Fatigue Behavior of Joule-cured and Oven-cured Carbon/Epoxy Laminates: a Generalized Additive Model Analysis

Abstract

[Abstract]: Joule (resistive) heating is a promising alternative to conventional oven curing for carbon/epoxy composites because it provides fiber interior heating and can reduce cycle time and energy consumption. From a fatigue perspective, however, the influence of the curing route on long-term mechanical performance is less understood. Here we compare the fatigue response (three-point bending load versus cycle count) of [90/0/90] laminates manufactured by Joule heating and by oven cure. Using a data-driven framework based on generalized additive models (GAMs), we analyze the effects of curing route, isothermal temperature and dwell time, ramp rate, displacement-controlled testing, and specimen orientation. Nonlinear degradation trends are captured by semiparametric GAMs fitted to 27 coupons, totaling 365,059 observations. The curing route emerges as the dominant driver of fatigue degradation: Oven-cured coupons start at higher load but lose capacity more rapidly, whereas Joule-cured coupons exhibit a smoother and more stable decline with cycling. Vertical orientation consistently yields higher loads, while within the explored Joule design space (110–130, 3–12 min) the effects of isothermal temperature, dwell time, and ramp rate are comparatively modest. These results support the viability of Joule heating as an alternative to conventional curing from the standpoint of fatigue behavior, in addition to its known gains in processing efficiency. The GAM approach identifies the key design parameters, quantifies their relative importance, and provides an interpretable tool for comparing curing programs and guiding the optimization of electrically cured composite structures.