Light Aircraft Main Landing Gear Design and Development

The need for lightweight, high performance flying machine has today shifted the emphasis from the use of conventional advanced metallic materials to that of composites. High specific strength and stiffness characteristics coupled with techno economic feasibility are a password to the acceptability of any material in aircraft construction. This paper presents an approach for “Design; Analysis; of a Main Landing Gear of an Aircraft” made of advanced composites materials using advanced CAE tools and techniques. In this paper, first of all, functional specification of the part has been specified. General principles of composite design were followed in arriving at suitable designs. In the design phase using the FEA tool ANSYS 5.7, starting form shape and wall construction, choosing a proper element type, loadings, constraints, materials and behavior modeling have been done. Various constants and lamination parameters were used to define the element. In the development phase, a rigorous non-linear stress and buckling analysis was carried out for the part. The Finite Element Analysis software ANSYS was used for this purpose. Various experimentations were done using different combinations of loads and orientations. The most significant feature of the analysis was perhaps the thickness and orientation optimization with buckling, stress and different failure criteria. This optimization was the key to utilize the directional properties of the laminated composites. Tsai-Wu laminated failure criterion and Maximum Stress Failure Criterion had been specified. Results such as stresses in layer coordinate system, deflections, failure index had been determined. A true assessment of the critical regions in the part was made so as to predict the behavior of the gear at extreme landing conditions. It had been made sure that all stress values lie well within the limits. A margin of Safety was determined for each combination. Finally design was optimized and conclusions were drawn.

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