NET-SHAPE MACHINING AND THE PROCESS-DEPENDENT FAILURE OF FIBER-REINFORCED PLASTICS UNDER STATIC LOADS

The effects of net-shape machining on the mechanical properties of a g raphite/bismaleimide (Gr/Bmi) laminate were investigated under pure be nding. An experimental evaluation of the acoustic emission during load ing, bend load and energy to failure, and optical documentation of fir st ply failure was conducted. Experimental results were also compared with predictions for failure from a finite element model using convent ional failure criteria. It was found that surface texture has a signif icant influence on the mechanical properties of fiber-reinforced plast ics (FRPs) and that the static bend strength decreased with increasing surface roughness. Acoustic emission prior to the onset of failure in dicated that damage accumulation was clearly dependent on the method o f machining. It was also found that the location of first ply failure was influenced by the process-dependent surface structure, but not by the magnitude of surface roughness.