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COPYRIGHT DASSAULT SYSTEMES Generative Assembly Structural Analysis CATIA Training Foils Version 5 Release 8 March 2002 EDU-CAT-E-GAS-FF-V5R8
COPYRIGHT DASSAULT SYSTEMES Course Presentation Objectives of the course In this course you will learn how to perform Static and Modal analysis (create analysis document, compute and visualize) on an assembly of parts. Targeted audience CATIA V5 Users Prerequisites Assembly Design Fundamentals in CATIAV5 0.5 day
COPYRIGHT DASSAULT SYSTEMES Introduction to GAS Analysisp Accessing the Workbenchp User Interfacep User Settingsp Saving an Analysis Documentp Defining Part Connections on the Assemblyp Connection Propertiesp Slider Connectionp Contact Connectionp Fastened Connectionp Rigid Connectionp Smooth Connectionp Advanced Connectionsp Analysis Connections Workbenchp Static Analysisp Modify the Element Type for an Assemblyp Static Results Visualizationp Frequency Analysisp Hybrid assembly analysisp.36 Frequently-Asked Questionsp.37 Table of Contents
COPYRIGHT DASSAULT SYSTEMES Introduction to GAS Analysis In this lesson, you will learn about the Generative Assembly Structural Analysis Workbench by : Accessing the Workbench User Interface User Settings Saving an Analysis Document
COPYRIGHT DASSAULT SYSTEMES Be sure that all the parts making up the product have a material assigned. This action can only be performed in the Part Design Workbench 3- Modal Analysis or Static Analysis 2- Analysis & Simulation 1.1. Accessing the Workbench 1- Start
COPYRIGHT DASSAULT SYSTEMES Standard toolbar Structure Compute Restraints Loads Mass Results Management Image Reports 1.2. User Interface - Toolbars External Storage Management
COPYRIGHT DASSAULT SYSTEMES User Interface - Icons Structure Mesh Specification Connection Advanced Connection Virtual Part Analysis Results Basic Analysis Report Historic Of Computations Listing Image Creation Deformation Stress Von Mises Displacement Solver Tools Storage Location Clear Storage Temporary Data Directory Mass Equipment Mass Restraints Application Clamp Mechanical Restraint Advanced Restraint Results Visualization Animate Cut Plane Analysis Deformation Scale Factor Search Image Extrema Informations Image Layout Computation Compute Loads Application Pressure Force Acceleration Force Density Enforced Displacement
COPYRIGHT DASSAULT SYSTEMES Analysis tree Generative Assembly Mesh Specifications Pre-Processing Input Images Parts Constraints User Interface - Tree
COPYRIGHT DASSAULT SYSTEMES When the cursor is hovering over a constraint in 3D, the involved elements can be highlighted, which helps in understanding the constraint. We will activate highlight so that geometrical elements get highlighted User Settings - Turning Highlight Constrained Elements ON 3- Click Symbols 2- Click Parameters 4- Activate Highlight constrained elements 1- Select Options… from the Tools menu
COPYRIGHT DASSAULT SYSTEMES General Process Ensure that part has a material assigned then Open Analysis Workbench Define Part Connections on Assembly Pre-Process Create Image Perform Computation Analyze Results
COPYRIGHT DASSAULT SYSTEMES There are various ways to save an Analysis Document and child documents.It is important to achieve this correctly with an assembly analysis document, for the assembly has to be properly linked with all the parts it is made from. Only those documents that been modified will be saved or proposed to be saved Saving an Analysis Document Save will save the active Analysis Document Save As... is similar to Save, but it allows you to specify the name and folder for the active Analysis Document Save All will propose saving all open documents and children of these documents
COPYRIGHT DASSAULT SYSTEMES Save Management… is an easy way to save all modified documents under user specified names. 1- Save Management… All modified open documents will be proposed for saving, regardless of which document is active Saving an Analysis Document - Under Specified Names 2- Specify which documents to save
COPYRIGHT DASSAULT SYSTEMES Defining Part Connections on the Assembly In this lesson, you will learn about the Connections between Parts. Connections are used to specify the boundary interaction between bodies in an assembled system. The user can specify the physical nature of the component linking (connection properties) depending on positioning constraints (from Assembly Design) or on general Analysis-wise connections (from the Analysis Connection Workbench). Connection Properties Slider Connection Contact Connection Fastened Connection Rigid Connection Smooth Connection Advanced Connections Analysis Connections Workbench
COPYRIGHT DASSAULT SYSTEMES Connection Properties (1/2) Definition of Connections between two solid parts
COPYRIGHT DASSAULT SYSTEMES Connection Properties (2/2) Definition of connections between two surfaces or between a surface and a solid part
COPYRIGHT DASSAULT SYSTEMES A Slider Connection is the link between two bodies which are constrained to move together in the local normal direction at their common boundary, and will behave as if they were allowed to slide relative to each other in the local tangential plane. The Slider Connection relations take into account the elastic deformability of the interfaces Slider Connection 1- Click on the Slider Connection icon in the Connection toolbar. A symbol representing the Slider Connection is visualized on the involved face. The Slider Connection dialog box is displayed. A Slider Connection object appears in the features tree under the active Properties objects set. 3- Click OK. 2- Select a contact assembly constraint previously created in the Assembly Design workbench.
