The Research On Elastic-plastic Buckling Of Cylindrical Shells Of Functionally Graded Materials With Initial Imperfection

Functionally graded materials(FGM) is a kind of two phase mixture of new composite materials. This material is generally composed of ceramic and metal composite, material volume content of components on the macro scale along the material thickness direction changes continuously, so the macro properties also shows the characteristics of continuous variation; Thanks in large part to avoid or reduce the traditional laminated composites because of the property of discontinuity in the interface stress concentration phenomenon, therefore, the mechanical properties of functionally graded materials with mechanical properties on the superiority, has very high application potential. Because of the function graded material of metallic phase in the process of buckling tend to show some toughness, therefore, using the elastoplastic constitutive model describes the functionally graded materials, has an important significance.This article first study of functionally graded materials commonly used current model is analyzed, pointing out some shortcomings of existing research, then elastic-plastic constitutive theory, combining the theory of laminated composite panels, in view of the functional graded materials elastic-plastic constitutive model put forward a complete architecture and in the software of ABAQUS UMAT definition. In the UMAT module defines the multiple material properties and the elastic-plastic Jacobin matrix is obtained, and proved the practicability of the approach.This article adopts the analysis method of the above basis, the finite element analysis model was established, through the calculation results are analyzed, such as modal analysis of the model is verified availability. This article also through the finite element analysis model, the introduction of the modal of the initial defects, for containing defects of functionally graded material cylindrical shell with the numerical calculation, discusses the defects, diameter, thickness ratio gradient parameters, such as cell factors on the calculation results, the influence of defect is expounded and the connection between the limit buckling load, reveals the various factors and the relationship between the buckling load.At the end of the content of this paper, using the explicit dynamic finite element method(fem) of ABAQUS software, the establishment of a functionally graded material cylindrical shell buckling model, calculation and analysis have been carried out on the model, and the model of grid density and other factors on the basis of the comparison. The research results show that the various parameters on the dynamic buckling of the functionally graded material cylindrical shell has important influence.