abaqus帮助文档翻译 2.1.11 一摞积木在通用接触下的倒塌分析.docx

2.1.11 Collapse of a stack of blocks with general contactProduct: Abaqus/Explicit This example illustrates the use of the general contact capability in a simulation involving a large number of contacting bodies. The general contact algorithm allows very simple definitions of contact with very few restrictions on the types of surfaces involved (see “Defining general contact interactions in Abaqus/Explicit,” Section 35.4.1 of the Abaqus Analysis Users Manual).Problem descriptionThe model simulates the collapse of a stack of blocks. The undeformed configuration of the model is shown in Figure 2.1.111. There are 35 blocks, and each block is 12.7 12.7 76.2 mm (0.5 0.5 3 inches) in size. The blocks are stacked on a rigid floor. The stack is subjected to gravity loading. It is assumed that a key block near the bottom of the stack has been removed just before the start of the analysis, initiating the collapse.Each block is modeled with a single C3D8R element. The use of a coarse mesh highlights the edge-to-edge contact capability of the general contact algorithm, because the majority of the block-to-block interactions do not result in penetrations of nodes into faces.Two different cases are analyzed. In the first analysis the blocks are rigid. In the second analysis the blocks are deformable. In the latter case, the material of the block is assumed to be linear elastic with a Youngs modulus of 12.135 GPa (1.76 106 Psi), a Poissons ratio of 0.3, and a density of 577.098 kg/m3 (5.4 105 lb s2/in4). Only the density is relevant for the analysis assuming rigid blocks. In addition, ENHANCED hourglass control is used for the deformable analysis. The rigid floor is modeled as a discrete rigid surface using a single R3D4 element.This model involves a large number of contacting bodies. The general contact capability greatly simplifies the contact definition, since each of the 595 possible block-to-block pairings does not need to be specified individually. The general contact inclusions option to automatically define an all-inclusive surface is used and is the simplest way to define contact in the model. Coulomb friction with a friction coefficient of 0.15 is assumed between the individual blocks and between the blocks and floor. The general contact property assignment is used to assign this nondefault contact property.By default, the general contact algorithm in Abaqus/Explicit accounts for edge-to-edge contact of perimeter edges on structural elements. Geometric feature edges of a model can also be considered for edge-to-edge contact by the general contact algorithm; including the geometric feature edges is crucial in this analysis. A cutoff feature angle of 20 is specified for the feature angle criterion of the surface property to indicate that all edges with feature angles greater than 20 should be considered for edge-to-edge contact. The feature angle is the angle formed between the normals of the two facets connected to an edge.The magnitude of the gravity loading is increased by a factor of 10 to facilitate demonstration of the edge-to-edge contact capability with a short analysis time. The analysis is performed for a period of 0.15 seconds. For the analysis with rigid blocks there is no deformable element available in the model to control the stable time increment. A fixed time increment of 1 106 seconds is specified for this purpose, which is similar to the time increment used by the analysis with deformable blocks. The time increment chosen for the analysis with rigid blocks will affect the penalty stiffness used by the contact algorithm since the penalty stiffness is inversely proportional to the time increment squared.Results and discussionResults are shown for the rigid body case. Results for the deformable case are very similar to the rigid model results.Figure 2.1.112 shows the displaced shape of the block assembly after 0.0375 seconds. The stack of blocks has started to collapse under gravity loading. Figure 2.1.113 shows a close-up view of the collapsing blocks after 0.1125 seconds. This figure clearly shows that the geometric feature edges of individual blocks contact each other during collapse. Figure 2.1.114 shows the final configuration of the blocks. The stack has collapsed completely on the rigid surface.Input filesblocks_rigid_gcont.inp Input file for the rigid body analysis.blocks_rigid_assembly.inp External file referenced by the rigid body analysis.blocks_deform_gcont.inp Input file for the deformable analysis.blocks_deform_assembly.inp External file referenced by the deformable analysis.FiguresFigure 2.1.111 Initial configuration of the stack of blocks.Figure 2.1.112 Displaced shape after 0.0375 s.Figure 2.1.113 Close-up view of the collapsing blocks after 0.1125 s.Figure 2.1.114 Final configuration of the model.2.1.11 一摞积木在通用接触下的倒塌分析 Product：Abaqus/Explicit这个例子说明通用接触的使用在涉及大量接触物体倒塌的模拟中应用。通用接触算法可以非常简单的定义接触很少的限制类型的表面。(see “Defining general contact interactions in Abaqus/Explicit,” Section 35.4.1 of the Abaqus Analysis Users Manual).问题描述该模型模拟了一堆木块倒塌。未变形的模型如图2.1.11-1所示。有35块,每个块12.712.776.2毫米(0.50.53英寸)。木块堆放在钢性地面上。堆积的木块收到重力荷载。假定一个关键块的底部附近的木块在分析之前已经移除，,开始倒塌模拟。每一木块都是单个的C3D8R建模元素。使用粗网格强调了边缘接触通用接触算法的能力,因为大多数block-to-block交互的节点不会导致渗透到表面。对两个不同的案例进行了分析。在第一个分析块是刚性的。在第二块是可以变形的。在后一种情况下,材料的块被假定为线性弹性杨氏模量为12.135 GPa(1.76106 Psi),泊松比为0.3,密度为577.098公斤/立方米(5.4 lb / )。对刚性木块的分析只有假设的密度。此外,增强沙漏控制用于变形分析。刚性层建模为离散的刚性表面使用单一R3D4元素。这个模型涉及大量的接触物体。一般的接触能力极大地简化了接触定义,因为每个block-to-block配对的595可能不需要单独指定。一般接触物体会选择自动定义一个使用广泛的表面和最简单的方式来定义接触模型。假定个体之间的块，块和之间的地板上的库仑摩擦摩擦系数为0.15。一般接触属性分配用于分配这个默认的接触属性。默认情况下，在Abaqus/Explicit中的通用接触算法在结构元素与e