混合型剛體顆粒系統之數值模擬; Numerical Simulations for Granular Assemblies with Mixed 3D Ridge Body

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Title:	混合型剛體顆粒系統之數值模擬;Numerical Simulations for Granular Assemblies with Mixed 3D Ridge Body
Authors:	林佳宏;Cha-Hom Lin
Contributors:	土木工程研究所
Keywords:	剛體;接觸判斷;Contact detection;Rigid body
Date:	2005-12-21
Issue Date:	2009-09-18 17:15:36 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	自然界中石頭或是砂土顆粒充滿不同形狀，有角狀顆粒，也有球狀顆粒，二者常常混合在自然界或是工程應用上，例如混凝土攪拌中，預拌材料總是混合著角狀及球狀顆粒。前人曾研究利用頂點對面及稜邊對稜邊二種接觸情況發展出三維多面塊體程式及四圓弧逼近法發展三維混合型橢球顆粒堆積程式，本研究將二者所發展的多面體程式與橢球堆積程式進行結合並修改，藉由加入橢球與多面塊體的接觸判斷，使得修改之程式能增加執行混合型剛體運動數值模擬之功能。本研究加入橢球與多面塊體的接觸判斷方法，以四圓弧逼近法所形成的橢球，可先行判斷球面與弧面何者可能與多面塊體接觸，若是可能與球面接觸，則以球面球心到接觸點距離跟球面半徑大小比較判斷橢球是否入侵多面塊體，反之若是弧面可能與多面體接觸，橢球以弧面球心到接觸點距離與弧面球心半徑大小比較，以此方法分順序與多面體的(1)頂點(2)稜線(3)面做接觸判斷，而稜線的還須判斷所接觸點是否在稜線之中，面的接觸判斷須判斷接觸點是否在面的範圍之中，以此方法結合橢球與多面塊體的接觸碰撞。完成修改後的程式進行各種不同情況模擬及驗証，其中包含長扁橢球對(1)面、(2)稜線與(3)頂點的碰撞驗証，並進行混合多顆剛體自由落體碰撞測試，確認程式無誤後，應用程式模擬陀螺儀運動及單剪試驗。 The stone or sand particle are full of different forms in the nature. There are angle or spherical particles . The two particles often mix in the nature or apply to engineer .For example in the concrete is mixed , mix materials always mix angle and spherical particles. Forefather who use contact types are categorized by contacts of vertex-to-face and edge-to-edge only write 3-D polyhedral blocks program. And ever develop granular assemblies with mixed ellipsoidal particles program. In this research, we assemblies two programs.Add ellipsoidal and polyhedral contact detection let can simulate mixed 3D ridge body In the study, we add ellipsoid and polyhedron contact method. we use the ellipsoid with four arcs. First ,we determine which arcs will contact polyhedron. If polyhedron may touch with the sphere ,we determine contact or not which use comparing distance of contact point to sphere center and radius of sphere . If polyhedron may touch with the arc face , we compare distance of contact point to arcs face center and radius of arcs face. We use this kinds of method in order contact detection : (1) vertices (2 ) edges (3) planes , but edges contact must check contact point in the edge line or not. In the planes contact must check contact point in the planes range. Finish correctional program, we simulate contact include: (1) planes (2 ) edges (3)vertices contact prove . And simulate freely falling body and contact test.After confirming , we use program to simulate simple shear test and gyroscope motion.
Appears in Collections:	[Graduate Institute of Civil Engineering] Electronic Thesis & Dissertation

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