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Application and validation of production planning simulation in shipbuilding
Ocean Engineering 114 (2016) 154–167
Contents lists available at ScienceDirect
Ocean Engineering journal homepage: www.elsevier.com/locate/oceaneng
Application and validation of production planning simulation in shipbuilding Kwang-Phil Park a, Seung-Ho Ham b,n, Chan-Young Lee a a b
R&D Institute, Daewoo Shipbuilding and Marine Engineering Co., Ltd., Republic of Korea Department of Naval Architecture and Ocean Engineering, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul 151-744, Republic of Korea
art ic l e i nf o
a b s t r a c t
Article history: Received 26 December 2014 Accepted 15 January 2016
As the weight and size of assembly blocks are getting increased, new production procedures by using floating cranes have been proposed to enhance the efficiency in shipyards. In this situation, simulation technology is required to evaluate potential risks of the procedure in advance. By such a necessity, we have developed a simulation system, named SIMSON (SIMulation System Of New production planning). SIMSON calculates the motion of the lifted block and floating bodies such as vessels and floating cranes based on the multibody system dynamics with the hydrostatic and hydrodynamic forces. The calculated motion and wire rope tension are used for dynamic effect estimation. In this paper, we present the application cases of SIMSON to real production process. The simulation results are compared by observing the situation in the real operations. The observation illustrates the simulation results are in harmony with the real situation and the application of SIMSON to production planning simulation in shipyards is quite feasible. & 2016 Elsevier Ltd. All rights reserved.
Keywords: Crane lifting Floating crane Lifting simulation Turnover Production planning
1. Introduction When a new production method is planned in shipyards, it is not easy to predict any potential risks in the new operation. Moreover, it is not easy for production planning engineers to prove that the lifting plan is perfectly safe and there is no reason for disqualification. Fig. 1 shows an example of derrick erection plan and operation with two floating cranes. And there are three points that the production planning engineer is typically want to check. ① Interference between boom tip and top structure of derrick. ② Interference between the drillship and bottom structure of derrick. ③ Angle between the wire rope and the sheave. The check points listed above usually require the results considering the dynamic motion because the crane is moving on the water. In this situation, Fig. 2 shows the procedure that the simulation is used between the planning and the operation. A production engineer can preview the plan and confirm it referring to the result of simulation whose model is based on the input data like drawings, environmental conditions and so on. SIMSON (SIMulation System Of New production planning) is a simulation
n
Corresponding author. Tel.: þ 82 2 880 8378. E-mail address: [email protected] (S.-H. Ham).
http://dx.doi.org/10.1016/j.oceaneng.2016.01.008 0029-8018/& 2016 Elsevier Ltd. All rights reserved.
system developed in DSME to support the procedure in 2007 (Cha et al., 2007). In this paper, we present several application cases of SIMSON to production planning. Based on the comparison between the simulation and the real operation, we discuss the validation the simulation system.
2. Related works MSC/ADAMS (Fig. 3, ①) is a multibody dynamics system which is used for dynamic simulation of mechanical parts such as landing gear of aircraft, suspension of vehicle and cranks inside the engine, etc. It is also able to integrate FE (Finite Element) analysis considering a flexible body. While it has plenty of functions for the dynamic simulation, there is a limitation when it is to be used for production planning process in shipyard in that hydraulic external force is not included in the system. In many cases, floating bodies like a ship, a floating crane are used in the process, the hydrostatic force and hydrodynamic force are basically required to for the simulation. Ultramarine developed MOSES (Fig. 3, ②) for dynamic analysis of offshore transportation, lifting, installation and so on (MOSES, 2008a; MOSES, 2008b). Since the system is originated from the hydrodynamic analysis for the floating bodies, it has an advantage for the motion analysis of the floating bodies and interaction among them. On the other hand, it is difficult to make a
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Fig. 1. Example of derrick lifting plan with two floating cranes and its potential risks during the operation.
Fig. 2. Example of the way how simulation is used between plan and operation.
mechanical model of onshore production facilities like block loader, crawler crane and so on. Because facilities on shore are also used in production process in shipyard, the model based on multibody system dynamics and functions for them is required. SIMO (Fig. 3, ③) is numerical tool for simulation of marine operations in the time domain and a part of the SESAM package as provided by DNV (DNV, 2009). It is specialized in marine operation simulation. However, it is not suitable to simulation shipbuilding production which includes complicated scenario and many cranes.
3. System configuration The main feature of SIMSON is multibody dynamic simulation coupled with hydraulic external forces. Especially, since it is oriented to production planning simulation, it provides easy availability of facility modeling and scenario composing for the purpose. Fig. 4 shows the screenshot of main window in SIMSON. The functions in SIMSON are related to the configuration of basic system architecture called ‘DSME Simulation Framework’ (Cha et al., 2007, 2010b) and its applications (Cha et al., 2010a,
2010c). The framework mainly consists of 5 componentsapplication-specific modules, simulation coordinator, simulation kernel, development tools and post-processing tools. Each module in the components is mapped to the required function in the simulation system. It is developed by C þ þ programing language. – Dynamic Analysis Module (Fig. 5, ①): This is a dynamics engine for a multibody system like the interconnected bodies which are constrained by joints, links and wire ropes. Users can select either Open Dynamics Engine (ODE) or Algoryx. The detail theory of the mulatibody system dynamics will be followed at the end of this section. – Collision Detection Module (Fig. 5, ②): This is for interference check between bodies. The detection code itself is not separated from the dynamic analysis module. – Visualization Module (Fig. 5, ③): Open Scene Graph (OSG) is used for this module to visualize the simulation result in real time. – Wire Rope Force Calculation Module (Fig. 5, ④): Wire rope can be modeled simply as an incompressible spring or more complicatedly
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–
–
–
–
–
–
as it has the properties such as stretching, bending and twisting according to the dynamic analysis module. Hydrostatic/Hydrodynamic Forces Calculation Module (Fig. 5, ⑤): Cummins equation (Cummins, 1962) is used to calculate the motion of a floating body in time domain. The motion of the floating barge exerted by a hydrodynamic force is validated in the previous study. Hydrostatic force is also calculated by the fluid density and the submerged volume under the water plane of the body. Simulation Middleware (Fig. 5, ⑥): It takes a role of data management among the modules and provides plug-in capability for a new module or to replace one with another. Simulation Kernel (Fig. 5, ⑦): This module can handle the combined discrete event and discrete time. This allows the user to simulate complicated scenarios based on events and time. CAD Data Interface (Fig. 5, ⑧): The building blocks which are to be subjects in the simulation are usually modeled in 3D CAD system used in shipyards. This module is used in importing the 3D geometry readily into the simulation model. Development Tools (Fig. 5, ⑨): This module helps the developer to use simulation framework more conveniently. Especially, it provides simulation kernel templates to generate simulation model. Post-Processing Tools (Fig. 5, ⑩): This module furnishes the user-friendly graphs to show the motion and tension during the simulation.
