Introduction to Engineering Analysis

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Clemence Norton
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1 Chapter 1 Introduction to Engineering Analysis This chapter introduces you to the Stress Analysis and Dynamic Simulation environments. You learn how digital prototyping can be used to simulate your designs before you build costly physical prototypes. Objectives After completing this chapter, you will be able to: Describe the Stress Analysis environment and the processes you use to analyze designs. Describe the Dynamic Simulation environment and the processes you use to create simulations to evaluate motions in an assembly. Chapter Overview 3

2 Lesson: Stress Analysis Overview This lesson provides an overview of the Stress Analysis environment, interface, and tools. The lesson also describes the processes you use to create simulations to evaluate the strength, deflection, and natural frequencies of your designs. When you design products, you need to examine how your designs perform under real-world conditions. When the product will be exposed to loads during normal use, it is important that you design the product to function properly so that it can withstand these loads. Proving the validity of your designs before you build saves time and money by eliminating costly reworking and alterations after the build process has begun. Simulation data serves as a valuable presentation tool for customers if you want assure them that you are providing a design that meets their requirements. The following image shows the stresses that result from an analysis on the arms of a front-end loader. Objectives After completing this lesson, you will be able to: Describe stress analysis and how you can use it to validate your designs. Describe how the Stress Analysis environment is integrated into the Autodesk Inventor user interface. List the steps required to perform a stress analysis. Describe and identify the types of files that are created when you perform a stress analysis. Perform a basic stress analysis and review the results. 4 Chapter 1: Introduction to Engineering Analysis

3 About Stress Analysis You use Stress Analysis to estimate the deformation, stress, and natural frequencies of your designs. Stress Analysis helps you to create better parts by indicating areas of your digital prototypes that require further attention. You can reduce the number of design-test-redesign cycles by using Stress Analysis early in the design cycle to find and fix your models before you build the first prototype. Stress Analysis does not completely eliminate physical testing; however, using analysis tools early in the design process can significantly reduce the number of physical tests that are required. You often use Stress Analysis to help design the test by identifying locations of high stress or deformation and to design test jigs and fixtures. You use the test results to fine-tune your stress analysis so that you can predict the stress on similar parts with greater confidence. The following image shows the stress and displacement plots for a wrench. In Stress Analysis, results are displayed graphically on the deformed model. Definition of Stress Analysis Stress Analysis uses a technique called finite element analysis (FEA) to calculate the deformation, stress, and mode shapes of a model. FEA is an approximation method that estimates the behavior of a model. If a model has simple geometry, it is straightforward to solve for stress and deflection manually by using available equations. However, most models have complex geometry, and equations to predict the stress, deflections, or mode shapes are not normally available. In FEA the model is subdivided into a number of pieces called elements, each of which have simple shapes that have available solutions. The solutions for all of the elements are combined to get the behavior of the entire model. The process of generating the elements in FEA is called meshing, and the resulting set of connected elements is called the mesh. In the following illustration, the original and meshed models for a bracket are shown. The meshed model's shape is approximated using a large number of tetrahedral-shaped solid elements. Lesson: Stress Analysis Overview 5

The size of each element in the mesh determines the resolution of the results. The smaller the elements, the more accurate the numerical results, but the longer the model takes to process.

required. Learning how to set up an appropriate mesh and determining if it gives accurate results are key skills in performing a stress analysis.

4 The size of each element in the mesh determines the resolution of the results. The smaller the elements, the more accurate the numerical results, but the longer the model takes to process. In areas of the model where the stress is fairly constant, large elements are adequate; however, where the stress changes rapidly, such as near a stress concentration, smaller elements are required. Learning how to set up an appropriate mesh and determining if it gives accurate results are key skills in performing a stress analysis. Example of Stress Analysis The following image shows the stress on a bellcrank from the rear suspension in a small racecar. The stress results were used to lighten the part in areas where the stress was low. 6 Chapter 1: Introduction to Engineering Analysis

