【機械類畢業(yè)論文中英文對照文獻(xiàn)翻譯】模型飛機機翼的模態(tài)分析

【機械類畢業(yè)論文中英文對照文獻(xiàn)翻譯】模型飛機機翼的模態(tài)分析,機械類畢業(yè)論文中英文對照文獻(xiàn)翻譯,機械類,畢業(yè)論文,中英文,對照,對比,比照,文獻(xiàn),翻譯,模型,飛機,機翼,分析 8.1.Modal Analysis of a Model Airplane Wing 8.1.1.Problem Specification Applicable ANSYS Products: ANSYS Multiphysics, ANSYS Mechanical, ANSYS Structural, ANSYS ED Level of Difficulty: easy Interactive Time Required: 30 to 45 minutes Discipline: structural Analysis Type: modal Element Types Used: PLANE182 and SOLID185 ANSYS Features Demonstrated: extrusion with a mesh, selecting, eigenvalue modal analysis, animation Applicable Help Available: Modal Analysis in the Structural Analysis Guide, PLANE182 and SOLID185 in the Element Reference. 8.1.2.Problem Description This is a simple modal analysis of a wing of a model airplane. The wing is of uniform configuration along its length and its cross-sectional area is defined to be a straight line and a spline as shown. It is held fixed to the body of the airplane on one end and hangs freely at the other. The objective of the problem is to find the wings natural frequencies and mode shapes. 8.1.2.1.Given The dimensions of the wing are as shown above. The wing is made of low density polyethylene with a Youngs modulus of 38x103 psi, Poissons ration of 0.3, and a density of 8.3E-5 lbf-sec2/in4. 8.1.2.2.Approach and Assumptions Assume the side of the wing connected to the plane is completely fixed in all degrees of freedom. The wing is solid and material properties are constant and isotropic. Solid modeling is used to generate a 2-D model of the cross-section of the wing. You then create a reasonable mesh and extrude the cross-section into a 3-D solid model which will automatically be meshed. Additionally, the mesh used in this example will be fairly coarse for the element types used. This coarse mesh is used here so that this tutorial can be used with the ANSYS ED product. 8.1.2.3.Summary of Steps Use the information in this description and the steps below as a guideline in solving the problem on your own. Or, use the detailed interactive step-by-step solution by choosing the link for step 1. Input Geometry 1. Read in geometry input file. Back To Top Define Materials 2. Set preferences. 3. Define constant material properties. Back To Top Generate Mesh 4. Define element type. 5. Mesh the area. 6. Extrude the meshed area into a meshed volume. Back To Top Apply Loads 7. Unselect 2-D elements. 8. Apply constraints to the model. Back To Top Obtain Solution 9. Specify analysis types and options. 10. Solve. Back To Top Review Results 11. List the natural frequencies. 12. Animate the five mode shapes. 13. Exit the ANSYS program. 8.1.3.Input Geometry 8.1.3.1.Step 1: Read in geometry input file. You will begin by reading in a file that includes the model. 1. Utility Menu File Read Input from . 2. File name: wing.inp UNIX version: /ansys_inc/v130/ansys/data/models/wing.inp PC version: Program FilesAnsys IncV130ANSYSdatamodelswing.inp 3. OK 8.1.4.Define Materials 8.1.4.1.Step 2: Set preferences. You will now set preferences in order to filter quantities that pertain to this discipline only. 1. Main Menu Preferences 2. (check) “Structural” 3. OK 8.1.4.2.Step 3: Define constant material properties. 1. Main Menu Preprocessor Material Props Material Models 2. (double-click) “Structural”, then “Linear”, then “Elastic”, then “Isotropic” 3. “EX” = 38000 4. “PRXY” = 0.3 5. OK 6. (double-click) “Density” 7. “DENS” = 8.3e-5 8. OK 9. Material Exit 8.1.5.Generate Mesh 8.1.5.1.Step 4: Define element types. Define two element types: a 2-D element and a 3-D element. Mesh the wing cross-sectional area with 2-D elements, and then extrude the area to create a 3-D volume. The mesh will be extruded along with the geometry so 3-D elements will automatically be created in the volume. 1. Main Menu Preprocessor Element Type Add/Edit/Delete 2. Add. 3. “Structural Solid” (left column) 4. “Quad 4node 182” (right column) 5. Apply to choose the Quad 4 node ( PLANE182) 6. “Structural Solid” (left column) 7. “Brick 8node 185” (right column) 8. OK to choose the Brick 8 node ( SOLID185) 9. Options for Type2 SOLID185 10. Choose “Simple Enhanced Str” for the element technology. 11. OK 12. CLOSE 13. Toolbar: SAVE_DB 8.1.5.2.Step 5: Mesh the area. The next step is to specify mesh controls in order to obtain a particular mesh density. 1. Main Menu Preprocessor Meshing Mesh Tool 2. “Size Controls Global” = Set 3. “Element edge length” = 0.25 4. OK 5. Mesh 6. Pick All 7. Close Warning. 