Meanwhile, the simulation is based on the multibody system dynamics, which was introduced in Shabana (1994). The relative motion that is permitted between bodies in the multibody system is often constrained by connections between those bodies. Therefore, Newton's equation of motion for the multibody system can be stated as Mr€ ¼ Fe þ Fc
Fig. 3. Related works – ① MSC/ADAMS, ② Ultramarine/MOSES, and ③ DNV/SIMO.
ð1Þ
The vectors in Eq. (1) are represented in terms of the Cartesian coordinates. M is the mass and the mass moment of inertia matrices, and r is the position vector of the center of gravity of the bodies with respect to the Cartesian coordinates. The resultant force consists of the external force Fe and the constraint force Fc caused by kinematic constraints. The position vector r of the Cartesian coordinates can be presented as a function of the generalized coordinates q according to r ¼ rðqÞ
ð2Þ
Differentiating Eq. (2) yields the velocity relation r_ ¼ Jq_
ð3Þ
where the velocity transformation matrix J transforms the velocity of generalized coordinates q_ into the velocity of the Cartesian coordinates. Differentiating Eq. (3) yields the acceleration r€ ¼ Jq€ þ _Jq_
ð4Þ
Substituting Eq. (4) into Eq. (1), we can obtain the equation MJq€ þ M_Jq_ ¼ Fe þ Fc
ð5Þ
Multiplying both sides of Eq. (5) by JT yields JT MJq€ þ JT M_Jq_ ¼ JT Fe þ JT Fc
Fig. 4. Screenshot of SIMSON.
ð6Þ
The constraint reaction forces are perpendicular to the path along which the bodies are constrained to move. This says that the constraint reaction force Fc may be suppressed by taking the scalar product of both sides of Newton’s equation of motion with vectors
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Fig. 5. Mapping between components in ‘DSME Simulation Framework’ and functions in SIMSON.
Fig. 6. Case 1 – 3D geometry of building block and lug arrangement.
that are tangent to the path. Then, we can derive ~ q€ þ k~ ¼ F~ e M
ð7Þ
e ~ is the mass and the ~ ¼ JT MJ, k~ ¼ JT M_Jq, _ and F~ ¼ JT Fe ; M where M generalized mass moment of the inertia matrix, k~ is the
e generalized Coriolis and centrifugal force, F~ is the generalized external force, J is the velocity transformation matrix, and _J is the acceleration transformation matrix. Eq. (7) is the final form of the equations of motion of the multibody system based on the multibody system dynamics.
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Fig. 7. Case 1 – Modeling of the gantry crane.
Fig. 8. Case 1 – Block turnover and erection scenario.
4.1.1. Problem definition ‘Turnover’ means to turn a building block upside down for a production purpose and it happens very frequently in shipyards. In this case, while a building block is in turnover by a gantry type crane of 900 t lifting capacity, they want to check the position and orientation of the block and the tension change in wire ropes from the perspective of safety.
breadth, and height of the block are 25.6 [m], 23.2 [m], and 7.1 [m] respectively, and the weight is 290 [t]. Lug points which connected to block loaders of the gantry crane by wire ropes are also arranged at the same positions as in the drawing. The gantry crane is modeled to reflect its operational mechanism as shown in Fig. 7. There are lower and upper trolleys on the girder of the crane. Two of the block loaders with equalizer are connected to the upper trolley and the other one to the lower trolley. Considering the traveling of the block from the initial position to the erection position after turnover, the dock and preerection area are modeled around the crane in the same scale. Inside the equalizer, several fixed and moving pulleys are placed by turns. All of the pulleys are connected by a single wire rope, which should have the same tension anywhere in its length. Thus, if the tension is denoted by T, all of the moving pulleys are exerted by 2T from the equalizing wire rope. Instead of the real pulleys, we developed approximated mechanism of the equalizer which controls the length of the wire rope logically to make them equal.
4.1.2. Modeling The 3D geometry of the building block is obtained from CAD database by the interface function as shown in Fig. 6. The length,
4.1.3. Scenario The simulation scenario for this case is composed following the major event sequence in the production planning as shown in
4. Simulation cases In this section, we present 3 application cases of SIMSON in the order of problem definition, modeling and scenario. For some of these cases, the simulation results are compared with the observed situation in real operations. Because of the lack of the sensing measure and operation procedure in real operation, the comparison is not exactly same as the simulation results. However it gives enough implications for the validation. 4.1. Case 1: block turnover simulation by gantry crane
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Fig. 9. Case 1 – Comparison of the block position and orientation between simulation and real operation.
Fig. 10. Case 1 – Comparison of wire rope tension between simulation and real operation.
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Fig. 11. Case 2 – Arrangement of the floating crane and two crawler cranes for block turnover.
Fig. 12. Case 2 – Block turnover scenario.
Fig. 13. Case 2 – Interference between block and wire rope during simulation.
