Learning Forum

[Raghav]

Hi everyone,

I am facing a problem in validating the composite model for high velocity impacts. My simulations are underpredicting the value. The velocity drop I am getting is significantly lower compared to the existing literature. I have used solid (MAT_59) and shell (MAT_54) elements with quater model. SPC node set boundary onditions were provided with x (1 0 0 0 1 1) and y (0 1 0 1 0 1) symmetry. EFFEPS and VOLEPS is set for solid elements as erosion criteria. For shell, DFAILM, DFAILT, DFAILC, DFAILS are taken as failure criteria. 

Eroding surface to surface contact is used between projectile and target whereas automatic surface to surface tiebreak contact is used for contacts between layers with option 4 for both the models. Soft constraint is used (SOFT=1). I can provide the material properties if needed. 

Please guide me where I am making a mistake.

Thankyou 

[Dennis Chen]

 

Hello, if you are using element erosions, it’s like mass just suddenly disappeared and that’s likely why the velocity drop is way less than reality or other similar studies.   I made a video several months ago about this topic and below is the link.    I would also maybe use nonreflecting BC instead of SPC to allow shock wave to propogate outwards if it’s applicable (not always applicable).   

Other than that, it’s the proper material model/EOS wtih the properly captured rate effects.    I hope this helps. 

https://www.youtube.com/watch?v=wl68V2h4cJw=0s

 

 

[Raghav]

Hi Dennis, Thank you for the information. This is really helpful. But since I am not using SPH modelling and replicating the existing model thats already published in journals, where they have not used any kind of SPH modelling.

This will help me in improving my simpulations further.

Regards