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Creating the Solid Model Chapter 5
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Training Manual October 30, 2001 Inventory #001569 5-2 The purpose of this chapter is to review some preliminary modeling considerations, discuss how to import one’s geometry into ANSYS, and finally discuss how to create one’s geometry using ANSYS native commands. Chapter 5 – Creating the Geometry Overview
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Training Manual October 30, 2001 Inventory #001569 5-3 Many modeling decisions must be made before building an analysis model: –How much detail should be included? –Does symmetry apply? –Will the model contain stress singularities? Chapter 5 – Creating the Geometry What to model?
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Training Manual October 30, 2001 Inventory #001569 5-4 Details Small details that are unimportant to the analysis should not be included in the analysis model. You can suppress such features before sending a model to ANSYS from a CAD system. For some structures, however, "small" details such as fillets or holes can be locations of maximum stress and might be quite important, depending on your analysis objectives. Chapter 5 – Creating the Geometry …What to model?
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Training Manual October 30, 2001 Inventory #001569 5-5 Symmetry Many structures are symmetric in some form and allow only a representative portion or cross-section to be modeled. The main advantages of using a symmetric model are: –It is generally easier to create the model. –It allows you to make a finer, more detailed model and thereby obtain better results than would have been possible with the full model. Chapter 5 – Creating the Geometry …What to model?
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Training Manual October 30, 2001 Inventory #001569 5-6 To take advantage of symmetry, all of the following must be symmetric: –Geometry –Material properties –Loading conditions There are different types of symmetry: –Axisymmetry –Rotational –Planar or reflective –Repetitive or translational Chapter 5 – Creating the Geometry …What to model?
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Training Manual October 30, 2001 Inventory #001569 5-7 Axisymmetry Symmetry about a central axis, such as in light bulbs, straight pipes, cones, circular plates, and domes. Plane of symmetry is the cross-section anywhere around the structure. Thus you are using a single 2-D “slice” to represent 360° — a real savings in model size! Loading is also assumed to be axisymmetric in most cases. However, if it is not, and if the analysis is linear, the loads can be separated into harmonic components for independent solutions that can be superimposed. Chapter 5 – Creating the Geometry …What to model?
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Training Manual October 30, 2001 Inventory #001569 5-8 Rotational symmetry Repeated segments arranged about a central axis, such as in turbine rotors. Only one segment of the structure needs to be modeled. Loading is also assumed to be symmetric about the axis. Chapter 5 – Creating the Geometry …What to model?
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Training Manual October 30, 2001 Inventory #001569 5-9 This model illustrates both reflective and rotational symmetry Planar or reflective symmetry One half of the structure is a mirror image of the other half. The mirror is the plane of symmetry. Loading may be symmetric or anti-symmetric about the plane of symmetry. Chapter 5 – Creating the Geometry …What to model?
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Training Manual October 30, 2001 Inventory #001569 5-10 This model illustrates both repetitive and reflective symmetry. Repetitive or translational symmetry Repeated segments arranged along a straight line, such as a long pipe with evenly spaced cooling fins. Loading is also assumed to be “repeated” along the length of the model. Chapter 5 – Creating the Geometry …What to model?
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Training Manual October 30, 2001 Inventory #001569 5-11 In some cases, only a few minor details will disrupt a structure's symmetry. You may be able to ignore such details (or treat them as being symmetric) in order to gain the benefits of using a smaller model. How much accuracy is lost as the result of such a compromise might be difficult to estimate. Chapter 5 – Creating the Geometry …What to model?
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Training Manual October 30, 2001 Inventory #001569 5-12 Stress singularities A stress singularity is a location in a finite element model where the stress value is unbounded (infinite). Examples: –A point load, such as an applied force or moment –An isolated constraint point, where the reaction force behaves like a point load –A sharp re-entrant corner (with zero fillet radius) As the mesh density is refined at a stress singularity, the stress value increases and never converges. P = P/A As A 0, Chapter 5 – Creating the Geometry …What to model?
