Fatigue life prediction of polymer-matrix composites using fracture fatigue entropy concept

Fatigue testing of polymer-matrix composites (PMCs) is traditionally conducted at low frequency range (below10 Hz), resulting in long testing durations and increased expenses. A viable strategy is to accelerate fatigue testing at higher frequencies within a feasible time duration. However, at higher frequencies, the self-heating effect becomes a critical factor, affecting the structural response and potentially altering the fatigue behaviour. The entropy-based thermodynamic framework effectively captures the impact of self-heating and improves fatigue response analysis by incorporating the correlation among heat dissipation rate, applied stress, and loading frequency. Unlike the conventional S-N curve methods, which may skip the self-heating effect, entropy-based models provide a rapid and more general assessment of fatigue behaviour under arbitrary applied stresses and frequencies. This study focuses on the application of entropy-based modelling to capture the complex interplay between stress, frequency, and temperature rise. This allows for predicting the life of a fatigue-loaded PMC specimen by accounting for the interplay between mechanical loading and thermal effects. The proposed framework provides a rapid methodology for characterizing the fatigue performance of PMCs, playing a key role in refining the structural integrity assessment of PMCs.