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Fig. 8. Three block loaders are lifted simultaneously at the first time (Fig. 8, ①), and then two block loaders of the upper trolley are hoisted up to make the block stand vertically (Fig. 8, ② and ③). After the block loader of the lower trolley is disconnected from the block, the lower trolley is moved to connect the block loader and the block again at the other side (Fig. 8, ④–⑥). It is hoisted up (Fig. 8, ⑦) again to complete the block turnover and, finally, both trolleys are moved to the destination near the other block (Fig. 8, ⑧ and ⑨). Three block loaders are hoisted down to lay down the block next to the other (Fig. 8, ⑩). 4.1.4. Validation The validation for this case is conducted by observing of the block position and orientation the real operation. The pictures taken in the operation and screen shots in the simulation are compared as shown in Fig. 9. It shows very similar situation in block position and orientation and this suggests the mechanical calculation in the simulation is in good agreement with the real operation. In the comparison of wire rope tensions as shown in Fig. 10, the graph for the real operation came from manual record during the operation. The simulation results and the results from the real operation were not exactly identical because the way how to control crane could affect the wire rope tension. In addition, the
Fig. 14. Case 2 – Rearrangement of the floating crane and two crawler cranes for block turnover.
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weight and center of gravity of the block at the operation time could be slightly differ from the initial estimation. However, the comparison can be interpreted that the simulation results are consistent with the real operation in terms of tendency and values. 4.2. Case 2: block turnover simulation by floating crane 4.2.1. Problem definition In this case, a floating crane is used for a block turnover together with cranes on shore due to the weight and the location that is placed. During the planning, interference between wire ropes and the block was forecasted from the drawing of the structure dimension. They, therefore, should evaluate how much the interference would be severe during the operation. Based on the simulation results, another type of floating crane could be used as an alternative method. 4.2.2. Modeling The block geometry is exported from TRIBON cad system which is used for detail design in DSME while cranes are newly modeled from other 3D cad system. The block dimension is 34.3 [m] 27.1 [m] 10.8 [m] in its length, breadth and height, and the weight is about 580 [t]. The block has four legs as shown in Fig. 11 which are forecasted to be adjacent to wire ropes. The white spheres were the lug points connected with the hooks of the crawler cranes or block loaders of the floating crane. In the initial plan, a floating crane of 3600 t lifting capacity is the main crane for the turnover operation and two crawler cranes are to lift the other side of the block. 4.2.3. Initial scenario When they start the operation, the block is lifted by the floating crane alone by using all four block loaders (Fig. 12, ①). The hoisting-up of two block loaders in back is stopped while the other two block loaders in front keep being hoisted when the block is reached to the height enough to the turnover (Fig. 12, ②). When the block stands vertically, the two block loaders in back are lowered (Fig. 12, ③). Because of the center of mass, the block is expected to incline while the lowering. It is not allowed to release the wire ropes from the block loaders in back until the block is connected to the crawler cranes at the opposite side (Fig. 12, ④) for safety reason, wire rope interference with the leg structures is forecasted in this step. Finally, the hooks of crawler cranes are hoisted up to finish the block turnover (Fig. 12, ⑤ and ⑥).
Fig. 15. Case 2 – Modified block turnover scenario.
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Fig. 16. Case 2 – Comparison of the block position and orientation between simulation and real operation, and interference that SIMSON predicted the wire rope touch the block.
Fig. 17. Case 2 – Comparison of wire rope tension between simulation and real operation.
4.2.4. Result From the simulation, they find wire ropes from the block loaders in back start to reach to the edge in the leg structure before the block stand vertically as shown in Fig. 13. As the scenario proceeded, the legs keep going through the wire ropes in the visualization and the interference is evaluated to be able to cause a severe deformation of the legs. 4.2.5. Modified crane and scenario By the simulation results, the production planning engineer made a decision to modify the turnover procedure by replacing the floating crane with the other type which has 1500 t lifting capacity with one block loader which can rotate 360° as shown in Fig. 14. With the replaced floating crane, the turnover scenario was changed to rotate the block after it stands vertically. The floating crane and crawler cranes lift block together to the height enough
to rotate the block (Fig. 15, ①). While the floating crane keeps hoisting up, crawler cranes release the wire ropes slowly to let the block stand steadily (Fig. 15, ② and ③). Some interference between the wire ropes and the legs was still expected in this moment. However, the simulation shows that it is just slightly touch the body. This results are evaluated by the expert engineer who has much experience in production planning. Therefore, the changed procedure was accepted. On the block standing, the wire ropes from the crawler cranes are disconnected (Fig. 15, ④) and then the block is rotated (Fig. 15, ⑤). After the block rotates by 180°, the hooks of crawler cranes are connected at this other side again and start to hoist up (Fig. 15, ⑥ and ⑦). In this step, a virtual moment was assigned on the axis of the block loader in the simulation model but a forklift pulled the block to rotate in real operation. Finally, the block loader of the floating crane and the hooks of crawler cranes are hoisted down to lay down the block on the ground (Fig. 15, ⑧).
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Fig. 18. Case 3 – Problem definition of flare tower turnover.
Fig. 19. Case 3 – Geometry of flare tower and crane arrangement.
4.2.6. Validation The validation is conducted by observing the real operation to the simulation as shown in Fig. 16. The comparison shows that the block position and orientation agree with those of the simulation in each step. It means that the mechanical calculation under the given conditions is correct. The estimation of the interference that it would be so severe when the wire ropes are approaching to the legs is also confirmed by the comparison. The wire rope tension is changed during the operation as shown in Fig. 17. In this graph, the value is total tension of the wire ropes. At the beginning, the load kept on increasing until the block is vertically suspended by the floating crane. While it rotates, the tension maintains its value around the block weight. The fluctuation in the simulation is mainly come from the oscillation in the numerical integration when the simulation is stared and the step proceeds in the scenario. On the other hand, the fluctuation in the real operation could be affected by several reason such as lifting height, hoisting speed, temporarily position change of the crane and so on. After the hooks of crawler cranes are re-connected and
hoisted up, the tension was decreased. In the real operation, the block was lifted again because it was laid on the trestle inappropriately. Therefore, the tension was increased. Then, we finished recording the graph in the floating crane before the block was fully laid on the trestle. Therefore, the tension still remains at the end of the operation. 4.3. Case 3: flare tower turnover simulation 4.3.1. Problem definition Flare tower is a truss structure installed in the topside of an offshore production unit. Along the structure, an outfitting system which supports to burn gas out on the top of the tower is put in place. For the safety of workers and topside equipment, the burning point is required to be far enough from the topside and, therefore, the length of the tower is very long. Due to the length, the tower is usually produced in horizontal position and transported in the same way. But it should be is turned over by 90° to hold its vertical position for the installation. In this case, the
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Fig. 20. Case 3 – History of flare tower turnover simulation.