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Training Manual October 30, 2001 Inventory #001569 5-13 Real structures do not contain stress singularities. They are a fiction created by the simplifying assumptions of the model. So how do you deal with stress singularities? –If they are located far away from the region of interest, you can simply ignore them by deactivating the affected zone while reviewing results. –If they are located in the region of interest, you will need to take corrective action, such as: adding a fillet at re-entrant corners and reruning the analysis. replacing a point force with an equivalent pressure load. “spreading out” displacement constraints over a set of nodes. Chapter 5 – Creating the Geometry …What to model?
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Training Manual October 30, 2001 Inventory #001569 5-14 The general procedure to import an IGES file has already been discussed in Chapter 4. In this section, we will explore some of the options available: –the two methods, No Defeaturing and Defeaturing –the Merge, Solid, and Small options Chapter 5 – Importing Geometry IGES Imports
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Training Manual October 30, 2001 Inventory #001569 5-15 No Defeaturing Method — Imports and stores geometry in the standard ANSYS database. [ioptn,iges,nodefeat] +Faster and more reliable than the Defeaturing method. +Allows the full set of solid model operations. –No defeaturing tools are available. +This is the DEFAULT and recommended method. Chapter 5 – Importing Geometry …IGES Imports
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Training Manual October 30, 2001 Inventory #001569 5-16 Defeaturing Method — Imports and stores geometry in a special database that allows you to repair and defeature the model. [ioptn,iges,defeat] +Ability to defeature, i.e, to remove minor details such as protrusions, cavities, and small holes. –Because of the special database used to store geometry, only a limited number of solid model operations are available. –Generally requires more memory and is somewhat slower than the “No defeaturing” method. +This method is efficient for single solid models that will be imported, loaded, meshed and solved. –In general, it is NOT recommended when advanced geometry capabilities are required. Chapter 5 – Importing Geometry …IGES Imports
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Training Manual October 30, 2001 Inventory #001569 5-17 Merge Option –YES by default, to merge coincident entities so that adjacent areas meet at a common line, and adjacent lines meet at a common keypoint. –Switch it to NO only if you are using the Defeaturing method and your initial attempt runs out of memory. –ioptn,merge,yes/no merge Chapter 5 – Importing Geometry …IGES Imports
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Training Manual October 30, 2001 Inventory #001569 5-18 Solid Option –YES default, to automatically create a volume (solid) after importing and merging. –Switch it to NO if you want to import surfaces only and create a shell or 2-D plane model. –ioptn,solid,yes/no Chapter 5 – Importing Geometry …IGES Imports
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Training Manual October 30, 2001 Inventory #001569 5-19 Small Option –YES by default, to automatically delete small, sliver-like areas that might be troublesome for meshing. –Available only for the Defeature method. –Switch it to NO if you find gaps or “holes” in the model. –ioptn,small,yes/no Chapter 5 – Importing Geometry …IGES Imports
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Training Manual October 30, 2001 Inventory #001569 5-20 IGES importing works quite well, but because of the dual translation process — CAD IGES ANSYS — there are many cases when a 100% translation is not achieved. ANSYS Connection products help overcome this problem by directly reading the “native” part files produced by the CAD package: –Connection for Pro/ENGINEER (“Pro/E” for short) –Connection for Unigraphics (“UG” for short) –Connection for SAT –Connection for Parasolid –Connection for CATIA To use a connection product, you need to purchase the appropriate license. Chapter 5 – Importing Geometry Connection Products
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Training Manual October 30, 2001 Inventory #001569 5-21 Connection for Pro/E –Reads.prt file produced by Pro/ENGINEER (from Parametric Technology Corp.). –Requires Pro/ENGINEER software. –Can also read a Pro/Engineer assembly file (.asm) –Utility Menu > File > Import > Pro/E... –Or ~proein Defeaturing option available No Defeaturing is default Command that launches your Pro/E Chapter 5 – Importing Geometry … Connection Products
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Training Manual October 30, 2001 Inventory #001569 5-22 Connection for UG –Reads.prt file produced by Unigraphics (from Electronic Data Systems Corp.). –Requires Unigraphics software. –Utility Menu > File > Import > UG... –Or ~ugin Defeaturing option available No Defeaturing is default Option to read only selected layers and geometry types Chapter 5 – Importing Geometry … Connection Products
