Structural design of aircraft skin stretch-forming die using topology optimization

This paper demonstrates a topology optimization method for the large scale stretch-forming die design. The implementation of the topology optimization depends on the surface loads obtained from the numerical simulation of the sheet metal stretch-forming process. Typically, the design variables are defined based on a linear interpolation to generate directional structures satisfying the manufacturing requirement. To further validate the design procedure, mathematical derivations have proved that the design sensitivities are strictly continuous. More explanations and numerical tests are presented to show the variation of the surface loads versus the stiffness of the die. A stretch-forming die design example is solved on account of gravity and surface loads. The final solution is compared with the traditional design. The numerical results have shown that the topology design can improve the stiffness and strength of the stretch-forming die significantly.