Volumes), The Society of Materials Science, Japan, 1987.