SYSTEMATIC CREATION OF COMPOSITE STRUCTURES WITH PRESCRIBED THERMOMECHANICAL PROPERTIES

A computer program system for creating composite structures with prescribed thermomechanical properties is presented. The solution of this type of problem can be called the solution of an inverse problem. The problem is formulated as a constrained nonlinear minimization problem where ply orientations and/or ply thicknesses can be used as design variables. The objective function and the inequality constraints are derived from the classical laminate theory. Two nonlinear optimization algorithms have been used as tools in solving the problem. Thus far, the program system developed can be used to obtain prescribed values (or minimum/maximum values) for the following properties: in-plane and bending stiffnesses, coefficients of thermal expansion, strains and curvatures due to in-plane forces and moments or due to lateral pressure in a laminated plate, strength, buckling loads and eigenfrequencies.