Femap梁板单元模型实例操作BeamPlateModel

IntroductionIn this example we will read in simplified wireframe geometry of the following assembly.The top plate will be modeled with plate elements, and the underlying support beams will be modeled with beam elements.The steps you will follow in this exercise are:•Import a Femap Neutral File containing wireframe geometry.•Create a Material and the Plate and Beam Properties for the model•Create the surfaces for the model•Mesh the surfaces•Constrain the plate•Add the support beams•Apply a load to the plates•Analyze the model and review the resultsStep 1:Import a Femap Neutral FileImport the geometry from a Femap Neutral file.•Select the File, Import, Femap Neutral command•Select the file, ex9 –Plate Geometry.neu,located in your training class’ Geometry folder. Click OK in theNeutral File Read Options dialog box.This geometry will be meshed with elements, whoseproperties and materials we will now define.•Save your model in the Exercises folder as ex9-BeamPlate.modfem.Step 2:Create a Material and the Plate and BeamProperties for the modelCreate the Material•Select the Model, Material command or right-click on the Materials object in the Model Info window andselect New.•In the Define Material –ISOTROPIC dialog box, click Load.•Select the material, Aluminum 7075 Heat Treated(T6) Wrought in the Select from Library dialog box.•After selecting the Aluminum 7075 Heat Treated (T6)Wrought material, click OK to create the material.•Click Cancel or use the esc key to exit the command.Note :mat_eng_in-lbf-If your default library is not set topsi-degF-BTU.esp, you can easily change thelibrary to this by clicking the Choose Librarybutton in the Select from Library dialog box.The library referenced above is in both theLibraries and Settings folder under you classfiles folder or in the main Femap installationfolder.•To create the plate property, right-click the Properties object in the Model Info window and select New.•In the Define Property –PLATE Element Type dialog box select the material previously created from the Material drop-down list.•Enter the Title as 2.5 mm Thick Plate.•Enter the Thickness as 2.5.•Click OK to continue.Create the a Beam property.•FEMAP will automatically prompt you for the next property. To change to a beam property, click theElem/Property Type button, and change theElem/Property Type to Beam.•FEMAP now displays the Define Element -BEAM Element Type dialog box.•Set the Title to 25 X 12.5 X 15 X 2.5 C-Channel•Set the Material to the aluminum material created earlier.•Instead of entering the beam properties manually, click the Shape button to enter the cross-section data directly.•In the Cross Section Definition dialog box, select Channel (C) Section from the Shape drop-down list.•Enter the following:Height25Width, top12.5Width,bottom15Thick,top 1.5Thick, bottom 2.5Thickness 2.5•Check the option for Reference Point on. Using the arrow buttons, move the Reference Point to theupper left corner of the channel cross section. You should see the letter R as the indication of thelocation of the reference point.•Click OK to confirm your entries in the Cross Section Definition dialog box.Note how the fields in the Define Property dialog boxhave been filled in with the calculated values for thebeam property.•Click OK to create the first beam’s property.•Click Cancel or use the Esc key to exit the property command.Save your model.Step 3:Create the surfaces for the modelCreate the Boundary Surfaces that will be meshed with plates. Boundary Surfaces are composed of exterior, and optionally, interior closed connected curves.•In our example, we will create two boundaries.Select the Geometry, Boundary Surface, FromCurves command.•Select the six curves (curves 1-6) that make up the left boundary in any order. Click OK in the EntitySelection… dialog box to create the boundarysurface.•Create another Boundary Surface using the four curves (curves 2, 7, 8, and 9) in the right boundary.•Click Cancel or press Esc key to exit the command.Convert the Boundary Surfaces to Parasolid surfaces and create a single sheet body.•Select the Geometry, Surface, Convert command.•Click Select All to choose both boundary surfaces and click OK.•When prompted to “OK to delete original surfaces?”, click YES•Click Cancel or press Esc key to exit the command.Note how the two surfaces now appear in the ModelInfo window as sheet solids.•Select the Geometry, Solid, Stitch command.•In the Entity Selection dialog box, click Select All, and then click OK.•In the Surface/Solid Stitching dialog box, Disable (uncheck the box) for the option, Cleanup Mergeable Curves.