Parametric Modeling Introduction PDF

Unit – I IN TR O D U CTIO N 1.1 Parametric Modelling Parametric is a term used to describe a dimension’s ability to change the shape of model geometry as soon as the dimension value is modified. It eliminates the need for a design engi...

Unit – I IN TR O D U CTIO N 1.1 Parametric Modelling Parametric is a term used to describe a dimension’s ability to change the shape of model geometry as soon as the dimension value is modified. It eliminates the need for a design engineer to constantly redraw a design every time one of the design’s dimensions change. Feature-based is a term used to describe the various components of a model. For example, a part can consists of various types of features such as holes, grooves, fillets, and chamfers. A ‘feature’ is the basic unit of a parametric solid model. Parametric modelling uses the computer to design objects with real world behaviour. Parametric models use feature-based, solid and surface modelling design tools to manipulate the system attributes. One of the most important features of parametric modelling is that attributes that are interlinked automatically change their features. For example, to modify a 3D solid, the designer had to change the length, the breadth and the height. However, with parametric modelling, the designer need only alter one parameter; the other two parameters get adjusted automatically. There are two popular parametric representation models : 1) Constructive Solid Geometry (CSG) : CSG defines a model in terms of combining basic (primitive) and generated (using extrusion and sweeping operation) solid shapes. It uses Boolean operations to construct a model. CSG is a combination of 3D solid primitives (for example a cylinder, cone, prism, rectangle or sphere) that are then manipulated using simple Boolean operations. 2) Boundary Representation (BR) : In BR, a solid model is formed by defining the surfaces that form its spatial boundaries (points, edges, etc.) The object is then made by joining these spatial points. Many Finite Element Method (FEM) programs use this method, as it allows the interior meshing of the volume to be more easily controlled. Advantages of parametric modelling The following are the benefits of 3D parametric modelling over traditional 2D drawings: è Capability to produce flexible designs è 3D solid models offer a vast range of ways to view the model è Better product visualization, as you can begin with simple objects with minimal details è Better integration with downstream applications and reduced engineering cycle time è Existing design data can be reused to create new designs è Quick design improvement, increasing efficiency 1 1.2 Parametric modelling softwares There are many software choices available in the market today for parametric modelling. A few of the leading industry softwares are : 1) SOLIDWORKS SOLIDWORKS is a parametric modelling software owned by Dassault Systemes. It is more popular with engineers as it can easily create electrical, mechanical and automotive components. Key functions and use : è It comes with numerous tools for planning, fabrication, simulations and validation. è In addition to parametric modelling, it also combines CADD (Computer-aided design and drafting), CAM (Computer-aided manufacturing) and CAE (Computer-aided engineering) systems. è The model can be used to estimate cost and manufacturability checks. è With SOLIDWORKS, any advanced designs, from product to mechanical to parametric architecture, can be efficiently planned and created. 2) CATIA CATIA (Computer Aided Three-Dimensional Interactive Application) is also owned by Dassault Systèmes. It is widely used for product design, as parametric modelling software and also PLM (Product Lifecycle Management) software. Its is effectively used in the automotive and aeronautics industries. Key functions and use : è CATIA combines shape sculpting modelling (control-points manipulation) with parametric associativity. This enables designers to explore more design ideas and make relevant changes efficiently. è CATIA can also create and animate virtual human models for better simulation and validation of the product according to user requirements and experience. This is an advantage, especially in the automotive industry where human avatars are needed for ergonomics and safety checks. è This software allows users to venture into virtual reality. è The Collaborate Designer feature also enables creating and visualising linear infrastructures, electrical, piping and mechanical components. 3) Siemens NX (Unigraphics) NX is an advanced high-end CAD/CAM/CAE software owned by Siemens Digital Industries Software. Siemens NX software is a flexible and powerful integrated solution that helps you deliver better products faster and more efficiently. NX delivers the next generation of design, simulation, and manufacturing solutions that enable companies to realize the value of the digital twin. 2 Key functions and use : è Supports every aspect of product development, from concept design through engineering and manufacturing. è NX gives an integrated toolset that coordinates disciplines, preserves data integrity and design intent, and streamlines the entire process. è It is used for design (parametric and direct solid/surface modelling), engineering analysis (static, dynamic, electro-magnetic, thermal, and fluid dynamics), manufacturing finished design by using included machining modules. 