Study on the stress intensity factor of a compact specimen under the pre-compressed load condition

Structural components are often operated under combined stress conditions (primary and secondary stresses), but the stress levels generated by residual stress (or secondary stress) is hardly ever evaluated. Hence, stress intensity factors at the crack tips of a compact tension (CT) specimen under a pre-compressed load condition are analyzed using the finite element method. Then, the average residual stress intensity factor is calculated and analyzed. As the crack length a 0 /W increases, the average residual stresses σ ave /σ 0 grows under the same pre-compression load. σ ave /σ 0 increases rapidly at a low range of the pre-compression load but tends to a constant in a high range of the load. The distribution of the average residual stress intensity factors K ave and σ ave /σ 0 of the CT specimen with same crack length under different pre-compression loads have the same tendency. Additionally, the distribution of K ave and K FEM under different pre-compression loads are also similar. Nevertheless, K ave estimated by the average residual stress is too conservative and not accurate, and the method is complex, which depends on the analysis of simulation. Therefore, a simple method for calculating Mode I stress intensity factor K for this model is presented. A group of examples is presented to verify the accuracy of the method.