Investigation of Scaling Effects in Fiber—Metal Laminates

Abstract

The results of a series of quasi-static and impact tests on four scale-model sizes of fiber—metal laminate (FML) are compared to a scaling law that predicts response parameters based on a simple geometrical relationship of the input parameters. The FMLs consist of an aluminum alloy and a self-reinforced thermoplastic composite based on polypropylene fibers in a polypropylene matrix. The scaled FML laminates were arranged in a 2/1 configuration, and ply-level scaling of the FML constituent materials was employed to yield specimens with a nominally constant composite volume fraction, as well as correctly scaled in-plane and bending stiffness properties. In the initial part of this experimental program, the tensile and flexural properties of these hybrid materials were investigated at quasi-static rates of loading. Here, no significant scaling effects were observed in the mechanical response of the laminates. Following this, simply-supported scaled beams and plates were subjected to low-velocity impact loading in order to investigate scaling effects in the processes of damage development and target perforation. Here, response parameters such as the target deflection, the impact force, and the damage threshold energy were found to obey the scaling law. It is believed that experimental data of this nature will give greater confidence to engineers involved in the design of components based on hybrid materials such as fiber—metal laminates.