Part 2 Seminar Notes by ASCENT for review only and reuse strictly forbidden. Sample provided All copying

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2 2016 Autodesk, Inc. All rights reserved. Autodesk Simulation Mechanical 2017 Part 2 Except as otherwise permitted by Autodesk, Inc., this publication, or parts thereof, may not be reproduced in any form, by any method, for any purpose. Certain materials included in this publication are reprinted with the permission of the copyright holder. Trademarks The following are registered trademarks or trademarks of Autodesk, Inc., and/or its subsidiaries and/or affiliates in the USA and other countries: 123D, 3ds Max, Alias, ATC, AutoCAD LT, AutoCAD, Autodesk, the Autodesk logo, Autodesk 123D, Autodesk Homestyler, Autodesk Inventor, Autodesk MapGuide, Autodesk Streamline, AutoLISP, AutoSketch, AutoSnap, AutoTrack, Backburner, Backdraft, Beast, BIM 360, Burn, Buzzsaw, CADmep, CAiCE, CAMduct, Civil 3D, Combustion, Communication Specification, Configurator 360, Constructware, Content Explorer, Creative Bridge, Dancing Baby (image), DesignCenter, DesignKids, DesignStudio, Discreet, DWF, DWG, DWG (design/logo), DWG Extreme, DWG TrueConvert, DWG TrueView, DWGX, DXF, Ecotect, Ember, ESTmep, FABmep, Face Robot, FBX, Fempro, Fire, Flame, Flare, Flint, ForceEffect, FormIt 360, Freewheel, Fusion 360, Glue, Green Building Studio, Heidi, Homestyler, HumanIK, i-drop, ImageModeler, Incinerator, Inferno, InfraWorks, Instructables, Instructables (stylized robot design/logo), Inventor, Inventor HSM, Inventor LT, Lustre, Maya, Maya LT, MIMI, Mockup 360, Moldflow Plastics Advisers, Moldflow Plastics Insight, Moldflow, Moondust, MotionBuilder, Movimento, MPA (design/logo), MPA, MPI (design/logo), MPX (design/logo), MPX, Mudbox, Navisworks, ObjectARX, ObjectDBX, Opticore, P9, Pier 9, Pixlr, Pixlr-o-matic, Productstream, Publisher 360, RasterDWG, RealDWG, ReCap, ReCap 360, Remote, Revit LT, Revit, RiverCAD, Robot, Scaleform, Showcase, Showcase 360, SketchBook, Smoke, Socialcam, Softimage, Spark & Design, Spark Logo, Sparks, SteeringWheels, Stitcher, Stone, StormNET, TinkerBox, Tinkercad, Tinkerplay, ToolClip, Topobase, Toxik, TrustedDWG, T-Splines, ViewCube, Visual LISP, Visual, VRED, Wire, Wiretap, WiretapCentral, XSI. NASTRAN is a registered trademark of the National Aeronautics Space Administration. Microsoft and Windows are either registered trademarks or trademarks of Microsoft Corporation in the United States and/or other countries. SOLIDWORKS is a registered trademark of Dassault Systèmes SolidWorks Corporation. All other brand names, product names or trademarks belong to their respective holders. Disclaimer THIS PUBLICATION AND THE INFORMATION CONTAINED HEREIN IS MADE AVAILABLE BY AUTODESK, INC. "AS IS." AUTODESK, INC. DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE REGARDING THESE MATERIALS. Published by: Autodesk, Inc. 111 Mclnnis Parkway San Rafael, CA 94903, USA Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7, 2016 III

3 Table of Contents Introduction... 1 Overview... 1 Software Installation, Services, and Support... 1 Installing and Running Autodesk Simulation Mechanical... 1 System Requirements... 2 Autodesk Simulation Mechanical Help... 2 InfoCenter... 4 Web Links... 4 New User Quick Start... 4 Tutorials... 5 Autodesk Knowledge Network... 5 Simulation Community... 5 How to Receive Technical Support... 5 Updates... 6 Background of MES... 7 Introduction... 7 Stress and Strain Review... 8 Contrasting Event Simulation with Classical Methods... 8 Numerical Example Force Estimation Methods Conclusions Steps for MES Chapter 1: Example Using MES Chapter Objectives Example Open and Mesh the Model Adding Loads and Constraints Specifying the Element Definition and Material Defining the Analysis Parameters Analyzing the Model Reviewing the Results Create a New Design Scenario and Revise the Analysis Parameters Analyzing Design Scenario Reviewing the Results for Design Scenario Chapter 2: Setting up the Event and Prescribing Motion Chapter Objectives Introduction Dynamic Analysis Techniques Determining the Time Step Size Setting up a Model for a Nonlinear Natural Frequency (Modal) Analysis Modeling Options Element Options Analysis Type Options Brick Elements D Kinematic Elements D Hydrodynamic Elements Midside Nodes Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7, 2016 VII

