Study On Models And Solution Of FEM Basic Formulation Of Theory Of Duality Disturbance

Under the effect of load and environment, mechanical properties of engineering materials changes inevitably, such as degradation and the reduction of its bearing capacity, this phenomenon is called damage. Disturbance concept is the extension of damage theory, can be used not only to describe the behavior of damaged material but also to describe the behavior of restoration or strengthened material. Therefore, Theory of Duality Disturbance (TDD) is a more unified and more effective theory on the basis of classic mechanics of deformable solid, which of great extension, deepening and improvement. FEM is the most effective way of mechanical analysis or numerical analysis of complex structures and large scale structures, however there has not been any finite element commercial software that can make analysis based on damage theory yet, let alone involving disturbance concept.The following are the main work of this research:(1) Based on the TDD, the whole process of stress-strain of the material with stress-softening after stress-peak is analyzed, and the point is put on the effects of complete disturbance models on the predicted results. The four RCD models, i.e., Constant Stress, Void Stress, Hydrostatic Stress, and Linear Stress models are selected as RCD states to predict the observed stress-strain relation. As a result, it is shown that the stress-strain curves predicted by the four RCD models are of consistence with the observed stress-strain curve. Thus, it can be seen that the select of RCD midels has a great deal of flexibility, the method presented in this paper can be applied to predict mechanical behavior of a variety of disturbed material.(2) Learning the theory and effective methods of elastoplastic finite element analysis, and ascertaining the basic formulation of FEM based on TDD. Obtained a complex stiffness matrix, for the characteristics of its components present three solution schemes, i.e.,"Coupled solution method","Transposition solution method","Correction method for Relative Non-Disturbance result". Introduce into"Drift correction"and"Iterative method"correct result error of the basic formulation, and design steps and details for the solution process Implementation on computer.(3) Using MATLAB to develop the software named Finite Element Analysis of Duality Disturbance with graphical user interface as main window, establish the analysis platform of TDD. Plate-column structures are simulated only by twenty-nodes isoparameter element with FEADD. Though analysis results, it is shown that twenty-nodes isoparameter element can instead of plane elements, beam elements and plate elements, so what have the ability of simulating complex structures. Coupled solution method and Transposition solution method are more similar, both reflected the self-adjuted concept of TDD, Correction method is closed to enhance disturbance materials. Summary, TDD can solve practical problems effectively.