On optimal physically nonlinear trusses

Optimization problems for physically nonlinear hyperelastic trusses statically loaded by a single system of loads are investigated. Several possible formulations of the problems for a prescribed truss layout are considered. It is demonstrated that the problems lead to the design of equal absolute stress values in some rods and of active technology constraints in other rods. Some general properties of the trusses are examined. Optimal physically nonlinear hyperelastic truss layout problems under static loading are also considered. It is shown that the well-known results of Maxwell, Michell and Prager concerning linear-elastic structures are generalized for the considered problems. It is demonstrated that the results of the paper are extended to optimization problems for structures in stationary creep with an arbitrary concave stress-strain velocity relation.