Identification Of Impact Location And Force On Composite Sandwich Structure

The safety and reliability of the composite sandwich structure will be affected when the impact happens.It is a very important work to identify the impact location and the time history of the impact force timely and accurately in a composite sandwich structural health monitoring system after the impact happens.In this paper,the identification of impact load of composite sandwich structures is studied.The passive monitoring method is used to identify the impact location and reconstruct the time history of impact force.Firstly,the impact location identification problem of composite sandwich structure is studied based on two-step identification method.The appropriate initial identification area is selected according to the arrangement and the number of the sensors.The error of impact reconstruction of three sensors is selected as the objective function,and the final impact position is determined by minimizing the objective function.Secondly,on the basis of identifying the impact location,the reconstruction of the impact force is studied.The layerwise theoretical model based on the three-order shear deformation theory is used according to the properties of composite sandwich structure,which is called through-thickness theoretical model.This model decomposes the structural displacement field into the form of linear displacement,two-order displacement and three-order displacement.According to this theoretical model,the motion equation of the impact system is constructed,and the state space equation of the system is established by using the Guyan order reduction method.The state space equation is discretized and then the transfer function matrix between the impact force and the response of the sensor is derived.The ill-posed characteristic of transfer function matrix is solved through the Tikhonov regularization method and then the time history of the impact force at any location can be reconstructed through the received sensor signals.Finally,the feasibility and effectiveness of the methods proposed in this paper are verified by simulation and experimental study on the glass fiber composite foam sandwich structure.