Analytical Buckling Analysis And Numerical Simulation Of Stiffened Composite Laminated Plate

Advanced composite laminated stiffened plates are widely used in engineering structures due to their high specific stiffness,large specific strength and strong designability.One of the most common forms of failure is buckling.In practical applications,due to the complexity of the working conditions,the structure is usually subjected to compression,shear or compressive-shear composite loads,which may cause instability.In this paper,the composite material laminated stiffened plate is reasonably simplified.We analyzed and studied.the elastic buckling and post-buckling behaviors of plates and stiffened plates under three working conditions.The main contents are as follows:(1)Based on the theory of thin plates and the principle of minimum potential energy,the theory of stability analysis of isotropic plates and stiffened plates is derived.We used Matlab program to realize the theory and carried out the critical loads and buckling modes of isotropic plates and stiffened plates.Compared the output with the results from software Abaqus,shows that the calculation results from the software Matlab program are basically consistent with the calculation results from software Abaqus when the isotropic plate and the stiffened plate undergoing compressive load,shear load or compressive and shear coupling loads.The accuracy and feasibility of the theoretical derivation are verified,which lays the foundation for further research on the stability analysis of orthotropic materials.(2)Based on the orthotropic theory and the Ritz method,the stability analysis theory of orthotropic plates and stiffened plates is derived.The displacement field of the stiffener is expressed by the displacement of the plate at its position,thus obtaining the expression of strain energy of the composite plate and stiffener.Through discreting the displacement field and applying the principle of minimum potential energy,a system of equations for specifying buckling loads and buckling modes are derived via Matlab.The above derivation is used to analyze the critical loads and buckling modes of composite plates stiffened with one stiffener or three stiffeners undergoing compressive load,shear load or compressive and shear coupling loads,and compared with the results obtained from software Abaqus.The results are basically consistent.The accuracy and feasibility of the theory derived from this paper in solving the problem of elastic instability of orthotropic composite laminated stiffened plates are verified.(3)Establishing the finite element model of composite laminated stiffened plate to perform linear and nonlinear buckling analysis,and implement progressive damage analysis through the USDFLD program interface with Fortran code.The model uses the Tsai-Wu failure criterion as the failure criterion,the cohesive interface element is used to simulate the interface between the rib and the skin.The secondary stress failure criterion is used to simulate the interface debonding failure.Analysis of the post-buckling path of composite laminates and stiffened plates undergoing compressive load,shear load or compressive and shear coupling loads,: After the composite laminates and stiffened plates reach the critical buckling load,there is still ability to bear load,which is called the post-buckling strength.Composite laminated stiffened plates not only have higher eigenvalue buckling loads than plates,but their ultimate loads and residual loads are all higher than plates.Reinforcement can also reduce post-buckling deformation.It can be seen that the reinforcement is one of the main methods to improve the bearing capacity and rigidity for plate structure.(4)Analyze the failure modes of composite laminates and stiffened plates undergoing compressive load,shear load or compressive and shear coupling loads: when undergoing compressive load,the main failure mode of composite laminates is matrix tensile failure.The four corners first failed,and gradually extended to the centroid,the stiffened plate mainly occurred matrix tensile failure and fiber tensile failure;when undergoing shear load,the main failure mode of the composite laminate and the stiffened plate was matrix tensile failure occurs from the four corners,and then gradually extends to the centroid;when undergoing the compressive and shear coupling loads,the composite laminates and stiffened plates occurs mostly matrix tensile failure and fiber tensile failure.The ribs occurs mostly matrix tensile failure.