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The progressive failure analysis of composite bolted joints under thermal environment has been investigated using the finite element method. The emphasis has been on the computational aspects of the problem. The ultimate failure loads and pin-bearing stresses have been computed using different failure criteria and the results have been compared with the experimental data as published in the open literature. In reality, bolted joints have been employed to various situations where the amount of load to be transferred is relatively high and on many occasions thermal effect is an important consideration. So the effect of material property degradation due to temperature has also been considered in this investigation. Progressive damage analyses have been performed for different laminates to give complete load-deflection path beyond failure load that will serve as a future reference. The pin has been modeled as a rigid object and load has been imparted on the structure as a displacement-controlled process to simulate the experimental situation in the laboratory environment. Contact between the bolt and the laminate has been considered in the analysis. A number of “User Subroutines” for ABAQUS software have been developed to incorporate Hashin, maximum stress, and Tsai-Wu failure criteria in the analysis. The effectiveness and performance of various well-known failure criteria as mentioned above have been evaluated and the results have been presented in graphical form.

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Composite stiffened shells have been analysed with the help of two dif ferent elements—a nine-noded Lagrangian isoparametric element and the Heterosis ele ment. Both the elements have the advantages of accommodating curved boundaries and in corporating shear deformation. In the formulation, the stiffener need not be placed along the nodal line as it takes care of the placement of the stiffener anywhere within the shell element. This makes the modelling more flexible. Concentric and eccentric stiffened com posite shells have been analysed with the help of these two elements. The results obtained on the basis of these two have been compared. Parametric studies of the different variables have been conducted.

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