Experimental Investigation for Characterization of Formability of Epoxy based Fiber Metal Laminates using Erichsen Cupping Test Method

Abstract

Fiber Metal Laminates are now-a-days a dominant material for applications such as automobile body panels, aircrafts cabins and railway wagons, because of reasons such as superior mechanical properties such as high strength and less weight. Hand Lay-up technique was used to fabricate four fiber metals laminates comprising of aluminium alloy 5052-H32 as the skin material and E-glass fiber as the core. The formability behavior of the laminate was found using Erichsen cupping test using an indigenously developed test setup. The Erichsen cupping index on the specimen varied from 5.95 to 7.28 respectively. The test specimens were investigated through microscope and macroscopic approach. Macroscopic examination revealed that the laminate was ductile in nature, which was backed by the aluminium skin. The defect created on the specimen during the test was smaller than the diameter of the ball used during the test. Microscopic examination through Scanning Electron Microscope revealed that the laminates had microscopic defects such as fiber pullout and surface cracks in the skin materials. The fibers were subjected to brittle failure while the skin material sustained ductile fractures. The Erichsen cupping index value depended upon the factors such as complexity of composite sheet forming operations, simple mechanical property measurements made from the tension test area of tested value. Ductile fracture was observed in the specimen due to the influence of progressive loading through Erichsen cupping test. There was non-uniform distribution of reinforcement in material, Microstructure revealed fiber cracks which were oriented in line to the crack growth on the skin material. Hence, it can be concluded that the proposed material can be safely applied for automotive, aeronautical and locomotive body panels or as a skin material.