Wrinkle Criterion Establishment And Wrinkle Resistance Analysis Of Metal Composite Plate Under Normal Gap Constraint Condition

With the continuous development of social economy and industry,the demand for metal composite plates is also increasing.The application field has expanded from traditional chemical industry to energy,environmental protection,metallurgy,aerospace,defense industry and other industries.The metal composite plate still has the problem of plastic instability in the actual forming process,so it is urgent to study and solve the wrinkling instability phenomenon of the composite metal plate during the forming process.In this paper,the rolled copper-aluminum composite plate was used as the research material.Based on the tensile wrinkling model of the wedge under the normal gap constraint boundary condition,the wrinkling mechanism and the influencing factors of the wrinkle resistance of the composite plate under the above load conditions were studied by means of ABAQUS finite element simulation software.The main research contents of this paper are as follows:(1)Taking the tensile wrinkling test under the normal gap constraint boundary condition as the research object,the tensile wrinkling tests of specimens with different thicknesses,different thickness ratios and different sizes were carried out respectively.Combined with DIC(Digital Image Correlation)system,the wrinkling process and data of specimens under different test conditions were obtained.At the same time,the finite element simulation model of tensile wrinkling of composite plate was established.By comparing the thickness displacement cloud map and the thickness displacement change map along the path with the experimental results,the accuracy and versatility of the above simulation model were confirmed.(2)Based on the calculation results of the finite element simulation model,the strain paths of each metal layer of the composite plate under different thickness ratios were extracted.Combined with the stress analysis in the thickness direction of the composite plate,it is found that the strain path of the composite plate will bifurcate.Through analysis,the definition method of the critical wrinkling time was determined.The time corresponding to the separation and development after the bifurcation of the strain path is the critical wrinkling time.At the same time,it is found that the stress neutral layer will gradually shift the geometric neutral layer.In view of this phenomenon,the offset of the stress neutral layer is theoretically calculated,and the influencing factors of the offset of the stress neutral layer are explored.(3)According to the calculation results of the finite element simulation model,the evaluation index of the wrinkle resistance of the composite plate was established.In the determination of wrinkle resistance based on the characteristics of wrinkle morphology,by changing the thickness ratio of the composite plate and the angle of the specimen,it is concluded that the wrinkle resistance of copper-aluminum composite plates with different thickness ratios is between single-layer copper and single-layer aluminum;the change of the specimen angle will also affect the wrinkle resistance of the sheet.The larger the angle,the stronger the wrinkle resistance.In the study of wrinkle resistance based on critical wrinkling data,the method of establishing the critical wrinkling strain line of composite plate is established,and it is found that the slope value of the critical wrinkling strain line can reflect the strength of the wrinkle resistance of the sheet.Combined with the wrinkle derivative law and the comparison of the critical wrinkling strain lines with different thickness ratios,it is confirmed that the smaller the absolute value of the critical wrinkling strain line slope,the stronger the wrinkle resistance of the sheet.