•With highlighting enabled in the Model Info pane toolbar, select the solid (3..Stitched Body) and notehow the vertical mid-line is still part of the body. Ifyou had had not disabled the option for CleanupMergeable Curves, the stitching operation wouldrecognize that the two surfaces share a commonedge and lie on a tangent plane resulting in a into asingle surface sheet body.Step 4:Mesh the surfacesSet a new default mesh size.•Select the command, Mesh, Mesh Control, Default Size.•In the Default Mesh Size dialog box, set the Size to25.0and then, click OK to apply the new setting.Visualize the mesh size.•To visualize the mesh spacing, press the F6key.This activates the View Options command.•Under the Labels, Entities and Color category, select the Curve –Mesh Size option. In the Show Assection, choose 3..Symbols and Count to turn on theMesh Size indicators on curves. Also, check theDraw Entity option on (this can also be toggled onand off from the View Style, Mesh Size icon on theView toolbar).•Click OK to display the Mesh Size indicatorsTurn off display of the surfaces.•On the Entity Display toolbar, click the ViewGeometry Toggle iconNote that the display of all geometry has been turnedoff. Also note how the display of icons on the toolbarhave changed from filled to unfilled. Filled iconsindicate the entity type is displayed and unfilled icons indicate the entity type is not displayed.•On the Entity Display toolbar, click the View Curves Toggle icon. This will turn on display of curves.Adjust the mesh sizes on the surface.•Select Mesh, Mesh Control, Size Along Curve command.•Select the vertical midline splitting the two surfaces and the vertical edge on the right side of the body(curves 13 and 17) and click OK to confirm yourselection and set the mesh size on those two curves.•Change the Number of Elements to 20and click OK.Note how the mesh size indicators have beenupdated to show the finer mesh size as well as thenumber of elements along the two curves youupdated the mesh size on. Only those curves,surfaces and solids that have had mesh sizes setmanually with the Mesh, Mesh Control, Size Along…command will have the number of elements ontheir respective curves displayed. No mesh sizenumber indicates that the default mesh size is beingused.Set the mesh attributes on the surfaces.•Select the command, Mesh, Mesh Control, Attributes on Surface.•In the Entity Selection dialog box, click the Select All button, and then click OK.•In the Surface Mesh Attributes dialog box, set the Property to 1..2.5 mm Thick Plate.Set the option for Offset to Surface To Bottom Face.This will automatically set the offset of the mesh sothat the bottom face of the elements lie on thesurface.Enable the option for Map Subdivisions.•Click OK to set the mesh attributes.•Click the Esc key to exit the command.Mesh the surfaces.•Select the command, Mesh, Geometry, Surfaces.•In the Entity Selection dialog box, click the Select All button, and then click OK.Your model should appear as below.The view is set to display elements by element color, and in this case, the default color for elements arewhite, making the display appear as if it is inwireframe mode.Change the color of the elements.•In the Model Info pane, expand the Model, Elements object, and then the By Type object.You should see an element object, Plate, Linear.The number indicates the number of this type ofelement in the model.•Right-click the Plate, Linear object and select Color from the menu.•In the Color Palette dialog box, select one of the colors and click OK.Change the display of the elements to the property color.•On the View toolbar, select the View Style icon and then the Color With, Property Colors command.Modify the mesh using by setting the mesh size on surfaces and then remeshing the model.•Select the command, Mesh, Mesh Control, Size on Surfaces.•In the Entity Selection dialog box, click the Select All button, and then click OK.•In the Automatic Mesh Sizing dialog box, set the Element Size to 12.5.Enable the option for Replace Mesh Sizes on AllCurves.Disable the options for both Max Angle Toleranceand Max Elem on Small Feature.Click OK to set the mesh sizes.Note how the mesh size indicators on the curveshave been updated to show the new mesh size.Modify the mesh size on the arc.•Select the command, Mesh, Mesh Control, Interactive.•In the Interactive Mesh Sizing dialog box, click the Subtract button. Make sure you do this beforeselecting any curves.•Select the arc, then click Done. The mesh size on the curve should now be shown as 12.Remesh the surfaces.•Select the Mesh, Geometry, Surfaces command.•In the Entity Selection dialog box, click the Select All button, then click OK.•Since the surfaces have already been meshed, the Meshing Already Meshed Surfaces dialog box isopened. Accept the default setting, Delete ExistingMesh and Remesh option and click OK to remeshthe surfaces.•Click OK in the Automesh Surfaces dialog box.Your mesh should appear as below.Display the quality of the mesh.