Fig. 21. Case 3 – Flare tower turnover scenario.
floating crane of 3600 t lifting capacity with two booms is planned to be used in turnover. The booms are required to be lowered in the start. As the boom angle is lowered, the interference of the upper part of the tower can be avoided because the gap between the booms is increasingly wider as it goes toward the tip of them.
But the boom angle needs to be checked again to see it is possible to make the tower stand vertically after the interference is avoided. They, therefore, want to confirm the operability of the turnover scenario and the optimum boom angle without any interference between them as shown in Fig. 18.
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Fig. 22. Case 3 – Distance graph between the top platform and boom.
4.3.2. Modeling Two floating cranes are included in the simulation model and the geometry model is created according to the drawing. Because internal truss elements in the tower have nothing to do with the problem definition, only columns outside are considered in the geometry. On the other hand, ladder geometry model which is used for crane survey are added between of the booms to check the interference. The tower is laid down on a barge which is moored to quay shows and connected by two floating cranes. The weight of the flare tower is 760 [t] and the length is 127 [m]. The breadth of the top platform is 4.46 [m] ( Fig. 19). 4.3.3. Simulation history Typically, production method is planned before the manufacturing started. In many cases, simulation is requested a couple of times to check the problem defined. But this case asked repeated simulation according to the planning review in detail, and the simulation history shows a good example how the SIMSON can be used until they fix the production method. The initial proposal for the boom angle was 52° (Fig. 20, ①) but interference was found with the angle and following several simulation with SIMSON gave 48° as an optimum angle without interference (Fig. 20, ②). While discussing the procedure with yard workers, they noted that there are ladders on the path along with the tower pass between the booms (Fig. 20, ③). And then, the platform on top of the tower was designed and the dimension was reported from the contractor. Consequently, the turnover procedure was simulated again considering the ladder and top platform geometry together (Fig. 20, ④). Until this time, the flare tower had been assumed to be placed on the quay. But according to the changed transportation plan, the operation concept was changed to be done on a barge. The simulation, therefore, was repeated to check the clearance
considering the motion caused by the hydrodynamic forces (Fig. 20, ⑤). Based on the results that the turnover would not be possible under the given conditions, they decided change the design of the top platform (Fig. 20, ⑥). Finally, SIMOSN found the optimum angle considering all of these conditions (Fig. 20, ⑦). 4.3.4. Scenario This scenario is the finalized one for the operation based on the simulation with SIMSON. Both floating cranes start to lift the flare tower with the initial boom angle, 36° (Fig. 21, ① and ②). The top platform of the flare tower is passing through the gap between the booms (Fig. 21, ③–⑤). After the top platform passed through, the boom angle is shifted to 54° (Fig. 21, ⑥) and the other floating crane which hold the bottom part of the tower moves simultaneously to the left and lowers the hook to make the tower stand vertically (Fig. 21, ⑦–⑨). 4.3.5. Result The simulation result for the interference check shows the distance graph according to the wave height 0 [m] and 0.3 [m] as shown in Fig. 22. The results are interpreted that the operation should be conducted under condition that the wave height is below 0.3 [m] at least. 4.3.6. Validation The clearance obtained from the simulation was compared with the real operation as shown in Fig. 23. Although the distance was not measured in the operation, the similarity between the simulation and the real operation can be discussed based on the pictures taken from the same direction as the simulation screen. They show the tower position and orientation when the top platform passed through between two booms are changed as
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Fig. 23. Case 3 – Comparison of the block position and orientation between simulation and real operation.
estimated from the simulation result of SMISON. Any interference between the boom and the top platform was not founded at the real operation in the operation procedure simulated with SIMSON.
production simulation of shipbuilding area. Additional production facilities like another type of crane, block loader are to be modeled and interface possibility between the simulation and structural analysis is investigated in the future work.
5. Conclusions SIMSON is developed to support production planning engineers in checking safety risks in advance when a new production method is considered. It has been applied to many real operations in which the basic tasks like block lifting, turnover, and transportation are included. It provides the simulation capability of production procedure with the function of clearance check, motion analysis and tension calculation considering the given environmental conditions. Three cases presented in this paper lead us that the concept and functionalities of SIMSON are appropriate for the
Acknowledgments This work was partially supported by (a) Daewoo Shipbuilding and Marine Engineering Co., Ltd., Republic of Korea, (a) BK21 Plus, Education & Research Center for Offshore Plant Engineers (COPE) of Seoul National University, Republic of Korea, (b) Engineering Research Institute of Seoul National University, Republic of Korea,
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(c) Research Institute of Marine Systems Engineering of Seoul National University, Republic of Korea, and (d) Engineering Development Research Center (EDRC) funded by the Ministry of Trade, Industry & Energy (MOTIE), Republic of Korea.
References Algoryx. 〈http://www.algoryx.se/products/agx-dynamics/〉. Cha, J.H., Ham, S.H., Lee, K.Y., Roh, M.I., 2010c. Application of a topological modelling approach of multi-body system dynamics to simulation of multi-floating cranes in Shipyards. J. Multi-body Dyn. 224 (4), 365–373. Cha, J.H., Roh M.I., Ham, S.H., Lee, K.Y., Park, K.P., Suh, H.W., 2007. Development of an Integrated Simulation Framework and Its Application to Shipbuilding Process Planning. In: Proceedings of ICCAS (International Conference on Computer Applications in Shipbuilding), pp. 283–290.