4) Creo Parametric (Pro-Engineer) This is a 3D CAD parametric modelling software owned by PTC Inc. (Parametric Technology Corporation). It provides digital solutions to engineering, manufacturing and industrial services. Key functions and use : è The 3D design in Creo is aided by parametric and freestyle surfacing features as well as CAM and Generative design. These features allow curves and surface manipulation by transforming, scaling, stretching, tapering the geometry etc. è The 3D parts and their assembly are created with precise geometry, regardless of the complexity, for efficiency, time and cost-effectiveness. These models can then be accessed for both static and dynamic interference detection. è As Creo Parametric is heavily focused on mechanical and product design, its design capabilities also aid in such design projects. Sheet metal design, piping and cabling designs are all feasible with Creo with its modelling and analysis capabilities. 5) Fusion 360 Fusion 360 is an Autodesk cloud-based 3D modelling software that integrates CAD, CAM and PCB (Printed circuit board) features for product design and manufacturing. Key functions and use : è As a 3D modelling software, it comprehensively includes both parametric and non-parametric, or direct, mesh and surface modelling tools. Therefore the user can choose what to work on based on the need and the skill of the user. è As it is also cloud-based, Fusion 360 allows a design team to centralise all activities and communicate effectively in real-time. è The software also includes electronics and PCB design tools for powerful product modelling. 6) Autodesk Inventor Inventor is used as a parametric modelling and CAD software mainly for mechanical designs. It has an intuitive user interface and is capable of direct, free-form and rules-based design, in addition to parametric modelling. 3 Key functions and use : è Inventor tests the combination of the design by accessing the fit and function and identifying interference patterns before rendering, documentation and planning for manufacturing processes can begin. è Components can be easily placed and assembled with a list of commands available. è It also supports inserting third party design components and models directly into the assembly. 1.3 Starting SOLIDWORKS application The SOLIDWORKS software can be started by è Clicking in Windows Start Menu è Double clicking icon on the Desktop The SOLIDWORKS Welcome dialog box is displayed by default. To open the Welcome dialog box, you can click Welcome SOLIDWORKS from the Standard toolbar. è Home Tab : You can open new and existing documents, view recent documents and folders, and access SOLIDWORKS resources. è Recent Tab : You can view a list of recent documents and folders. è Learn Tab : It gives access for instructional resources to help you learn more about the SOLIDWORKS software. è Alerts Tab : It provides important SOLIDWORKS news. 4 Select an option from Home Tab to open a new or existing document: Option Description Part Opens a new document to create a Part Assembly Opens a new document to create an Assembly Drawing Opens a new document to create engineering drawing. Opens the New SOLIDWORKS Document dialog box, where you can open a Advanced new document based on an alternate template. Open Specifies an existing document to open. After selecting an option, the SOLIDWORKS Graphics window is displayed. 1.4 Solidworks User Interface The figure shows the main elements in SOLIDWORKS user interface. It includes the following : 1) Menu Bar The menu bar contains the SOLIDWORKS menus, a set of Quick Access tools, the SOLIDWORKS Search, and the Help options. 2) Toolbars Toolbars are available for most SOLIDWORKS tools. Named toolbars assist you in performing specific design tasks. To display SOLIDWORKS toolbars: Click Tools > Customize. On the Toolbars tab, select the toolbars to display. 3) Context Toolbars When you select items in the graphics area or Feature Manager design tree, context toolbars appear and provide access to frequently performed actions for that context. 4) Flyout Tool Buttons Similar commands are grouped into flyout buttons on toolbars and the Command Manager. For example, variations of the rectangle are grouped together in a button with a flyout control. 5 6 SOLIDWORKS User Interface 5) Command Manager The Command Manager is a context-sensitive toolbar that dynamically updates based on the toolbar you want to access. By default, it has toolbars embedded in it based on the document type. When you click a tab below the Command Manager, it updates to show that toolbar. For example, if you click the Sketches tab, the Sketch toolbar appears. 6) Manager Pane The left panel of the SOLIDWORKS window manages part and assembly designs, drawing sheets, properties, configurations, and third-party applications. The Command Manager provides access to the SOLIDWORKS tools. 7) Feature Manager Design Tree è Names of features display from top to bottom in the order created in the Feature Manager design tree, unless you reorder them. Features can be considered as components of parts. è The Feature Manager design tree in assemblies displays components (parts or subassemblies and their features), a Mates folder, and assembly features. è The Feature Manager design tree in drawings contains an icon for each sheet. Under each sheet are icons for the sheet format and each view. Under each view are the parts and assemblies that belong to the view. 8) Feature Manager Design Tree Filter It helps to search for specific features of parts and components of assemblies. 