Help to validate Plastic deformation

[shrihari_sampathkumar]

Hello, 

I have a drop-impact simulation of a Glass+Plastic (polycarbonate) assembly. I'm get results that look like the Polycarbonate is undergoing plastic deformation.

However, I have limited experience validating plastic deformation in LS-DYNA and would like some help on this. I'm especially worried if i've artificially introduced some non-physical plastic deformation in my attempts to eliminate Hourglass energy. 

Setup:

• Materials: Glass - Proprietary (substrate) , Plastic, PC High viscosity - Ansys default library (around the glass perimeter) , Steel - Default library(rigid body- shell) 
• Contacts:
  • Glass <-> PC : Shared topology
  • PC <-> Plate : Frictional
    • Behavior: Asymmetric
    • Formulation: Pure Penalty (Automatic_nodes_to_surface)
    • Viscous damping coefficient: 0.1
    • Contact / Target Penalty Scale Factors: 10 
    • Soft Constraint Formulations: Segment Based
    • Soft constraint Scale Factor: 1
    • Depth: 2
• Mesh: Hex8 (for glass, PC), and Quad4 (plate)
• Hourglass controls: 
  • PC: ID 7 (Belytschko-Bindeman Linear Total Strain), coefficient = 1
• Element Controls:
  • PC: Fully Integrated S/R Solid
• Analysis setting:
  • Global Hourglass control: ID 5 (Exact Volume Flanagam-Belytschko Stiffness Form), coefficient = 0.1

Points to note / Concerns: 

• High distortion of the PC (not sure how I can check this is actually physical/ potential mesh issue)
• The contact energy increases and stays high (I think this is ok since there's sliding at the frictional interface)
• Internal energy stays high after impact (again, I think this is physical since there's work done on the PC layer)