COPYRIGHT DASSAULT SYSTEMES A Contact Connection is the link between two bodies which are prevented from inter-penetrating at their common boundary, and will behave as if they were allowed to move arbitrarily relative to each other as long as they don't come into contact within a user-specified normal clearance. The Contact Connection relations take into account the elastic deformability of the interfaces Contact Connection Enter a clearance value, if any. 1- Select the contact constraint. 2- Click OK.
COPYRIGHT DASSAULT SYSTEMES A Fastened Connection is the link between two bodies which are fastened together at their common boundary, and will behave as if they were a single body. The Fastened Connection relations take into account the elastic deformability of the interfaces Fastened Connection 1- Select the contact constraint. 2- Click OK.
COPYRIGHT DASSAULT SYSTEMES A Rigid Connection is the link between two bodies which are stiffened and fastened together as if there were a rigid virtual part between them. The Rigid Connection relations do not take into account the elastic deformability of the interfaces Rigid Connection A symbol representing the Rigid Connection is visualized on the corresponding faces. 1- Select the distant constraint. 2- Click OK.
COPYRIGHT DASSAULT SYSTEMES A Smooth Connection is the link between two bodies which behave as if there were a smooth virtual part between them. The Smooth Connection relations take into account the elastic deformability of the interfaces Smooth Connection A symbol representing the Smooth Connection is visualized on the corresponding faces. 2- Click OK. 1- Select the distant constraint.
COPYRIGHT DASSAULT SYSTEMES A Pressure fitting Connection is the link between two bodies which are assembled in a Pressure Fitting configuration, more precisely when there are interferences or overlaps between both parts. The connection behaves as a contact connection with negative clearance value (positive overlap for pressure fitting connection) Advanced Connections - Pressure-Interference Fitting 1- Click on the Pressure fitting icon. A symbol representing the Pressing fitting Connection is visualized on the corresponding faces and in the tree. After computation, the user can visualize the Pressure fitting stress. 2- Select the Surface Contact and enter a positive Overlap. 3- Click OK.
COPYRIGHT DASSAULT SYSTEMES A Real Bolt Tightening connection models a bolt-tightened assembly where the bolt is included : it takes the pre-tension into account and is created on a Surface Contact type of Assembly Constraint. The elastic deflection of the interface is addressed and incompatible meshes of the components are implicitely managed. Advanced Connections - Bolt Tightening 1- Click on the Bolt Tightening icon. A symbol representing the Real Bolt Tightening Connection is visualized on the corresponding faces and in the tree. 2- Select the Surface Contact Constraint and enter the Tightening Force value 3- Click OK.
COPYRIGHT DASSAULT SYSTEMES Advanced Connections - Virtual Spring Bolt Tightening A Virtual Spring Bolt Tightening Connections specify the boundary interaction between bodies in an assembled system. It takes into account pre-tension in a bolt-tightened assembly in which the bolt is not included. 1- Click on the Virtual Spring Bolt Tightening icon. A symbol representing the Virtual Spring Bolt Tightening Connection is visualized on the corresponding faces and in the tree. 2- Select the Coincidence Constraint and enter the Tightening Force value 4- Click OK. 3- Give the Translation and Rotation Stiffness value
COPYRIGHT DASSAULT SYSTEMES A Virtual Bolt Tightening connection models a bolt-tightened assembly where no bolt is included : it takes the pre-tension into account and is created on a Coincidence type of Assembly Constraint. The elastic deflection of the interface is addressed and incompatible meshes of the components are implicitely managed Advanced Connections - Virtual Bolt Tightening 1- Click on the Virtual Bolt Tightening icon. A symbol representing the Virtual Bolt Tightening Connection is visualized on the corresponding faces and in the tree. 2- Select the Coincidence Constraint and enter the Tightening Force value 3- Click OK.
