Response Analysis On Small-Mass Impact Of Honeycomb Sandwich Composites

In order to study the composite impacted by small mass objects,the small-mass impact instrument is improved,and then the oblique impact can be achieved.Two kinds of honeycomb sandwich composites underwent small-mass oblique impact tests.The contact force can be measured with an acceleration sensor,and the acoustic emission(AE)sensor is used to capture the damage response signal.The force is analyzed and compared with the simulation results,and the AE signal is analyzed and compared with the result of laminate impact tests.On the basis of the previous theoretical simulation methods of smallmass impact of honeycomb sandwich composites,the stiffness reduction model is introduced to simulate the decrease of stiffness of the face sheet due to delamination.The model can be used to simulate the contact force of small-mass oblique impact on honeycomb sandwich composites.By changing the parameters in the model,it is found that the effective stiffness of the panel and the compressive strength of the core have a greater influence on the time period of the impact and the maximum contact force,while the influences of thickness and modulus of the core are slight.In the drop weight impact test,when the contact force suddenly drops due to delamination,the frequency of the AE signal will increase.,and the abnormal signal can be highlighted by the empirical mode decomposition(EMD).For small-mass impact on laminates,the damage can be detected with by combining EMD and Fourier transform.For the honeycomb sandwich composite,the AE signal still conforms to the above rule before the fiber is broken,but the AE signal cannot be well transmitted because the honeycomb core material is crushed after the fiber breaks.Therefore it is not easy to find the relation between the damage and the AE signal.