Nonlinear constitutive behavior of orthotropic materials

The problem of optimal material orientation is studied in the case of nonli near elastic materials. Optimal orientations corresponding to extreme (maxi mal or minimal) energy density are obtained for orthotropic materials. The material behavior (the stress-strain relation) is simulated in a general fo rm, which includes, as particular cases, different versions of the power la w stress-strain relations. The optimality conditions are derived for the ge neral cases. Local and global extremums are determined for particular cases .