4 Table of Contents MES Loading Options Setting up Time-Dependent Loads Multiplier Table Editor Event Setup Load Curves Tab Loading Options Prescribed Translations and Rotations Results Options Load Cases Graphing Results Prescribed Motion Example Open the Model Suppressing Unwanted Parts and Meshing the Model Defining the Element Type and Verifying Material Adding the Prescribed Displacement and General Constraints Defining the Analysis Parameters Running the Analysis Viewing the Results Exercise A: Impeller Model Chapter 3: Overview of Material Models Chapter Objectives Material Model Options Elastic Material Models Hyperelastic Material Models Foam Material Models Viscoelastic Material Models Plastic Material Models Electrical Material Models Analysis Type Small Displacement versus Large Displacement Advanced Tab Results Options Example using von Mises Material Models Exercise B: Elastic Deformation of a Beam Chapter 4: Introduction to Contact and Impact Chapter Objectives Uses for Contact and Impact Contact Options General Contact Settings Default Contact Type for Contact Pairs Contact Settings Contact Options Surface Contact Example Completing the Model Setup Running the Analysis Reviewing the Results Acceleration Impact Planes Defining the Impact Plane Location Defining an Impact Plane Offset VIII Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7, 2016

5 Table of Contents Defining the Type of Impact Plane Additional Impact Plane Settings Impact Planes Example Open and Set up the Model Run the Analysis Drop Test Wizard Results Options Exercise C: Sphere and Ramp Model Chapter 5: Geometric Nonlinearities Chapter Objectives Overview Buckling Analyses Restarting Existing Analyses Example of an MES Restart Analysis Exercise D: Buckling Column Model Chapter 6: Results-Based Loading and Thermal Stress Analyses.. 95 Chapter Objectives Results Based Loading Defining and Editing Lookup Values: Specifying the Equation Conditional Statements and Multiple Load Curve Multipliers: Magnetic Force Example Thermal Stress Analyses Shrink Fit Analysis Procedure in MES Using the Thermal Analysis Results as an MES Load Exercise E: Thermal Stress Analysis of a Coiling Furnace Drum Chapter 7: Planar Elements Chapter Objectives Element Options Shell Elements Membrane Elements Loading Options Surface Loads Shell Element Example Exercise F: Sail Model Self Study: Line and 2-D Elements and Analysis Options Other Element Types Line Elements D Elements When to Use Different Element Types Line Elements Self Study Objectives Line Element Types and Options Truss Elements Beam Elements General Contact Elements Pipe Elements Slider Elements Actuator Elements Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7, 2016 IX

6 Table of Contents Spring Elements Pulley Elements Line Element Loading Options Initial Axial Forces and Strains Beam Preloads Internal Pressure Line Element Result Options Truss Element Example Exercise SS1: Mechanism Analysis (using Line Elements) Exercise SS2: Beam Model D Elements Self Study Objectives D Element Options Plane Stress Plane Strain Axisymmetric D Loading Options Surface Pressure/Traction: Surface Hydrostatic Pressure: D Hydrodynamic Element Example Snap-Through Analysis Example Exercise SS3: Pressurized Rubber Seal Analysis Comparing Analysis Options Linear versus Nonlinear Analysis When are Nonlinear Material Models Important Typical Examples of Nonlinear Analysis Implicit Time Integration Schemes MES Time Integration Scheme ("General: MES, NLS") Newmark Time Integration Scheme ("Static: NLS, LS") Wilson Theta Time Integration Scheme ("Static II: NLS") Iterative Solution Methods and Convergence Criteria Full Newton-Raphson Method Modified Newton-Raphson Method Combined Full and Modified Newton-Raphson Method Convergence Criteria Controls Affecting Convergence Behavior Nonlinear Static versus Dynamic Analyses Exercise SS4: Cable Model X Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7, 2016

7 Introduction Overview This course will introduce you to performing Mechanical Event Simulation (MES) analyses with the Autodesk Simulation Mechanical software. You will work with models built in CAD solid modelers as well as some built within the Autodesk Simulation Mechanical user interface. All of the relevant element, loading, and result options will be covered. For information regarding the basics of the user interface, refer to the Autodesk Simulation Mechanical, Part 1 Seminar Notes and course, which is a prerequisite to this MES course. Also, consult the program online Help for basics not covered within the seminar notes. Software Installation, Services, and Support Installing and Running Autodesk Simulation Mechanical Installation steps may vary according to your product, installation environment, operating system, and other factors. In general terms, you prepare your system, choose installation options, install the product, and launch it. For product-specific installation help you can access the online help documentation at the following link. Once the software is installed, you can also click Start & Learn: Learn: Help to access this same online Help site. From there, use the Table of Contents to navigate to one of the following sections: Installation Basics: Workflow: Basic Product Installation Installation Administrator s Guide: Workflow: Planning, Installing, and Configuring Network Licenses Installation Administrator s Guide: Workflow: Creating a Network Deployment Simulation Mechanical Installation Supplement Note: If your team works in a multi-seat stand-alone environment, you can repeat these basic instructions for each computer seat. Alternatively, an administrator can create a deployment, which is described in a separate workflow. By default, Autodesk SimStudio Tools 2016 R2 is installed along with Simulation Mechanical You can deselect SimStudio Tools to prevent it from being installed. However, this is not recommended because an Edit: SimStudio Tools command is provided within the Simulation Mechanical Tools tab of the ribbon. Use this command to modify CAD geometry in SimStudio Tools regardless of the source of the CAD data. To customize the installation location on your computer, type in the desired "Installation Path," or click the "Browse" button to navigate to the desired parent folder on your hard drive. A Simulation 2017 subfolder is created within the parent folder you specify and the software is Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7,