5 Potential Uses for Stress Analysis You use Stress Analysis to identify the following: Areas of your models that are highly stressed that may lead to part failure during the prototype or production phase. Areas that carry little load, which may warrant a change in geometry to save weight or material. Components that deform beyond an allowable limit and that may need to be stiffened through model or material changes. Parts with modal frequencies near the operating frequency that may result in excess vibration, stress, wear, or noise. Stress Analysis Assumptions You use Stress Analysis to solve linear static problems. Although many engineering components can be analyzed using Stress Analysis, you might find situations in which the following assumptions do not apply: The deflection and stress are linearly proportional to the load. If you double the load, the deflection and stress double. Material properties are linear. The stress-strain curve is a straight line, with the stress remaining proportional to the strain. There is no yielding of the material. The loading is static and is applied slowly. Dynamic loading effects, such as sudden load application or impact, are not considered. Temperature has no effect on the part geometry or material properties. The deformation of the part is small when compared to the dimensions of the part. Large deflection requires a nonlinear analysis to account for changing part and load geometry, and is not considered in linear analysis. Other nonlinear effects, such as buckling, are not considered. If you have a design for which these assumptions are not valid, you should pass the problem on to an analyst with the appropriate knowledge and software to solve it. Lesson: Stress Analysis Overview 7

Stress Analysis User Interface The Stress Analysis environment uses the same major interface components that you use in the part or assembly environments, including the graphics window, panel bar,

6 Stress Analysis User Interface The Stress Analysis environment uses the same major interface components that you use in the part or assembly environments, including the graphics window, panel bar, and browser. The tools presented on the panel bar, and the elements in the browser, are specific to the Stress Analysis environment. In the following illustration a part is shown in the Stress Analysis environment. Specific Stress Analysis tools and features are shown in the panel, browser, and graphics window. Stress Analysis tab. Stress Analysis panels. Stress Analysis browser. The browser contains reference to the part or assembly geometry, loads, constraints, contacts, other input data, and finally, the results. Graphical display. Results are displayed graphically on models. The color bar displays the result range for each color. 8 Chapter 1: Introduction to Engineering Analysis

7 Stress Analysis Panels The Stress Analysis panels contain the tools for the Stress Analysis environment. Manage The Manage panel contains tools that enable you to create a new simulation and to set up parameters for a parametric analysis. Materials, The Materials, Constraints, Loads, and Contacts panels contain tools that you use to Constraints, prepare your model for analysis. Loads, Contacts Prepare The Prepare panel contains tools that you use to view and adjust the mesh and set up automatic convergence. Solve The Solve panel contains the Solve tool, which you use to run an analysis. Result, Display, Report Settings Exit The Result, Display, and Report panels contain tools to view results. The Settings panel contains the Stress Analysis Settings tool, which you use to set default mesh and analysis settings. Most of the same settings can be changed from within the various tools in the Stress Analysis environment. The Exit panel contains the tool to exit the Stress Analysis environment and return to either the part or assembly environment. Stress Analysis Browser The Stress Analysis browser contains reference to the part or assembly geometry, loads, constraints, contacts, other input data, and finally, the results. You use the browser to exclude geometry, edit or delete existing loads, constraints, contacts, and mesh settings, as well as to select the results that you want to display. Lesson: Stress Analysis Overview 9

An analysis can contain multiple simulations, all of which are listed in the browser. You use the browser to switch between simulations. For a part, the features are displayed.

8 An analysis can contain multiple simulations, all of which are listed in the browser. You use the browser to switch between simulations. For a part, the features are displayed. For an assembly, the parts are displayed. You use the model tree to exclude features or parts from the analysis or to change the visibility of parts in an assembly. The browser lists all of the constraints and loads and provides an interface to edit or delete existing items. The browser lists all of the contacts and provides an interface to edit or delete them. The icon next to contacts indicates that the contacts are out of date and need to be updated. The mesh settings node in the browser contains a list of any local mesh settings. The Results folder contains all of the results for the analysis. You use the browser to select which results are displayed in the graphics window. 10 Chapter 1: Introduction to Engineering Analysis

Performing a Stress Analysis The process of performing a stress analysis involves several steps, some of which must be repeated as you refine the model geometry based on the analysis results.

