The Effect of Fiber Breakage Caused by Transient Shear Stress Distribution in Single-Lap Adhesive Joint Composite Material

In this research, the transient shear stress distribution in an adhesive joint due to fiber breakage has been investigated. Transient stress is a dynamic response of the joint to the fiber discontinuities till their static equilibrium state. To study this behavior, equations governing the motion of fibers in the matrix, due to their breakage, are derived and the effect of number of broken fibers is studied on transient response of the structure. Shear lag model is used to extract fiber displacement. The equilibrium equations are solved using the explicit finite difference method. The effect of fiber materials and adhesive thickness is also studied on stress distribution. Results show that for an increase in the number of broken fibers, the stress concentration in the composite structure increases. Moreover, the shear stress created in the matrix and the adhesive layer is reduced with an increase in fiber elastic modulus, such that for glass and graphite fibers (E=74 and 130 GPa respectively), the maximum shear stresses in the adhesive are 0.861 and 0.461 MPa, while in the adherends, they are equal to 3.192 and 2.409 MPa respectively.