Fatigue Life Evaluation of Single and Two Riveted Coach Peel Joints Using Strain-Life Criteria

In the present paper, an experimental investigation was carried out to estimate fatigue life of single and double riveted coach peel joints of 2024 aluminum alloy. Load controlled fatigue tests were conducted with load ratio and frequency of 0.1 and 10 Hz, respectively. Observations on failure of coach peel specimens revealed three major failure modes of folded region fracture (A-type), fracture from edge of the rivet hole (B-type) and mixed mode fracture (both of A & B). Although all failure modes contributes equally in single riveted joint, mixed mode fracture was observed as dominant mode in two riveted ones. A numerical approach is applied to estimate fatigue life of single and two riveted coach peel joints. Finite element analysis was performed by ABAQUS commercial software as the first step of this numerical approach in order to estimate stress distribution, stress concentration factor, stress and strain amplitude. Fatigue lives of the coach peel joints were then calculated using three fatigue life theories of Monson-Hirschberg (MH), Smith-Watson-Topper (SWT) and Morrow. Finally, good accordance between numerical and experimental results revealed that the finite element approach combined with fatigue life theories is capable for fatigue life prediction of coach peel joints. It is also concluded that adding a rivet in longitudinal direction to the single riveted coach peel joint decreases the life cycles by increasing the stress concentration factor. Moreover, results of finite element approach showed that Monson-Hirschberg and experimental data has the best agreement in compare with SWT and Morrow.