8 Introduction installed there. In addition, a SimStudio Tools 2016 R2 subfolder is created for the installation of that product, unless you choose not to install it. Any time after the installation, you will be able to start the software by using the found in the "Start" menu folder, "All Programs: Autodesk: Autodesk Simulation Mechanical..." The version number is included in the start menu folder name and the shortcut. In the dialog box that appears when the program is launched, you will be able to open an existing model or begin a new model. The simulation software will be used to create, analyze, and review the results of an analysis within a single user interface, regardless of the analysis type. System Requirements Consult the system requirements webpage for the latest information regarding the recommended or minimum hardware and operating systems for running Simulation Mechanical. Use the link provided in the program installer or navigate to the following page using your web browser: Autodesk Simulation Mechanical Help Simulation Mechanical Help is available via an online Help website. This resource contains the following information: What's New: A new feature list for the three most recent program versions. New User Quick Start: Videos and tutorials specifically designed with the new user in mind. Essential Skills videos * Meshing, modeling, and analysis tutorials Comprehensive User's Guide containing documentation for the following topics o FEA fundamentals o Model import and creation options o Description & setup for available analysis types o Modeling and analysis examples o User interface o Meshing o Result evaluation and reports Autodesk Fatigue Wizard Autodesk Vault Basic Add-In Installation and Licensing Guides and Simulation Mechanical Installation Supplement NOTE: For those without Internet access at their workstation, or with a slow Internet connection, a local help installer is available from the webpage Download and run the appropriate installer, following the instructions provided on the same webpage. The program will use the online Help when an Internet connection is available and will use the locally installed help when not connected to the Internet. * Essential Skills videos are not included within the local help. These must be watched from the online Help. 2 Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7, 2016

9 Introduction How to Access the Help Files Select the "Start and Learn" tab. Click on the "Help" command in the Learn panel of the ribbon. The homepage of the Autodesk Simulation Mechanical Help will appear. Alternatively, click on the question mark icon within the InfoCenter (see page 4) to access the same Help homepage. Type one or more keywords into the search field within the InfoCenter (see page 4) to search the online Help contents. A webpage showing the resultant search hits will display in your web browser. NOTE: You can navigate through the online Help via the Table of Contents frame on the left half of the webpage, or by entering keywords in the Search tab. For locally installed help, a navigation frame appears along the left side of the browser window. This frame includes Contents, Index, and Search tabs for convenient help topic navigation. Features of the Online Help We all learn differently, Autodesk online Help accommodates these differences by offering content in an array of formats including video instructions, tutorials, examples, and articles. To make this wide assortment of information available, the online Help search tool extends beyond the core help content, automatically searching the Autodesk support knowledgebase, discussion forums, blogs and other community sites. Figure I.1: Simulation Mechanical Online Help Search the Help Files using Keywords All of the pages in the Help files can be searched based on keywords. The keywords are entered at the top of the "Search" tab on the left side of the online Help screen. Topics that match the search criteria are listed below. Keywords are used to search the Help files. You may use single or multiple keywords. Boolean operators (AND, OR, NEAR, and NOT) are available to enhance the search utility. Also, phrases may be enclosed in quotes to search only for a specific series of words. Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7,

10 Introduction InfoCenter Web Links Figure I.2: Infocenter At the right end of the Simulation Mechanical title bar is a Help search field. You can search the online Help from within the program by entering keywords or phrases within this field. There is also a collection of icons for reaching other various resources, as follows: Communication Center: To setup and access Autodesk Channels and RSS Feeds. Reach the Autodesk Exchange Apps website. Access the About dialog box, which provides the software version, license information, and trademarks and credits. Within the Start & Learn tab of the ribbon, in the New Features and Learn panels, there are several commands that launch web pages, as detailed below. What's New Launches the What's New section of the Help Start Here Launches the New User Quick Start section of the Help Tutorials Launches the Tutorials section of the Help Videos Goes to the index page of the Essential Skills Videos Help Accesses the title page of the Simulation Mechanical Help In addition, the following commands in the Community tab of the ribbon access webpages as detailed below: Discussion Forum Simulation Mechanical discussion groups IdeaStation A place to share your product improvement ideas directly with developers Simulation Community Find answers, share expertise and connect with peers Autodesk University Discover what is happening at Autodesk University Autodesk Labs where you may obtain free tools and explore developing technologies Figure I.3: "Start & Learn" and "Community" Ribbon Tabs New User Quick Start This portion of the product Help is designed to quickly familiarize new users with the Simulation Mechanical program background, user interface, workflow, and learning resources. There are five Quick Start Videos and two Quick Start Tutorials. These tutorials provide additional guidance and videos as compared to the main set of meshing, modeling, analysis, and results evaluation tutorials (next paragraph). Click the "Start & Learn: Learn: Start Here" command to reach the New User Quick Start section of the Help. 4 Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7, 2016

