Experimental Investigation of Spring-in Behavior of Composite Laminates

摘要

Spring-in behavior of composite materials is the deformation arising from therndifference between the cure induced in-plane and out-of-plane residual stresses afterrncuring. While this is a well observed problem, the exact mechanisms for spring-inrnbehavior are not well understood. Additionally, work on specific laminaternconfigurations has been conducted widely within industries but the results are oftenrnnot published. As such, the standard industry approach is either to ignore the spring-inrnbehavior through fit-up or to compensate for it in the tooling design In thisrninvestigation, the spring-in of different families of L-shaped composite laminates,rnnamely [45/-45]ns and [0/90]ns, [q4/-q4]s, and [q/(q-90)]4s and [q4/(q-90)4]s, arernexperimentally studied to assess the effect of the following factors on spring-in angle:rnthickness, ply angle, lumped beam stiffness, and packing plies together versusrndispersing plies.