stress-strain curves in nonlinear analysis

i am trying to do nonlinear analysis in CWAP and the resultskeeps going linear.

upon some research in solidworks on "how to input stress-strain"curves in cosmos, it says that i am to input in a "stretch ratio"rather than strain. could this be why cosmos is just rejecting myinput?

also, if the FEA analysis goes beyond my stress strain curve that Iinput, what happens? does it just extrapolate the curve?

any help would be greatly appreciatedSolidworksSimulation