Learning Forum

[lvega2019]

Hello, I'm looking for help. I've been trying to simulate a low-caliber impact on a Kevlar plate for over a month.

I modeled the Kevlar with the MAT_ENHANCED_COMPOSITE_DAMAGE option from some parameters obtained from a paper which I will attach "Finite Element Analysis on ballistic impact performance of multi-layered bulletproof vest impacted by 9 mm bullet" from this same paper. I obtained the properties to characterize the bullet, which I worked on as isotropic elasticity, using the LEAD values ​​only.

When the bullet approaches the plate (10 plates of 0.5 [mm] thickness of Kevlar) the finite elements begin to disappear without simulating the impact of this and how the Kevlar bullets should react by trying to cushion the impact, as attached in the photograph.

The contact I made was the bullet and the 10 layers of Kevlar using frictional, with a friction coefficient of 0.2 and a dynamic coefficient of 0.1.
Also use "Fixed Support" to fix the 4 faces of the plates and establish another contact in order to add the "ERODING_SURFACE_TO_SURFACE" option

The Ansys LS-DYNA "KEYWORDS" that I use are CONSTRAINED_GLOBAL both on the X and Y axis, leaving "Translational constraint" (constrained x and y translation), "Rotational constraint" (constrained x, y, and z rotations in both cases) and "Direction of normal" (global x and y in both cases).

In "Analysis Settings" my END TIME is 5E-05 and my TIME STEP SAFETY FACTOR is 0.7 also in the "HOURGLASS TYPE" I used Exact Volume Flanagan-Belytschko Stiffness Form.

I forgot to emphasize that the speed of the bullet I am simulating is -398m/s on the Z axis.

So I would like to know if someone could give me a hand on how to solve this problem or what factor I am not considering in order to obtain a sane simulation.

I have tried everything and I can't find the solution.

[Ashish Khemka]

Hello,

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Regards,

Ashish Khemka

 

 

[Dennis Chen]

 

lvega2019, are you able to share your k file?  if so zchen6@gatech.edu.  I see you used workbench Dyna, so a workbench archive also works (make sure to delete mesh first (right click model and clear generated data before archiving).   If not, can you please provide some details for me, I am going to model this up for fun

1) thickness and dimension of the kevlar layers (each)

2) Mat and section cards you used for the kevlar and the projectile, including any EOS cards

Thanks, and happy holidays :)