•Activate the Meshing Toolbox. If it is already activated and in the background or tabbed closed,click the Meshing Toolbox tab. If the toolbox is notopen, click the Meshing Toolbox icon on the Panestoolbar.•On the Meshing Toolbox’s toolbar, click the Quality icon.The mesh quality should be displayed as shownbelow. The red colored elements indicate elementswith a Jacobian value exceeding 0.6.Expand the Quality tool to display the maximum value of the Jacobian quality measurement.The Jacobian value is the comparison of all theelement’s quality values (aspect ratio, etc.) versus anideal element of the same type.•Expand the Quality tool by clicking on the Quality object in the Meshing Toolbox.Note how the worst element quality is at a value of.642246.•Click the Quality icon again on the MeshingToolbox’s toolbar to turn off display of the meshquality.Turn off display of the mesh size indicators•On the View toolbar, select the View Style icon and select Mesh Size from the menu.Step 5:Constrain the plateConstrain the Model. For this example, we will add boundary conditions to the geometry of the modelbefore meshing. FEMAP will automatically expand the boundary conditions out to the nodes when exporting the analysis model to your solver.•Create a constraint set by expanding the Model Info pane and selecting New from the menu.•In the New Constraint Set dialog box, set the Title to Pinned Edges and then click OK to create the newconstraint set.Create pinned constraints on the edges of the panels.•Expand the Pinned Edges constraint set in the Model Info pane.•Right-click Constraint Definitions and select On Curve from the menu.•In the Entity Selection dialog box, select the four curves parallel to the model’s X-axis and the right edge of the plates. Use the Preview button tohighlight the selected curves before clicking the OK button to confirm you’ve selected the correct curves.•In the Create Constraints on Geometry dialog box, enter a descriptive Title for the constraint definition and set the constraint to Pinned –No Translation.•Click OK to create the constraints.•With highlighting enabled, click the newly created constraint in the Model Info pane. The geometry that is attached to the constraint should be displayed as highlighted.Step 6:Add the support beamsAdd the support beams.•Select Mesh, Geometry, Curve command. Select the left straight edges and the center vertical edge as indicated below.•Select the channel, 2..25 X 12.5…C-Channelproperty created earlier from the Property drop-down list. Click OK to continue.Add the support beams (continued).•FEMAP will now ask for a vector to orient the Y-Axis of the beam elements, align the beam Y-Axis withthe Global X-Axis (Base: 0,0,0Tip: 1,0,0).Since the element cross section displays are not turned on, you will need to turn this on at this time to display the beam shape and the element thickness of theshells.•Select the View Style icon on the View toolbar, and then select Thickness/Cross Section from the menu.The plate and beam offset are also not displayed.Reorient the view to the front view orientation byselecting the Orient Front icon on the ViewOrientation toolbar.Note how the offsets are not displayed.Select the View Style icon on the View toolbar, and then select Offsets from the menu.Visualize the resulting mesh.•Rotate the view so that you can see the entire model.In the next set of steps, you will modify the offsets ofthe beams and for some of the beams, their directionwill need to be reversed.Modify the color of the beam property.•Right-click the property 2..25 X 12.5 X 15 X 2.5in the Model Info pane and select Color from the menu.•Change the color of the property to some other color different than the existing channel property.Modify the offsets of the beam so that their offset location is set to the reference location you set whencreating the property.•Select the command, Modify, Update Elements, Line Element Offsets.•In the Entity Selection dialog box, click the Method button and select Property from the menu.Note how the title of the dialog box changed to Entity Selection –Select Element(s) to Update Offsets (ByProperty).•Select one of the beam elements, and then click OK.•In the Update Element Offsets dialog box, click the Move to Reference Point button and then click OK.You will need to refresh your graphics pane to update it to display the beam offsets correctly.•Press the Ctrl+g hotkey to refresh the display.The beam offsets should appear as below, indicating that some of the beams need to have their directionreversed.Reverse the direction of the channel elements that are incorrectly oriented.•Select the command, Modify, Update Elements, Line Element Reverse Direction.•In the Entity Selection dialog box, click the Methods button and select On Curve from the menu.