11 Introduction Tutorials Tutorials are available that demonstrate many of the capabilities of the Autodesk Simulation Mechanical software. Each analysis is presented through step-by-step instructions with illustrations to assist the user. The tutorials are accessed from the "Start & Learn: Learn: Tutorials" command. You can download the tutorial models from our online Data & Downloads site, linkable from the top page of the tutorials. Install the models to a local folder of your choice, such as My Documents\Simulation Mechanical Tutorial Models. We recommend that you store your tutorial models in a location outside of the Program Files branch. The tutorials will appear in your default web browser. Autodesk Knowledge Network The Simulation Mechanical pages on the Autodesk Knowledge Network provide a variety of resources for new and experienced users. Go to the following webpage and explore the Getting Started, Learn & Explore, Downloads, and Troubleshooting tabs. You can order searches within this website according to those that are Most Helpful or those that are Most Recent. How To articles and links to relevant sections of the product Help are listed within the search hits. Simulation Community The Simulation Community website is a source of useful tips, events, discussions, and technical white papers. In addition, you can use this website to access Autodesk University learning content, Simulation TV, a blog, and a projects gallery. Autodesk Simulation TV is an informative resource that is available within the Simulation Community website to help customers get the most value out of their simulation tools (Mechanical, CFD, Moldflow, and more). This tool provides a personal, scalable, and on-demand system to help gather technical information about the Autodesk Simulation portfolio. Simulation experts (the SIM Squad) provide in-depth information on various simulation topics from pre- and post-processing to meshing and best practices. How to Receive Technical Support Technical support is reachable through three contact methods. The method you can use depends upon the level of support that your organization has purchased. For example, customers with Basic support must obtain their technical support from the reseller that sold them the software or through written support requests to Autodesk. Advanced support customers can obtain direct Autodesk telephone support. Other options include Enterprise and Per-Incident support. Consult your sales contact for more information. Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7,

12 Introduction Updates Three ways to contact Technical Support: Reseller: Obtain phone, fax, and/or information from your reseller. Autodesk Account portal: Access the Autodesk Account portal at Sign in with your ID or address and password. Click the Create an Account link if you have not yet set up your account. Click the MANAGEMENT link. Finally, from the Support pull-down menu, choose Browse support & learning or Contact us. Autodesk Product Support Phone: (866) When contacting Technical Support: Have your account CSN number or Express Service ID ready before contacting Technical Support. Know the current version number of your software. Have specific questions ready. Remember, Technical Support personnel cannot perform, comment on, or make judgments regarding the validity of engineering work. The software is updated with new functionality on a continual basis. The following three types of releases are provided: 1. A major version: Indicated by the four-digit year of the software release (based upon the Autodesk fiscal year, not the calendar year) 2. A "subscription" version: Customers with a current maintenance subscription are eligible for additional releases that may be made available between major product version releases. These are designated by the addition of the word "Subscription" after the major version number. 3. A service pack: Incorporates minor improvements to a major or subscription release and is indicated by the letters "SP" and a service pack number after the major or subscription version number. How to Determine the Software Version Click on the down-arrow to the right of the question mark icon at the right end of the program title bar. Depending on the state of the InfoCenter display, this icon might be hidden. If so, click the double-arrows at the right end of the InfoCenter icons to expand the InfoCenter and reveal the hidden icons. Select the "About" command from the drop-down box. The dialog box that appears displays the complete version information (with build number, and date). In addition, the program title bar and the splash screen that appears at each program launch will indicate the major version number of the software. However, as with the start menu group name and program shortcut, it will not indicate the subscription and service pack variants. 6 Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7, 2016

13 Introduction How to Obtain an Update The Autodesk Desktop App is an installed content delivery solution. This desktop component installs with Microsoft Windows -based Autodesk 2017 products and suites. It replaces the previous in-product update components and the Autodesk Application Manager. The Autodesk desktop app keeps Autodesk Subscription customers informed of product updates, new releases, patches, new features, and special subscriber-only learning and training materials, as they become available. Background of MES Introduction Event simulation, as an engineering methodology, is vastly different from the techniques that have been taught to engineers since the onset of formal engineering training, begun by the Greek mathematician Archimedes around 200 B.C. Event simulation is engineering by simulating a physical event in a virtual laboratory. To perform an engineering analysis using event simulation requires a different viewpoint from that of a classical stress analysis. Here, we will not only define event simulation, but also contrast it with classical stress analysis. In school, engineers are taught that stress is a function of force, or σ = f(force), and that the deformation, or displacement, is another function of force, or d = g(force). In MES, however, we assume that the design force is usually indeterminate and it results from some type of action or motion. In this scenario, force and stress are functions of displacement or deformation; that is force = f(d) and σ = g(d). The deformation or displacement is calculated directly from the governing equations of physics. A simple analysis that would require an MES solution is shown in Figure I.3. Figure I.4: A Model That Cannot be Accurately Solved without MES This is a simple structure consisting of three truss elements constrained with pin joints. A force is applied vertically downward at the intersection of the three truss elements. If we were to perform a linear static stress analysis, the entire load would be carried by the vertical member. A linear static solution is based on the initial geometry, in which the horizontal members are at right angles to the applied force. There can be no component of the applied force acting in the direction of the horizontal members [cos(90º) = 0]. So, they do nothing. Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7,