COPYRIGHT DASSAULT SYSTEMES Advanced Connections - Spot Welding A Spot Welding Connection is the link between two bodies, using analysis welding point connections. 1- Click on the Spot Welding icon. A symbol representing the Spot Welding Connection is visualized on the corresponding faces and in the tree. 2- Select the Analysis Connection 3- Click OK. Additional informations : First of all, you need to select the Welding Point Connection icon. After selecting the two planes in contact, multiselect the points which will be the weld spots on a single surface. The Spot Welding Analysis connections are made. You are now ready to create a Spot Welding Property connection.
COPYRIGHT DASSAULT SYSTEMES Analysis Connections Workbench Analysis Connections are assembly connections which cannot be created from the Generative Assembly Structural Analysis workbench : they do not imply any relative positioning of the involved two components. Face Face Analysis connections are connections used for connecting either faces that are parallel to each others or concentric cylinders, on an assembly model. Distant Analysis connections are connections used for connecting any part from an assembly with or without point type geometrical elements, on an assembly model. Welding Point Analysis connections are connections used for projecting welding points onto parallel faces, on an assembly model. The connections creation is the same for the three constraints.This is an Analysis Connection example. 1- Click on the Welding Points Analysis icon. The Welding Point Analysis appears in the tree and on the assembly 3- Click OK 2- Select both faces and welding spots
COPYRIGHT DASSAULT SYSTEMES Property and analysis connections : creation process Methodology to create connections from assembly constraints 1. Select the constraint in the tree : 2. Choose the connection type (depending on the constraint type and the kinematics) : 3. Select surfaces, then click OK : a connection is made from the constraint between the 2 parts. WARNING ! Take care not superposing two connections. Methodology to create connections from analysis constraints 1. Choose an analysis connection : 2. Select the faces of the parts by clicking on the tree or on the product, then click OK : a link is created between the 2 parts. Once all the connections are made, meshing can be launched.
COPYRIGHT DASSAULT SYSTEMES Static Analysis Once the proper connections have been defined between all the parts of the assembly, a static analysis of the assembly is performed exactly the same way as a static analysis on a single part. Modify the Element Type for a Whole Assembly Static Results Visualization Here we will go through a recap exercise performed on the foot peg assembly, before performing a static analysis in the context of the main exercise.
COPYRIGHT DASSAULT SYSTEMES Modify the Element Type for a Whole Assembly You can modify the finite element type of all the parts of an assembly in only one interaction. 1- Select Element Type 2- Select a type
COPYRIGHT DASSAULT SYSTEMES Static Results Visualization - Selective Visualization (1/2) Once you have successfully completed a Static Analysis Results Computation and created Von Mises Stress images, you have the possibility to choose the part on which you want to visualize the results. Here well use a the Von Mises Stress image. Only Von Mises Stress Flange.2 appear 2- Click on Selections in Image Edition and select one of parts 3- Right click on Connections, Restraints and Loads to hide those data in order to only visualize Flange.2 1- Double-click on StressVonMises Iso Smooth in the tree
COPYRIGHT DASSAULT SYSTEMES Static Results Visualization - Selective Visualization (2/2) The selection allows you to see constraints on the mesh. Here some example:
COPYRIGHT DASSAULT SYSTEMES Static Results Visualization - Reactions Between Parts (1/2) Once you have successfully completed a Static Analysis Results Computation, you have the possibility to visualize reactions between parts with analysis sensors. 1- Right click on Sensors.1 and select reaction Study of reaction between the parts LandingGear + Ring symbolized by Fastened Connection.1 connection and the Flange Reaction sensor appears in the tree 2- Double-click on Reaction sensor to display the values
COPYRIGHT DASSAULT SYSTEMES Static Results Visualization - Reactions Between Parts (2/2) 3- Creating an other Reaction sensor by the same operation as before Study of the reaction between the part Flange symbolized by Slider Connection.2 connection and the parts LandingGear + Ring The reaction sensor is displayed in the tree 4- Double-click on Reaction sensor to display its values You may check that the resultant between the applied forces and the reactions is null.
