Effects of tensile elongation on the fatigue life of discontinuous carbon fiber-reinforced composites manufactured by FDM

Purpose This study aims to investigate the fatigue behavior of discontinuous carbon fiber-reinforced composites (DCFRC) manufactured using fused deposition modeling (FDM). It examines the effects of tensile elongation amplitude and test frequency on fatigue life, aiming to improve understanding of how these parameters influence structural performance. Design/methodology/approach Tensile fatigue tests were performed at two frequencies (10 and 20 Hz) and four elongation amplitudes (2, 3, 4 and 5 mm). Cycles to failure and temperature variations were recorded to assess material behavior under cyclic loading. Findings Fatigue life decreases as elongation amplitude increases, with higher frequencies accelerating softening and failure. Thermal monitoring revealed a strong correlation between frequency, temperature rise and reduced fatigue life. Higher frequencies led to rapid heating, causing earlier failure. In addition, plastic deformation at high elongation amplitudes contributed to stress reduction and premature failure. Originality/value This study offers a novel and comprehensive analysis of the combined effects of cyclic loading frequency and elongation amplitude on the fatigue life and thermal response of FDM double carbon fiber-reinforced composites (DCFRCs). While previous studies have largely examined these parameters in isolation, this research uniquely investigates their interaction and its influence on fatigue failure mechanisms. Through real-time thermal monitoring, the study reveals how internal heat accumulation correlates with material degradation, thus providing deeper insight into the role of self-heating in fatigue performance. These findings help identify operating conditions that may induce excessive thermal buildup, thereby aiding in the avoidance of temperature-driven thermomechanical fatigue in practical applications.