《BeamModeling》由会员分享，可在线阅读，更多相关《BeamModeling（20页珍藏版）》请在金锄头文库上搜索。
1、Beam ModelingModule 5INTRODUCTION TO ANSYS 6.0 - Part 2INTRODUCTION TO ANSYS 6.0 - Part 2Training Manual5. Beam ModelingBeam elements are line elements used to create a one-dimensional idealization of a 3-D structure.They are computationally more efficient than solids and shells and are heavily used
2、 in several industries:Building constructionBridges and roadwaysPeople movers (trams,railcars, buses)Etc.October 30, 2001INTRODUCTION TO ANSYS 6.0 - Part 2INTRODUCTION TO ANSYS 6.0 - Part 2Training Manual.Beam ModelingIn this chapter, we will present a brief introduction to beam modeling via the fol
3、lowing topics:A. Beam PropertiesB. Beam MeshingC. Loading, Solution, ResultsD. WorkshopOctober 30, 2001INTRODUCTION TO ANSYS 6.0 - Part 2INTRODUCTION TO ANSYS 6.0 - Part 2Training ManualBeam ModelingA. Beam PropertiesThe first step in beam modeling, as with any analysis, is to create the geometry us
4、ually just a framework of keypoints and lines.Then define the following beam properties:Element typeCross sectionMaterialOctober 30, 2001INTRODUCTION TO ANSYS 6.0 - Part 2INTRODUCTION TO ANSYS 6.0 - Part 2Training ManualBeam Modeling.Beam PropertiesElement TypeChoose one of the following types:BEAM1
5、88 3-D, linear (2-node)BEAM189 3-D, quadratic (3-node)ANSYS has many other beam elements, but BEAM188 & 189 are generally recommended.Applicable to most beam structuresSupport linear as well as nonlinear analyses, including plasticity, large deformation, and nonlinear collapseAbility to include mult
6、iple materials to simulate layered materials, composites, reinforced sections, etc.Ability to create “user defined” section geometryEasy to use, both in preprocessing and postprocessing phasesOctober 30, 2001INTRODUCTION TO ANSYS 6.0 - Part 2INTRODUCTION TO ANSYS 6.0 - Part 2Training ManualBeam Mode
7、ling.Beam PropertiesCross SectionTo completely define a BEAM188 or 189 element, you also need to specify its cross section properties.The BeamTool provides a convenient way to do this.Preprocessor Sections Common Sectns.Select the desired shape, then enter its dimensions.Press the Preview button to
8、view the shape, then OK to accept it.If there are multiple cross sections, specify a different section ID number (and an optional name) for each.October 30, 2001INTRODUCTION TO ANSYS 6.0 - Part 2INTRODUCTION TO ANSYS 6.0 - Part 2Training ManualBeam Modeling.Beam PropertiesA sample preview (SECPLOT)
9、of an I-beam cross section is shown below.In addition to the predefined cross-section shapes, ANSYS allows you to create your own, “user-defined” shape by building a 2-D solid model.You can save user-defined sections as well as standard sections with the desired dimensions in a section library for l
10、ater use.See Chapter 15 of the ANSYS Structural Analysis Guide for more information.October 30, 2001INTRODUCTION TO ANSYS 6.0 - Part 2INTRODUCTION TO ANSYS 6.0 - Part 2Training ManualBeam Modeling.Beam PropertiesMaterial PropertiesBoth linear and nonlinear material properties are allowed.After all b
11、eam properties are defined, the next step is to mesh the geometry with beam elements.October 30, 2001INTRODUCTION TO ANSYS 6.0 - Part 2INTRODUCTION TO ANSYS 6.0 - Part 2Training ManualBeam ModelingB. Beam MeshingMeshing the geometry (lines) with beam elements involves three main steps:Assign line at
12、tributesSpecify line divisionsGenerate the meshThe MeshTool provides a convenient way to perform all three steps. October 30, 2001INTRODUCTION TO ANSYS 6.0 - Part 2INTRODUCTION TO ANSYS 6.0 - Part 2Training ManualBeam Modeling.Beam MeshingStep 1: Line AttributesLine attributes for beam meshing consi
13、st of:Material numberSection IDOrientation keypointDetermines how the cross section is oriented with respect to the beam axis.Must be specified for all cross-section types.A single keypoint can be assigned to multiple lines (i.e, no need to specify a separate keypoint for each line).Each end of a li