COPYRIGHT DASSAULT SYSTEMES Frequency Analysis Once the proper connections have been defined between all the parts of the assembly, a frequency analysis of the assembly is performed exactly the same way as a frequency analysis on a single part. Here we will go through a recap exercise performed on the foot peg assembly, before performing a frequency analysis in the context of the main exercise.
COPYRIGHT DASSAULT SYSTEMES We choose parabolic element type ONLY for footpeg_mount.CATPart. The interest is that you can increase DOF, therefore precision, locally in the assembly. We could also remesh only a surface with FMS tools. 1- The mesh is uniform with the same linear type elements. We will remesh the most important stress gradient part. 3- We must do another computation to update the analysis. For every different mix of elements properties, connections mesh will be always modify, and by the same way the compatibility between the different types of elements. Parabolic (12 DOF) Linear (6 DOF) 5. Hybrid assembly analysis
COPYRIGHT DASSAULT SYSTEMES What is the meaning of smooth virtual part (real case) Distributed force applied at the centroid of the missing parts. This assembly has three loading points and two restraints points. After computation, we see that only the SMOOTH virtual part surface is deformed (the clamp inner diameter has changed) : Moment and distributed force applied at the centroid of the clamp. These forces will be transmitted by RIGID virtual parts. This loading will be transmitted by a SMOOTH virtual part, because the clamp is supposed to get out of shape unrestrainedly. without loading with SMOOTH virtual part with RIGID virtual part Frequently-Asked Questions (1/5)
COPYRIGHT DASSAULT SYSTEMES What is the difference between sliding connection and contact connection Does the common boundary of the 2 parts stay in contact ? If No : Need a contact connection. If Yes : Do they slide along a common direction ? If Yes :Need a slider connection. If No :Need a fastened connection. Are they tightened together ? If Yes :Need a Bolt Tightening connection. Are they fitted together ? If Yes :Need a Pressure Fitting connection. Which type of elements is the better to use for an adaptivity analysis One better use parabolic elements, because linear elements need a higher mesh refinement and a slower convergence. What is the difference between analyze a part and analyze an assembly The difference is the use of connections in assemblies to link meshes parts. In FMS, we can also do edges or nodes captures. Frequently-Asked Questions (2/5)
COPYRIGHT DASSAULT SYSTEMES Is there a limit on the number of parts for an assembly The unique limit is the hardware capability. How can I analyze a part in an assembly or a sub-assembly One can deactivate parts from the assembly which one does not want to analyze before entering Generative Structural Analysis workbench. Is there an access to the reaction forces Go to the report generated after the analysis, or select Generate Image of the reaction tensor in the appropriated Static Case Solution. What is the result to post-treat with a welding spot connection analysis You have to go to Point Force Vector result, and in Filters/position select node of element. Otherwise, there will be nothing to visualize. Can I use contact connections in a modal analysis No, it is not possible to have contact connections in your model in a modal analysis context. Frequently-Asked Questions (3/5)
COPYRIGHT DASSAULT SYSTEMES What means the Singularities detected message Singularities are often division per zero solving problems which occur when your mesh is not completely compatible, or if your finite elements model is not enough constrained. What are analysis connections Analysis connections allow to put a constraint on the assembly which is not geometrical but only made for the analysis. You must use them to apply Welding Spots, or if you cannot use assembly connections (over constrained,..). This example illustrate the last case : Here is an under-pressure tank. To assembly the cover with the tank, we just need two coincidences and a contact constraints. But if we want to apply Virtual Bolt Tightening connections for analyzing, we dont have enough constraints. The Solution is to use Distant Analysis connections we can select to apply Bolt Tightening. Frequently-Asked Questions (4/5)
COPYRIGHT DASSAULT SYSTEMES What type of elements must I use with my contact connection model You may use parabolic elements which are better than linear elements in terms of accuracy, even if solving time is longer. Do I use contact or fastened connections Contact connections are often used, more than others connections, but it takes a lot of memory space. You must see if your model connection do not move or slide, and so prefer a fastened or a slider connection, less memory space consuming. Frequently-Asked Questions (5/5)