Low Velocity Impact Damage on CFRPs: A Parametric Study

Carbon Fiber Reinforced Plastics (CFRPs) are extensively used in modern aircraft structures due to their high specific strength and stiffness properties. Upon impact by the foreign objects, the strength and stiffness of CFRP structures reduces drastically which is of major concern for aircraft designers since aircraft structures often witness sudden impact events during their life cycle. Typical impact events include tool drop during manufacturing and maintenance, runway debris during take-offs/landings or bird strike events. In particular, low velocity impact (LVI) events have been found to be specially detrimental to the load-carrying capability of aero-structures. It is therefore very important to characterize the loss of strength and stiffness accompanying such impacts on composite structures. The present work presents an idealized problem of LVI on a square CFRP plate using a spherical impactor. A parametric study has been carried out to investigate the behaviour of CFRP plate under varying impactor velocity, size, laminate thickness and stacking sequence. Impact damage initiation data has been developed for the parameters considered using the numerical framework developed for LVI. It is believed that the numerical simulations discussed in this paper will help aircraft designers to predict the response of different laminate systems under various impact scenarios and will guide them to choose appropriate material system.