WS11-3 VND101, Workshop 11 Objectives Introduction to MSC.visualNastran Desktop 4D. Introduction to Model Viewing environment Determine the failure stresses (von Mises stresses) generated in the object as a result of an applied pressure. Calculate the factor of safety based on von Mises stresses with minimum acceptable factor of safety = 1. Exercise Overview Introduction to MSC.visualNastran Desktop 4D features. Import/Open a model from various CAD applications. Simulation and Display Settings. Specify material to Steel-ANSI 304. Apply loads and restraints. Solve model. Evaluate result.
WS11-4 VND101, Workshop 11 Introduction MSC.visualNastran 4D MSC.visualNastran 4D has the capability of performing integrated Motion and FEA simulation on any part of an assembly. Stress simulation at all frames (time-steps) in the Motion simulation, or pick specific frames and perform FEA stress, vibration, or buckling simulation. Using the industry-standard MSC.Nastran solver, MSC.visualNastran 4D is optimized for faster meshing, faster solution times, and faster results animations. An adaptive meshing feature automatically refines the mesh in areas of high stress gradients, delivering highly accurate results. MSC.visualNastran 4D uses Automatic Load Transfer™ (ALT) technology to convert reaction forces on assembly joints into loads on part facets. Body accelerations are also used in the FEA simulation, making this more than just a static simulation. The load transfer and acceleration features take the guesswork out of your stress simulation. And that makes your FEA simulation and analysis a more accurate representation of the world.
WS11-5 VND101, Workshop 11 I - Open New File / Import Part 1)Open the part “Bracket” or “Bracket.x_t”. (Figure 1) 2)If the ACIS Import Settings window that appears, pick “Override units” and pick inches from the pull-down menu. (Figure 2) 3)Click “OK”. One you click “OK”, the ACIS dialog box will close and a bracket is imported into visualNastran4D. You can familiarize yourself with visualNastran4D by studying Figure 3, or just use Figure 3 as a reference for this exercise. Figure 1 Open file Figure 2 Unit selection
WS11-6 VND101, Workshop 11 II - Introduction to MSC.vN4D Environment Figure 3 visualNastran Desktop environment Object List Annotation List Button Connections List Properties List Playback Controls Toolbar Status Bar Global/World Coordinate
WS11-7 VND101, Workshop 11 III - Simulation and Display Setting 4)From the World menu pick Simulation Settings or click the Simulation Settings tool in the toolbar. The Settings menu will appear. 5)Click the FEA tab. (Figure 4) 6)In the “Analysis Type” area, make sure “Stress” is set and leave everything else default. (Figure 4) 7)Click “Close”. 8)From the World menu pick Display Settings or click on the Display Settings tool in the toolbar. You will notice that the Display Settings menu is the same as the Simulation Settings menu. Figure 4 Simulation Settings - FEA
WS11-8 VND101, Workshop 11 9)Click the Units tab and pick English (pounds) in the “Unit Systems” pull-down. (Figure 5) All the dimensions in the exericse are automatically converted to the English unit system. 10)Click the Vectors tab. 11) In the “Arrow width” area, uncheck “Automatic”. (Figure 6) 12)In the field, enter “0.5”. (Figure 6) You can adjust the length and color of different types of vectors to make them more or less prominent when the simulation is running. 13)Click “Apply” and/or “Close”. The changes will automatically apply when you hit the close button, but it is a better habit to always hit “Apply” after any modification to the simulation. III - Simulation and Display Setting Figure 5 Display Settings - Units Figure 6 Display Settings - Vectors
WS11-9 VND101, Workshop 11 IV - Specify Material 14)Double-click on the bracket in the drawing area. The Properties dialog box for that bracket will appear. 15)Pick the Material tab. (Figure 7) 16)Click “Change” to change the material. The Material Properties window appears. (Figure 8) 17)Pick Steel –ANSI 304 and click “OK”. (Figure 8) 18)Choose the Appearance tab and type “Bracket” in the “Name”. 19)Click “Apply” and/or “Close”. Figure 7 Properties of body - Material Figure 9 Properties of body - Appearance Figure 8 Material Selector
WS11-10 VND101, Workshop 11 V - Apply Loads and Restraints 20)Use the Rotate Around and Pan tools to rotate the bracket to look like Figure 10. You can also click on the middle mouse button (the scroll wheel) to immediately rotate the view. 21)Hit the “S” key to “Set” this view as the home view. Now, this view can be retrieved by hitting the “H” key at anytime. 22)Click the Structural Load tool. 23)Select the top surface of the bracket. Green arrows (load vectors) appear on the top surface now. (Figure 10) 24)Double-click on one of the green load arrows. The Properties dialog box of the constraint (Structural Load) appears. (Figure 11) Figure 10 Applied load 3 4
