William Elliot Bachrach

Effective mechanical properties strategy for modal analysis and optimization of composite structures

Abstract Many effective mechanical property models exist in the composite structural design and analysis community for approximating the ply layers and different ply orientations through the local cross-section of a composite structure. Either from a global or a local design environment, it is shown that effective mechanical property models formulated independently of ply stacking sequence in the laminate are sufficient for determining the modal frequencies of a geometrically complex structure. By using these models, the modal analysis-optimization design cycle time is significantly reduced. The optimization procedure presented here determines the different ply orientations necessary in a laminate to achieve a desired frequency requirement. The effective mechanical property models presented are used in the frequency analysis and ply orientation optimization of a composite beam and a composite engine fan blade and the modes determined from each model are compared.