The effect of typical flight temperatures on the fatigue behaviour of Al 7075-T6 clamped plates

In this research work, fatigue behaviour of aircraft structural bolted plates at typical working temperatures has been studied. A holed plate of aluminium alloy 7075-T6 was clamped with the purpose of subjecting to both flight representative temperatures and longitudinal cyclic loadings simultaneously. In order to investigate the effect of the service temperature on the fatigue life of both lightly and firmly bolted plates, six different batches of specimens were considered. The specimens were clamped with two different tightening torques and then fatigue tested at ambient (25 °C), low (−50 °C) and high (60 °C) temperatures. The obtained results revealed that the fatigue life of the clamped plates significantly improved when the temperature was lowered to −50 °C. However, the fatigue behaviour of the clamped plates at 60 °C is different compared to ambient temperature depending on the amount of applied clamping force.