Ibrahim Stracey

Development of a Small Punch Test rig for embrittlement testing of metallic materials
Machine components in service suffer from various forms of damage causing environments which invariably result in the degradation of the component’s life cycle. This can result in component failure if not addressed in time. Due to this, many machine components’ life cycle is estimated as conservatively as possible to avoid the possibility of unforeseen failure. This results in many parts being replaced long before they reach critical failure, resulting in unnecessary costs. It is therefore useful to know, with a higher degree of accuracy, the approximate life cycle of critical components.

Current methods of life cycle estimation use conservative calculations to account for potential part degradation. Large samples can be taken from a specific part in service to assess its level of degradation by conventional mechanical testing which can be used to inform the life cycle estimation. This process is however typically destructive, which compromises the component life. It would therefore be useful to be able to take samples of negligible size from a part in service and perform tests on it, allowing one to further assess the damage a part has sustained, without affecting the part from which the sample was taken.

The Small Punch Test method for material testing has been developed previously using various correlation techniques. This project will focus on finalising the technique by incorporating Digital Image Correlation to identify crack initiation to a higher degree of accuracy, thus making the SPT technique more feasible. A stand-alone rig will be designed and built which will allow a greater degree of freedom when designing the SPT, and therefore ensure a more accurate test can be performed. All the data from the rig will be combined into a single interface for ease of use using various control systems.