Extended Layerwise Method Of Low Velocity Impact Of Composite Laminated Structure

Composite laminates are the main components of aeronautics and astronautics,which have the disadvantage of poor impact resistance.Therefore,it is of great significance to analyze and predict the dynamic characteristics of composite structure parts for the flight safety of the aircraft.During the flight,aircraft may be subjected to a continuous impacts,such as hail and bird strike.If there is matrix crack and delamination damage in composite structure,it will seriously affect flight safety under low velocity impact.Therefore,it is of great significance to study the dynamic characteristics of composite laminates with damage.The Extended Layerwise Method(XLWM)has been shown to study static characteristics of laminated composite structures with multiple transverse matrix cracks and delamination,the XLWM is introduced to analyze the dynamic characteristics in this paper,including the free vibration,transient response and low velocity impact of composite laminated structures with damage.In this paper,the mass matrix,Newmark method,Hertz contact law and progressive damage theory are introduced into the XLWM and established with damage of composite laminates of free vibration,transient response and low velocity impact analysis model.By comparing the numerical examples with the results in the literature and the three-dimensional solid element model,the correctness and accuracy of the XLWM analysis of the dynamic characteristics of composite laminated structures are validated.At the same time,the effects of crack on free vibration,transient response and low velocity impact response are investigated,and the effect of delamination on transient response analysis is studied as well.The results show that the cracks and delamination will reduce the stiffness of composite laminates,and have obvious effects on free vibration,transient response and low velocity impact.The free vibration problem was negatively related to natural frequency and crack length.For the transient response of composite laminates subjected to impulsive loading,the period and amplitude will increase with an increasing of the crack length and the delamination area,the hierarchical position only affect on amplitude.For the low velocity impact problem,there is a consistent effect of length and location of the crack no matter consider the condition of progressive damage or not.there is a longer length of the crack,a higher peak of contact force and a more obvious contact phenomenon when the crack position is closer to the impact point.