3D multi-material and multi-joint topology optimization with tooling accessibility constraints

This paper proposes a method for performing both multi-material topology optimization and multi-joint topology optimization. The algorithm can determine the optimum placement and selection of material while also optimizing the choice and placement of joint material between components. This method can simultaneously minimize the compliance of the structure as well as the total joint cost while subjected to a mass fraction constraint. A decomposition approach is used to break up the coupling between optimum structural design and optimum joint design. Multi-material and multi-joint topology optimization are then solved sequentially, controlled by an outer loop. By decomposing the problem, gradient-based optimization algorithms can be utilized, enabling the algorithm to solve large computational models efficiently. The proposed process is applied to three 3D standard TO problems. Through these example problems, the need for an iterative process is demonstrated. Improvements to joint manufacturability using the tooling and stress constraints are discussed. Finally, a review of computational cost is performed.