9) Property Manager Most sketch, feature, and drawing tools in SOLIDWORKS open a Property Manager in the left panel. The Property Manager displays the properties of the entity or feature so you specify the properties without a dialog box covering the graphics area. 7 10) Configuration Manager The Configuration Manager is a means to create, select, and view multiple configurations of parts and assemblies. 11) DimXpert Manager The DimXpert Manager lists the tolerance features defined by DimXpert for parts. It also displays DimXpert tools that you use to insert dimensions and tolerances into parts. You can import these dimensions and tolerances into drawings. 12) Search You can use SOLIDWORKS Search to find information in documentation and forums. You can also find files and models, and find and run a SOLIDWORKS command with just a few keystrokes. 13) Graphics Area The graphics area displays and lets you manipulate parts, assemblies, and drawings. 14) Reference Triad A triad appears in part and assembly documents to help orient you when viewing models. You can also use it to change the view orientation. You can hide the triad but you cannot use it as an inference point. 15) Triad The triad facilitates manipulating various objects such as 3D sketch entities, parts, certain features, and components in assemblies. 16) Origin The model origin represents the (0,0,0) coordinate of the model. When a sketch is active, a sketch origin represents the (0,0,0) coordinate of the sketch. 8 17) Heads-up View Toolbar It is a transparent toolbar in each viewport provides all the common tools required for manipulating the view. It includes the following : Icon Description Icon Description View Orientation Hide/Show Items Previous View View Planes Redraw View Live Section Planes Zoom to Fit View Axes Zoom to Sheet View Temporary Axes Zoom to Area View Origins Zoom In/Out View Coordinate Systems Zoom to Selection View Datum Reference Frame View Orientation View Curves Rotate View View Sketches Roll View View Grid Turn Camera View 3D Sketch Plane 3D Drawing View View Sketch Dimensions Pan View All Annotations Display Style View Dimension Names Wireframe View Points Hidden Lines Visible View Routing Points Hidden Lines Removed View Parting Lines Shaded with Edges View Lights Shaded View Cameras Draft Quality HLR/HLV View Decals Perspective View Sketch Relations Shadows in Shaded Mode Change Display States Section View View Simulation Symbols 9  Icon Description Icon Description Camera View View Weld Beads Curvature Add Walk-through Zebra Stripes Ambient Occlusion Body Compare Take Snapshot Surface Curvature Combs Filter Modified Components Draft Analysis View Center of Mass Undercut Analysis View Top Level Annotations Parting Line Analysis View Component Annotations RealView Graphics Hide/Show Primary Planes Apply Scene Cartoon Edit Appearance Simulation Display Copy Appearance View Bounding Box Paste Appearance View Component Envelopes Edit Sketch or Curve Color View Top Level Envelopes The View Orientation flyout tool bar can be accessed by pressing SPACEBAR. It consists of the following : Icon Description Icon Description Front Normal To Back Single View Left Two View - Horizontal Right Two View - Vertical Top Four View Bottom Link Views Isometric View Selector Trimetric New View Dimetric 10 18) Task Pane The Task Pane provides access to SOLIDWORKS resources, libraries of reusable design elements, views to drag onto drawing sheets, and other useful items and information. Right-click when the pointer changes to to accept the preview, or click to return to the preview without accepting the values. 19) Confirmation Corner Confirmation Corner is used to accept features. You can Click the OK or Cancel icons that appear in the Confirmation Corner of the SOLIDWORKS graphics area. Click the Exit Sketch icon in the Confirmation Corner to finish the sketch or click the Cancel Sketch icon to discard changes to the sketch. 20) Status Bar The status bar at the bottom of the SOLIDWORKS window provides information related to the function that you are performing. To display or hide the status bar : Click View > User Interface > Status Bar. Information provided in the status bar : è A brief description as you move the pointer over a tool or click a menu item. è A rebuild icon , if you change a sketch or part that requires the rebuild of the part. è Sketch status and pointer coordinates, when you are working in a sketch. è Common measurements for selected entities, such as the length of an edge. è A message to indicate that you are editing a part while in an assembly. è An icon for accessing the Reload dialog box when you use collaboration options. è Unit System , which shows the unit system for the active document in the status bar and lets you change or customize the unit system. è An icon to display or hide the Tags box, used to add keywords to features and parts to aid in searching. 1.5 SOLIDWORKS Options To open the SOLIDWORKS Options dialog box: è Click Options (Standard toolbar) or Tools > Options. 