8. Close Meshtool 9. Toolbar: SAVE_DB In designing this problem, the maximum node limit of ANSYS ED was taken into consideration. That is why the 4-node PLANE182 element, rather than the 8-node PLANE183 element was used. Note that the mesh contains a PLANE182 triangle, which results in a warning. If you are not using ANSYS ED, you may use PLANE183 during the element definitions to avoid this message. Note: The mesh you see on your screen may vary slightly from the mesh shown above. As a result of this, you may see slightly different results during postprocessing. For a discussion of results accuracy, see Planning Your Approach in the Modeling and Meshing Guide. 8.1.5.3.Step 6: Extrude the meshed area into a meshed volume. In this step, the 3-D volume is generated by first changing the element type to SOLID185, which is defined as element type 2, and then extruding the area into a volume. 1. Main Menu Preprocessor Modeling Operate Extrude Elem Ext Opts 2. (drop down) “Element type number” = 2 SOLID185 3. “No. Elem divs” = 10 4. OK 5. Main Menu Preprocessor Modeling Operate Extrude Areas By XYZ Offset 6. Pick All 7. “Offsets for extrusion” = 0, 0, 10 8. OK 9. Close Warning. Using SOLID185 to run this problem in ANSYS ED will generate the warning message. If ANSYS ED is not being used, then SOLID186 (20-node brick) can be used as element type 2. Using PLANE183 and SOLID186 produces a warning message about shape warning limits for 10 out of 160 elements in the volume. 10. Utility Menu PlotCtrls Pan, Zoom, Rotate 11. Iso 12. Close 13. Toolbar: SAVE_DB 8.1.6.Apply Loads 8.1.6.1.Step 7: Unselect 2-D elements. Before applying constraints to the fixed end of the wing, unselect all PLANE182 elements used in the 2-D area mesh since they will not be used for the analysis. 1. Utility Menu Select Entities 2. (first drop down) “Elements” 3. (second drop down) “By Attributes” 4. (check) “Elem type num” 5. “Min,Max,Inc” = 1 6. (check) “Unselect” 7. Apply 8.1.6.2.Step 8: Apply constraints to the model. Constraints will be applied to all nodes located where the wing is fixed to the body. Select all nodes at z = 0, then apply the displacement constraints. 1. (first drop down) “Nodes” 2. (second drop down) “By Location” 3. (check) “Z coordinates” 4. “Min,Max” = 0 5. (check) “From Full” 6. Apply 7. Main Menu Preprocessor Loads Define Loads Apply Structural Displacement On Nodes 8. Pick All to pick all selected nodes. 9. “DOFs to be constrained” = All DOF 10. OK Note that by leaving “Displacement” blank, a default value of zero is used. Now, reselect all nodes. 11. (second drop down) “By Num/Pick” 12. Sele All to immediately select all nodes from entire database. 13. Cancel to close dialog box. 14. Toolbar: SAVE_DB 8.1.7.Obtain Solution 8.1.7.1.Step 9: Specify analysis type and options. Specify a modal analysis type. 1. Main Menu Solution Analysis Type New Analysis 2. (check) “Modal” 3. OK 4. Main Menu Solution Analysis Type Analysis Options 5. (check) “Block Lanczos” (Block Lanczos is the default for a modal analysis.) 6. “No. of modes to extract” = 5 7. “No. of modes to expand” = 5 8. OK 9. OK All default values are acceptable for this analysis. 10. Toolbar: SAVE_DB 8.1.7.2.Step 10: Solve. 1. Main Menu Solution Solve Current LS 2. Review the information in the status window, then choose: File Close (Windows), or Close (X11 / Motif), to close the window. 3. OK to initiate the solution. 4. Yes 5. Yes Based on previous discussions, the warnings are accepted. The messages presented in the verification window are due to the fact that PLANE182 elements have been defined but not used in the analysis. They were used to mesh a 2-D cross-sectional area. 6. Close to acknowledge that the solution is done. 8.1.8.Review Results 8.1.8.1.Step 11: List the natural frequencies. 1. Main Menu General Postproc Results Summary 2. Close after observing the listing. 8.1.8.2.Step 12: Animate the five mode shapes. Set the results for the first mode to be animated. 1. Main Menu General Postproc Read Results First Set 2. Utility Menu PlotCtrls Animate Mode Shape 3. OK Observe the first mode shape: 4. Make choices in the Animation Controller (not shown), if necessary, then choose Close. Animate the next mode shape. 5. Main Menu General Postproc Read Results Next Set 6. Utility Menu PlotCtrls Animate Mode Shape 7. OK Observe the second mode shape: Repeat red steps 4 through 7 above, and view the remaining three modes. Observe the third mode shape: Observe the fourth mode shape: Observe the fifth mode shape: 8.1.8.3.Step 13: Exit the ANSYS program. 