A novel model to predict the mechanical behavior of single-lap composite joints

In the present research, using a micromechanical approach, a novel analytical method was developed to predict the stiffness and damage initiation load of single-lap composite joints. The elastic and strength properties of fiber and matrix were used to characterize the elastic and strength properties of unidirectional composites. Based on the layup and geometrical parameters of the single-lap joint and using a nonlinear spring-mass model, the stiffness of the joint was predicted. Then, by defining the stress concentration factor and using the maximum stress failure criteria, the damage initiation load of the single-lap composite joint was predicted with a good accuracy. This model was used to simulate the mechanical behavior of single-lap joints with layups 〖[-45/0/45/90]〗_s and〖[90/〖-45〗_2/45]〗_s. Composite joints with these two layups were manufactured and tested. A comparison between the results of the model and experiments shows maximum errors of 2.17% and 3.91% for joints with these two layups, respectively.