Learning Forum

[Afzal3012]

I am trying to do an explicit dynamic analysis of a bullet hitting a composite plate. I designed the composite plate using Ansys ACP(pre) and then transferred the file to an explicit dynamic module. but whenever I am doing the analysis I am not getting the accurate result. "the bullet tip just toches the plate". I tried to change the analysis settings.

# changing the end time

# changing the no. of cycle

# increasing the mesh size

# increasing the initial velocity of the bullet

# making bullet closer to the plate

even after this I am not getting accurate results i.e either bullet penetrate the plate or give significant deformation to the plate.

please help

with regards

[Bhargava Sista]

From the model tree I do not see any Connections defined. You need to define a contact connection between the bullet and the plate so they detect each other and contact forces are applied on both of them.nCheck out the examples from this course to understand why and how to define contacts.n/courses/index.php/courses/contact-mechanics/n

[Afzal3012]

thank you for the reply,nearlier there was a connection pre-defined but due to that bullet was jumping coming a little forward(in the air) and was jumping back...after that, I suppressed that connection, and the bullet at least reached near the plate. nbut i will look forward to define connection nthank youn

[Bhargava Sista]

It sounds like when you define the connection, the bullet is rebounding after hitting the plate. If you do not have enough time steps, then you may have missed the time step at which the impact happens. A few pointers to remember:nIf you wish to model the bullet piercing the plate, then you need to define element erosion so the failed elements will be removed and allow the bullet to go through the plate.nIf the stress/strain generated is not high enough for the elements to erode, then check if the erosion criteria are defined properly.nAlso, make sure that the initial velocity of the bullet is large enough to overcome the rebound forces and generate stress/strain that is large enough for element erosion to kick in.n