Bidirectional evolutionary optimization design of material stiffness for the uniformity of the contact stress

An investigation into the material stiffness design for enhancing the uniformity of the contact stress is conducted in this paper. A bidirectional evolutionary optimization design approach for interface material stiffness is developed, in which the standard deviation of the contact stress is defined as the objective function and the Young's modulus is treated as the design variable. A design case of a single bolted joint verifies that the proposed bidirectional material stiffness optimization approach can effectively improve the uniformity of the contact stress. A region-averaging treatment is proposed as the post-processing of the optimized Young's modulus distribution to make the optimized structure more manufacturable. The capabilities for homogenizing the contact stress distribution with various geometry sizes are addressed. A comparison study with the interface shape optimization indicates that with nearly the same improvement of the standard deviation of the contact stress, the material stiffness design around the contact region is more effective on enlarging the effective contact area and is much more computationally efficient than the interface shape optimization.