Numerical and experimental comparative study on damage mechanisms induced by different types of embedded defects in tapered composite laminates

Composite fan blades are typically designed with increased thickness near the root and adopt a tapered cross-section to bear mechanical loads. However, this geometry can introduce local material and geometric discontinuities, making the structure more susceptible to defects. Among the most common manufacturing defects are delamination and wrinkling, which can induce significant interlaminar stresses and serve as initiation sites for damage. This study investigates the damage mechanisms of tapered composite laminates with embedded defects through both experimental and numerical analyses, focusing on static damage characteristics and failure modes under tensile and bending loads. Experimental results reveal notable differences in strain distribution and failure modes between pristine and defective specimens. While pristine laminates primarily fail through concentrated fiber fracture, specimens with embedded defects exhibit progressive failure dominated by delamination propagation. Numerical findings further show that inter-fiber tensile damage is the most critical failure mode, highlighting delamination as the dominant mechanism. Under tensile loading, laminates with embedded wrinkle defects exhibit the most severe interlaminar damage. Under bending loads, wrinkle defects are particularly sensitive to compressive stress. This study provides a deeper understanding of how embedded defects influence the mechanical performance of tapered composite laminates and offers valuable theoretical support and evaluation metrics for designing more damage-tolerant composite structures.