Engineering Analysis with Ansys Software Episode 2 Part 10 pdf

Ch07-H6875.tex 24/11/2006 18: 34 page 364 364 Chapter 7 Application of ANSYS to contact between machine elements A Figure 7.57 Move Volumes. Selecting volume 1 and clicking [A] OK button calls up another frame shown in Figure 7.58. B A Figure 7.58 Move Volumes. Ch07-H6875.tex 24/11/2006 18: 34 page 365 7.2 Example problems 365 Figure 7.58 shows that the cylinder was moved by [A] 0.05 cm downward, i.e., toward the block, after clicking [B] OK. From Utility Menu select Plot → Replot to view the cylinder positioned in required location. Finally, from Utility Menu select PlotCtrls → View Settings → Viewing Direction. The frame shown in Figure 7.59 appears. B A Figure 7.59 Viewing Direction. By selecting [A] X, Y, and Z, coordinates as shown in Figure 7.59, clicking [B] OK button, and activating Plot → Replot command (Utility Menu), a half-symmetry model, shown in Figure 7.50, is finally created. 7.2.2.3 MATERIAL PROPERTIES Before any analysis is attempted, it is necessary to define properties of the material to be used. From ANSYS Main Menu select Preferences. The frame in Figure 7.60 is produced. From the Preferences list [A] Structural option was selected as shown in Fig- ure 7.60. From ANSYS Main Menu select Preprocessor → Material Props → Material Models. Double click Structural → Linear → Elastic → Isotropic.The frame shown in Figure 7.61 appears. Enter [A] EX =2.1 ×10 9 for Young’s modulus and [B] PRXY =0.3 for Poisson’s ratio. Then, click [C] OK and afterward Material: Exit. After defining properties of the material, the next step is to select element type appropriate for the analysis performed. From ANSYS Main Menu select Preprocessor → Element Type → Add/Edit/Delete. The frame shown in Figure 7.62 appears. Click [A] Add in order to pull down another frame, shown in Figure 7.63. In the left column click [A] Structural Solid and in the right column click [B] Brick 8node 185. After that click [C] OK and Close in order to finish element type selection. Ch07-H6875.tex 24/11/2006 18: 34 page 366 366 Chapter 7 Application of ANSYS to contact between machine elements A Figure 7.60 Preferences: Structural. A B C Figure 7.61 Material Properties. Ch07-H6875.tex 24/11/2006 18: 34 page 367 7.2 Example problems 367 A Figure 7.62 Element Types. B C A Figure 7.63 Library of Element Types. Ch07-H6875.tex 24/11/2006 18: 34 page 368 368 Chapter 7 Application of ANSYS to contact between machine elements 7.2.2.4 MESHING From ANSYS Main Menu select Preprocessor →Meshing →MeshTool. The frame shown in Figure 7.64 appears. There are a number of options available. First step is to go to Size Control: Lines option and click [A] Set button. This opens another frame, as shown in Figure 7.65, prompting to pick lines on which element size is going to be controlled. A Figure 7.64 MeshTool options. A Figure 7.65 Element Size on Picked Lines. Ch07-H6875.tex 24/11/2006 18: 34 page 369 7.2 Example problems 369 Pick two horizontal lines on the front edge of the cylinder and click [A] OK. The frame shown in Figure 7.66 appears. A B C Figure 7.66 Element Sizes on Picked Lines. In the box [A] No. of element divisions type 3 and change selection [B] SIZE, NDIV can be changed to No. by checking the box and click [C] OK. Both selections are shown in Figure 7.66. Similarly, using MeshTool frame, click Set button in the Size Controls →Lines option and pick the curved line on the front of the block. Click OK afterward. The frame shown in Figure 7.66 appears. In the box [A] No. of element divisions type 4 this time and press [C] OK button. In the frame MeshTool (see Figure 7.67) pull down [A] Volumes in the option Mesh. Check [B] Hex/Wedge and [C] Sweep options. This is shown in Figure 7.67. Pressing [D] Sweep button brings another frame asking to pick volumes to be swept (see Figure 7.68). Pressing [A] Pick All button initiates meshing process. The model after meshing looks like the image in Figure 7.69. Pressing [E] Close button in MeshTool frame ends mesh generation stage. After meshing completed, it is usually necessary to smooth element edges in order to improve graphic display. It can be accomplished using PlotCtrls facility in Ch07-H6875.tex 24/11/2006 18: 34 page 370 370 Chapter 7 Application of ANSYS to contact between machine elements A B C D E Figure 7.67 Checked Hex and Sweep options. A Figure 7.68 Volume Sweeping. the Utility Menu. From Utility Menu select PlotCtrls → Style → Size and Shape. The frame shown in Figure 7.70 appears. In the option [A] Facets/element edge select 2 facets/edge and click [B] OK button to implement the selection as shown in Figure 7.70. In solving the problem of contact between two elements, it is necessary to create contact pair. Contact Wizard is the facility offered by ANSYS. Ch07-H6875.tex 24/11/2006 18: 34 page 371 7.2 Example problems 371 Figure 7.69 Model after meshing process. A B Figure 7.70 Control of element edges. Ch07-H6875.tex 24/11/2006 18: 34 page 372 372 Chapter 7 Application of ANSYS to contact between machine elements 7.2.2.5 CREATION OF CONTACT PAIR From ANSYS Main Menu select Preprocessor →Modelling → Create → Contact Pair. As a result of this selection, a frame shown in Figure 7.71 appears. A Figure 7.71 Contact Manager. Contact Wizard button is located in the upper left-hand corner of the frame. By clicking [A] on this button a Contact Wizard frame, as shown in Figure 7.72, is produced. B A C Figure 7.72 Contact Wizard (target). Ch07-H6875.tex 24/11/2006 18: 34 page 373 7.2 Example problems 373 A Figure 7.73 Select body for Target. In the frame shown in Figure 7.72 select [A] Body (volume), [B] Flexible, and press [C] Pick Target. The frame shown in Figure 7.73 is produced. Select block as target by picking on it and press [A] OK button in the frame of Figure 7.73. Again Contact Wizard frame appears and this time Next button should be pressed to obtain the frame shown in Figure 7.74. Press [A] Pick Contact button to create the frame in Figure 7.75. Pick cylinder as contact and press OK but- ton. Again Contact Wizard frame appears where Next button should be clicked. The frame of Figure 7.76 appears. In this frame select [A] Coefficient of Fric- tion =0.2 and check box [B] Include initial penetration. Next press [C] Optional settings button to call up another frame. In the new frame (Figure 7.77), Normal penalty stiffness =0.1 should be selected. Also, Friction tab located in the top of the frame menu should be activated and Stiffness matrix =Unsymmetric selected. A Figure 7.74 Contact Wizard (contact). [...]... Application of ANSYS to contact between machine elements Figure 7.84 Full model with mesh of elements and applied constraints A B Figure 7.85 Read Results by Load Step Number 7 .2 Example problems 381 A B C Figure 7.86 Contour Nodal Solution Data Figure 7.87 Contour plot of nodal solution (von Mises stress) 3 82 Chapter 7 Application of ANSYS to contact between machine elements Figure 7.88 7 .2. 3 Figure... block by 0.05 cm, in order to create interference load, the analysis involves a large displacement effects From ANSYS Main Menu select Solution → Analysis Type → Sol’n Controls The frame shown in Figure 7. 82 appears In the pull down menu select [A] Large Displacement Static Further selected options should be: [B] Time at end of load step = 100 ; [C] Automatic time stepping (pull down menu) = Off; and... established between elements This is a 3D analysis and advantage could be taken of the inherent symmetry of the model Therefore, the analysis will be carried out on a quarter-symmetry model only The objective of the analysis is to observe the stresses in the cylinder and the rail when an external load is imposed on them 7 .2 Figure 7.89 Example problems 383 Cylinder with surface elements (174) B A C Figure... settings) Figure 7.78 Contact Pair created by Contact Wizard 7 .2 A Figure 7.79 Apply SYMM on Areas Figure 7.80 Symmetry constraints applied on three horizontal areas Example problems 377 378 Chapter 7 Application of ANSYS to contact between machine elements A Figure 7.81 Apply U,ROT on Areas A B C D E Figure 7. 82 Solution Controls 7 .2 Example problems 379 everything is correct, select File → Close... press Close button In order to return to the previous image of the model select Utility Menu → Plot → Replot 7 .2. 2.7 POSTPROCESSING Solution results can be displayed in a variety of forms using postprocessing facility For the results to be viewed for the full model, the half-symmetry model used for analysis has to be expanded From Utility Menu select PlotCtrls → Style → Symmetry Expansion → Periodic/Cyclic... the analysis presented here was to observe stresses in the cylinder produced by the reduction of the initial gap between two blocks by 0.05 cm (an interference fit) Therefore, form ANSYS Main Menu select General Postproc → Read Results → By Load Step The frame shown in Figure 7.85 is produced The selection [A] Load step number = 1, shown in Figure 7.85, is implemented by clicking [B] OK button From ANSYS. .. selections are shown in Figure 7. 82 Pressing [E] OK button implements the settings and closes the frame Now the modeling stage is completed and the solution can be attempted From ANSYS Main Menu select Solution → Solve → Current LS A frame showing review of information pertaining to the planned solution action appears After checking that 376 Chapter 7 Application of ANSYS to contact between machine... the cylinder with pressure contours is produced as shown in Figure 7.91 Wheel-on-rail line contact 7 .2. 3.1 PROBLEM DESCRIPTION Configuration of the contact to be analyzed is shown in Figure 7. 92 This contact problem, which in practice is represented by a wheel-on-rail configuration, is well known in engineering Also, the characteristic feature of the contact is that, nominally, contact between elements... Application of ANSYS to contact between machine elements A Figure 7.75 Select Bodies for Contact Pressing [A] OK button brings back Contact Wizard frame (see Figure 7.76) where the [D] Create button should be pressed Created contact pair is shown in Figure 7.78 Finally, Contact Wizard frame should be closed by pressing Finish button Also, Contact Manager summary information frame should be closed 7 .2. 2.6 SOLUTION... at the interface From ANSYS Main Menu select General Postproc → Plot Results → Contour Plot → Nodal Solu The frame shown in Figure 7.90 Select Entities appears In the frame shown in Figure 7.90, the following selections are made: [A] Contact and [B] Pressure These are items to be contoured Pressing [C] OK implements selections made In response to that an image of the cylinder with pressure contours . Properties. Ch07-H6875.tex 24 /11 /20 06 18: 34 page 367 7 .2 Example problems 367 A Figure 7. 62 Element Types. B C A Figure 7.63 Library of Element Types. Ch07-H6875.tex 24 /11 /20 06 18: 34 page 368 368. offered by ANSYS. Ch07-H6875.tex 24 /11 /20 06 18: 34 page 371 7 .2 Example problems 371 Figure 7.69 Model after meshing process. A B Figure 7.70 Control of element edges. Ch07-H6875.tex 24 /11 /20 06 18:. edges. Ch07-H6875.tex 24 /11 /20 06 18: 34 page 3 72 3 72 Chapter 7 Application of ANSYS to contact between machine elements 7 .2. 2.5 CREATION OF CONTACT PAIR From ANSYS Main Menu select Preprocessor →Modelling