Micro-fatigue test - A new dimension towards cyclic load test for interface characterisation

The quality of fibre-matrix interphase is commonly characterised via microscale testing methods that show good sensitivity for differences in properties of the interphase. Most approaches focus on quasi-static performance, which while valuable, does not provide all the necessary information needed for characterising the performance of the interphase in real use cases. This paper presents a novel cyclic test approach based on the microbond test concept that provides statistically reliable fatigue data from micro-composite samples. A reasonable throughput is achieved by using relatively high strain rates, which needs to be considered in the analysis. This paper offers insights into the advantages and disadvantages of the approach through comparison with quasi-static experiments. As expected, the results show a clear strain rate dependence but otherwise fit the expected behaviour of a fatigue test. More than 30 droplets were measured per sample for varying number of cycles ranging from 1 to 10 ⁶. Based on the results, the method offers a novel, relatively high throughput approach for dynamic testing of microcomposite samples with applications for studying the dynamic behaviour of the composite interphase.