The effects of partial surface shot peening on the fatigue crack growth behaviour of a ferritic steel have been experimentally investigated in this paper. Dog‐bone specimens fabricated from Optim700QL were tested under tension‐tension fatigue loads. Three distinct extents of partial shot peening, with respect to the crack tip and specimen symmetry line, were tested. The fatigue crack growth results from these experiments have been compared with those obtained from the same specimen geometry but with no peening. The results show that the residual stress fields formed ahead of the initial notch tip due to the partial peening process play a significant role in the fatigue crack growth behaviour of the material and effectively result in accelerated crack propagation at the midwidth of the specimens. It has been shown in this study that partial peening can lead to a fatigue crack growth rate around twice as fast as that of the unpeened specimen.

The effects of partial surface shotless peening on the fatigue crack growth behaviour of a ferritic steel have been experimentally investigated in this paper. Seven fatigue tests were performed on 4-point bend specimens fabricated from 700 Optim QL high strength steel. Three distinct extents of partial cavitation shotless peening, with respect to the crack tip and specimen symmetry line, were applied on the specimen geometry. Alternating Current Potential Difference (ACPD) was used to measure and monitor the crack depth during fatigue tests. The tests on partially surface peened specimens were conducted under two different load levels.The fatigue crack growth results from these experiments on partially peened specimens have been presented and compared with the results from an additional test on an unpeened specimen.The results show that the residual stress distribution fields formed due to the peening process play a significant role in the fatigue crack shape evolution, crack retardation and crack propagation behaviour of the material.

Aluminum alloys have a wide range of applications, such as the aerospace and automotive industries. The effect of V-notch on fatigue life of cylindrical beam made of aluminum alloys under rotating bending fatigue load has been investigated experimentally and numerically. The experimental work involved the tensile strength, hardness, impact test, and fatigue life behavior at room temperature. The fatigue life test was conducted with a fully reversed cycle with a mean stress ratio (R= -1). The experimental data were compared with the numerical result, and a good agreement was found. The results show that the notch has reduced the fatigue life of aluminum alloy beams.

In the present investigation, the fatigue life detection of composite material by adding copper particle of about than 25 μm diameter with 5, 10, 15 % volume fraction, as a reinforcements into the unsaturated polyester polymer composite material on fatigue life detection of composite material were studied experimentally and numerically. Composites were made using hand lay-up technique and evaluated for mechanical and fatigue properties in accordance with ASTM standards. The experimental results of the tensile test showed that adding 15% of copper particle in unsaturated polyester gives maximum ultimate tensile stress. Fatigue tests including test rod specimens made of composite materials under completely reversed cyclic loading in a rotating cantilever reversed bending machine. It is found that, the fatigue life and fatigue strength increase with increasing in the copper percentage volume fraction in unsaturated polyester resin compared with pure polyester composites. The experimental work was compared with numerical work, which was done by using ANSYS/19 and good agreement has been found. The maximum overall difference between the experimental and numerical work was around 9 %.