The influence of temperature gradient thermal shock cycles on the interlaminar shear strength of fibre metal laminate composite determined by the short beam test

The paper presents research on the interlayer adhesion of fibre metal laminate composites in a 3/2 configuration made of 0.4 mm thick 2024-T3 ALCLAD aluminium sheets. A polymer-fibrous layer is used to make a prepreg based on glass fibres with a thermosetting epoxy matrix. Experimental research presented in this paper was aimed at determining the impact of thermal shocks on the mechanism of composite destruction in the three-point-bending test. The samples were subjected to 100 °C temperature gradient thermal shocks in the form of cyclic temperature changes in the range of −40 °C and +60 °C. The number of cycles was 500 and 1000, according to the specific variant. The damage characteristics were observed by Scanning Electron Microscopy to assess failure modes. Samples subjected to thermal shocks are characterised by lower stiffness in relation to samples not exposed to repeated thermal shocks. It was found that both the failure mode and interlaminar shear strength depend on the number of thermal shock cycles. Under the influence of cyclic temperature changes in the test samples, metallic layers undergo cyclic expansion and shrinkage while the layer of fibre-reinforced composite with relatively low thermal expansion does not undergo large deformations.