Learning Forum

[Raghav]

Hello everyone,

I am modelling impacts on ceramics and have some doubts regarding that. I am using MAT_110 for Alumina (Al2O3). The model consist of cermic and metal (Al) and steel impactor. Both the metals are using JC material model with linear EOS. I am using hourglass 5 (Qm=0.08) and TSSFAC =0.9. I used accuracy card and turned on the hourglass energy in control_energy. I am using Eroding contacts for ceramic and metal against the impactor and Automatic surface to surface between ceramic and metal plate. Some doubts I have are:-

1. Is MAT_ADD_EROSION necessary for ceramic modelling? When i didnt used the erosion card, the penetration is not happening and my projectile is simply passing through the ceramic plate. Or do I have to improvise my contact definations.
2. How to determine the erosion criteria and which parameter to use for the erosion (MXEPS, EFEPS etc.)? Most literature defines it as 0.06 for Alumina. I am defing it for MXEPS but not getting good results. What is the best erosion criteria that should be used for for simulating ceramic impacts?
3. https://www.dynalook.com/conferences/european-conf-2003/implementation-and-validation-of-the-johnson.pdf defines erosion for ceramics as total plastic strain (FS) or if the value is enetered as negative then it represents maximum tensile pressure. Which criteria should be used and when?
4. Is there any standard ceramic-metal armor paper for impact analysis as there may be a chance I am modelling metal incorrectly.

Thankyou