Presentation on theme: "Comparison of EFG and Standard Elements for the Rubber Membrane in a Biomedical Valve in LS-DYNA 970.5434 Rudolf Bötticher www.rudolf-boetticher.de."— Presentation transcript:
Comparison of EFG and Standard Elements for the Rubber Membrane in a Biomedical Valve in LS-DYNA Rudolf Bötticher
Dresden, www.rudolf-boetticher.de Motivation Assess whether EFG with FSI and MMALE is possible. Compare the results with standard elements. Assess whether EFG is more robust.
Dresden, www.rudolf-boetticher.de EFG is easy! *CONTROL_EFG $ in 970 EFG and (dormant) IMPLICIT cards are not tolerated $ in the same deck $ implicit and axisymmetric EFG not implemented! *SECTION_SOLID_EFG 5,41 $ the non-default bigger support helps to have consistent $ EFG simulations for *MAT_MOONEY-RIVLIN_RUBBER 1.5,1.5,1.5
Dresden, www.rudolf-boetticher.de MM-ALE is easy, if you got a working deck to refine! *ALE_MULTI-MATERIAL_GROUP Proceedings
Dresden, www.rudolf-boetticher.de FSI: Tweaking of *CONSTRAINED_LAGRANGE_IN_SOLID TSSFAC NADV METH CTYPE DIREC PFAC ILEAK 3854, 5434 and newer beta versions deliver different results for identical decks!
Dresden, www.rudolf-boetticher.de Why LS-DYNA for this problem? Curiosity Code is at your disposal Expect the same efficiency as for parallel crash simulation Rely on the advanced material modeling CFX may be better
Dresden, www.rudolf-boetticher.de Membrane covered with null shells Filling with *MAT_VACUUM
Dresden, www.rudolf-boetticher.de A=500MPa A=100MPa PR=0.49 near incompressibility and mm dimensions require tiny time step no implicit, no time step split between rubber/ALE domain, no mass scaling!
Dresden, www.rudolf-boetticher.de 5831 beta version delivers different results. However, problem not solved. FSI not robust against artificial shortening of time step. No difference between EFG and standard elements.
Dresden, www.rudolf-boetticher.de Robustness It proves difficult generating an extreme situation where EFG works but standard elements do not! EFG may be superior preventing hourglass modes.
Dresden, www.rudolf-boetticher.de EFGELFORM=1 *HOURGLASS,6 EFG performance lack: 10% elements switched, CPU time +20%
Dresden, www.rudolf-boetticher.de Conclusions FSI simulations with MMALE and structural EFG solids are possible in LS- DYNA. Here no real advantage of EFG over standard elements. EFG may be better in hourglass prevention. Time step dependence of FSI needs further investigation!