Study On Delamination Damage Analysis And Evaluation Method Of Composite Laminates

Fiber-reinforced composites are widely used in the aerospace field because of their excellent mechanical properties.However,composite laminates often produce layered damage in the process of preparation and service,which affect the bearing capacity of the structure due to many uncertain factors And reduce the service life.The damage caused by the non-destructive testing method is not necessarily complete,which seriously affects the discrimination and accurate analysis of the stratified damage.Furthermore,even if the damage is found in the stratified layer,Layer damage,in view of the current is not a very good and effective means o f assessment to evaluate its strength and damage tolerance to determine,this has been China's aircraft development and service in the process of one of the urgent problems to be solved.Therefore,this paper analyzes and evaluates the layered damage in the aircraft panel.In this paper,the damage of the test piece containing the stratified damage is detected by ultrasonic C scanning,and the damage image information is obtained.In order to facilitate the evaluation of the stratified damage,the image is further processed by MATALB image processing technology based on the image geometric moment.It can automatically extract the damage contour information and equate the damage contour with ellipse to obtain the elliptical geometric characteristic parameters,So as to provide accurate stratified damage geometric model for the next stratified damage assessment.Secondly,the ABAQUS finite element software is used to develop the USDFLD progressive damage subroutine and the finite element model of the stratified damage analysis is established based on the cohesion theory model.The remaining strength of the laminates,the failure modes and the stratification expansion laws were analyzed and evaluated according to different factors such as different stratification size,different thickness position and different bedding angle.Finally,two layers of polytetrafluoroethylene(PTFE)films were used to prepare layered test specimens with different thicknesses and different thicknesses.The test pieces were subjected to compression test and graded loading.Abnormal C-scan test.The experimental results are in good agreement with the finite element simulation results,which meet the requirements of engineering calculation and verify the accuracy of the finite element model with the analysis of the strength of the layered layer.