AN experimental study of low velocity impact on carbon, glass and mixed fiber composite plates

One of the problem with composites is their poor impact damage resistance and low post-impact mechanical properties. Composites are prone to delamination damage when impacted by low speed projectiles because of the poor through-thickness strength. . To combat the problem of delamination damage, composite parts are often over-designed with extra thickness. However, this increases the cost, weight and volume of the composite and in some cases may provide only moderate improvements to impact damage resistance. The selection of the optimum parameters for composite plates that give high impact resistance under low velocity impact loads should consider several factors related to the materials properties as well as to the way of manufacturing of the composite product. To get the desired impact resistance, it is essential to know interrelationships between these parameters and the absorbed energy by the plate or the pipe. The process of developing this relationship is not an easy task because there are some unknown, nonlinear process parameters. Knowing which parameters have an effect on the improvement on the composite impact resistance and which parameters give the most significant effect are the main issues in composite industry. In this work, impact response of composite laminates was experimentally studied with drop-tower Instron 9250G to determine the energy absorption. Three types of composites were used: carbon fiber, glass fiber and mixed fiber composite laminates. In addition, these composites were characterized by different stacking sequences and resin types. Impact loads were applied at the center of each plate with a dimensions of 129 mm by 129 mm. The effect of several composite structural parameters on the absorbed energy of composite plates is studied.