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Cha, J.H., Roh, M.I., Lee, K.Y., 2010a. Integrated simulation framework for the process planning of ships and offshore structures. Robot. Comput.-Integr. Manuf. J. 26 (5), 430–453. Cha, J.H., Roh, M.I., Lee, K.Y., 2010b. Dynamic response simulation of a heavy cargo suspended by a floating crane based on multibody system dynamics. Ocean Eng. 37 (14–15), 1273–1291. Cummins, W.E., 1962. The impulse response function and ship motions. Schiffstechnik 9, 101–109. DNV, 2009. SIMO (Simulation of Marine Operations) Theory Manual, SINTEF. MSC/ADAMS. 〈http://www.mscsoftware.com/product/adams/〉. Open Dynamics Engine (ODE) Homepage. 〈http://www.ode.org/〉. Open Scene Graph (OSG). 〈http://www.openscenegraph.org/〉. Shabana, A., 1994. Computational Dynamics. John Wieley & Sons. Ultramarine, Inc., 2008a. Reference Manual for MOSES. Ultramarine, Inc., 2008b. Verification Document for Ultramarine Offshore Software. Reference Manual for MOSES.
Contents lists available at ScienceDirect
Ocean Engineering journal homepage: www.elsevier.com/locate/oceaneng
Application and validation of production planning simulation in shipbuilding Kwang-Phil Park a, Seung-Ho Ham b,n, Chan-Young Lee a a b
R&D Institute, Daewoo Shipbuilding and Marine Engineering Co., Ltd., Republic of Korea Department of Naval Architecture and Ocean Engineering, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul 151-744, Republic of Korea
art ic l e i nf o
a b s t r a c t
Article history: Received 26 December 2014 Accepted 15 January 2016
As the weight and size of assembly blocks are getting increased, new production procedures by using floating cranes have been proposed to enhance the efficiency in shipyards. In this situation, simulation technology is required to evaluate potential risks of the procedure in advance. By such a necessity, we have developed a simulation system, named SIMSON (SIMulation System Of New production planning). SIMSON calculates the motion of the lifted block and floating bodies such as vessels and floating cranes based on the multibody system dynamics with the hydrostatic and hydrodynamic forces. The calculated motion and wire rope tension are used for dynamic effect estimation. In this paper, we present the application cases of SIMSON to real production process. The simulation results are compared by observing the situation in the real operations. The observation illustrates the simulation results are in harmony with the real situation and the application of SIMSON to production planning simulation in shipyards is quite feasible. & 2016 Elsevier Ltd. All rights reserved.
Keywords: Crane lifting Floating crane Lifting simulation Turnover Production planning
1. Introduction When a new production method is planned in shipyards, it is not easy to predict any potential risks in the new operation. Moreover, it is not easy for production planning engineers to prove that the lifting plan is perfectly safe and there is no reason for disqualification. Fig. 1 shows an example of derrick erection plan and operation with two floating cranes. And there are three points that the production planning engineer is typically want to check. ① Interference between boom tip and top structure of derrick. ② Interference between the drillship and bottom structure of derrick. ③ Angle between the wire rope and the sheave. The check points listed above usually require the results considering the dynamic motion because the crane is moving on the water. In this situation, Fig. 2 shows the procedure that the simulation is used between the planning and the operation. A production engineer can preview the plan and confirm it referring to the result of simulation whose model is based on the input data like drawings, environmental conditions and so on. SIMSON (SIMulation System Of New production planning) is a simulation
n
Corresponding author. Tel.: þ 82 2 880 8378. E-mail address: [email protected] (S.-H. Ham).
http://dx.doi.org/10.1016/j.oceaneng.2016.01.008 0029-8018/& 2016 Elsevier Ltd. All rights reserved.
system developed in DSME to support the procedure in 2007 (Cha et al., 2007). In this paper, we present several application cases of SIMSON to production planning. Based on the comparison between the simulation and the real operation, we discuss the validation the simulation system.
2. Related works MSC/ADAMS (Fig. 3, ①) is a multibody dynamics system which is used for dynamic simulation of mechanical parts such as landing gear of aircraft, suspension of vehicle and cranks inside the engine, etc. It is also able to integrate FE (Finite Element) analysis considering a flexible body. While it has plenty of functions for the dynamic simulation, there is a limitation when it is to be used for production planning process in shipyard in that hydraulic external force is not included in the system. In many cases, floating bodies like a ship, a floating crane are used in the process, the hydrostatic force and hydrodynamic force are basically required to for the simulation. Ultramarine developed MOSES (Fig. 3, ②) for dynamic analysis of offshore transportation, lifting, installation and so on (MOSES, 2008a; MOSES, 2008b). Since the system is originated from the hydrodynamic analysis for the floating bodies, it has an advantage for the motion analysis of the floating bodies and interaction among them. On the other hand, it is difficult to make a
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Fig. 1. Example of derrick lifting plan with two floating cranes and its potential risks during the operation.
Fig. 2. Example of the way how simulation is used between plan and operation.
mechanical model of onshore production facilities like block loader, crawler crane and so on. Because facilities on shore are also used in production process in shipyard, the model based on multibody system dynamics and functions for them is required. SIMO (Fig. 3, ③) is numerical tool for simulation of marine operations in the time domain and a part of the SESAM package as provided by DNV (DNV, 2009). It is specialized in marine operation simulation. However, it is not suitable to simulation shipbuilding production which includes complicated scenario and many cranes.