9 Performing a Stress Analysis The process of performing a stress analysis involves several steps, some of which must be repeated as you refine the model geometry based on the analysis results. When you perform a stress analysis, your goal is to simulate real-world conditions on your part by duplicating forces, loads, and constraints in the design environment. In the following illustration, Equivalent Stress results are shown on a simple part model. Process: Performing a Stress Analysis The following steps describe the process of performing a stress analysis. 1. Identify the goals of the analysis: Are you concerned about the deflection? Is the stress a concern? Is the model subjected to vibrations, meaning that a modal analysis is required? 2. Learn about the model and how it interacts with its environment: Determine where and how loads are applied. Determine the magnitude (or range of magnitudes) and direction of the loads. Determine how the model is constrained from motion by external constraints or by its interaction with other parts. 3. Prepare your model for analysis: If you plan to analyze an assembly, create a Level of Detail for each analysis if you want to eliminate nonstructural parts and other parts that you do not need to analyze. For parts, identify features that do not contribute to the strength but may add significantly to the number of elements. Typical features to exclude from the analysis include holes that are in low stress areas, external rounds, cosmetic embossing, and so on. 4. Enter the Stress Analysis environment. Lesson: Stress Analysis Overview 11

10 5. Create a new simulation. Specify the simulation type and default settings. Multiple simulations can be created in the same file, each with different settings. For example, a single assembly part file might contain simulations for static analysis of several different configurations of components and modal analyses of those same configurations. 6. Add loads to the model. You can add forces, moments, pressure, bearing, and body loads such as gravity and acceleration. 7. Add constraints to represent the physical connection of the model to other parts in the design. For example, use a constraint where the part is bolted or welded, or where it contacts other components. 8. For assemblies, add contacts to represent the connection between components. Contacts can simulate rigidly bonded joints or allow sliding and separation under loading. 9. Run the analysis. The model is meshed according to the settings and the results for the active simulation are determined and displayed on the model. 10. View the results: When the analysis is complete, the results are displayed graphically on the model. You can view contours for stress, deformation, factor of safety, or the different mode shapes. You can also display or hide the mesh, loads, or constraints; change the display range for contours; and display or hide minimum and maximum markers. 11. Determine if the model behaved as expected: Does the displacement make sense? Do the reaction forces at the constraints add up to the applied loads? Does the area of high stress make sense? If the model's behavior does not look correct, review the loads and constraints and adjust them as necessary. 12. Prove that results are accurate. Stress Analysis uses a mathematical technique that approximates the actual stress in a part. Stress singularities and inadequate mesh size can lead to results that are not accurate. Before you accept any results, you must prove that the results are accurate by performing a convergence study. Stress Analysis contains several tools that help you to adjust the mesh automatically in areas of concern while ignoring the stress at singularities. 13. Refine the model: If there are areas of concern, return to the part or assembly environment, make appropriate model changes, and then update the stress analysis. Repeat this cycle until you are satisfied with the model's results. 14. Document the results: Create a report that summarizes the input values and results, including images of the results. The report is in HTML format; therefore, you can share it with others on the design team and include it in documentation. 12 Chapter 1: Introduction to Engineering Analysis

11 Guidelines Keep the following guidelines in mind when performing a stress analysis: Determine the smallest number of parts that you can analyze. You typically do not analyze an entire assembly with all of its parts.determine the load path and decide which components are critical.can you analyze one part on its own? Can you isolate a small number of partsin the assembly? Can you perform several analyses, each with differentparts of interest? For parts, suppress features that do not affect the results, especially if the features are small. Typical features to suppress include small cosmetic rounds or chamfers on outside corners, and small holes or other features in areas where the stress is low. These features do not contribute to the stiffness of the model but can greatly increase the time to generate the mesh and solve for the results. For assemblies, exclude parts from the analysis that do not contribute to the strength or stiffness. Small parts, fasteners, bearings, cosmetic parts such as plastic or sheet metal covers do not contribute to the strength but may take considerable time to mesh and solve. A Level of Detail is an efficient method to exclude parts from Stress Analysis. Stress Analysis Files When you add stress analysis information to a part or an assembly, and then save the file, folders and files are created to hold the stress analysis results. You need to be aware of the folder names and locations so that you can manage them along with the model files. Example of Stress Analysis Files The following image shows the files and folders that result from running an analysis on a single part file (1). When the file is saved, a folder (2) with the same name as the part file is created. It contains multiple subfolders and files that contain the results. If a report is generated and saved to the model folder, the report HTML file (3) and Images folder (3) are also created. Lesson: Stress Analysis Overview 13

By default, OLE links are created to each of the analysis files so that other applications, such as Autodesk Vault, are aware of the link to the files.