14、ne can have its own orientation keypoint, allowing the cross section to be “twisted” about the beam axis.October 30, 2001INTRODUCTION TO ANSYS 6.0 - Part 2INTRODUCTION TO ANSYS 6.0 - Part 2Training ManualBeam Modeling.Beam MeshingExamples of using orientation keypoints:October 30, 2001INTRODUCTION T
15、O ANSYS 6.0 - Part 2INTRODUCTION TO ANSYS 6.0 - Part 2Training ManualBeam Modeling.Beam MeshingTo assign line attributes, use the “Element Attributes” section of the MeshTool (or select desired lines and use the LATT command).Pick lines Additional attributes for BEAM188 & 189October 30, 2001INTRODUC
16、TION TO ANSYS 6.0 - Part 2INTRODUCTION TO ANSYS 6.0 - Part 2Training ManualBeam Modeling.Beam MeshingStep 2: Line DivisionsFor BEAM188 and 189 elements, a single element spanning the entire beam length is not recommended.Use the “Size Controls” section of the MeshTool (or the LESIZE command) to spec
17、ify the desired number of line divisions.October 30, 2001INTRODUCTION TO ANSYS 6.0 - Part 2INTRODUCTION TO ANSYS 6.0 - Part 2Training ManualBeam Modeling.Beam MeshingStep 3: Generate the MeshFirst save the database (Toolbar SAVE_DB or SAVE command).Then press the Mesh button in the MeshTool (or issu
18、e LMESH,ALL) to generate the mesh.Pick lines October 30, 2001INTRODUCTION TO ANSYS 6.0 - Part 2INTRODUCTION TO ANSYS 6.0 - Part 2Training ManualBeam Modeling.Beam MeshingTo see the cross-section shape in the element display, activate the element shape key:Utility Menu PlotCtrls Style Size and ShapeO
19、r /ESHAPE,1October 30, 2001INTRODUCTION TO ANSYS 6.0 - Part 2INTRODUCTION TO ANSYS 6.0 - Part 2Training ManualBeam Modeling.Beam MeshingAfter beam meshing is completed, the next step is to apply loads and solve.October 30, 2001INTRODUCTION TO ANSYS 6.0 - Part 2INTRODUCTION TO ANSYS 6.0 - Part 2Train
20、ing ManualBeam ModelingC. Loading, Solution, ResultsTypical loading for beam models consists of:Displacement constraintsapplied at keypoints or nodesForcesapplied at keypoints or nodesPressuresload per unit lengthapplied on element facesSolution Apply Pressures On BeamsOr SFBEAM commandGravity or ro
21、tational velocityacts on entire structureOctober 30, 2001INTRODUCTION TO ANSYS 6.0 - Part 2INTRODUCTION TO ANSYS 6.0 - Part 2Training ManualBeam Modeling.Loading, Solution, ResultsTo obtain the solution:First save the database.Then solve. (Or write the loads to a load step file and solve all load st
22、eps later.)Results review is the same as for other stress analyses:View the deformed shapeCheck reaction forcesPlot stresses and strainsThe main advantage of BEAM188 and 189 is that with the element shape key activated (/ESHAPE,1), stresses can be directly viewed on the elements (similar to solids a
23、nd shells).October 30, 2001INTRODUCTION TO ANSYS 6.0 - Part 2INTRODUCTION TO ANSYS 6.0 - Part 2Training ManualBeam Modeling.Loading, Solution, ResultsDemo:Resume frame.db (contains lines, kps, loading, element type, material, and two cross sections)Plot the two cross section already defined (SECPLOT
24、,1 & 2)Define a third cross section using the BeamTool:ID=3: Name = peak, Sub-type = box (hollow rectangle), W1=6, W2=6; T1=T2=T3=T4=0.25Bring up MeshTool, GPLOT, then assign the following line attributes:Sloping lines: mat=1, secnum=3, orientation KP = topmost KP (#100)Left vertical lines: mat=1, s
25、ecnum=2, orientation KP = #102Right vertical lines: mat=1, secnum=2, orientation KP = #101Left & front horizontal lines: mat=1, secnum=1, orientation KP = #1Right & back horizontal lines: mat=1, secnum=1, orientation KP = #3Specify size=20 on all linesSave, then LMESH,ALL; then EPLOT with /ESHAPE,1C
26、onstrain the 4 bottom keypoints in all DOFs and apply a force of -10,000 lb in the fy direction on keypoint #9Solve, then review results: deformed shape (animate), reaction forces, SX stresses (= axial + bending). Select elements with section ID=3 and replot stresses. Repeat for ID=2.October 30, 2001INTRODUCTION TO ANSYS 6.0 - Part 2INTRODUCTION TO ANSYS 6.0 - Part 2Training ManualBeam ModelingD. WorkshopThis workshop consists of the following problem:W4. Building FramePlease refer to your Workshop Supplement for instructions.October 30, 2001
