1--几何模型建立.doc

W3.12这个实例中要用到的cad模型文件和脚本文件都可以在 abaqus的sample文件夹（或者那个*.zip文件）里找到。 这个实例涉及到了用abaqus进行分析的整个流程中的各个细节，是入门的好帮手。像我这样的新手一定会喜欢的：） 部件：泵体+垫片+底盖+螺栓 荷载条件：螺栓预紧+内压 ABAQUS IntroductionThe structural response of the pump assembly shown in Figure W31 will be determined. The assembly components include the pump housing (imported as an orphan mesh), a gasket, a cover, and eight bolts (all imported as CAD geometry). The analysis involves application of pre-tensioning loads in the bolts followed by internal pressure. pump housinggasketcoverboltsFigure W31. Pump assemblyIn this workshop, you will create the parts of the model. Use the Part module of ABAQUS/CAE to import the mesh of a pump housing. Some modifications of its geometric features follow. The other components of the pump assembly (cover, gasket, and bolts) will be imported as CAD geometry. All of the parts will be halved to take advantage of symmetry.Note: The parts created in this workshop will be used in subsequent workshops to build the complete model and to perform the analysis. It is important that you use the dimensions stated and not deviate from the workshop instructions; otherwise, you may find it difficult to complete the subsequent workshops.Orphan mesh import Follow the steps below to import the mesh of the pump housing model.1. Start a new session of ABAQUS/CAE from workshops/pump directory.ABAQUS/CAE automatically loads the Part module.2. From the main menu bar, select FileImportModel. From the list of available models, select pump_ribs.inp.3. ABAQUS/CAE takes a few seconds to import the model. Once the model is imported, you will be in the Assembly module. Switch back to the Part module. Notice that a new model (named pump_ribs) which contains the imported part (named PUMP1) has been created. The model appears as shown in Figure W32. Figure W32. Orphan mesh of pump housingEditing nodal coordinatesYour first task will be to change the inner diameter of the hole that goes through the top of the pump. The coordinates of the nodes along the inner diameter need to be changed. Since these nodes lie on a circular surface, it will be advantageous to define a cylindrical coordinate system and simply change the radial coordinate of the nodes. Follow the steps below to achieve this task.1. From the main menu bar, select ViewViews Toolbox. In the Views dialog box, select the 12 view. Turn off the perspective view by clicking the Turn Perspective Off tool (), and zoom into the component so that the hole is clearly visible (see Figure W33).Figure W33. Top view of pump housing2. From the main menu bar, select ToolsDatum. The Create Datum dialog box appears (see Figure W34). Select CSYS as the datum type. Select the 3 points method, and click OK. When prompted for the type of coordinate system, choose Cylindrical. Place the coordinate system at the origin (0.0, 0.0, 0.0) and click Create Datum.A cylindrical datum coordinate system is created. The origin of the coordinate system coincides with the position of the center of the hole.Figure W34. Create Datum dialog box3. You will now modify the inner diameter of the hole. From the main menu bar, select ToolsEdit Mesh. In the Edit Mesh dialog box, select Node as the category and Edit as the method, as shown in Figure W35. Click OK to close the dialog box and proceed.Figure W35. Edit Mesh dialog box4. You will be prompted to select the nodes to be modified. Begin by setting the selection filters as shown in Figure W36 by clicking the Show/Hide Selection Options tool, in the prompt area.Select entities inside the drag shapeCircular drag shapeToggle off the selection of entities closest to the screenFigure W36. Selection filters5. The nodes can be selected in one of two ways: Try selecting the nodes individually (the default selection technique) using a Circular Drag Shape. The center of the drag shape should be the center of the cylindrical coordinate system defined earlier (see step 2). Select a perimeter point for the drag shape such that you include all the nodes on the inside surface of the hole. The selected nodes will be highlighted in red after the selection, as shown in Figure W37. You may wish to rotate your model to check whether all the nodes have been selected properly. You may also select the nodes using the face angle method (i.e., by specifying the maximum deviation in the angle between adjacent element faces). This technique is generally more efficient than selecting the nodes individually: all nodes that pertain to the element faces that satisfy the face angle criterion are automatically selected. In the prompt area, choose by face angle as the method by which the nodes will be selected. Then, click on any element face located on the inner surface of the hole. The nodes on the inner surface are highlighted in red after the selection. As before, rotate your model to make sure all the nodes have been selected properly.Once you are satisfied with the selection (using either method), click Done in the prompt area.Figure W37. Modified nodes6. The Edit Nodes dialog box appears, as shown in Figure W38. This dialog box will be used to change the diameter of the hole. Click Select in the upper right corner of the dialog box, and choose the cylindrical coordinate system defined in step 2 by clicking on it in the viewport when prompted to choose a local coordinate system.7. Using the Coordinates specification method, change the 1coordinate (i.e., the radial coordinate) by selecting Specify from the pull down list and entering 0.65. Click OK to close the dialog box and then Done in the prompt area to complete the operation.Figure W38. Edit Nodes dialog boxDeleting elementsYou will now remove the ribs on the pump housing and then you will remove half of the part. Begin by removing some of the elements in the rib located near the front of the housing, as shown in Figure W39. Use the 13 view from the Views Toolbox, and rotate the pump to view one of the front ribs, as shown in Figure W39.Figure W39. Rib elements1. From the main menu bar, select ToolsEdit Mesh. In the Edit Mesh dialog box, select Element as the category and Delete as the method. Click OK.2. When prompted to select the elements to be deleted, use the Show/Hide Selection Options tool to change the drag shape to a Polygon. Select some of the elements located near the 90 bend of the rib, as shown in Figure W39. 