V-shape forming of super hybrid material plate
Haga Osamu; Koyama Hideo; Kawada Katsumi; Iwase Yasutoshi
Abstract:The composite material plate used in this study is called super hybrid plate which is built up from many thin aluminum alloy sheets and unidirectional CFRP and KFRP layers. This plate can be formed plastically at room temperature under certain limiting conditions. Super hybrid plate is very flexible and has a wide plastic deformation range if it is not cured. Moreover, plastically deformed aluminum layers themselves may act as a mold for FRP layers. Therefore a new V-shape forming process was developed based on these properties. First of all, a stacked material, consisting of aluminum and FRP layers, is pre-formed at room temperature, and then cured under an appropriate temperature and pressure by using hot-press. It became possible to form a shape V-bent with radius 2.5 mm which is nearly equal to the plate thickness. On the other hand, this causes fluctuation of thickness of the formed article. To solve the problem the article formed at room temperature was cured in an autoclave with a simple device which can cancel the spring back of the article. As a result, the new V-shape forming process to get articles with no spring back and with exact 90 degree bending angle was developed. Key Words:CFRP, KFRP, aluminum, super hybrid, plastic working, forming process, bending displacement analysis and back-analysis of viscoelastic medium with arbitrary shaped tunnel under quasi 3-dimensional rock stresses