Formability Characterization of Composite Sheet Materials by Erichsen Cupping Testing Method

Erichsen cupping testing can be used for grading, selecting and sort ing of incoming composite materials for manufacturing of various sheet materi als application. The objective of this experiment is to find out the Erichsen number (EN) of unidirectional lami nated polymer composite sheet materials by Erichsen cupping testing machine (Model ET-20, least count of 0.01 mm) in forming operations (stretching). In the Erichsen test, the punch is pressed into the sheet until fracture occurs, at which point the test is s topped immediately and the depth of the bulge noted. This depth (mm) gives the Erichsen number. The Erichsen number obviously gives a measure of the ductility o f the sheet in the plane of drawing under biaxial s tress condition. It is observed from the present experiment that in general the Erichsen number is influenced by fiber and matrix properties, orientation of fiber, and th ickness of the sheet material. In this experiment a total force of around 10 KN was applied on the sample sheet materials by a ball shaped indenter (20mm diameter) until the cracks begin to occur in the specimen.