12 By default, OLE links are created to each of the analysis files so that other applications, such as Autodesk Vault, are aware of the link to the files. The links are listed in the 3rd Party folder in the Model browser as shown in the following image. Because the results files are linked to the model file, if the results files cannot be found when the model file is opened, you must resolve the file links before you can open the file. If the Results folder is deleted, the results can be recreated by running the analysis again because the part or assembly file contains the inputs and settings for the stress analysis. However, the analysis may take a while to run, especially if the model is complex and there are multiple analyses. 14 Chapter 1: Introduction to Engineering Analysis

Exercise: Perform a Basic Stress Analysis In this exercise, you determine the stress and safety factor in a wrench.

You complete the analysis by excluding some features from the analysis, reviewing the current constraints, adding a load, and

Select both Hole1 and Emboss1. Right-click and select Exclude from Simulation. The completed exercise 5.

Move the cursor over the fixed constraint and confirm that two faces are fully constrained.

13 Exercise: Perform a Basic Stress Analysis In this exercise, you determine the stress and safety factor in a wrench. The analysis has been started but is not complete. You complete the analysis by excluding some features from the analysis, reviewing the current constraints, adding a load, and running the simulation. 2. Click Environments tab > Begin panel > Stress Analysis. 3. In the browser, expand Stress_Overview.ipt. 4. Select both Hole1 and Emboss1. Right-click and select Exclude from Simulation. The completed exercise 5. In the browser, expand the Constraints folder. Move the cursor over the fixed constraint and confirm that two faces are fully constrained. Completing the Exercise To complete the exercise, follow the steps in this book or in the onscreen exercise. In the onscreen list of chapters and exercises, click Chapter 1: Introduction to Engineering Analysis. Click Exercise: Perform a Basic Stress Analysis. 6. On the Loads panel, click Force. Select the three faces as shown. 1. Open Stress_Overview.ipt. Lesson: Stress Analysis Overview 15

7. In the Force dialog box, click the Direction Selection button. Select the edge of the face as shown. The forces align with the edge. 12. Click Mesh View again to turn off the mesh. 13.

In the Force dialog box, for Magnitude, enter 500N. Click OK. 9. On the Solve panel, click Simulate. Click Run. 10.

14 7. In the Force dialog box, click the Direction Selection button. Select the edge of the face as shown. The forces align with the edge. 12. Click Mesh View again to turn off the mesh. 13. In the browser, in the Results folder, doubleclick Safety Factor. The minimum safety factor of less than one is a cause for concern. Further analysis and model changes may be required. 8. In the Force dialog box, for Magnitude, enter 500N. Click OK. 9. On the Solve panel, click Simulate. Click Run. 10. When the analysis is complete, the Von Mises stress is displayed on the displaced model. 14. In the browser, in the Results folder, doubleclick Von Mises Stress. 15. On the Result panel, click Animate. 16. In the Animate Results dialog box, click Play. Watch the animation for a few cycles. Click OK. 17. On the Exit panel, click Finish Stress Analysis. 18. Save the file. 19. In the browser, expand the 3rd Party folder. The files containing the stress results are listed. 11. On the Prepare panel, click Mesh View. The mesh is displayed. 20. In Windows Explorer, navigate to the location of the part file. Confirm that a folder containing the results was created. 21. Return to Autodesk Inventor. Close the file. 16 Chapter 1: Introduction to Engineering Analysis

