Spring-back and failure characteristics of roll bending of GLARE laminates

Roll bending is a cost-effective and efficient sheet forming process. In this paper, spring-back of glass fiber reinforced aluminum laminates (GLARE) in roll bending process was investigated by numerical and experimental methods to explore the formability characteristics of the laminates. Failure modes of GLARE with diverse curvatures were revealed using scanning electron microscope (SEM). Moreover, the curvature radii of the laminates after roll bending were measured with an arc height gauge. The results definitely corroborated that distinct differences existed among three GLARE variants in spring-back and damage modes. GLARE 2A (which fibers direction are parallel and same with roll direction) exhibited larger spring-back than the other two laminates. Meanwhile, greater top roller displacement led to smaller spring-back. Tensile fracture appeared in the 0° fiber/epoxy layers, while matrix cracking occurred in the 90° fiber/epoxy layers along with the growth of curvature. However, no obvious delamination was observed at different layers. Besides, the critical curvature radius of GLARE 2A, GLARE 2B (which fibers direction are parallel and perpendicular to roll direction) and GLARE 3 (which fibers direction are perpendicular to each other)was located in 100 mm ∼ 114 mm, 67 mm ∼ 100 mm and 118 mm ∼ 131 mm, respectively, which proved roll bending feasible for manufacturing GLARE with small curvature. In order to facilitate further research in the future, the finite element model of roll bending was established, and the accuracy of the model was verified by experiments.