Topology Optimization of Vehicle Body Structure in the Early Design Phase

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Topology Optimization of Vehicle Body Structure in the Early Design Phase

  1. 1. Topology Optimization of Vehicle Body Structure in the Early Design Phase Harald Hasselblad Volvo Car Corporation 5th EHTC 2011, 8-9 Nov 2011, Bonn, Germany Harald Hasselblad, Volvo Car Corp.
  2. 2. Based on a Master Thesis ProjectStudents: • Sebastian Lövgren • Emil Norberg Linköping University SwedenSupervisor Harald Hasselblad Advanced Body Engineering Volvo Car Corporation Altair Engineering, AB Regional Office: Gothenburg Sweden 5th EHTC 2011, 8-9 Nov 2011, Bonn, Germany Harald Hasselblad, Volvo Car Corp.
  3. 3. Topology Optimization of Rod/Beams for Body StiffnessState of the ArtBolted components are commonly used for Nissan improvement of vehicle body stiffness.IdeaBased on topology optimization identify locations and layout of beams in the front area for improved vehicle body stiffness. 5th EHTC 2011, 8-9 Nov 2011, Bonn, Germany Harald Hasselblad, Volvo Car Corp.
  4. 4. Optimization Problem Min Compliance (Max stiffness) s.t. mass constraint (volume fraction)Industrial tradition: Mass minimization with performance constraint.However, requirements and mass on topology model is of less importance.General guidelines on architecture is sufficient.Load Cases A reduced model of the front of a vehicle has been used. 9 load cases divided into 4 groups, due to similarities, are applied related to: • Torsion stiffness • Lateral/Vertical stiffness • Chassis loadings… 5th EHTC 2011, 8-9 Nov 2011, Bonn, Germany Harald Hasselblad, Volvo Car Corp.
  5. 5. Design Space Geometrical Restrictions Design space Connection Surfaces 5th EHTC 2011, 8-9 Nov 2011, Bonn, Germany Harald Hasselblad, Volvo Car Corp.
  6. 6. Results from Topology OptimizationBy NOT performing a weighted topology optimization, a knowledge base can be generated to support the design process.Each load case has been optimized separately  Good understanding of the specific architecture for each load case.Torsion stiffness Lateral stiffness Vertical stiffness Chassis loadings 5th EHTC 2011, 8-9 Nov 2011, Bonn, Germany Harald Hasselblad, Volvo Car Corp.
  7. 7. Performance of Optimized Topology 5th EHTC 2011, 8-9 Nov 2011, Bonn, Germany Harald Hasselblad, Volvo Car Corp.
  8. 8. Visualize Topology Results 5th EHTC 2011, 8-9 Nov 2011, Bonn, Germany Harald Hasselblad, Volvo Car Corp.
  9. 9. Benchmarking of Topology Allowed connection to windscreen member 5th EHTC 2011, 8-9 Nov 2011, Bonn, Germany Harald Hasselblad, Volvo Car Corp.
  10. 10. Problems Encountered• For a light solution, reinforcements may be optimum instead of beams.• Real stiffness and mass constraints should not be used in topology optimization when the target is to identify a global architecture.• Large design volume compared to allowed result  Beam details are limited because of mesh resolution.Previous results has therefor been based on a stepwise approach.However, a “One-shot” method has also been used to find beam structures.One-shot optimization:• Gradually increase VOLCFRAC until beam structure appears• Remove connection areas to prevent reinforcements 5th EHTC 2011, 8-9 Nov 2011, Bonn, Germany Harald Hasselblad, Volvo Car Corp.
  11. 11. Topology Convergence StrategyDifferent approaches for topology optimization Stepwise “One shot” with different volume fraction “One shot” with different volume fraction and contact reduction 5th EHTC 2011, 8-9 Nov 2011, Bonn, Germany Harald Hasselblad, Volvo Car Corp.
  12. 12. Realization of Topology• Translating topology into beam structure. Hollow circular beams were drawn• Size optimization of beams (tubes) based on topology result r1 r2 5th EHTC 2011, 8-9 Nov 2011, Bonn, Germany Harald Hasselblad, Volvo Car Corp.
  13. 13. Realization and Size OptimizationTorsion Loadcase Topology Load case Topology optimum Beam realization 5th EHTC 2011, 8-9 Nov 2011, Bonn, Germany Harald Hasselblad, Volvo Car Corp.
  14. 14. Realization and Size Optimization 5th EHTC 2011, 8-9 Nov 2011, Bonn, Germany Harald Hasselblad, Volvo Car Corp.
  15. 15. Finding One Solution for all Load Cases Reduced connection areas Topology result (To prevent reinforcements) Problem formulation Realization Minimize mass • Remove reinforcements Subject to: • Translate topology into beams Compliance ≤ Current design • Size Optimization (For all load cases) No solution found!! To remove the reinforcements reduced the performance of one load case in such extent that the beams cannot compensate for it. 5th EHTC 2011, 8-9 Nov 2011, Bonn, Germany Harald Hasselblad, Volvo Car Corp.
  16. 16. Finding One Solution for all Load CasesThe knowledge of each load case is used to increase the performance in thefailed load case. Beams from the specific load case optimum are inserted intothe structure and a new size optimization is preformed. Multi-Loadcase OptimumSingle Loadcase Optimum 5th EHTC 2011, 8-9 Nov 2011, Bonn, Germany Harald Hasselblad, Volvo Car Corp.
  17. 17. Possible Use of Beam/Rod Architecture.Summarize the results from each loadcase and combine them into a bigger solution 5th EHTC 2011, 8-9 Nov 2011, Bonn, Germany Harald Hasselblad, Volvo Car Corp.
  18. 18. Summery and ConclusionsIt is hard to know what material usage is necessary to make the results consist of beams instead of reinforcements.Results should be treated as suggestions for the future realization process.Create the design problem in such a way that no realizable solutions are prevented.It is preferable to optimize each load case separately to create knowledge how to increase stiffness for a certain load case.The results could work as architecture guidelines in early phases of the product development, or it could be used to find weaknesses in a structure. 5th EHTC 2011, 8-9 Nov 2011, Bonn, Germany Harald Hasselblad, Volvo Car Corp.
  19. 19. Thank!5th EHTC 2011, 8-9 Nov 2011, Bonn, Germany Harald Hasselblad, Volvo Car Corp.

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