Aircraft Connectors Detailed Stress Analysis And Optimization Of The Design Study

Due to the design requirement and the limitation of aircraft manufacturing, joints are unavoidably needed for the connections of different assemblies and internal forces pass and distribution. The around-hole vicinity of joints is one of stress concentration source, and prone to leading to structural strength and fatigue failure. Therefore, it is essential for the design and life improvement of the joints to carefully study the detailed characteristics and stress distribution around hole of the joints.Joint connection manifests typical nonlinear contact mechanical feature, which makes it complicated to analyze the stress distribution at this region. This thesis apples finite element (FE) method and computational software to build the numerical model of the joints, and refines the mesh and boundary of joint hole-area by FE sub-model technique. Some refined around-hole stress distribution results are obtained numerically with aid of the FE technology and computation.The real-world joints in the aircraft structure usually consist of multi-row fasteners. This thesis builds the 3D FE contact analysis model of a typical aircraft joint with three-row countersunk screws, and studies pin-load distribution and stress characteristics under constant and varied cross-section thicknesses as well as with and without pre-tighten screw conditions for the joint. Many applied pin-load numerical distribution laws for different conditions in the joint are recognized.The thesis also applies FE sub-model and numerical optimization design techniques to conduct the cross-section configuration optimization for the wing's joint of some unpiloted air vehicle project, with the light weight objective and the balance of pin-load distribution at each row screws, which lays an excellent design foundation for reducing the around-hole stress concentration and its life improvement. Based on foregoing work, through 2D sub-model access and numerical analysis, more refined around-hole stress distributions are obtained. This research work reaches the dual destinations of decreasing the joint weight and the stress concentration, and provides some significant conclusions for engineering practice.