Fatigue Analysis of Novel <scp>3D</scp> Hybrid Natural Fiber‐Reinforced Composites

ABSTRACT The growing demand for sustainable engineering materials has intensified research into natural fiber‐reinforced composites (NFRCs). However, critical aspects of their structural performance, particularly fatigue behavior, remain insufficiently understood, and the application of three‐dimensional (3D) woven architectures in NFRCs is still an emerging field. This study investigates the tension–tension fatigue response of a novel hybrid NFRC featuring an orthogonal through‐the‐thickness (OTT) 3D woven architecture, designed to overcome the inherent limitations of conventional 2D laminates. Composites reinforced with sisal and curauá fibers were fabricated in both 2D and 3D configurations and subjected to cyclic loading at three normalized stress levels (0.7, 0.6, and 0.5 of ultimate tensile strength, UTS) The experimental results demonstrate that the 3D OTT architecture significantly enhances fatigue life and damage tolerance relative to 2D laminates, particularly at higher load levels, due to enhanced through‐thickness reinforcement. Furthermore, 3D specimens retained stiffness after one million cycles at 0.5 UTS, demonstrating superior long‐term durability. Analysis of failure mechanisms (crack propagation, delamination, and damage evolution) clarifies the role of fiber architecture in governing fatigue behavior. These findings highlight the potential of 3D hybrid NFRCs as sustainable, high‐performance composites for advanced engineering applications.