Integrated design of landing gear clevis joints

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SPP Canada Aircraft Inc. (SPPCA) is a wholly owned subsidiary of Sumitomo Precision Products (SPP) that has opened up a landing gear division in Mississauga, Ontario in April 2012. SPPCA is involved in engineering, design, procurement, assembly, sales & marketing and customer support for commercial landing gears and systems. Currently, SPPCA is focused on expanding its capabilities and has a strong desire to increase its R&D activity. Of the total landing gear weight, approximately 80% is comprised of major structural joints, such as clevis joints. A landing gear clevis joint typically consists of a number components including lug, socket, bushing and pin. The joint design involves the determination of the dimensions of these components based on contact mechanics. The current sequential joint design procedure is time and cost intensive as it must be iterated a number of times before a joint can be sized. This design drawback has affected the company's competitiveness. Therefore, the company has approached Ryerson to investigate an integrated design method that can combine all contact problems together and solve them simultaneously. In this project, the underlying design problem is formulated as a design optimization problem. The objective function is to maximize the strength to weight ratio of the joint. Design variables include joint geometry, component sizes and materials. Required analyses are treated as constraints covering static contact stress, dynamic contact stress (related to fatigue), and shear stress due to friction/slip motion. Commonly used search methods, such as Generic Algorithms, will be applied to solve this problem. Program validation will be carried out against the results of the same design achieved by a commercial package. With the development of a cost-effective design tool that can reduce in design turnaround time, the company will become more competitive for contract