15 Lesson: Dynamic Simulation Overview This lesson describes the Dynamic Simulation environment, and its interface and tools. The lesson also describes the processes you use to create simulations to evaluate motions in an assembly, size actuators, determine bearings, and compute stresses in parts. Proving the validity of your designs before you build saves time and money by eliminating costly reworking and alterations after the build process has begun. Simulation data serves as avaluable presentation tool for customers because it assures them that youare providing a design that meets their requirements. The integration of Dynamic Simulation with Autodesk Inventor, and the Dynamic Simulation evaluation mechanisms, provide you with valuable tools to test, refine, and prove your designs. In the following image, a revolution joint is applied to a glass window lever mechanism so that a simulation can be performed. Objectives After completing this lesson, you will be able to: Describe the Dynamic Simulation environment. Identify the Dynamic Simulation interface, its tools, and its unique browser nodes. Describe the basic process for creating a dynamic simulation. Lesson: Dynamic Simulation Overview 17

About Dynamic Simulation Dynamic Simulation is used to simulate and analyze dynamic characteristics of an assembly under various load conditions.

16 About Dynamic Simulation Dynamic Simulation is used to simulate and analyze dynamic characteristics of an assembly under various load conditions. You can also export load conditions at any motion state to the Stress Analysis environment to see how parts respond from a structural view to dynamic loads at any point in the assembly's range of motion. In addition, you have the option to transfer multiple load conditions in the assembly s range of motion to the Stress Analysis environment. This option enables you to validate and compare designs without the need to go back to Dynamic Simulation to transfer loads again. A wiper arm assembly in the Dynamic Simulation environment is shown. Definition of Dynamic Simulation Dynamic Simulation provides you with the tools to simulate the actual performance of your design before the product is built. By default, Dynamic Simulation automatically converts assembly constraints between components into mechanical joints. You also have the option to manually define mechanical joints between components. After the joints have been finalized, forces, accelerations, or velocities need to be applied to them where applicable if you want to reproduce real-world conditions. You can use the results of the simulation to determine the integrity of a design, calculate 18 Chapter 1: Introduction to Engineering Analysis

This data is used to perform Stress Analysis on a component.

17 the amount of force required to produce a desired motion, or view the effect of natural forces such as gravity and friction on the mechanism. An assembly in the middle of a simulation is shown. In the Output Grapher the force data is displayed. This data is used to perform Stress Analysis on a component. Starting Dynamic Simulation You can access Dynamic Simulation from an assembly file. On the Environments tab (1), Begin panel, click Dynamic Simulation (2). Lesson: Dynamic Simulation Overview 19

18 Example of Dynamic Simulation You have designed a windshield wiper assembly that is ready to be manufactured. Before the design is complete, you must determine the amount of driving torque required to rotate the drive arm at a velocity of 180 degrees per second. In Dynamic Simulation, you define the mechanism and impose the velocity on the drive arm. Using the Output Grapher, you can graph the torque curve for the drive arm. You can then extract the maximum drive torque on the drive arm, which you use to select the proper motor for the assembly. The drive mechanism of the wiper assembly is shown. Running the Output Grapher provides the data required to calculate the torque. 20 Chapter 1: Introduction to Engineering Analysis

19 The joint with the applied force. The selected option to be displayed in the window. The maximum force. The maximum force on the graph. Lesson: Dynamic Simulation Overview 21

The Dynamic Simulation Interface The DynamicSimulationenvironment uses the same major interface components that you use in the part or assembly environments, including the Autodesk Inventor window,

20 The Dynamic Simulation Interface The DynamicSimulationenvironment uses the same major interface components that you use in the part or assembly environments, including the Autodesk Inventor window, the graphics window, the ribbon, the application frame, the browser, and the shortcut menus. The tools presented on the ribbon, and the elements in the browser, are specific to the DynamicSimulationenvironment. Additionally, the Simulation Player window contains controls to runsimulations and set their time parameters. Dynamic Simulation tab Dynamic Simulation panels Dynamic Simulation tool Dynamic Simulation browser Simulation Player Dynamic Simulation Panels The Dynamic Simulation panels are divided into seven sections according to the types of operations that they perform. 22 Chapter 1: Introduction to Engineering Analysis

Tools to create joints, convert constraints, and check the status of the mechanism. Tools to apply force and torque. Tools used to display results and traces. Tools used to create animations.

