Analytical studies and numerical predictions of stresses in shear joints of layered composite panels for aerospace applications

Composite laminated structural members are joined to the neighbouring parts using mechanical fastening. The segmented composite motor case for solid rocket boosters is one of the typical examples where such a joint could be adopted effectively, in which segmentation of pressure vessels is essential to use such a joint. Design analysis of such a joint is made for assessing the load transfer mechanism among shear bolt rows, and a fitting factor is derived. The fastened joint is observed practically more reliable than bonded joints due to inherent bond quality issues. An analytical model is generated taking care of variation of laminate stiffness along bearing surface with consideration to vary the stiffness of laminates along the circumference using two layup sequences of Carbon Fibre Reinforced Polymer. Cutting of fibres around the shear hole causes strength properties to reduce significantly, around the drilled holes. Finite Element (FE) analysis is performed using ABAQUS to support the joint design and predict the propagation of damage using Tsai-Wu theory. The current study is to understand the stress conditions around the shear hole and check the proximity of FE predictions with analytical calculations on trends of stress components along the contact surface of each ply orientation.

Automated summary

Composite laminated structural members are mechanically joined to neighbouring parts for reliability. Design and finite element analysis are essential in assessing joint design and predicting damage propagation.