Numerical Simulation and Experimental Study On Non-Axisymmetric Spinning With a Groove At The Middle of The Tube

Spinning is widely used in aerospace and automobile industries, and non-axisymmetric spinning is developing with the increasing demand of irregular shape forming. Based on this, an avoidance groove at the middle of the tube (AGMT) which has potential application value in aircraft structure weight reduction is proposed and formed by using non-axisymmetric die-less spinning. The roller path is analyzed. The relationship between radial displacement of roller and the rotation angle of the tube is deduced. Based on the roller path, 3D finite element model is established. Then, the AGMT spinning experiment is carried out to verify the simulation results. The maximum deviation between the simulation and experimental results is less than 15%. It is indicated that the 3D finite element model established in this study is reliable and the method for the AGMT forming is feasible. The wall thickness and strain-stress distributions are analyzed. The severe wall thicken and thinning occur in the transition zones, so more attention should be paid to these positions. The depth of the groove has great impact on the forming quality. Deeper groove results in distortion and larger wall thickness difference. The research laid a foundation for the further development and optimization of the AGMT spinning.

Thermal Influence on the Stiffness of Hybrid Metal-Composite Countersunk Bolted Joints

This paper presents the effects of temperature on the axial stiffness of a hybrid metal-composite countersunk bolted joint designed for the bearing failure mode. A detailed 3D finite element model incorporating geometric, material and friction-based full contact nonlinearities is developed to numerically investigate the temperature effects on joint stiffness. In order to validate the temperature effects, experiments were conducted using an Instron testing machine coupled to a temperature controlled chamber. The results showed that the temperature effects on axial joint stiffness were quite accurately predicted by the 3D finite element model, denoting a reduction in the stiffness of the axial joint with an increase in temperature for hybrid metal-composite countersunk bolted joints.