1. Toolbar: QUIT 2. (check) “Quit - No Save!” 3. OK Congratulations! You have completed this tutorial. Even though you have exited the ANSYS program, you can still view animations using the ANSYS ANIMATE program. The ANIMATE program runs only on the PC and is extremely useful for: Viewing ANSYS animations on a PC regardless of whether the files were created on a PC (AVI files) or on a UNIX workstation (ANIM files). Converting ANIM files to AVI files. Sending animations over the web. Meshing OverviewPhilosophyThe goal of meshing in ANSYS Workbench is to provide robust, easy to use meshing tools that will simplify the mesh generation process. These tools have the benefit of being highly automated along with having a moderate to high degree of user control. Physics Based MeshingWhen the Meshing application is launched (that is, edited) from the ANSYS Workbench Project Schematic, the physics preference will be set based on the type of system being edited. For analysis systems, the appropriate physics is used. For a Mechanical Model system, the Mechanical physics preference is used. For a Mesh system, the physics preference defined in Tools Options Meshing Default Physics Preference is used.Upon startup of the Meshing application from a Mesh system, you will see the Meshing Options panel shown below. This panel allows you to quickly and easily set your meshing preferences based on the physics you are preparing to solve. If you remove the panel after startup, you can display the panel again by clicking the Options button from the Mesh toolbar. Physics PreferenceThe first option the panel allows you to set is your Physics Preference. This corresponds to the Physics Preference value in the Details View of the Mesh folder. Setting the meshing defaults to a specified “physics” preference sets options in the Mesh folder such as Relevance Center, midside node behavior, shape checking, and other meshing behaviors. Note: The Physics Preference is selectable from the Meshing Options panel only if the Meshing application is launched from a Mesh component system or a Mechanical Model component system. If the Meshing application is launched from an analysis system (whether it be via the Model cell in a non-Fluid Flow analysis system or the Mesh cell in a Fluid Flow analysis system), you must use the Details View of the Mesh folder to change the Physics Preference. See Determination of Physics, Analysis, and Solver Settings for more information. Mesh MethodSetting the Physics Preference option also sets the preferred Mesh Method option for the specified physics. All of the meshing methods can be used for any physics type, however we have found that some of our meshers are more suitable for certain physics types than others. The preferred ANSYS Workbench Mesh Methods are listed below grouped by physics preference. Note: Changing the Mesh Method in the Meshing Options panel changes the default mesh method for all future analyses, regardless of analysis type.For CutCell meshing, you should retain the default setting (Automatic).Presented below are the ANSYS Workbench meshing capabilities, arranged according to the physics type involved in your analysis.Mechanical: The preferred meshers for mechanical analysis are the patch conforming meshers (Patch Conforming Tetrahedrons and Sweeping) for solid bodies and any of the surface body meshers.Electromagnetics: The preferred meshers for electromagnetic analysis are the patch conforming meshers and/or the patch independent meshers (Patch Independent Tetrahedrons and MultiZone).CFD: The preferred meshers for CFD analysis are the patch conforming meshers and/or the patch independent meshers. See Method Control for further details.Explicit Dynamics: The preferred meshers for explicit dynamics on solid bodies are the patch independent meshers, the default sweep method, and the patch conforming mesher with Virtual Topologies. The preferred meshers for explicit dynamics on surface bodies are the uniform quad/quad-tri meshers or the quad dominant mesher when used with size controls and Virtual Topologies. See the Method Control section for further details. Set Physics and Create MethodThis option sets the Physics Preference for the current Mesh object in the Tree Outline for Mesh component systems. It inserts a Method control, sets the scope selection to all solid bodies, and configures the definition according to the Mesh Method that is selected on the panel. To enable this option, you must attach geometry containing at least one solid body and remove any existing mesh controls. Set Meshing DefaultsThis option updates your preferences in the Options dialog box. The Options dialog box is accessible by selecting Tools Options from the main menu of the Meshing application.If a Mesh Method has already been set for the current model and the Set Meshing Defaults option on the Meshing Options panel is unchecked, the OK button on the Meshing Options panel will be grayed out (unavailable). This is because in such cases where the Mesh Method has already been set, the Meshing Options panel would be useful only for setting meshing defaults in the Options dialog box. Thus if you uncheck Set Meshing Defaults, the Meshing Options panel cannot provide any additional functionality and the OK button is disabled. Display This Panel at Meshing StartupThis option controls whether the Meshing Options panel appears at startup of the Meshing