I have a problem with the contact interface while simulating a ballistic impact problem, having a 30

I have a problem with the contact interface while simulating a ballistic impact problem, having a 30mm armor-piercing projectile impacting a 40mm RHA steel plate. Both the projectile and the armor plate is following the JC material and the JC failure model. So when it starts to penetrate the armor plate, the failure model elements are deleted, but after some time these elements are not deleted as the projectile is getting deformed. So as a result when it comes out from the other side there are some failure model elements are still presenting inside . so what will be the resason behind it . all the three parts are modelled by hexahedral elements and projectile is assigned as slave node and armour plate is assigned as master node using type 7 contact interface.