WS11-11 VND101, Workshop 11 V - Apply Loads and Restraints 25)Click the Appearance tab, name it “pressure”, and click “Apply”. Accept all other defaults. (Figure 11) 26)Click the Structural Load tab. (Figure 12) In this tab, you can assign the type of loading, the amount of loading, to which frame this loading will act on, and the coordinate type of this loading. 27)Pick Pressure as the load “Type” in the pull-down menu. 28)Type in “50 psi” in the “normal” field. The pressure is normal to the surface and in the units of pounds per square inch. (Figure 12) 29)Click Apply and Close. Notice that the Frame options are eliminated and the Coordinates is in Face normal. This assumes a uniform pressure on the selected surface of the bracket. Figure 11 Properties of constraint - Appearance Figure 12 Properties of constraint – Structural Load
WS11-12 VND101, Workshop 11 V - Apply Loads and Restraints 30)Rotate the view to show the back face of the bracket. (Figure 13) This can be done with the Rotate Around tool. 31)Use the “View All” button to center the part in the simulation window. 32)Pick the Restraint tool. 33)Hover the mouse over the back side of the bracket click once it is highlighted. Blue restraint symbols are displayed along the edges. (Figure 13) 34)Double-click on one of the blue restraint symbols. The properties of the constraint (Restraint) appear. Figure 13 Applied restraint
WS11-13 VND101, Workshop 11 V - Apply Loads and Restraints 35)Pick the Appearance tab and name the restraint “fixed”. Accept all other defaults and click “Apply”. (Figure 14) 36)Pick the Restraint tab and make sure that all directions are restrained. (Figure 15) The directions X, Y, and Z will be restrained if there is a check in the box to the left of it. (Figure 15) 37)Click “Apply” and “Close”. Figure 14 Properties of constraint - Appearance Figure 15 Properties of constraint - Restraint
WS11-14 VND101, Workshop 11 VI - Mesh 38)Hit the “H” key to return to the “Home” view. Your simulation window now returns to the view set earlier as the “Home” view. 39)Double-click on the “Bracket” in the drawing area. The properties dialog box for that bracket appears. 40)Go to the FEA tab. (Figure 16) 41)Check the “Include in FEA” box. (Figure 16) Once “Include in FEA” is check-marked, the “Mesh” area becomes activated. 42)Accept the “Default Mesh Size” of “1.83 in.” and set the “Mesh Factor” to “1”. Keep the “Force all features to mesh” option checked. (Figure 16) 43)Check the “Show mesh” box. 44)Click “Mesh” and close the Properties dialog box. Figure 16 Properties of body – FEA
WS11-15 VND101, Workshop 11 VI - Mesh The simulation window now displays the meshed bracket. Rotate the bracket to get a better view of the elements. Figure 17 Meshed bracket
WS11-16 VND101, Workshop 11 VII - Solve FEA 45)To begin FEA analysis, click the “Solve FEA” button in the Playback Controls. MSC.visualNastran Desktop should display the resulting FEA analysis with color contours showing critical points of stress. (Figure 18) 46)The stress magnitude can be view by rolling the mouse arrow over the bracket and hovering until the value appears. (Figure 19) Figure 19 Stress magnitude Figure 18 FEA stress result
WS11-17 VND101, Workshop 11 VIII - Display and Evaluate Results MSC.visualNastran Desktop can also display other results such as Deformation. 47)Double-click on the bracket in the drawing area. 48)Pick the FEA Display tab in the Properties dialog box that appears. You may need to open the FEA Display from the Properties List. (Figure 20) 49)Check the “Show Deformed” box to show the resulting deformation from the load. Notice the immediate change of the model in the simulation window. 50)Close the Properties dialog box. 51)To get numerical values of displacement, right-click on the “FEA Contour Legend”. 52)In the resulting pull-down menu, pick Dataset>Displacement. Three types of datasets are available: Stress, Strain and Displacement. 53)Rotate the bracket to get a better view of the deformation. (Figure 21) Figure 21 FEA deformation result Figure 20 Properties Window
WS11-18 VND101, Workshop 11 Review You have familiarized yourself with Model Viewing environment. You determined the failure stresses (von Mises stresses) generated in the object as a result of an applied pressure. You learned how to calculate the factor of safety based on von Mises stresses with minimum acceptable factor of safety = 1. You also learned how to display results.