14 Introduction Contrarily, if we perform an MES, the horizontal members will carry a portion of the load. Geometric nonlinearity will be considered and, as the top member elongates, the horizontal members will become slightly non-horizontal and must also elongate slightly. Therefore, the tension in these members will have a component that resists the applied force, decreasing the load being carried by the vertical member. So, to capture the contribution of the horizontal members, a nonlinear analysis that is not based solely on the initial geometry is required. Stress and Strain Review Contrasting Event Simulation with Classical Methods Let us use a simple cantilever beam to highlight the differences between classical stress analysis and mechanical event simulation. Figure I.5: Cantilever Beam Diagram Using an engineering handbook, one finds that, for a cantilever beam subjected to a force at the end opposite of the fixed end (A), the maximum stress (at A) is given by: Mc σ = I where M is the moment generated by the force F (M = Fl), c is the distance from the neutral axis to the edge of the beam (c = t/2), and I is the area moment of inertia (I = wt 3 /12). This result is obtained by considering the bending of a beam in conjunction with Hooke's law ( F = k d ). This law states that force is a linear function of displacement. This statement forms the basis of classical stress analysis and, thus, of modern finite element analysis. In finite element analysis, the matrix equation {F} = [K]{d} is solved for the displacement vector, {d}, from the force vector, {F}, and the stiffness matrix, [K]. Subsequently, the stresses are calculated from the equation {σ} = E{ε}, where {ε} is the strain vector, which is just a normalized displacement vector and E is the modulus of elasticity, which corresponds to Hooke's constant, k. All would be well if the beam was always at rest, which is the only valid application of the above equation. In practical mechanical engineering, the static case would never dictate the design. The design must consider the worst-case scenario, which generally occurs when the beam is in motion and the forces, and thus the stresses, are greater than those under static conditions. 8 Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7, 2016

15 Introduction Here is where MES enters the design process it allows us to simulate the entire event, not simply obtain a static solution. A useful byproduct of this type of event simulation is that the forces generated by the motion are calculated and accounted for within the analysis. Let us briefly discuss the theory of how force produces motions. According to Newton's second law: F = ma where force equals mass multiplied by acceleration. Mass is an inherent property of matter and acceleration is the rate of change of velocity. This law quantifies the fact that mass is the property of matter that causes resistance to changes in motion. It should be noted that, under the influence of gravity, a body at rest of mass m generates a force mg, where g is the acceleration due to gravity. In the special cases of constant acceleration (such as the gravity field near the Earth's surface) and short-lived events (say of length t), Newton's second law can be rewritten as: Δv F = m or FΔ t = mδv Δt where v is the amount by which the velocity changes during t time. Thus, a force of 1,000,000 lb. acting over seconds produces the same impulse (change in momentum) as a force of 1 lb. over 1 second. Mechanical event simulation relies on the combination of Newton's second law with Hooke's law as follows: F = ma = kd or ma + kd = 0 The negative sign in front of k is because the force is in the opposite direction from the displacement. Also, note that the force quantity can be eliminated and that the concept of time has been introduced through the acceleration term. In order to simulate real-world problems, one must also take damping or friction into account. Such dissipative forces can be modeled by: F = cv where v is the velocity and c is a constant. Note how dissipation also opposes motion. Combining the two previous equations for F, we obtain: or in matrix form: ma + cv + kd = 0 [ M ]{} a + [ C]{} v + [ K]{} d = 0 This is the basic equation of MES. Note how it models the combination of motion, damping, and mechanical deformation. If the stresses are still of interest, they can be calculated at any time during the analysis by application of the formula {σ} = E{ε}, where {ε} (the strain vector) is easily obtained from the displacement vector {d}. MES provides a means by which to design for the "worst-case scenario." Even for the relatively simple example of the cantilever beam, the solution of the above equation is beyond the realm of hand calculations. However, with today's computer technology, the solution of significantly more complex problems has been reduced to the practical level. Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7,

16 Introduction Numerical Example Now, we will consider a numerical example to further demonstrate the power of MES. Imagine a cube of mass m impacting a rigid surface along a face. We are interested in the maximum deformation experienced by the cube. We first perform a hand calculation for the maximum compression length. Then, we use MES to solve the same problem and compare the results. Cube just prior to contact. Figure I.6: Cube Impact Cube at time of maximum deformation. By Newton's second law, the impact force is given by FΔ t = mδv. Following the principles of classical physics, we assume that the cube's entire mass is located at its centroid. If we also assume that, for any particular location on the cube, the acceleration is constant throughout the impact, then the equation takes the form: 1 Δv F = m 2 Δt where v is the change in velocity of the top of the cube during the impact interval, t. The factor of 1 / 2 in the equation is needed because we are applying Newton's second law at the centroid. A linear relationship between the location and acceleration is expected. In other words, once contact is made, we expect the top of the cube to move twice as fast as its centroid. The constant acceleration assumption combined with basic kinematics allows us to obtain an expression for the amount by which the cube deforms during impact: at L = 2 2 Δ or ΔvΔt Δ L = or 2 v Δ L = impact Δ where v impact is the velocity of the cube, and thus of its top face, at the moment that contact is made. The negative sign in the equation is needed since v is negative and we seek a positive value for L. Note how v has been replaced by just v impact because at the time of greatest deformation, the top of the cube is not moving. By Hooke's law, the force on the cube is given by: Combining the last three equations yields: F = kδl v Δ L = impact 2 m k 2 t 10 Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7, 2016

