Research On Virtual Testing Of Buckling And Damage In Stiffened Composite Panel

Stiffened composite panel, as a typical composite structure, has been widelyused in the field of aerospace, aviation, etc. Virtual testing couples computationalsimulation techniques, physical testing methods and infrastructure, whichonly requires a few experiments to analyze and forecast the mechanical behavior ofcomposite structure. It can greatly shorten the design and test cycle and reducedevelopment costs. On the basis of research results at home and abroad, the papermainly studied the virtual test technology of buckling and damage of stiffenedcomposite panel, developed an engineering algorithm to judge the buckling modecomposite stiffened panel and to calculate buckling load and failure load, presentedan accurate simulation model to study buckling and damage of stiffened compositepanels, developed an virtual test system software platform.On the basis of the analysis of the structure form and the main mechanicalcharacteristics of the stiffened composite panel and the experimental requirementswhich is necessary for design of the stiffened composite panel, the paper developedthe overall plan of the virtual testing system of stiffened composite panel,set up the system function model, and completed the interface design between thesystem and the relevant software.An engineering method was presented which can calculate the buckling loadand post-buckling load of the stiffened composite panel with multiple geometricforms quickly. Based on segmentation processing method, the general diagram wasproposed. Based on the equivalent stiffness method and the effective width method,the general diagram and the mathematical models which can calculate the bucklingload and failure load of stiffened panel in different buckling mode were established.This program implemented parameterization and automation function, which can beused in different composite stiffened panel with different materials, layers, stringerand geometric size. Some examples of I and T types stiffened composite panels wastested in this program. By comparing the calculated results with the test results andthe FEA results, the correctness and precision of this engineering method wasverified.A numerical analysis model which considered the meso-scopic damage and debonding damage was presented to analysis the buckling and damage of stiffenedcomposite panels. Based on the secondary development of Python scripts, theparametric modeling program of stiffened composite panel was developed. Basedon the gradual stiffness degradation model which bring in continuum damagevariables, the progressive damage analysis model was developed. Based on thesecondary development of the UMAT subroutine, the progressive damage modelwas embedded in the finite element model. This model can accurately predict thebuckling mode, buckling load and ultimate failure load, the post-buckling path, andthe whole damage process of panels and cemented layer. By comparing the resultsof numerical simulation with the test results and the calculated results, theReasonable and effective of this numerical model was verified.Based on the above technique, the system structure and technical process ofvirtual test system software platform of composite stiffened panel was designed.The system development was completed with VC++. The supporting database andknowledge base of virtual testing was established. The integration of engineeringmethod, virtual test and physical test was realized in this system. The feasibility ofthe system was validated by Some examples of virtual testing.