3. System configuration The main feature of SIMSON is multibody dynamic simulation coupled with hydraulic external forces. Especially, since it is oriented to production planning simulation, it provides easy availability of facility modeling and scenario composing for the purpose. Fig. 4 shows the screenshot of main window in SIMSON. The functions in SIMSON are related to the configuration of basic system architecture called ‘DSME Simulation Framework’ (Cha et al., 2007, 2010b) and its applications (Cha et al., 2010a,
2010c). The framework mainly consists of 5 componentsapplication-specific modules, simulation coordinator, simulation kernel, development tools and post-processing tools. Each module in the components is mapped to the required function in the simulation system. It is developed by C þ þ programing language. – Dynamic Analysis Module (Fig. 5, ①): This is a dynamics engine for a multibody system like the interconnected bodies which are constrained by joints, links and wire ropes. Users can select either Open Dynamics Engine (ODE) or Algoryx. The detail theory of the mulatibody system dynamics will be followed at the end of this section. – Collision Detection Module (Fig. 5, ②): This is for interference check between bodies. The detection code itself is not separated from the dynamic analysis module. – Visualization Module (Fig. 5, ③): Open Scene Graph (OSG) is used for this module to visualize the simulation result in real time. – Wire Rope Force Calculation Module (Fig. 5, ④): Wire rope can be modeled simply as an incompressible spring or more complicatedly
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–
–
–
–
–
–
as it has the properties such as stretching, bending and twisting according to the dynamic analysis module. Hydrostatic/Hydrodynamic Forces Calculation Module (Fig. 5, ⑤): Cummins equation (Cummins, 1962) is used to calculate the motion of a floating body in time domain. The motion of the floating barge exerted by a hydrodynamic force is validated in the previous study. Hydrostatic force is also calculated by the fluid density and the submerged volume under the water plane of the body. Simulation Middleware (Fig. 5, ⑥): It takes a role of data management among the modules and provides plug-in capability for a new module or to replace one with another. Simulation Kernel (Fig. 5, ⑦): This module can handle the combined discrete event and discrete time. This allows the user to simulate complicated scenarios based on events and time. CAD Data Interface (Fig. 5, ⑧): The building blocks which are to be subjects in the simulation are usually modeled in 3D CAD system used in shipyards. This module is used in importing the 3D geometry readily into the simulation model. Development Tools (Fig. 5, ⑨): This module helps the developer to use simulation framework more conveniently. Especially, it provides simulation kernel templates to generate simulation model. Post-Processing Tools (Fig. 5, ⑩): This module furnishes the user-friendly graphs to show the motion and tension during the simulation.
Meanwhile, the simulation is based on the multibody system dynamics, which was introduced in Shabana (1994). The relative motion that is permitted between bodies in the multibody system is often constrained by connections between those bodies. Therefore, Newton's equation of motion for the multibody system can be stated as Mr€ ¼ Fe þ Fc
Fig. 3. Related works – ① MSC/ADAMS, ② Ultramarine/MOSES, and ③ DNV/SIMO.
ð1Þ
The vectors in Eq. (1) are represented in terms of the Cartesian coordinates. M is the mass and the mass moment of inertia matrices, and r is the position vector of the center of gravity of the bodies with respect to the Cartesian coordinates. The resultant force consists of the external force Fe and the constraint force Fc caused by kinematic constraints. The position vector r of the Cartesian coordinates can be presented as a function of the generalized coordinates q according to r ¼ rðqÞ
ð2Þ
Differentiating Eq. (2) yields the velocity relation r_ ¼ Jq_
ð3Þ
where the velocity transformation matrix J transforms the velocity of generalized coordinates q_ into the velocity of the Cartesian coordinates. Differentiating Eq. (3) yields the acceleration r€ ¼ Jq€ þ _Jq_
ð4Þ
Substituting Eq. (4) into Eq. (1), we can obtain the equation MJq€ þ M_Jq_ ¼ Fe þ Fc
ð5Þ
Multiplying both sides of Eq. (5) by JT yields JT MJq€ þ JT M_Jq_ ¼ JT Fe þ JT Fc
Fig. 4. Screenshot of SIMSON.
ð6Þ
The constraint reaction forces are perpendicular to the path along which the bodies are constrained to move. This says that the constraint reaction force Fc may be suppressed by taking the scalar product of both sides of Newton’s equation of motion with vectors
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Fig. 5. Mapping between components in ‘DSME Simulation Framework’ and functions in SIMSON.
Fig. 6. Case 1 – 3D geometry of building block and lug arrangement.
that are tangent to the path. Then, we can derive ~ q€ þ k~ ¼ F~ e M
ð7Þ
e ~ is the mass and the ~ ¼ JT MJ, k~ ¼ JT M_Jq, _ and F~ ¼ JT Fe ; M where M generalized mass moment of the inertia matrix, k~ is the
e generalized Coriolis and centrifugal force, F~ is the generalized external force, J is the velocity transformation matrix, and _J is the acceleration transformation matrix. Eq. (7) is the final form of the equations of motion of the multibody system based on the multibody system dynamics.
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Fig. 7. Case 1 – Modeling of the gantry crane.
Fig. 8. Case 1 – Block turnover and erection scenario.
4.1.1. Problem definition ‘Turnover’ means to turn a building block upside down for a production purpose and it happens very frequently in shipyards. In this case, while a building block is in turnover by a gantry type crane of 900 t lifting capacity, they want to check the position and orientation of the block and the tension change in wire ropes from the perspective of safety.
breadth, and height of the block are 25.6 [m], 23.2 [m], and 7.1 [m] respectively, and the weight is 290 [t]. Lug points which connected to block loaders of the gantry crane by wire ropes are also arranged at the same positions as in the drawing. The gantry crane is modeled to reflect its operational mechanism as shown in Fig. 7. There are lower and upper trolleys on the girder of the crane. Two of the block loaders with equalizer are connected to the upper trolley and the other one to the lower trolley. Considering the traveling of the block from the initial position to the erection position after turnover, the dock and preerection area are modeled around the crane in the same scale. Inside the equalizer, several fixed and moving pulleys are placed by turns. All of the pulleys are connected by a single wire rope, which should have the same tension anywhere in its length. Thus, if the tension is denoted by T, all of the moving pulleys are exerted by 2T from the equalizing wire rope. Instead of the real pulleys, we developed approximated mechanism of the equalizer which controls the length of the wire rope logically to make them equal.
4.1.2. Modeling The 3D geometry of the building block is obtained from CAD database by the interface function as shown in Fig. 6. The length,
4.1.3. Scenario The simulation scenario for this case is composed following the major event sequence in the production planning as shown in
4. Simulation cases In this section, we present 3 application cases of SIMSON in the order of problem definition, modeling and scenario. For some of these cases, the simulation results are compared with the observed situation in real operations. Because of the lack of the sensing measure and operation procedure in real operation, the comparison is not exactly same as the simulation results. However it gives enough implications for the validation. 4.1. Case 1: block turnover simulation by gantry crane
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Fig. 9. Case 1 – Comparison of the block position and orientation between simulation and real operation.
