Experimental Study And Numerical Simulation On Mechanical Properties Of Z-Reinforced Foam Sandwich Composites

Foam sandwich composite structure has many advantages such as high specific strength,high weight ratio,high designability,heat insulation,sound insulation and water resistance,etc.It is more popular in the market of composite structures such as wind power blades,square nacelles,fairings and aircraft wings.However,traditional sandwich composites have problems such as poor interfacial bonding performance between panels and core materials and low strength of core materials,which seriously limit the application of composite sandwich structures on main bearing structures.In order to solve this problem,this paper investigates the face/core interface properties and Z-directional fiber-reinforced foam core composites on the basis of traditional foam sandwich composites,designs and prepares a foam sandwich composite reinforced with ± 45° in the Z-direction,and combines it with Abaqus finite element software for numerical simulation.Firstly,in this paper,based on the traditional foam sandwich composites,the fiber bundle is penetrated inside the foam structure by ± 45° using a piercing process,and the fiber bundle forms a three-dimensional network structure inside the foam.The introduction of reinforcing fibers connects the upper and lower panels of the sandwich structure into a single unit,effectively improving the structural face/core bonding and load-bearing capacity.In addition,it can improve the limitation of Z-Pin reinforced structure in edge profile reinforcement as well as take into account the advantages of simple preparation process and easy operation.Secondly,the Z-reinforced sandwich composites were prepared as preforms,and the structural parameters of the preforms were designed.The Z-reinforced foam sandwich composites were prepared by vacuum infusion(VARI)molding process,and bending,in-plane compression and edge compression tests were performed respectively with reference to ASTM standards.Finally,the responses of Z-reinforced foam sandwich composites under three-point bending,in-plane compression and edge compression were investigated to analyze the effects of Z-reinforced fibers and foam thickness parameters on the mechanical properties of the sandwich composites.Based on the experimental results,the equivalent models of Z-reinforced sandwich composites were established by using Abaqus finite element software for three-point bending,in-plane compression and edge compression,respectively,and the intrinsic structure curves of reinforcing fibers and foam materials were introduced.The results show that the bending load and bending stiffness of Z-reinforced foam sandwich composites gradually increase with the decrease of reinforcing fiber spacing under the same conditions,and the bending load value can be increased up to 4 times.The reinforcing fibers can enhance the compressive properties of the sandwich composites and increase with the decrease of the reinforcing fiber spacing.Among them,the in-plane compression strength is enhanced up to 167 %.However,the damage to the foam and glass fiber bundles caused by the puncture during the preparation of the preform affects the overall structural performance.The bending load and bending stiffness of Z-reinforced sandwich composites increase with increasing foam thickness,and the in-plane compression and edge compression properties of Z-reinforced foam sandwich composites increase with decreasing foam thickness.The maximum load values obtained from numerical simulations are in good agreement with those obtained from experimental tests,and the error is controlled at about12 %.