弹性力学基础及有限元法-7

Review the Results with Postprocessors
You can review these results using POST1, the h general l postprocessor, and d POST26, PO T26 the time-history processor. POST1 is used to review results over the entire model at specific p substeps p (timepoints). POST26 6 is used u in n nonlinear n n n ar static a ana analyses y to track specific result items over the applied pp load history. y.

3. Pressures (PRES)


4. Temperatures (TEMP)
Solve the Analysis
1. Save a backup copy of the database to a named file.
Command(s): SAVE GUI: Utility Menu> File> Save as
弹性力学基础及有限元法-7 Elasticity & Finite Element Method (FEM)
ANSYS简介，静态分析（1）
FEM & ANSYS-7
内蒙古科技大学 机械工程学院 刘学杰 2011-11 2011 11
http://sme.imust.cn/UploadFile/Elasticity-FEM/Elasticity-FEM.htm
Introduction of ANSYS

2. The function of ANSYS (功能）


Contact analysis (接触分析） Thermal analysis（热分析） Electromagnetic field analysis（电磁场分析） Fluid analysis （流体分析）：① Computational fluid dynamics (CFD)， ② Acoustics analysis Couple field analysis （耦合场分析）

1. Graphical User Interface (GUI) 图形用 户界面

1) Utility Menu（通用菜单）：File; Select; List; Plot; ; WorkPlane; ; PlotCtrls; 2) Main Menu（主菜单）：Preferences; PREP7; Solution; POST1; POST26; 3) Graphical window （图形窗口） 4) ) Input p window （输入窗口） 输 窗 5) Output window （输出窗口） 6) Tool bar （工具条）


Finite element method (FEM)

FEM procedure The Th body b d i is di divided id d i into some fi finite i elements. l to get the stiffness matrix of every element in th single the i l element l t analysis l i . The whole stiffness matrix is integrated from all element matrixes. matrixes To solve the equation and to obtain displacements of the nodes. nodes To draw the unknown values from the values of the nodes.
B ild the Build h M Model d l

Building a finite element model requires more of your time than any other part of the analysis.

First, you specify a jobname and analysis title First title. Then, you use the PREP7 preprocessor to f define the element types, element real constants, material properties, and the model geometry.
2 St 2. Start t solution l ti calculations. l l ti
Command(s): SOLVE GUI: Main Menu> Solution> Solve> Current LS
R i Review th the R Results s lts

Results from a static analysis are written to the structural t t l results lt fil file, J Jobname.RST. b RST Th They consist of the following data: 1 Primary data: 1.
O tli Outline 概要
1 R 1. Review i 回顾 2. ANSYS简介 3.静力学分析实例—平面桁架



Βιβλιοθήκη Baidu
Review 回顾

Finite Element Method FEM （有限元法）

1. Model and concept 模型和概念 1 2. FEM basic idea 有限元法的基本思想 3. 基本步骤 本步
A l th Apply the L Loads ds

Load Types: in a static analysis. 1. Displacements (UX, UY, UZ, ROTX, ROTY, ROTZ)



2. Forces (FX, FY, FZ) and Moments (MX, MY, MZ)
I t d ti of Introduction f ANSYS

3. Features of ANSYS（特点）

The individual physical field analysis such as structural, thermal, etc. and the coupled field analysis are both possible. possible Unified Database Powerful non-linear analysis Friendly interface and easy to use A strong function of the secondary development A variety of automatic meshing tools

1、离散化原则 2、位移函数 缘由,形式,收敛； ·单元刚度矩阵导出,性质 3、整体刚度方程




整体刚度矩阵构建方法； 等效载荷处理方法； 位移边界条件处理方法


4、求解方程组 求得直接未 求得直接未知量,导出未知量 量,导出未 量 求取节点应力
I t d ti of Introduction f ANSYS


Case No. 5: A static analysis y of f the truss structuresPlane truss (杆系结构的静力学分析实例—平面桁架 )
图 5-1 平面桁架

如图所示为一平面桁架，长度L=0.1 m，各杆横截面面积均 为A=1×10-4 m2，力P=2000 N，计算各杆的轴向力Fa、轴向 应力σa。 a

These are DOF constraints usually specified at model boundaries to define rigid support points. They can also indicate symmetry t b boundary d conditions diti and d points i t of fk known motion. ti These are concentrated loads usually specified on the model exterior. exterior These are surface loads, also usually applied on the model exterior Positive values of pressure act towards the element exterior. face (resulting in a compressive effect).



Case No. 5: A static analysis y of f the truss structuresPlane truss (杆系结构的静力学分析实例—平面桁架 )
图 5-1 平面桁架

如图所示为一平面桁架，长度L=0.1 m，各杆横截面面积均 为A=1×10-4 m2，力P=2000 N，计算各杆的轴向力Fa、轴向 应力σa。 a

离散化 单元分析 位移函数 单元刚度矩阵 整体分析 求解 整体刚度矩阵 节点载荷等效处理 节点约束处理

4. 整体分析


5.应力计算
The concept of FEM 有限元概念
有限元法的基本思想 ？
有限单元法解题的基本步骤

1、结构离散化 2、单元分析 单元分析 3、整体分析 整体分析 构建整体刚度矩阵 等效载荷处理 位移边界条件处理 4、求解方程组 求得直接未知量 求取导出未知量

2 D 2. Derived i dd data:

Nodal displacements (UX, UY, UZ, ROTX, ROTY, ROTZ) Nodal and element stresses Nodal and element strains Element forces Nodal reaction forces
An l sis procedure Analysis p d

1. Preference: static analysis 2 D 2. Define fi th the element l t types t 3. Define the real constants 4 Define material properties 4. 5. Build the model


Introduction of ANSYS

2. The function of ANSYS (功能 ）

Structural (结构分析） Static analysis （静力学分析） Dynamics y m analysis y （动力学分析 动力学分析）： ①modal analysis, ② harmonic response analysis, ③transient analysis l Buckling analysis（失稳分析）
The p procedure for a static analysis y in ANSYS
The procedure for a static analysis consists of these tasks: B ild th Build the M Model d l Apply the Loads Solve the Analysis Review the Results Analyze the Results and improve the design. design