•Select the curve on the lower left and the middle curve. Use the Preview button to confirm yourselection and then, click OK.•In the Update Element Direction dialog box, select the Reverse Direction radio button and then, clickOK.Note that the direction of the beams is now correct(the shorter flange is at the top of the beam),however, their offsets will need to be reset.Correct the offsets of the beams just reversed.•Select the command, Modify, Update Elements, Line Element Offsets.•In the Entity Selection dialog box, click the Previous button and then, click OK.You may want to use the Preview button to confirmthat the elements that you selected for reversing arestill the selected beams.•Again, in the Update Element Offsets dialog box, click the Move to Reference Point button and OK.Switch to the front view of the model to confirm that the beam elements are oriented and offset correctly.•Select Orient Front icon on the View Orient toolbar.Note how the top of the channels line on the bottomof the plates.Run final checks on the model. When you mesh different portions of a model at different times, there will be coincident nodes, essentially, sections of your model that overlap.•Select Tools, Check, Coincident Nodes.•Select All of the nodes and click OK.•In the Check/Merge Coincident dialog box, set the option for Keep ID to Lower ID.•Click the Preview button.•Click the Done button.•In the Check/Merge Coincident dialog box, click OK to merge the nodes.Step 7:Apply a load to the platesCreate a load on the plates.•In the Model Info pane, right-click the Loads object and select New from the menu.•In the New Load Set dialog box, enter a descriptive Title for the load set and then click OK.Add a force load to the left plate.•Expand the newly created load set.•Right-click the Load Definitions object and select On Surface.•Select both surfaces and click OK in the Entity Selection dialog box.•In the Create Loads on Surface(s)dialog box, add a descriptive Title.Set the load type to Force.Set the Direction to Normal to Surface.Set the Magnitude to -500.Disable(uncheck) the option for Total Load. This will apply a 500N load to each of the selected surfacesinstead of distributing a 500 N load among thesurfaces.•Click OK to apply the load to the two surfaces.Display the loaded surfaces.•Just like you did when you highlighted the constraint, click the newly created load. If highlighting is stillenabled, you should see the two surfaceshighlighted.•Press the Ctrl+g hotkey to refresh the display.Save your model.Step 8:Analyze the model and review the resultsAt this point, your model is ready to analyze with the NX Nastran solver.•Select the Model, Analysis command, or right-click on the Analyses object in the Model Info window andselect Manage, to open the Analysis Set Managerdialog box.•Click on New to create a new analysis set.•Give it a title, set the Solver to NX Nastran, the Analysis Type to 1..Linear Statics and, click OK.•Click on Analyze to start the analysis.This will open the Analysis Manager pane.•If no error or warnings are generated by thisanalysis, the results are automatically imported intoyour Femap model.Display the deformed model.•Activate the PostProcessing toolbox.•Expand the Deformed tool.•Set the Style to Deformed.Display the stress contours for the plates.•Expand the Contour tool.•Set the Style to Contour.Your graphics pane should appear similar to below.Note that you cannot simultaneously beam andshell/solid contours. In the next step, you’ll display a beam diagram.Turn off display of the deformed shape and stress contours.•On the PostProcessing Toolbox ’s toolbar, click the Set to Undeformed, No Contour, No Freebody icon.Display a beam diagram of the maximum stress on the beams.•For the Contour Style, select Beam Diagram.•Click the Select Output Vector icon.•In the Select Output Vector dialog box, enter Beam for Title Contains.•Click the Output Filter button and select 4..Line Elements. This will set the list to show only results available for the beam elements in the model.•Scroll down the list and select 3164..Beam End A Max Comb Stress.•Click OK to set the contour output vector.Turn off display of the plate elements.•In the Model Info pane, expand the Model, Elements, By Type object and uncheck the visibility check boxfor Plate, Linear.•Your model should now appear similar to the following.Turn off the display of all entities except for beams.•Press the Ctrl+q hotkey.In the View Visibility dialog box, click the All Offbutton, the check the box on for Elements.•Click the Done button.The default for beam directions is to display the results in the element y-direction. This step will change theresults to the element z-direction.•In the PostProcessing Toolbox’s Contour tool, expand the Show As tool•Set the Direction to Element Z.。