21 Tools to create joints, convert constraints, and check the status of the mechanism. Tools to apply force and torque. Tools used to display results and traces. Tools used to create animations. Tools used to manage simulation settings and parameters. Tool used to export data to FEA. Tool used to exit Dynamic Simulation. Dynamic Simulation Browser The Dynamic Simulation browser provides elements that are unique to the Dynamic Simulation environment. Components areclassified as Groundedor Mobile. Joints are grouped by category, as are external loads and traces. In the browser you access the shortcut menus to open joint properties, edit and delete joints, lock degrees of freedom, and control the display of joints. The elements in the Dynamic Simulation browser are shown. Rigid components linked to ground on one end and all parts not yet used by the dynamic definition of the mechanism. Subassemblies, weldments, and parts that are not grounded. Joints created automatically or manually. Loads such as gravity, individual forces, or individual torque. Lesson: Dynamic Simulation Overview 23

22 Simulation Player The Simulation Player is used to run or replay a simulation. With this tool, you control the simulation time, how many time steps are calculated, and the speed at which the simulation runs. The Simulation Player is synchronized with the mechanism in the graphics window and the Output Grapher so that you can see the position of the mechanism and the resultant force in the Output Grapher at any time step that you choose. Return to the construction mode. Deactivates the screen refresh. Sets the time for the simulation to run. Displays the number of images to save during the simulation. Displays the number of frames to display. Creating Dynamic Simulations With Dynamic Simulation, the intent is to build a functional mechanism, and then add dynamic, realworld influences of various types of loads to create a true kinematicchain.you thenrun the simulation to see how the joints, loads, and component structures interact as a moving dynamic mechanism. 24 Chapter 1: Introduction to Engineering Analysis

23 In this simulation, the maximum acceleration of a revolution joint (1) is displayed in the time steps pane (2) and the graphics window (3). Process: Creating Dynamic Simulations The following steps provide an overview of the process of creating dynamic simulations of your assembly designs. 1. Open an assembly file. 2. Enter the Dynamic Simulation environment. 3. Create standard joints by converting existing assembly constraints automatically or manually. 4. If required, insert other types of joints such as contact, rolling/sliding, or spring. 5. Define the physical environment in the joint properties and apply forces. 6. Run the simulation to see how joints, loads, and component structures interact. 7. Use the Output Grapher to analyze the results. 8. Select the loads on a part and export to the Stress Analysis environment to study the effect of the loads. 9. Analyze the results in the Stress Analysis environment. Lesson: Dynamic Simulation Overview 25

Exercise: Review a Cam Valve Simulation In this exercise, you run a simulation of a cam valve assembly with and without friction to

The completed exercise Completing the Exercise To complete the exercise, follow the steps in this book or in the onscreen exercise.

Click Exercise: Review a Cam Valve Simulation. 2. Click Environments tab > Begin panel. Click Dynamic Simulation. 3.

24 Exercise: Review a Cam Valve Simulation In this exercise, you run a simulation of a cam valve assembly with and without friction to determine the torque required to overcome the spring resistance and the friction force. 1. Open CamValve.iam. The completed exercise Completing the Exercise To complete the exercise, follow the steps in this book or in the onscreen exercise. In the onscreen list of chapters and exercises, click Chapter 1: Introduction to Engineering Analysis. Click Exercise: Review a Cam Valve Simulation. 2. Click Environments tab > Begin panel. Click Dynamic Simulation. 3. If required, click No to close the message window. 4. Review the cam valve assembly. The spring is a force joint and was inserted using Dynamic Simulation. 26 Chapter 1: Introduction to Engineering Analysis

5. On the Simulation Player, click Run or Replay the Simulation. 10. On the Results panel, click Output Grapher.

At the beginning of the simulation note that the valve is bouncing. You correct this and run the simulation again. 6.

The timeline (2) is displayed, and the cam position (3) is updated to show its position at that point of the simulation. 7.

