ABSTRACT This study investigates the influence of cyclic loading frequency on the fatigue limit of additively manufactured‐compression molded (AM‐CM) short carbon fiber thermoplastics (20 wt% CF‐ABS). Accelerated fatigue characterization was performed using passive infrared thermography under a staircase loading protocol at 5, 10, 15, and 20 Hz. Displacement accumulation, stabilized surface temperature (), and fatigue fracture entropy (FFE) were jointly analyzed to capture frequency‐dependent damage mechanisms. Results show a notable increase in fatigue limit from 52.14% at 5 Hz to 61.14% at 20 Hz. Higher frequencies suppressed viscoelastic deformation, reduced hysteretic energy dissipation, and shifted failure morphology from matrix‐dominated cracking to fiber breakage. Constant amplitude tests at 60% confirmed these trends, with specimens failing at 5 Hz but surviving 3 million cycles at 20 Hz. Across all frequencies, FFE remained consistent (0.096 0.0144 kJ/mK), supporting its role as a rate‐independent scalar indicator of fatigue damage.
Pathak et al. (Fri,) studied this question.