17 Putting k in terms of E (for a cube of length L deforming along an axis perpendicular to a face, k=el), we obtain: v Δ L = 2 impact Using Autodesk Simulation Mechanical software, we can analyze the same impact problem. We model a cube of length (L) = 1.0 inch and mass (m) = lb m, comprised of a material with Young's modulus (E) of 10 7 psi. The event simulated is actually the dropping of the cube from a height of 100 inches, which results in an impact velocity (v impact ) of 278 in/sec when under the influence of a gravitational field of strength in/sec 2. The software predicts a maximum deformation ( L) of inch, which compares very favorably with the value of given by the preceding equation. This example demonstrates how difficult it is to analyze a simple impact problem without using MES. Imagine how involved, or even impossible, the hand calculation would have been for a more complex geometry -- not a cube. Of course, one could resort to conventional, classical finite element analysis (FEA). Such an analysis neglects motion but might be adequate if we knew the impact force. The inadequacies occur primarily because such an analysis neglects the vibrations set off by fluctuations in the force during the actual impact. Force Estimation Methods Conclusions There are three commonly used methods to estimate force values for input into classical FEA experience, rigid-body dynamic analysis, and physical experimentation. Let us consider these three methods: Experience Some engineers rely on prior experience with similar problems to estimate these forces. Usually, these engineers rely on safety factors, hoping that they are sufficient to prevent failure, yet are not overly conservative so as to produce an over-designed part. Rigid-Body Dynamics Rigid-body dynamics applications calculate motion-generated forces using a model of the part. In order to arrive at numerical values for these forces, such programs use vaguely defined stiffnesses. Because these programs are limited by the rigid-body assumptions, using these stiffnesses to calculate forces is often not reliable. Physical Experimentation Performing an experiment on a prototype of the part is an accurate means by which to obtain these forces. However, such an approach defeats the economic savings of using computer analysis. m EL Introduction Event simulation allows one to model an entire physical event with the least number of assumptions. Specifically, one does not have to assume a static situation or estimate values for the forces that result from motion. Furthermore, event simulation has the useful byproduct of generating a "frame-by-frame" record of the event, not just a "snap-shot" at its conclusion. Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7,

18 Introduction Steps for MES 1. Setting up the model Create a mesh that represents the model. Define the element properties. Define the loads. Define the time history curve data. 2. Analyzing the model Run the analysis. View the analysis as it proceeds within the Results environment. 3. Reviewing the results Review displacement and stress results. Compare final results with failure criteria. Create an animation file. Generate a report. 12 Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7, 2016

19 Chapter 1 Example Using MES Chapter Objectives Example Overview of how to open a CAD solid model and create a mesh Overview of adding loads and constraints to a model Overview of defining material properties Overview of defining load curves Overview of performing an analysis Overview of reviewing results Overview of graphing results This example is an introduction to the capabilities of Autodesk Simulation Mechanical MES analyses. The example will give step-by-step instructions to create a mesh and analyze a cantilever beam. There are three sections: 1. Setting up the model Open the model in the FEA Editor environment and create a mesh. Then add the necessary loads and constraints and define the model parameters. 2. Analyzing the model Analyze the model using MES. 3. Reviewing the results View the displacements and stresses graphically within the Results environment. Use the 3-D solid model, Cantilever.step, located in the "Chapter 1 Example Model\Input File" folder of the class directory to analyze a simple model of the cantilever beam (see Figure 1.1). The cantilever beam is 72 inches long, has a 3.5 in x 1.5 in cross-section and is made of Steel (AISI 4130). We will keep the default "Large Displacement" analysis type with the "Element Definition" dialog box. One end of the model will be fully constrained and a nodal force of 400 pounds will be applied at the opposite end. The force will be gradually applied over a 1 second period and will then be removed by reducing it to zero in one millisecond. Continue the analysis for another 2 seconds to view the effect of the removal of the force. We will initially use a capture rate of 10 steps per second for the entire event, 30 steps total. After reviewing the results, we will adjust the time step scheme as needed to more accurately capture the event. Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7,