In the 2D Contact:4 (Cam:1, Valve:1) dialog box, for Restitution, enter 0. Click OK. 9.

25 5. On the Simulation Player, click Run or Replay the Simulation. 10. On the Results panel, click Output Grapher. Resize the Output Grapher and zoom and pan in the CamValve assembly to view both. At the beginning of the simulation note that the valve is bouncing. You correct this and run the simulation again. 6. On the Simulation Player, click Construction Mode (1). 11. In the Output Grapher, double-click the dashed line at 0.25 (1). The timeline (2) is displayed, and the cam position (3) is updated to show its position at that point of the simulation. 7. In the Dynamic Simulation browser, expand Contact Joints. Right-click 2D Contact:4 (Cam:1, Valve:1). Click Properties. 8. In the 2D Contact:4 (Cam:1, Valve:1) dialog box, for Restitution, enter 0. Click OK. 9. On the Simulation Player, click Run or Replay the Simulation. The valve does not bounce. 12. To cycle through the simulation, use the right and left arrow keys on the keyboard to step forward and backward in the simulation. Cycle through the simulation to 1.00 to show the cam at the end of the simulation. Lesson: Dynamic Simulation Overview 27

3. On the Simulation Player, click Run or Replay the Simulation.

In the next step, you change the color of the newly generated curve.

In the Output Grapher, right-click the U_imposed[1]/N mm column heading. Click Curve Properties. 13. In the Output Grapher, click Save Simulation.

Add a Coefficient of Friction The following steps describe how to add a coefficient of friction to calculate the effect on the torque that is

26 3. On the Simulation Player, click Run or Replay the Simulation. The Output Grapher is still open, so you see the graph being generated as the simulation is running. In the next step, you change the color of the newly generated curve. When you compare the saved graph curve with this new one, you can distinguish between the two of them. 4. In the Output Grapher, right-click the U_imposed[1]/N mm column heading. Click Curve Properties. 13. In the Output Grapher, click Save Simulation. Save the file as CamValve.iaa. 14. On the Simulation Player, click Construction Mode. Add a Coefficient of Friction The following steps describe how to add a coefficient of friction to calculate the effect on the torque that is required to rotate the cam and overcome the spring force and friction force. 1. In the Dynamic Simulation browser, under Contact Joints, right-click 2D Contact:4 (Cam:1, Valve:1). Click Properties. 2. In the 2D Contact:4 (Cam:1, Valve:1) dialog box, for Friction, enter Click OK. 5. In the Dynamic Simulation - Properties dialog box, click the color box. 6. In the Color dialog box, click the red color swatch. Click OK. 28 Chapter 1: Introduction to Engineering Analysis

7. In the Dynamic Simulation - Properties dialog box, click OK. The graph changes to red. 11.

Expand Driving Force and select the U_imposed [1] check box. 8. On the Output Grapher toolbar, click Import Simulation. 12.

Also, a new column is added in the time-steps pane for the numerical values. 9.

27 7. In the Dynamic Simulation - Properties dialog box, click OK. The graph changes to red. 11. In the Output Grapher, expand CamValve.iaa. Expand Revolution:2 (Support:1, Cam:1). Expand Driving Force and select the U_imposed [1] check box. 8. On the Output Grapher toolbar, click Import Simulation. 12. The Output Grapher displays the graphs of the torque required to rotate the cam without friction (blue) and with friction (red). Also, a new column is added in the time-steps pane for the numerical values. 9. In the Dynamic Simulation - Load file dialog box, select CamValve.iaa. Click Open. 10. Review the Dynamic Simulation browser. The CamValve.iaa element is added to the Output Grapher. 13. Close the file. Do not save changes. Lesson: Dynamic Simulation Overview 29

28 Chapter Summary In this chapter, you learned about the Stress Analysis and Dynamic Simulation environments. You learned how digital prototyping can be used to simulate your designs before you build costly physical prototypes. Having completed this chapter, you can: Describe the Stress Analysis environment and the processes you use to analyze designs. Describe the Dynamic Simulation environment and the processes you use to create simulations to evaluate motions in an assembly. 30 Chapter 1: Introduction to Engineering Analysis

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