Abstract
In this paper, we present a parameter-free free-form optimization method for weight reduction in the strength design of shell structures A volume is minimized under inequality constraints of von Mises stress The optimum design problem is formulated as a distributed-parameter shape optimization problem under the assumptions a shell is varied in the out-of-plane direction to the surface and the thickness is constant The local inequality stress constraints are transformed to an integral equality constraint The shape gradient function and the optimality conditions are derived using the material derivative method, and applied to the free-form optimization method With this method, the smooth optimal free-form of a shell structure is obtained without any shape design parameterization while minimizing the volume and satisfying the stress constraints The validity of this method is verified though a design example