20 Chapter 1: Example Using MES Open and Mesh the Model The FEA Editor environment is used to create a mesh for all solid models. You can open CAD models in the FEA Editor environment originating from any of the CAD solid modelers that are supported. You can also open models of any of the supported universal CAD formats. "Start: All Programs: Autodesk: Autodesk Simulation Mechanical 20xx: Autodesk Simulation Mechanical 20xx" "Start & Learn: Launch: Open" "STEP (*.stp, *.ste, *.step)" "Cantilever.step" Mouse "Nonlinear: MES with Nonlinear Material Models" "OK" "No" "Yes" If not already started, click the Windows "Start" button and access the "All Programs" pull-out menu. Select the "Autodesk" folder and then the "Autodesk Simulation Mechanical 20xx" pull-out menu. Choose the "Autodesk Simulation Mechanical 20xx" command. If the Open dialog box is not already displayed, click the "Open" command in the "Launch" panel of the Start & Learn ribbon tab. Alternatively, you can select "Open" from the quick access toolbar or Application Menu. Select the "STEP (*.stp, *.ste, *.step)" option in the CAD Files section of the "Files of type:" drop-down box. Select the file "Cantilever.step" in the "Autodesk Simulation Mechanical 2017 Exercise Files/Part 2/Chapter 1 Example Model\Input File" directory. If you have not previously extracted the exercise files for this class return to the Exercise Files page at the beginning of the training guide and complete the instructions. Click on the arrow in the "Choose Analysis Type" dialog box. Select the "Nonlinear" pull-out menu and then select the "MES with Nonlinear Material Models" command. Click the "OK" button. Click "No" when asked about using the default Simulation Mechanical color palette instead of the CAD model colors. Click "Yes" when asked about importing part names from the CAD model. The model will now appear in the FEA Editor environment, as shown in Figure 1.1. Figure 1.1: Cantilever Beam Model 14 Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7, 2016

21 "Mesh: Mesh: 3D Mesh Settings" "Options " "Absolute mesh size" Chapter 1: Example Using MES Select the "Mesh" tab. Click on the "3D Mesh Settings" command in the "Mesh" panel. Click the "Options " button. Select the "Absolute mesh size" option in the "Type" drop-down box. 1 Type "1" in the "Size" field, if not already specified. "OK" "Generate mesh" "No" Adding Loads and Constraints Click the "OK" button. Click the "Generate mesh" button to create a mesh using the specified options. Click the "No" button when asked to view the mesh results. The FEA Editor environment is also used to specify all of the element and analysis parameters for your model and to apply the loads and constraints. You will notice a red X and red text on certain headings in the browser (tree view). This signifies that this data has not yet been specified. You will need to eliminate all of the red Xs before analyzing the model. Since you have created a solid mesh, the "Element Type" heading in the browser is already set to "Brick" and the default "Element Definition" parameters have been applied. "View: Navigate: Orientation: Back View" "Selection: Shape: Point or Rectangle" "Selection: Select: Surfaces" Mouse "Setup: Constraints: General Constraint" "Fixed" "OK" "View: Navigate: Orientation: Isometric View" "Selection: Select: Edges" Mouse "Setup: Loads: Force" Select the "View" tab. Click on the options button at the bottom of the "Orientation" command in the "Navigate" panel. Select "Back View" from the pull-out menu. Go to the "Selection" tab of the ribbon. Make sure the "Point or Rectangle" mode is selected in the "Shape" panel. Also make sure the "Surfaces" mode is selected in the "Select" panel. Click on the end surface of the cantilever (facing you). Select the "Setup" tab. Click on the "General Constraint" command in the "Constraints" panel. Click the "Fixed" button. Click the "OK" button. Select the "View" tab. Click on the options button at the bottom of the "Orientation" command in the "Navigate" panel. Select "Isometric View" from the pull-out menu. Select the "Selection" tab. Select the "Edges" command in the "Select" panel. Click on the short top edge at the far left end of the cantilever beam. Select the "Setup" tab. Click on the "Force" command in the "Loads" panel Type "-400" in the "Magnitude" field. "Y" "Curve " "Add Row" Select the "Z" radio button. Click the "Curve..." button. Click the "Add Row" button Type "1.001" in the third row of the "Time" column. Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7,

22 Chapter 1: Example Using MES "Add Row" 3 : <Enter> "OK" "OK" <Esc> Click the "Add Row" button. Type "3" in the fourth row of the "Time" column and press <Enter>. Click the "OK" button to close the "Multiplier Table Editor." Click the "OK" button to close the "Edge Force Object" dialog box. Press <Esc> to clear the selected edge. The model should appear as shown in Figure 1.2. Figure 1.2: Meshed Cantilever with Applied Load and Constraint Specifying the Element Definition and Material Mouse "Edit Element Definition " "Large Displacement" "OK" Mouse Right-click on the "Element Definition" heading for Part 1 in the browser. Select the "Edit Element Definition " command. Notice that the "Large Displacement" option is already specified in the "Analysis Type" field (default for MES). Click "OK" to exit the Element Definition dialog box. Double-click the "Material" heading for Part 1 in the browser. "Steel (AISI 4130)" "OK" Expand the "Steel" folder and then expand the "AISI" folder. Select "Steel (AISI 4130)" within the Autodesk Simulation Material Library. Click the "OK" button. 16 Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7, 2016

