| Summary: | 碩士 === 國立臺灣海洋大學 === 河海工程學系 === 99 === Since the Discontinuous Deformation Analysis (DDA) method has the capability to deal with the contact problems, it is often adopted to analyze the granular particle problems. Due to the stiff spring constant for modeling the contact, the ill-conditioned problems are encountered in the simulation, especially in the granular debris flow simulation. The ill-conditioned matrix in the DDA method also raises the problems of convergence and accuracy. To deal with the ill-conditioned problems, a study on contact problems of debris particles using the DDA method incorporated with the Fictitious Time Integration Method (FTIM) and the Manifold-Based Exponentially Convergent Algorithm (MBECA) is proposed. In addition, this study also develops the preconditioned technique for FTIM and MBECA. Results obtained demonstrate that the proposed preconditioned technique for FTIM and MBECA can greatly improve convergence and accuracy for solving the ill-conditioned problems. With the combination of the proposed preconditioned technique with the FTIM and the MBECA, the DDA method can be an effective tool for modeling the granular debris flow problems.
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