3. In the prompt area, toggle on Delete associated unreferenced nodes. 4. Zoom out and rotate the view to confirm that only elements pertaining to the ribs have been selected. If any other elements are highlighted, deselect them using Control+Click. When you are satisfied with the selection, click Done to delete the elements and their associated nodes.5. The remaining ribs on the pump housing can be removed by carefully selecting them in a similar fashion. This can be a tedious and time-consuming process for large, complicated models. To facilitate such tasks, elements may also be deleted using sets.A. From the main menu bar, select ToolsEdit Mesh. In the Edit Mesh dialog box, click OK to continue deleting elements.B. In the prompt area toggle on Delete associated unreferenced nodes. C. In the prompt area, click Sets to open the Region Selection dialog box. In this dialog box, select the set RIBS and toggle on Highlight selections in viewport to highlight the elements belonging to this set. D. Click Continue to delete the remaining rib elements. E. Click Cancel to close the dialog box.You will now halve the pump housing. Use the 12 view from the Views Toolbox to facilitate element selection. 6. From the main menu bar, select ToolsEdit Mesh. In the Edit Mesh dialog box, click OK to continue deleting elements.7. In the prompt area, toggle on Delete associated unreferenced nodes. Tip: If the Region Selection dialog box appears, click Select in Viewport on the right side of the prompt area so you can select elements in the viewport.8. Select the upper half of the pump housing for deletion, as shown in W310. When you are satisfied with the selection, click Done to delete the elements and their associated nodes. The half pump housing without the ribs is shown in Figure W311. 9. Save the model database. Name the model database file PumpAssy.cae.rectangular drag shapeselected elementsFigure W310. Select half of the pump housing.Figure W311. Halved pump housing without ribsImporting CAD geometryYou will now import the remaining components of the assembly into ABAQUS/CAE.1. From the main menu bar, select FileImportPart to open the Import Part dialog box. 2. In this dialog box, set the file type to ACIS SAT. From the list of available files, select cover.sat. Click OK in the dialog box to proceed. 3. In the Create Part from Acis File dialog box, select the Name-Repair tab and toggle on all the available repair options. Click OK to close the dialog box and continue.The imported part is shown in Figure W312a.4. After the part is imported, use the Geometry diagnostics part query tools (ToolsQuery) to check for any invalid or imprecise entities. 5. Repeat steps 2 through 4 to import the part defined in file gasket.sat. The imported part is shown in Figure W312b.6. Import the part defined in file n_bolts.sat without any repair options turned on. The imported part is shown in Figure W312c.7. Review the different parts of your model. Query the important dimensions using the Query tools and note them for future reference.8. Save your model database as PumpAssy.cae.(a) cover(b) gasket (c) boltsFigure W312. Components of pump assemblyHalving the imported geometryYou will now remove half of each of the imported parts. Begin with the cover.1. From the Part list located under the tool bar, select cover to access the cover geometry.2. From the main menu bar, select ViewSpecify. Using the Viewpoint method, enter the coordinates of the viewpoint as 0,0,-1 and the coordinates of the up vector as 0,-1,0. Click OK to apply the view and close the dialog box.Next, create a datum axis using the steps outlined below. This axis will be used to orient the part in the sketch plane when creating the cut profile.3. From the main menu bar, select ToolsDatum.4. In the Create Datum dialog box, choose Axis as the type and Principal axis as the method. Click OK.5. Choose the principal Y-Axis as the datum axis.6. From the main menu bar, select ShapeCutExtrude.7. Select the top surface of the cover, indicated in Figure W313, as the plane on which to sketch.sketch planedatum axisFigure W313. Sketch plane and datum axis8. Select the datum axis as the edge that will appear vertical and on the right of the sketch.9. From the main menu bar, select AddLineRectangle. Sketch a rectangle enclosing the upper half of the cover, as shown in Figure W314. cut rectangleFigure W314. Cut profile10. Click mouse button 2 to continue, and click Done in the prompt area.11. In the Edit Cut Extrusion dialog box, choose the end condition Through All. The direction of extrusion is into the cover. Click OK.The final cover geometry is shown in Figure W315.Figure W315. CoverSimilarly, halve the gasket and bolt parts.12. From the Part list located under the tool bar, select gasket to access the gasket geometry. Use the 12 view from the Views Toolbox.13. As before, define the datum axis to orient the part. From t