LS-Dyna shell element formulation 16

- January 18, 2022 at 8:27 pm
  
  minchunh
  Subscriber
  
  Hello,
  I've done a patch test with uniaxial tensile force under displacement control for shell element formulation 16. The dimension of the plate is 4 in by 4 in and the thickness is 0.25 in. Under the boundary condition, the uniform distribution of the tensile stresses should be obtained. However, this is what I've got when using element 16 and the loading rate is 0.1in/s:
- January 20, 2022 at 7:43 am
  
  Ushnish Basu
  Ansys Employee
  
  Here are some things you can try:
  Use hourglass type 8 with shell type 16
  Try shell type -16
  Try with MAT_ELASTIC first
  With MAT_24, make sure you are not using strain-rate effects (check VP, LCSR, table LCSS)
- January 23, 2022 at 9:17 pm
  
  minchunh
  Subscriber
  
  Hello,
  Thanks for your reply. I've tried both hourglass type 8 and shell formulation -16, the model has the correct behavior only when control accuracy INN=2 is used. Furthermore, I tried shell formulation 2 with stiffness type hourglass (type 4 and coefficient 0.3), without INN=2 the analysis will mess up as well as the following figure:
  I wonder if control accuracy INN=2 is a must to obtain stable and reasonable results even for rectangular mesh and isotropic material. Thank you and I appreciate any recommendations.