23 Chapter 1: Example Using MES Defining the Analysis Parameters "Setup: Model Setup: Parameters" Click on the "Parameters" command in the" Model Setup" panel of the "Setup" ribbon tab. By default, the "Step input" mode is set to "Number of time steps." Other choices are "Capture rate" and "Time step size." We will keep the default step input method. 3 Type "3" in the "Duration" column. 30 Type "30" in the "Number of time steps" column. This is equivalent to ten steps per second. "OK" Click the "OK" button. Analyzing the Model "Analysis: Analysis: Run Simulation" Reviewing the Results Select the "Analysis" tab. Click on the "Run Simulation" command in the "Analysis" panel. The model will be displayed in the Results environment while solving. We will review the von Mises stress results in the cantilever as the load is applied and removed. "Results Contours: Stress: von Mises" "Results Contours: Load Case Options: First" "Results Options: Load Case: Next" Select the "Results Contours" tab. Click on the "von Mises" command in the "Stress" panel. Click on the "First" button in the "Load Case Options" panel. Click on the "Next" button in the "Load Case Options" panel. Use this command repeatedly to advance through the time steps. At 1 second, the maximum von Mises stress will be approximately 22,241 psi. Leave this time step active as you proceed to the next steps. We will now view the displacement of the cantilever beam in the Z direction during the analysis using the graph capability. "Results Contours: Displacement: Z" "Selection: Shape: Point or Rectangle" "Selection: Select: Nodes" Mouse Mouse Click on the "Z" command in the "Displacement" panel. The maximum Z displacement corresponds to the maximum stress time step and is approximately inches. Select the "Selection" tab. Make sure the "Point or Rectangle" mode is selected in the "Shape" panel. Also make sure the "Nodes" option is selected in the "Select" panel. Click on the node at the center of the beam end face (the end where the force is applied). Right-click in the display area. "Graph Value(s)" Mouse Select the "Graph Value(s)" command. Right-click in the graph area. Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7,

24 Chapter 1: Example Using MES A graph of the displacement in the Z direction is displayed. The graph should be similar to the one shown in Figure 1.3. Linear displacement can be seen as the load is applied. The vibration after the load is removed can also be seen, though it may not be what you expected. Figure 1.3: Z-Displacement at the End of the Cantilever Beam There is only one large overshoot and one additional, slight oscillation after the force is suddenly removed from the cantilever beam. In addition, there are only about five or six data points for each cycle of beam oscillation. This shows that the capture rate was not sufficient to accurately calculate the event. The capture rate should be 10 to 20 times the frequency of the motion (this is discussed in Chapter 2). You might typically expect at least ten oscillations of a cantilever when a load is suddenly applied or removed. Lastly, the vibration frequency is too low (due to over damping). We can observe two cycles in two seconds, or 1 Hertz. In reality, this cantilever beam has a natural frequency of about 9.5 Hz, which can be verified with a modal analysis. The default time integration parameters in MES will dampen high-frequency oscillations to improve the stability of the solution. The damped frequencies are dependent upon the capture rate. That is, a smaller capture rate (larger time step size) will cause lower frequency effects to be filtered out as compared to an analysis with a greater capture rate. We will next split our event into two different intervals, using a coarse capture rate when the load is being applied and a much finer capture rate after the force is removed. For the first second, not much is happening and the behavior of the beam is quite linear. We can keep the previous capture rate of 10 steps per second for this interval. A recommended minimum capture rate for the remainder of the event would then be about 95 per second (10 times the natural frequency of 9.5 Hz). Since there are two seconds remaining 18 Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7, 2016

25 Chapter 1: Example Using MES after the force is removed, the minimum recommended number of steps for the second interval is 190. Let s just round this up to 200. We will now create a new design scenario, change the event parameters, and rerun the analysis. Create a New Design Scenario and Revise the Analysis Parameters "FEA Editor" Mouse: "Copy" "Yes" "Setup: Model Setup: Parameters" Click the "FEA Editor" tab above the browser. Right-click the "1 < Design Scenario 1 >" heading in the browser and choose the "Copy" command. If prompted to save the current design scenario, click "Yes." Click on the "Parameters" command in the" Model Setup" panel of the "Setup" ribbon tab. "Add Row" Click the "Add Row" button one time. Type "1" in the first row of the "Duration" column, 1 replacing the previous input (copied from Design Scenario 1). 10 Type "10" in the first row of the "Number of time steps" column. 2 Type "2" in the second row of the "Duration" column. 200 Type "200" in the second row of the "Number of time steps" column. "OK" Click the "OK" button to accept the analysis parameters. Analyzing Design Scenario 2 The second design scenario will produce a total of 210 time steps, 10 for the first interval (load application) and 200 for the second interval (after load removal). "Analysis: Analysis: Run Simulation" Reviewing the Results for Design Scenario 2 "Results Contours: Displacement: Z" "Selection: Shape: Point or Rectangle" "Selection: Select: Nodes" Mouse Mouse Select the "Analysis" tab. Click on the "Run Simulation" command in the "Analysis" panel. The model will be displayed in the Results environment while solving. Select the "Results Contours" tab. Click on the "Z" command in the "Displacement" panel. Select the "Selection" tab. Make sure the "Point or Rectangle" mode is selected in the "Shape" panel. Also make sure the "Nodes" option is selected in the "Select" panel. Click on the node at the center of the beam end face (the end where the force is applied). Right-click in the display area. "Graph Value(s)" Select the "Graph Value(s)" command. Autodesk Simulation Mechanical 2016 Part 2 Seminar Notes June 7,