The design of laminates with given thermal/hygral expansion coefficients: A general approach based upon the polar-genetic method

The problem of finding laminates having null thermal and hygral expansion or curvature coefficients is addressed in the paper, as well as the case of laminates having an isotropic response to thermal or moisture variations. The main feature of this research is the fact that the problem is treated and solved in the most general case: no simplifying hypotheses are made about the type of the stacking sequence, and the design procedure can also take into account elastic properties of the laminate, such as orthotropy, uncoupling and so on. The authors state the problem as a nonlinear programming problem, where a unique objective function includes all the requirements to be satisfied by the solutions. The nonlinear optimisation problem is stated and solved in the framework of the polar-genetic approach: the formulation is a function of the laminate polar parameters, while a genetic algorithm is used as numerical solving technique. A large number of numerical results are shown in the paper.