Infrared Thermography‐Based Rapid Fatigue Characterization of Two‐Row Single Shear Composite Bolted Joints

ABSTRACT Bolted joints have been the primary method for joining carbon fiber‐reinforced polymer (CFRP) structures. Specifically, two‐row or multi‐row single‐shear joints are used in major load‐bearing applications. Under cyclic loading, establishing the no‐growth limit of such structures efficiently is crucial. Traditional stress life (SN) approaches for assessing the no‐growth limit are time and resource‐intensive. This study aims to assess the no‐growth limit of two‐row single‐shear woven CFRP laminates using infrared thermography (IRT), a rapid fatigue life characterization technique that requires fewer samples than traditional approaches. Furthermore, the harmonic components of the temperature signals were probed along with micro‐computed tomography of failed specimens to understand damage incipience and progression. The effect of laminate thickness on failure mode was investigated by testing specimens with different laminate thicknesses; a 20%–30% variation in the no‐growth limit was observed with a change in thickness. Specimens with barely visible impact damage (BVID) were also characterized for fatigue.