Bird impact on rigid plate - Contact Issue
Trying to model a bird impact on a flat plate, it seems that I have an issue with the contact. The bird goes pass the plate without any collision. Can anyone help me in understanding what’s going wrong with the model? While running I saw a message regarding contact which says “The LS-DYNA time step size should not exceed 6.538E-06 to avoid contact instabilities. If the step size is bigger then scale the penalty of the offending surface.” Does the contact issue related to this any way? First video shows the issue and the keyword file also attached.
Plate material properties assigned:
Mass density = 2.59000E-4 lbf.s2/in4
E = 10.5e6 psi
Poissons Ratio = 0.33
Bird material properties:
RO = 8.889e-05
PC = -14.50
MU = 3.916e-07
From the looks of things you have put everything into the contact cards correctly, so passing right through is definitely strange.
You are using the default contact formulation with a really thin plate though, have you tried increasing the thickness a little like .5, 1.0? The nodes might be passing right through between timesteps, and the funny part is that if they keep passing through the timestep will stay too high.
Invoking a SOFT contact miiiight help. They are usually the go-to for node issues since they are segment based, but to be honest I am not sure if they are as effective for SPH-Lag. I'd say try that too.
Thank you so much for your response @sbrrr. I tried with an increased thickness of 1.00” and I see things improved a little bit. Now few particles ahead of the bird impact with plate but most of these particles then leak through the plate itself. Still the issue exists as shown in the first part of the attached video. In next iteration, I also changed the TSSFAC value from 0.5 to 0.15. TSSFAC value change make the contact works correct, as shown in attached video. Is it possible to use a low value of TSSFAC = 0.15 for analysis? Can anyone make me understand why this change in TSSFAC value make the contact works correct?
include * CONTROL_SPH card . . . ( here NMNEIGH should be varied accordingly )
Also your Lsdyna Version matters.