Crashworthiness Analysis Of Foam-filled The Quasi-honeycomb Sandwich Structure

With the continuous promotion and application of sandwich structure materials in high weight and high energy consumption equipment in the fields of automobiles,aerospace,ships,etc.,traditional sandwich structure materials,including honeycomb sandwich structures,are gradually unable to meet engineering design requirements,and there is an urgent need to develop new sandwich structure material with high specific energy absorption,high specific strength and excellent crashworthiness.The core layer is an important part of the sandwich structure.The internal filling method usually improves the overall bearing capacity and crashworthiness of the sandwich structure.In this paper,a new type of the quasi-honeycomb sandwich structure filled with foam is taken as the research object,the numerical simulation method is used to study the crashworthiness of polyurethane foamfilled the quasi-honeycomb,and the multi-objective optimization design of the crashworthiness of foam-filled the quasi-honeycomb is conducted.The main research contents of this article are:(1)In-plane crashworthiness analysis of foam-filled the quasi-honeycomb sandwich structure.The numerical simulation analysis of the crashworthiness of foam-filled the quasihoneycomb under in-plane impact at different speeds shows that the specific energy absorption is negatively correlated with the honeycomb wall thickness(0.3mm> 0.5mm> 1mm).while reducing the honeycomb wall Thickness will reduce the initial peak force to improve the collision safety of the structure and improve the energy absorption efficiency;when the honeycomb wall thickness is the same,the smaller the impact speed,the higher the load stability and energy absorption efficiency of the structure;Within a reasonable range of values,appropriately reducing the thickness of the honeycomb wall can improve the in-plane crashworthiness of foam-filled the quasi-honeycomb;Comparing the in-plane crashworthiness indexes of foam-filled the quasi-honeycomb with the unfilled ones,it was found that the foam filling significantly improved the in-plane crashworthiness of the quasihoneycomb.(2)Study on the out-of-plane crashworthiness of foam-filled the quasi-honeycomb sandwich structure.The collapse mode and crashworthiness of foam-filled the quasihoneycomb were studied from the perspective of out-of-plane impact,and the influence of the honeycomb wall thickness on the crashworthiness index under out-of-plane impact at different speeds was analyzed.The results show that the out-of-plane compressive force of foam-filled the quasi-honeycomb increases with the increase of honeycomb wall thickness or impact velocity;During low-speed and medium-speed impacts,increasing the honeycomb wall thickness does not necessarily increase the total energy absorption,But during highspeed impact,increasing the honeycomb wall thickness can increase the total energy absorption;The specific energy absorption decreases with the increase of the honeycomb wall thickness,while the average collision force and initial peak force increase with the increase of the honeycomb wall thickness or impact velocity.Load stability and energy absorption efficiency are inversely related to the honeycomb wall thickness.Therefore,when the thickness of the honeycomb wall is within a certain range(0.1mm ? 1mm),appropriately reducing the thickness of the honeycomb wall can improve the crashworthiness of foamfilled the quasi-honeycomb in the out-of-plane direction.In addition,comparing the out-ofplane crashworthiness of the foam-filled quasi-honeycomb and the unfilled quasihoneycomb,it was found that the foam-filled quasi-honeycomb had better out-of-plane crashworthiness than the unfilled quasi-honeycomb.(3)A multi-objective optimization method for the crashworthiness of foam-filled the quasi-honeycomb sandwich structure integrating high average collision force,high specific energy absorption and low initial peak force is established.The research results show that the overall sensitivity of the optimization problem from high to low was the initial peak force,specific energy absorption,and average collision force.The difference between the overall sensitivity of the specific energy absorption and the average collision force was small,and the single sensitivity of each optimization target to honeycomb wall thickness from high to low was initial peak force,average collision force,and specific energy absorption.The single sensitivity of each optimization target to the impact speed is shown by the highest specific energy absorption,followed by the average collision force,and the lowest initial peak force.