Optimization of dynamic behaviors of an orthotropic composite shell subjected to hygrothermal environment

Dynamic responses of an orthotropic plate subjected to hygrothermal environments have been optimized. Non-gradient evolutionary genetic algorithm (GA) is employed to optimize dynamic behaviors of orthotropic composite. Presented optimization scheme, whose approach is advantageously conducted in conjunction with FEA, involves controlling locally fiber directions from element to element. The geometry is discretized into specially developed 3D shell composite elements which are able to handle hygrothermal effects of our own design. Shell, rather than plate, elements enable one to reliable account for features such as membrane and bending stress variations through the plate. By using the specially developed shell element, dynamic deflection and natural frequency are minimized by optimizing design variables which are local fiber directions within discrete finite elements. Since fiber orientations are optimized locally within a plate, the technique provides more than just a favorable ply angle of fiber reinforced rectilinearly orthotropic plate. Results presented, not available so far, could be useful to ascertain the effects of locally varying fiber direction on dynamic analysis under temperature and humidity boundary conditions.