I'm trying to figure out the effective strain of a frictionless punch on a deep plate. For simplicity's sake let's say it's in plane strain. Don't quite know where to start. Closest thing I can think of is the strain from a bulge test, but that involves a thin sheet. Looked at some indentor (Vickers, Brinell etc.) strains also, but these might not be applicable, since the indenter does not travel that far into the workpiece. I also looked at some of the literature concerning ballistics but they don't really report strain or how they calculated it. I feel like there's something very simple that I'm missing here. I'd be grateful if someone could put me on the right path.