Summary: | 碩士 === 國立中央大學 === 土木工程學系 === 102 === In this thesis, equivalent linear contact spring constants are developed for the contact between deformable particles such as spherical particles and egg-shaped particles, based on the Hertz contact theory and Mindlin contact theory of tangential stiffness. The physical significance of this study is that we can adopt an equivalent linear spring stiffness to model the non-linear contact behavior of Hertz’s contact; It’s shown that the theory normal equivalent linear contact spring stiffness is related to the initial relative velocity of the two contact particles, elastic constant and geometry of contact area; tangential stiffness is related to the normal mutual approach distance of the two particles and elastic constant.
The newly developed egg-shaped particles are designed by the revolution of an ellipse, formed by four connected arcs, about the major axis passing through its centroid. Surface of egg-shaped particles can be divided into two spherical surfaces and a curved surface. Mainly contact can be divided into spherical surface contact and curved surface contact. The surface of egg-shaped particles belongs to rotating surface, so that we can quickly determine the principal radius of curvatures in the two contacted curves.
Numerical simulations for granular assemblies used equivalent linear contact spring stiffness, simulate the behavior of direct impact and oblique impact and compare the result with theoretical solution.
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