Fig. 10. Case 1 – Comparison of wire rope tension between simulation and real operation.
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Fig. 11. Case 2 – Arrangement of the floating crane and two crawler cranes for block turnover.
Fig. 12. Case 2 – Block turnover scenario.
Fig. 13. Case 2 – Interference between block and wire rope during simulation.
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Fig. 8. Three block loaders are lifted simultaneously at the first time (Fig. 8, ①), and then two block loaders of the upper trolley are hoisted up to make the block stand vertically (Fig. 8, ② and ③). After the block loader of the lower trolley is disconnected from the block, the lower trolley is moved to connect the block loader and the block again at the other side (Fig. 8, ④–⑥). It is hoisted up (Fig. 8, ⑦) again to complete the block turnover and, finally, both trolleys are moved to the destination near the other block (Fig. 8, ⑧ and ⑨). Three block loaders are hoisted down to lay down the block next to the other (Fig. 8, ⑩). 4.1.4. Validation The validation for this case is conducted by observing of the block position and orientation the real operation. The pictures taken in the operation and screen shots in the simulation are compared as shown in Fig. 9. It shows very similar situation in block position and orientation and this suggests the mechanical calculation in the simulation is in good agreement with the real operation. In the comparison of wire rope tensions as shown in Fig. 10, the graph for the real operation came from manual record during the operation. The simulation results and the results from the real operation were not exactly identical because the way how to control crane could affect the wire rope tension. In addition, the
Fig. 14. Case 2 – Rearrangement of the floating crane and two crawler cranes for block turnover.
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weight and center of gravity of the block at the operation time could be slightly differ from the initial estimation. However, the comparison can be interpreted that the simulation results are consistent with the real operation in terms of tendency and values. 4.2. Case 2: block turnover simulation by floating crane 4.2.1. Problem definition In this case, a floating crane is used for a block turnover together with cranes on shore due to the weight and the location that is placed. During the planning, interference between wire ropes and the block was forecasted from the drawing of the structure dimension. They, therefore, should evaluate how much the interference would be severe during the operation. Based on the simulation results, another type of floating crane could be used as an alternative method. 4.2.2. Modeling The block geometry is exported from TRIBON cad system which is used for detail design in DSME while cranes are newly modeled from other 3D cad system. The block dimension is 34.3 [m] 27.1 [m] 10.8 [m] in its length, breadth and height, and the weight is about 580 [t]. The block has four legs as shown in Fig. 11 which are forecasted to be adjacent to wire ropes. The white spheres were the lug points connected with the hooks of the crawler cranes or block loaders of the floating crane. In the initial plan, a floating crane of 3600 t lifting capacity is the main crane for the turnover operation and two crawler cranes are to lift the other side of the block. 4.2.3. Initial scenario When they start the operation, the block is lifted by the floating crane alone by using all four block loaders (Fig. 12, ①). The hoisting-up of two block loaders in back is stopped while the other two block loaders in front keep being hoisted when the block is reached to the height enough to the turnover (Fig. 12, ②). When the block stands vertically, the two block loaders in back are lowered (Fig. 12, ③). Because of the center of mass, the block is expected to incline while the lowering. It is not allowed to release the wire ropes from the block loaders in back until the block is connected to the crawler cranes at the opposite side (Fig. 12, ④) for safety reason, wire rope interference with the leg structures is forecasted in this step. Finally, the hooks of crawler cranes are hoisted up to finish the block turnover (Fig. 12, ⑤ and ⑥).
Fig. 15. Case 2 – Modified block turnover scenario.
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Fig. 16. Case 2 – Comparison of the block position and orientation between simulation and real operation, and interference that SIMSON predicted the wire rope touch the block.
Fig. 17. Case 2 – Comparison of wire rope tension between simulation and real operation.
4.2.4. Result From the simulation, they find wire ropes from the block loaders in back start to reach to the edge in the leg structure before the block stand vertically as shown in Fig. 13. As the scenario proceeded, the legs keep going through the wire ropes in the visualization and the interference is evaluated to be able to cause a severe deformation of the legs. 4.2.5. Modified crane and scenario By the simulation results, the production planning engineer made a decision to modify the turnover procedure by replacing the floating crane with the other type which has 1500 t lifting capacity with one block loader which can rotate 360° as shown in Fig. 14. With the replaced floating crane, the turnover scenario was changed to rotate the block after it stands vertically. The floating crane and crawler cranes lift block together to the height enough
to rotate the block (Fig. 15, ①). While the floating crane keeps hoisting up, crawler cranes release the wire ropes slowly to let the block stand steadily (Fig. 15, ② and ③). Some interference between the wire ropes and the legs was still expected in this moment. However, the simulation shows that it is just slightly touch the body. This results are evaluated by the expert engineer who has much experience in production planning. Therefore, the changed procedure was accepted. On the block standing, the wire ropes from the crawler cranes are disconnected (Fig. 15, ④) and then the block is rotated (Fig. 15, ⑤). After the block rotates by 180°, the hooks of crawler cranes are connected at this other side again and start to hoist up (Fig. 15, ⑥ and ⑦). In this step, a virtual moment was assigned on the axis of the block loader in the simulation model but a forklift pulled the block to rotate in real operation. Finally, the block loader of the floating crane and the hooks of crawler cranes are hoisted down to lay down the block on the ground (Fig. 15, ⑧).
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Fig. 18. Case 3 – Problem definition of flare tower turnover.
Fig. 19. Case 3 – Geometry of flare tower and crane arrangement.
