| Summary: | 博士 === 國立中央大學 === 土木工程研究所 === 89 === The discrete element method (DEM) has been widely used in various scientific fields to simulate the behavior of particle conjectured medium. However, a lot of computation time has to be spent especially for the contact searching and detection of particles, if large amount of particles are used for the simulation. This thesis proposes a fast contact searching scheme which can reduce the computation time dramatically compared with conventional scheme in DEM.
When applied in simulating the behavior of granular assemblies, Discrete Element Method (DEM) usually need different particles to assemble analysis model. However, the determination of the values of the stiffness of normal contact spring, damping coefficient, and time steps size are still based on experience rule since the past decades. Certain amount of error would be accumulated and then leads to an inaccurate behavior prediction. In this thesis, a nonlinear normal impact analysis method is presented to simulate the dynamic behaviors of particles with different sizes and material properties. Besides, the so called “velocity summation method” is developed further to simulate the behavior of multi-particles. The accuracy and efficiency of all the proposed methods are demonstrated and verified through some benchmark problems.
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