Presentation on theme: "Fluid Structure Interaction with *MAT_SOFT_TISSUE and EFG elements Rudolf Bötticher www.rudolf-boetticher.de."— Presentation transcript:
Fluid Structure Interaction with *MAT_SOFT_TISSUE and EFG elements Rudolf Bötticher
Birmingham, www.rudolf-boetticher.de Motivation Assess whether EFG with FSI and MMALE is possible for *MAT_SOFT_TISSUE. Compare the results with standard elements. Assess whether EFG is more robust. Result will be: EFG is a luxury hourglass control !
Birmingham, 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_SOFT_TISSUE 1.4,1.4,1.4
Birmingham, www.rudolf-boetticher.de MM-ALE is easy, if you got a working deck to refine! *ALE_MULTI-MATERIAL_GROUP Proceedings
Birmingham, www.rudolf-boetticher.de FSI: tweaking of *CONSTRAINED_LAGRANGE_IN_SOLID TSSFAC NADV METH CTYPE DIREC PFAC ILEAK 5434a: always use the newest version for consistency and efficiency!
Birmingham, 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 other codes may be better
Birmingham, www.rudolf-boetticher.de Initial shortening of time step prevents intrusion *CONTROL_TIMESTEP,,,,,222 *DEFINE_CURVE 222
Birmingham, www.rudolf-boetticher.de no implicit, no time step split between tissue/ALE domain, no mass scaling! RI HG6EFG K=5 GPa near incompressibility and mm dimensions require tiny time step
Birmingham, www.rudolf-boetticher.de FSI, MMALE dependent on time step! RI HG6EFG TSSFAC=0.25
Birmingham, www.rudolf-boetticher.de Robustness It proves difficult generating an extreme situation where EFG works but standard elements do not! EFG is superior in preventing hourglass modes.
Birmingham, www.rudolf-boetticher.de EFGELFORM=1 *HOURGLASS,6 EFG performance lack: 10% elements switched, CPU time +15% 971: *SECTION_SOLID_EFG 1,41 1.4,1.4,1.4,,,3,2
Birmingham, www.rudolf-boetticher.de Conclusions FSI simulations with MMALE and *MAT_SOFT_TISSUE EFG solids are possible in LS-DYNA. EFG is superior in hourglass prevention for tricky cases. Time step dependence of FSI needs further investigation!