An investigation about interference fit effect on improving fatigue life of a holed single plate in joints

In this article, the effect of interference fit on fatigue life of holed plate of mechanical joints was investigated both experimentally and numerically. In the experimental part, fatigue tests were carried out on the holed specimens of Al 7075-T6 alloy in which oversized steel pins were force fitted to them. These fatigue tests were conducted on open hole specimen and specimens with 1, 1.5, 2 and 4% nominal interference fit sizes at different cyclic longitudinal loads. From these tests the stress-life (S-N) data for different interference fit sizes were obtained. The results show that interference fit increases fatigue life compared to open hole specimens. In the numerical part of the investigation, 3D finite element simulations have been performed to obtain stress (or strain) histories and distributions around the hole due to interference fit and subsequent cyclic longitudinal loading using FEM package. The stress history from finite element (FE) simulation was used to explain the reason for fatigue life improvement in the interference fitted specimens. © 2010 Elsevier Masson SAS. All rights reserved

Investigation of the fatigue life and crack growth in torque tightened bolted joints

The fatigue crack initiation and fatigue crack growth life estimations have been numerically investigated and the total estimated fatigue lives have been compared with available experimental fatigue test results for a single plate of aluminum 7075-T6 bolted with different applied torques. To do so, pre-stresses around the hole due to the torque tightened bolt and stress concentration factor of the combined longitudinally applied load and bolt clamping force were determined using 3D finite element simulations results. The calculated pre-stresses and stress concentration factors for different bolt clamping forces were employed in AFGROW computer package to predict fatigue crack initiation and fatigue crack growth lives. The results show that there is good agreement between the numerically predicted total fatigue lives and available experimental fatigue test results. The numerical results also show that bolt clamping force increases both fatigue crack initiation and fatigue crack growth lives individually. © 2010 Elsevier Masson SAS. All rights reserved