A NOVEL PROJECTION BASED METHOD FOR IMPOSING MAXIMUM LENGTH SCALE IN TOPOLOGY OPTIMIZATION

During the past decades, various topology optimization methods have been developed to design the optimal structure in many fields such as mechanical engineering, aerospace and electromagnetism. However, the optimized topologies are often considered as conceptual because they ignore the manufacturing constraints in the topology optimization model. As one of the important manufacturing constraints, a great effort has been devoted to the issue of length scale control which includes minimum length scale control and maximum length scale control in topology optimization. In this paper, a novel projection based method for imposing maximum length scale in topology optimization is presented. In this method, a new penal formulation for the density of the center element which violates the maximum length scale constraints is proposed and the maximum length scale control can be achieved without additional constraints. Furthermore, a combination of the new method and the robust formulation which is able to control the minimum length scale is realized by changing the penal formulation into a global constraint. By this way, simultaneous control of the minimum length scale and maximum length scale is achieved. Some numerical examples that consider the length scale control in topology optimization are presented to show the validity of this method.