In-situ computer tomography for analyzing the effect of voids on the damage behavior of composite materials

Due to their high specific stiffness and strength composites are ideally suited for applications in machine building, vehicle constructions, wind power technology and aviation. In the manufacture of composite structures voids are an unavoidable fact. Several non-destructive techniques are potentially able of detecting defects, but only the exact knowledge of the effects of defects on the mechanical properties allows the definition of thresholds for the purpose of quality management. Here, an experimental program for characterizing the effect of voids on the damage behaviour is presented. Flat specimens with glass fibre non-crimp fabric reinforcement and epoxy matrix (GF-NCF/EP) are produced using vacuum assisted resin transfer moulding. By means of a specific adjustment of the process parameters, test specimens with three different void contents are produced and compared. For detailed analysis of damage evolution in the vicinity of voids, in-situ computed tomography (in-situ CT) is used, for the volumetric visualization of the material during tensile loading. (paper)