Erichsen cupping test on thermosetting CFRP sheets

The deformation of carbon-fiber-reinforced plastic (CFRP) sheets consisting of a thermosetting resin and continuous fibers has been investigated. The bending of CFRP sheets was achieved under a suitable forming temperature and strain path. Formability indexes and a forming limit diagram (FLD) are indispensable data for showing the process window of CFRP sheets. There are four formability indexes: bendability, deep drawability, stretchability, and stretch-flangeability. Bendability and deep drawability can be evaluated by conducting a stretch-bending test, and stretchability can be evaluated by conducting an Erichsen cupping test. If the process window can be predicted, the range of applications using CFRP can be expanded. In this study, the Erichsen index of CFRP sheets indicates the stretchability of laminated CFRP structures.