Design of an impact loading machine based on a flywheel device: Application to the fatigue resistance of the high rate pre-straining sensitivity of aluminium alloys

This paper presents a device that has been designed for tensile loading at medium impact rates ( up to 103 s(-1)) and for performing either interrupted or failure tests. This machine allows us to apply prescribed pre-straining to the specimen, and then apply subsequent loading histories such as impact fatigue. Two specimen loading systems are considered, which make it possible to carry out tests with various ranges of force and various durations of time. A multi-CCD camera system is triggered by a chosen threshold from the force signal. The system is dedicated to the displacement measurement and gives both qualitative and quantitative information about the stretching mechanism leading to fracture. To illustrate the performance of the device, experimental results concerning impact tensile tests at a strain rate of about 300 s(-1) are presented, as well as consecutive impact-fatigue tests on two aluminium alloys.