11 The following tabs are available: System The system options are stored in the registry and are not part of the documents. Options Therefore, these changes affect all documents, current and future. Document The document properties apply only to the current document, and the Document Properties Properties tab is available only when a document is open. New documents get their document settings (such as Units, Image Quality, and so on) from the document properties of the template used to create the document. Use the Document Properties tab when you set up document templates. The options listed on each tab are displayed in tree format on the left side of the dialog box. As you click an item in the tree, the options for the item appear on the right side of the dialog box. The title bar displays the title of the tab and the title of the options page. 1.5.1 System options The system options include the following : è System Options - General è File Locations Options è MBD (Model Based Definitions )Options è FeatureManager Options è Drawings Options è Spin Box Increments Options è System Colors Options è View Options è Sketch Options è Backup/Recover Options è Display Options è Touch Options è Selection Options è Hole Wizard/Toolbox Options è Performance Options è File Explorer Options è Settings with OpenGL è Search Options è Assemblies Options è Collaboration Options è External References Options è Messages/Errors/Warnings è Default Templates Options è Synchronize Settings 1.5.2 Document Properties The document properties that are available on the left side of the Document Properties tab depend on the type of document that is open. Some document properties are relevant to all document types (parts, assemblies, and drawings). It includes the properties for the following: Option Description Drafting Standard Set the overall detailing drafting standard, and rename, copy, delete, export, or load saved custom drafting standards Annotations pages Fonts, attachments, leading and trailing zeros, and so on 12  Option Description Dimensions pages Text alignment, fonts, leaders, arrow styles and so on Centerlines / Fonts, slot options, and so on Center Marks DimXpert Dimensioning schemes and options for chamfers, slots, and fillets for use with the DimXpert tool Tables pages Various controls for tables View Labels pages Label content and format for detail, section, and auxiliary view labels Virtual Sharps Virtual sharp display styles Detailing Display filter, text scale, and so on Grid/Snap Grid display, spacing, and so on Units Specify how units are displayed Line Font Style and weight of lines for various kinds of edges in drawing documents Line Style Create, save, load, or delete line styles Line Thickness Set line weights that work best with your printer or plotter Image Quality HLR/HLV resolution Document Properties - Units Unit system : Sets the document-level units and precision to a standard system or lets you modify units. Standard systems are : è M K S (meter, kilogram, second) è CGS (centimeter, gram, second) è MMGS (millimeter, gram, second) è IPS (inch, pound, second) Click Custom to modify units in the table. è You can change the unit system without opening Document Properties - Units. In the status bar, click Unit System, then click a unit system. Basic Units: Displays document-level dimension units. Units Decimals Determined by your Unit Based on selection, displays from two to eight decimal places. system selection. None displays no decimal places. 13 1.6 Selection of entities You can use the Select tool (Quick Access toolbar) to Exit a command and return to select mode, which is useful when in sketches and with the viewing tools. The Select flyout menu consists of the following: Option Description Select Selects entities that you click in the graphics area or the FeatureManager design tree. Magnified Displays the magnifying glass so that you can inspect a model and make Selection selections without changing the overall view. Box Selection Selects all entities around which you drag a selection box using the pointer. When you select from left to right, all items within the box are selected. When you select from right to left, items that are crossed by the box boundaries are also selected. Lasso Selection Selects all entities around which you draw a free hand loop. You can lasso select items without closing the lasso loop. For clockwise lasso selection, the lasso selects only items contained in the lasso loop. For counter clockwise lasso selection, the lasso selects sketch entities in the lasso loop and items that cross the lasso. Select over Lets you select by dragging a box or lasso over a model without starting the Geometry drag from an empty space in the graphics area. Select All Selects all shown components and highlights them in the FeatureManager design tree. 14  Unit – II SKETCHING 2.1 Introduction When you open a new part document, first you create a sketch. The sketch is the basis for a 3D model. You can create a sketch on any of the default planes (Front Plane, Top Plane, and Right Plane), a created plane or face of a part. General procedure : 1) Click Sketch on the Sketch toolbar, or click Insert > Sketch. 2) Click a sketch entity tool (line, rectangle, and so on) on the Sketch toolbar. 3) Select one of the three planes (Front, Top, and Right) displayed or face of a part. Default Sketch Planes 4) Create a sketch with the sketch entity tool. 5) Dimension the sketch entities. 6) Click Exit Sketch on the Sketch toolbar. Also Click Exit Sketch or Cancel in the Confirmation Corner. 2.2 Sketch Modes è There are two modes for sketching in 2D: click-drag or click-click. è If you click the first point and drag, you are in click-drag mode. è If you click the first point and release the pointer, you are in click-click mode. è Double-click or press Esc to terminate the chain of entities. 15