Mechanical properties and drawing process of multilayer carbon-fiber-reinforced plastic sheets with various prepreg thicknesses

Abstract

In this study, multilayer carbon-fiber-reinforced plastic sheets with various pre-impregnated thicknesses were developed. Specimens were fabricated by the hand lay-up process from standard and thin-ply unidirectional carbon fiber/epoxy resin prepreg sheets, which were also cured in an autoclave. Tensile tests from room temperature to 120°C and interlaminar shear strength tests at room temperature were first conducted to investigate the mechanical behavior of the laminated carbon-fiber-reinforced plastic sheets. Furthermore, with a view to increase the formability, in this study, a state-of-the-art drawing process for laminated carbon-fiber-reinforced plastic sheets at an elevated temperature was investigated, and the drawing ratio was also determined for the case of elliptical cup drawing. To achieve this, the relation between the punch load and stroke, and the distribution of thickness were determined by measurement. To clarify the forming behavior in this case, evaluation of the effect of increasing the number of drawing steps was performed to investigate the deformation history. The microstructures showed reduced delamination with increasing radius of the punch. The experimental results obtained in this study are expected to help designers perform the press forming of multilayer carbon fiber/epoxy resin sheets.