| A systematic topology based approach is developed for optimal stiffener design of three dimensional shell/plate structures. As one major type of stiffener, bead pattern design, which involves the determination of bead location as well as bead orientation, is investigated in both static and dynamic problems. The bead location problem is solved by a stiffener layout optimization method, which is based upon a micro-structure composite model. The optimal bead orientation problem is carried out by solving its equivalent orthotropic material orientation problem, in which a new method called energy based method is proposed. Two existing methods, the strain based method and the stress based method, are also discussed and some new found theoretical results are presented.; Optimal stiffener configuration is also investigated in vehicle structures in order to minimize the interior sound level. To accurately model the system, a coupled acoustic-structure system is considered and model analysis method of the coupled system is used to evaluate the interior sound level. Both modal sensitivity analysis and frequency response analysis of coupled system are discussed in details. The topology optimization problem is formulated and solved using mathematical programming approach. |
