Experimental Study on the Tensile Behavior of Asymmetrically Tapered Composite Laminates

Tapered composite laminates are commonly adopted to accommodate the need of varying thickness in aircraft structures. In this work, experimental investigations on the damage evolution and the failure mechanism of tapered composite laminates under tensile load were conducted. Four types of tapered configurations were tested, consisting of different drop-off sequences and different thin section lengths. The results indicate that the geometric eccentricity of mid-planes between thin and thick sections leads to a bending tendency of the tapered laminates. High-level stress concentration caused by the terminated plies prompts the delamination occurrence and propagation. Different delamination initiation loads and propagation loads are observed in specimens with varying layup sequences in the tapered section. Nevertheless, the thin section length influences the ultimate strength and the failure mode evidently. The failure of all tested articles are characterized by the shearing out of the bulk of discontinuous plies, accompanied with fiber fracture in the vicinity of dropped plies.