4.2.6. Validation The validation is conducted by observing the real operation to the simulation as shown in Fig. 16. The comparison shows that the block position and orientation agree with those of the simulation in each step. It means that the mechanical calculation under the given conditions is correct. The estimation of the interference that it would be so severe when the wire ropes are approaching to the legs is also confirmed by the comparison. The wire rope tension is changed during the operation as shown in Fig. 17. In this graph, the value is total tension of the wire ropes. At the beginning, the load kept on increasing until the block is vertically suspended by the floating crane. While it rotates, the tension maintains its value around the block weight. The fluctuation in the simulation is mainly come from the oscillation in the numerical integration when the simulation is stared and the step proceeds in the scenario. On the other hand, the fluctuation in the real operation could be affected by several reason such as lifting height, hoisting speed, temporarily position change of the crane and so on. After the hooks of crawler cranes are re-connected and
hoisted up, the tension was decreased. In the real operation, the block was lifted again because it was laid on the trestle inappropriately. Therefore, the tension was increased. Then, we finished recording the graph in the floating crane before the block was fully laid on the trestle. Therefore, the tension still remains at the end of the operation. 4.3. Case 3: flare tower turnover simulation 4.3.1. Problem definition Flare tower is a truss structure installed in the topside of an offshore production unit. Along the structure, an outfitting system which supports to burn gas out on the top of the tower is put in place. For the safety of workers and topside equipment, the burning point is required to be far enough from the topside and, therefore, the length of the tower is very long. Due to the length, the tower is usually produced in horizontal position and transported in the same way. But it should be is turned over by 90° to hold its vertical position for the installation. In this case, the
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Fig. 20. Case 3 – History of flare tower turnover simulation.
Fig. 21. Case 3 – Flare tower turnover scenario.
floating crane of 3600 t lifting capacity with two booms is planned to be used in turnover. The booms are required to be lowered in the start. As the boom angle is lowered, the interference of the upper part of the tower can be avoided because the gap between the booms is increasingly wider as it goes toward the tip of them.
But the boom angle needs to be checked again to see it is possible to make the tower stand vertically after the interference is avoided. They, therefore, want to confirm the operability of the turnover scenario and the optimum boom angle without any interference between them as shown in Fig. 18.
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Fig. 22. Case 3 – Distance graph between the top platform and boom.
4.3.2. Modeling Two floating cranes are included in the simulation model and the geometry model is created according to the drawing. Because internal truss elements in the tower have nothing to do with the problem definition, only columns outside are considered in the geometry. On the other hand, ladder geometry model which is used for crane survey are added between of the booms to check the interference. The tower is laid down on a barge which is moored to quay shows and connected by two floating cranes. The weight of the flare tower is 760 [t] and the length is 127 [m]. The breadth of the top platform is 4.46 [m] ( Fig. 19). 4.3.3. Simulation history Typically, production method is planned before the manufacturing started. In many cases, simulation is requested a couple of times to check the problem defined. But this case asked repeated simulation according to the planning review in detail, and the simulation history shows a good example how the SIMSON can be used until they fix the production method. The initial proposal for the boom angle was 52° (Fig. 20, ①) but interference was found with the angle and following several simulation with SIMSON gave 48° as an optimum angle without interference (Fig. 20, ②). While discussing the procedure with yard workers, they noted that there are ladders on the path along with the tower pass between the booms (Fig. 20, ③). And then, the platform on top of the tower was designed and the dimension was reported from the contractor. Consequently, the turnover procedure was simulated again considering the ladder and top platform geometry together (Fig. 20, ④). Until this time, the flare tower had been assumed to be placed on the quay. But according to the changed transportation plan, the operation concept was changed to be done on a barge. The simulation, therefore, was repeated to check the clearance
considering the motion caused by the hydrodynamic forces (Fig. 20, ⑤). Based on the results that the turnover would not be possible under the given conditions, they decided change the design of the top platform (Fig. 20, ⑥). Finally, SIMOSN found the optimum angle considering all of these conditions (Fig. 20, ⑦). 4.3.4. Scenario This scenario is the finalized one for the operation based on the simulation with SIMSON. Both floating cranes start to lift the flare tower with the initial boom angle, 36° (Fig. 21, ① and ②). The top platform of the flare tower is passing through the gap between the booms (Fig. 21, ③–⑤). After the top platform passed through, the boom angle is shifted to 54° (Fig. 21, ⑥) and the other floating crane which hold the bottom part of the tower moves simultaneously to the left and lowers the hook to make the tower stand vertically (Fig. 21, ⑦–⑨). 4.3.5. Result The simulation result for the interference check shows the distance graph according to the wave height 0 [m] and 0.3 [m] as shown in Fig. 22. The results are interpreted that the operation should be conducted under condition that the wave height is below 0.3 [m] at least. 4.3.6. Validation The clearance obtained from the simulation was compared with the real operation as shown in Fig. 23. Although the distance was not measured in the operation, the similarity between the simulation and the real operation can be discussed based on the pictures taken from the same direction as the simulation screen. They show the tower position and orientation when the top platform passed through between two booms are changed as
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Fig. 23. Case 3 – Comparison of the block position and orientation between simulation and real operation.
estimated from the simulation result of SMISON. Any interference between the boom and the top platform was not founded at the real operation in the operation procedure simulated with SIMSON.
production simulation of shipbuilding area. Additional production facilities like another type of crane, block loader are to be modeled and interface possibility between the simulation and structural analysis is investigated in the future work.
5. Conclusions SIMSON is developed to support production planning engineers in checking safety risks in advance when a new production method is considered. It has been applied to many real operations in which the basic tasks like block lifting, turnover, and transportation are included. It provides the simulation capability of production procedure with the function of clearance check, motion analysis and tension calculation considering the given environmental conditions. Three cases presented in this paper lead us that the concept and functionalities of SIMSON are appropriate for the
Acknowledgments This work was partially supported by (a) Daewoo Shipbuilding and Marine Engineering Co., Ltd., Republic of Korea, (a) BK21 Plus, Education & Research Center for Offshore Plant Engineers (COPE) of Seoul National University, Republic of Korea, (b) Engineering Research Institute of Seoul National University, Republic of Korea,
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(c) Research Institute of Marine Systems Engineering of Seoul National University, Republic of Korea, and (d) Engineering Development Research Center (EDRC) funded by the Ministry of Trade, Industry & Energy (MOTIE), Republic of Korea.
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