Study On Allowable Damage Of Aircraft Radome For Honeycomb Sandwich Composite Material

The function of aircraft radome is to protect antenna.Due to its complicated and special working environment,it requires high specific strength,high specific stiffness and good electromagnetic wave permeability.Therefore,composite material and its sandwich structure become the first choice for radome.The honeycomb sandwich structure with plane woven faceplates is gradually used for the military radome with its excellent performance.The honeycomb sandwich structure with plane woven faceplates used in the military aircraft radome was studied,and the compression performance of the structure under the edgewise compression load was studied.Firstly,the non-damage specimen,specimens containing four kinds of damage:penetration,scratch,dent and debonding totally five honeycomb sandwich structures models were established by using ABAQUS finite element software,combined with the progressive damage analysis method,the failure of honeycomb sandwich structure is divided into faceplate failure,honeycomb failure and adhesive failure,and the degradation criterion of the material properties of three kinds of materials were established,and the structure's edgewise compression failure was predicted;Then the edgewise compression performance test of the honeycomb sandwich structure was carried out;Finally,the honeycomb sandwich structure models of four kinds of damage were re-established by using the accurate finite element analysis model,based on the edgewise maximum bearing capacity value of the non-damage model and the design margin,the allowable damage limits?ADL?of the four typical damages were found.The following conclusions are obtained:for the four typical damages,the biggest influence on the edgewise compression bearing capacity of the honeycomb sandwich structure is the dent damage,and the minimum influence is debonding damage;The validity of the experiment is known as the coefficient variance CV of the seven kinds of specimen were within 10%,the prediction results and the experimental results fitted well according to the values of the error mean d₁ and the mean error d₂ of the seven kinds of specimen,the test was effective,The failure mechanism during the edgewise compression of honeycomb sandwich structure can be revealed accurately by the damage analysis model established in this paper,and finally the edgewise compression failure load can be predicted.Under the edgewise compression load,combined with the relationship between the design load,the ultimate load and the design margin,new specimen models containing four typical damages were re-established and the corresponding ADL for each damage under edgewise compression load were found.On the premise of the design margin of 1.5,the ADL value of the penetration damage is:hole diameter 10mm,depth three layers;the ADL value of the scratch damage is:length 6mm,width 0.5mm and depth three layers;the ADL value of the dent damage is:dent diameter 4mm and depth two layers;for the debonding damage,the design margin is 1.15 and the ADL value is 20mm diameter.The conclusions obtained in this paper can provide some references for the determination of the ADL values of the domestic aircraft radome.