A probabilistic model for strength analysis of composite double-lap single-bolt joints

A probabilistic model involving the randomness of basic design parameters was presented to predict the probabilistic strength of a typical composite double-lap single-bolt joint. In the probabilistic model, statistical models of the random parameters including geometrical dimensions, fiber orientation angles and material properties were constructed. In addition, a parametric failure prediction model employing a modified characteristic curve method was established. Static tensile tests of fifteen composite double-lap single-bolt joints made of T800 carbon/epoxy composites were carried out. The probabilistic failure load of the joint obtained from the proposed model is in good consistency with that from the experiments, which verifies the effectiveness and accuracy of the proposed model. Meanwhile, it shows that the proposed model is not sensitive to the probability distribution type of random variables, although the probability distribution type of random variables slightly influences the statistical parameters of the probabilistic failure load. Furthermore, a relationship between the failure probability and the tensile load is determined, and longitudinal compressive strength X_C, ply thickness t_ply and longitudinal elastic modulus E₁₁ of T800 unidirectional lamina are the key factors affecting the probabilistic failure load and reliability of the joint remarkably.