A novel characteristic curve for failure prediction of multi-bolt composite joints

A novel characteristic curve determined by tensile, compressive and shear-out characteristic length is presented to predict failure load and failure mode of mechanically fastened composite joints. In contrast to the existing curves, the novel one introduces a shear-out characteristic length and provides capability to predict shear-out failure. A mathematics formulation of the novel curve is proposed based on the expression of Chang's characteristic curve and shear-out characteristic length. A series of tests were carried out and nonlinear finite element analyses were conducted to obtain the tensile, compressive and shear-out characteristic lengths for the novel curve. Following tensile tests of two-bolt and three-bolt joints were performed, and the failure loads and modes were numerically predicted by the characteristic curve method with the novel curve and Chang's. The numerical results obtained from the curve presented show good agreements with the experimental outcomes and better accuracy on both failure load and failure mode.