Given the constitutive equation below: ; = ; + 2 Express the principal strain invariants in terms of the principal stress invariants. a) tr(e) =&jij b) 1 = [(tr(e)) - tr ()] = [kjj - kij&j] c) 13 = det(o)= ijk12j3k Note: Stress invariants are the ff: I = tr() 1 = [(tr(a))* -tr(ij)] I = det(ij)