application.Meshing Implementation in ANSYS Workbench The meshing capabilities are available within the following ANSYS Workbench applications. Access to a particular application is determined by your license level. The Mechanical application - Recommended if you plan to stay within the Mechanical application to continue your work (preparing and solving a simulation). Also, if you are planning to perform a Fluid-Structure Interaction problem with CFX, and desire to use a single project to manage your ANSYS Workbench data, you should use the Mechanical application to perform your fluid meshing. This is most conveniently done in a separate model branch from the structural meshing and structural simulation. The Meshing application - Recommended if you plan to use the mesh to perform physics simulations in ANSYS CFX or ANSYS FLUENT. If you wish to use a mesh created in the Meshing application for a solver supported in the Mechanical application, you can replace the Mesh system with a Mechanical Model system. See Replacing a Mesh System with a Mechanical Model System. Note: In the 13.0 release, ANSYS AUTODYN runs inside the Mechanical application. The recommendation is to use an Explicit Dynamics analysis system, in which meshing comes as part of that system. As an alternative, you can also use this system to prepare a model for the traditional ANSYS AUTODYN application (AUTODYN component system). For simple ANSYS AUTODYN models, you can use the meshing tools within the traditional ANSYS AUTODYN application (AUTODYN component system). Types of Meshing The following types of meshing are discussed in this section. Meshing by Algorithm Meshing by Element Shape Conformal Meshing Between Parts When meshing in ANSYS Workbench, interfaces between parts are managed in a variety of ways. The first is through a concept referred to as “multibody parts.” The following applies when meshing in ANSYS Workbench: Parts are groups or collections of bodies. Parts can include multiple bodies and are then referred to as multibody parts. If your geometry contains multiple parts then each part will be meshed with separate meshes with no connection between them, even if they apparently share faces. You can convert a geometry which has multiple parts into one with a single part by using the Form New Part functionality in the DesignModeler application. Simply select all of the bodies and then select Tools Form New Part. If you have an external geometry file that has multiple parts that you wish to mesh with one mesh, then you will have to import it into the DesignModeler application first and perform this operation, rather than importing it directly into the Meshing application. By default, every time you create a new solid body in the DesignModeler application, it is placed in a new part. To create a single mesh, you will have to follow the instructions in the previous bullet point to place the bodies in the same part after creation. Since body connections are dependent on geometry attributes such as application of the Add Material and Add Frozen Boolean operations, it is advisable that you combine bodies into a single part only if you want a conformal mesh. Multiple solid bodies within a single part will be meshed with conformal mesh provided that they have topology that is “shared” with another of the bodies in that part. For a face to be shared in this way, it is not sufficient for two bodies to contain a coincident face; the underlying representation of the geometry must also recognize it as being shared. Normally, geometry imported from external CAD packages (not the DesignModeler application) does not satisfy this condition and so separate meshes will be created for each part/body. However, if you have used Form New Part in the DesignModeler application to create the part, then the underlying geometry representation will include the necessary information on shared faces when faces are conformal (i.e., the bodies touch). The Shared Topology tool within the DesignModeler application can be used to identify conformal faces/edges, along with defining whether nodes should be conformal (same node shared between two bodies), or coincident (separate nodes for separate bodies, but the locations could be identical). Conformal Meshing and Mesh Method Interoperability You can mix and match mesh methods on the individual bodies in a multibody part, and the bodies will be meshed with conformal mesh as described above. Through this flexible approach, you can better realize the value of the various methods on the individual bodies: For solid meshing, you can use a combination of these mesh methods: o Patch Conforming Tetrahedron o Patch Independent Tetrahedron o MultiZone o Sweep o Hex Dominant For surface meshing, you can use a combination of these mesh methods: o Quad Dominant o All Triangle