SIA Conference, March 2015, France. Session - Optimization. «RODIN Project» RODIN Robust structural Optimization for Design in INdustry

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1 SIA Conference, March 2015, France Session - Optimization «RODIN Project» Marc Albertelli Research engineer and coordinator of RODIN project RODIN Robust structural Optimization for Design in INdustry Accepted within the framework of the 13 th FUI call to project July the 1st 2012 July the 1st 2015 With the support from BPI France, CRIF and CGY78 Labelled by : 1

2 Motivations Organization Progress Plan Positioning Topics Numerical simulation Applied mathematics Deliverables Numerical tools Methodology Target population Industrial design center Industries : transport, aeronautic, etc Industrial expectations Time savings (productivity) Mass savings (material cost reduction, CO²) Design cycle production Intents 4 2

3 Topology : current process + Set of specifi. stiffness durability life cycle, NVH manufacturing etc Design space Topology Initial design Feedbacks From industrial point of view, the method is attractive for the following reasons: The execution is straigthforward (compared to parametric approach) One does not need to create parameters, automate computation workflow, etc It just requires a design space and the set of specifications It no longer depends on the designer. Mass savings : between 3% and 15% Time savings : achievable but delicate to assess Despite these advantages, we note that : Topology Optimization is not systematically used, The deployment remains modest, It seems difficult to further enlarge the scope of applications, And it appears that : The method is often used for approximately designing simple components, Engineers struggle to devise robust methodologies dedicated to more complex components, The solution is just a concept 3

4 Our (technical) analysis Threshold=0.1 Threshold=0.5 Threshold=0.9 1) Topology consists in managing the density per element. density 0 the element has virtually diseappeared density 1 the element is full. The optimal shape is defined by the set of full elements. 2) The SIMP approach (or «power law») clerverly proposes to relax the problem but : - It does not lead to a clear solution - There is a lot of intermediate densities that requires to manually adjust where the interfaces lies - The user has to guess the most probable density threshold 3) The absence of sharp boundary makes difficult the management : - Of manufacturing constraints (thickness, distance, etc) - Of surface criteria (pressure, t, acceleration, etc) - Of design dependent load, - Of the export of the solution Alternative : the level-set method 1) A new way to characterize the shape Given D, the «design space», The shape Ω, is characterized by a level-set function : x x x 0 x D 0 x 0 x D \ The boundary is now well defined. It is given by the iso-zero of the level-set. The problem of SIMP approach does no more exist. 2) Two other ingredients : J ' js nds d t, x v t, x. t, x 0, t, x IR t 4

5 Plan Motivations of the projet Organization Progress of the project Main purposes of the project Current process designer New process to design massive components Decision maker simulation + CDC tenue fiabilité acoustique durée de vie contraintes de fab. (fonderie, directe) performance etc Design space Topology Deliverables A Topology Optimization tool based on the Level-Set method An automatic tool A new design process In brief Topology has proved to be interesting but requires some changes to enlarge the scope of applications and to systematize its use The challenges are : handling manufact. constraints, dealing with true analyses, automat., etc A new technology is necessary, we choose «level-set method» 5

6 Some scientific and technical challenges n 1 : Scale up of Level-set Machinery level-set Large scale Large scale simulation Multi subcase,. n 2 : Manufacturing constraints Molding Maximum and minimum thickness Minimum distance Curvature, + Set of specifi. stiffness durability life cycle, NVH manufacturing etc Design space Topology n 3 : Analysis Static linear Modal analysis, Freq. responses Material non linearity Boundary conditions non linearity, n 4 : Pre/post treatment Parametrized CAD Mesh export Bulk export, Deliverables + Set of specifi. stiffness durability life cycle, NVH manufacturing etc Design space Topology Pre-treatment Optimization Post-treatment CAD environment TFC Bulk export ESI framework Visual Env. Topolev (Topol) Mesh export From Nastran Bulk Nastran Visual Env. 6

7 Partners Academic Ecole Polytechnique, CMAP University of Pierre et Marie Curie, labo. JLLions Inria Bordeaux, Bacchus Small and Medium Enterprises Digital Product Simulation Alneos Eurodecision ESI Group Industrial partners Renault (coordinator) AIRBUS Group Innovations Snecma Plan Motivations of the projet Organization Progress 7

8 1rst Use case Pilot Use case n 1 CDC min MASSE tenue x fiabilité raideur1 xxx acoustique durée de vie raideur... xxx contraintes de fab. (fonderie, directe) FreqProprei xxxhz performance etc VonMises xxx... Engine mount (Renault) + frequency responses + maximum thickness + Von Mises + molding constraints followers + eigenvalue Solve min mass st stiffnesss constraints Airbus and Snecma use-cases Optimization algortithm dedicated to level-set approach «level-set» machinery Engine mount (AIRBUS) Air cylinder Support (Snecma) Engine mount (1/2) SIMP result Topolev result Impact of the threshold density 8

9 Engine mount (2/2) Without molding constraints With molding constraints Unambiguous solution, sharp boundary! Extra use-cases (1/3) 9

10 Molding (2/3) Maximum thickness (3/3) Without max thickness control 10

11 Complete process Topology Geometry Thank you For your attention 11