Real-time quantification of damage in structural materials during mechanical testing

A novel methodology is introduced for quantifying the severity and morphology of damage created during testing in composite components. The method utilises digital image correlation combined with image processing techniques to monitor the rate at which the strain field changes during mechanical tests. The methodology is demonstrated using two distinct experimental datasets, a ceramic matrix composite specimen loaded in tension at high temperature and nine polymer matrix composite specimens containing fibre-waviness defects loaded in bending. The changes in the strain field due to damage creation are shown to be a more effective indicator that the specimen has reached its proportional limit than using load-extension diagrams. The technique also introduces a new approach to using experimental data for creating maps showing the spatio-temporal distribution of damage in a component. These maps indicate where damage occurs in a component, its morphology and the time of occurrence. This presentation format is both easier and faster to interpret than the raw data which, for some tests, can consist of tens of thousands of images. This methodology has the potential to reduce the time taken to interpret large material test datasets whilst increasing the amount of knowledge that can be extracted from each test.