| Abstract: | Flat uniform specimens were cyclically bent over formers. At room temperature two strain ratios were used, R = −1 and 0, i.e. reversed symmetrical and asymmetrical strains, respectively, the strain ratio being defined as the ratio of the minimum to the maximum strain in a cycle. The increase in the value of the strain ratio was found to decrease the fatigue life of the aluminium alloy and to increase it for the stainless steel. For room temperature tests and at R = −1, the bending moment at maximum strain was found to increase in the early part of the test and was then followed by a decrease until fracture occurred, whilst for R = 0 a continuous decrease occurred throughout the tests. The effect of test temperature on fatigue life was found to be considerable and throughout the tests at elevated temperature the cyclic bending moment decreased. |