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Training Manual October 30, 2001 Inventory #001569 5-23 Connection for SAT –Reads.sat file produced by CAD packages that use the ACIS modeler. –Does not require ACIS software. –Utility Menu > File > Import > SAT... –Or ~satin Defeaturing option available No Defeaturing is default Option to read only selected geometry types Chapter 5 – Importing Geometry … Connection Products
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Training Manual October 30, 2001 Inventory #001569 5-24 Connection for Parasolid –Reads.x_t or.xmt_txt file produced by CAD packages that use the Parasolid modeler. –Does not require Parasolid software. –Utility Menu > File > Import > PARA... –Or ~parain Defeaturing option available No Defeaturing is default Option to read only selected geometry types Option to scale geometry Chapter 5 – Importing Geometry … Connection Products
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Training Manual October 30, 2001 Inventory #001569 5-25 Chapter 5 – Importing Geometry … Connection Products Connection for CATIA –Reads.model or.dvl file produced by the CATIA –Requires CATIA software. –Utility Menu > File > Import > Catia –Or ~catiain Option to import blanked bodies
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Training Manual October 30, 2001 Inventory #001569 5-26 Refer to your Workshop Supplement for instructions on: W5A. Importing Geometry – IGES Import W5B. Importing Geometry – SAT Part Import W5C. Importing Geometry – SAT Assembly Import W5D. Importing Geometry – Parasolid Part Import W5E. Importing Geometry – Parasolid Assembly Import Chapter 5 – Importing Geometry Workshops
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Training Manual October 30, 2001 Inventory #001569 5-27 Importing geometry is convenient, but sometimes you may need to create it in ANSYS. Some possible reasons: –You may need to build a parametric model — one defined in terms of variables for later use in design optimization or sensitivity studies. –The geometry may not be available in a format ANSYS can read. –The Connection product you need may not be available on your computer platform. –You may need to modify or add geometry to an imported part or assembly. ANSYS has an extensive set of geometry creation tools, which we will discuss next. Chapter 5 – ANSYS Native Commands Overview
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Training Manual October 30, 2001 Inventory #001569 5-28 Solid Modeling can be defined as the process of creating solid models. Let’s review some earlier definitions: –A solid model is defined by volumes, areas, lines, and keypoints. –Volumes are bounded by areas, areas by lines, and lines by keypoints. –Hierarchy of entities from low to high: keypoints lines areas volumes. You cannot delete an entity if a higher-order entity is attached to it. Also, a model with just areas and below, such as a shell or 2-D plane model, is still considered a solid model in ANSYS terminology. Volumes Areas Lines & Keypoints Lines Areas Volumes Chapter 5 – ANSYS Native Commands Definitions
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Training Manual October 30, 2001 Inventory #001569 5-29 There are two approaches to creating a solid model: –Top-down –Bottom-up Top-down modeling starts with a definition of volumes (or areas), which are then combined in some fashion to create the final shape. add Chapter 5 – ANSYS Native Commands …Definitions
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Training Manual October 30, 2001 Inventory #001569 5-30 Bottom-up modeling starts with keypoints, from which you “build up” lines, areas, etc. You may choose whichever approach best suits the shape of the model, and also freely combine both methods. We will now discuss each modeling approach in detail. Chapter 5 – ANSYS Native Commands …Definitions
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Training Manual October 30, 2001 Inventory #001569 5-31 Top-down modeling starts with a definition of volumes (or areas), which are then combined in some fashion to create the final shape. –The volumes or areas that you initially define are called primitives. –Primitives are located and oriented with the help of the working plane. –The combinations used to produce the final shape are called Boolean operations. Chapter 5 – ANSYS Native Commands Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-32 Primitives are predefined geometric shapes such as circles, polygons, and spheres. 2-D primitives include rectangles, circles, triangles, and other polygons. Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-33 3-D primitives include blocks, cylinders, prisms, spheres, and cones. Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-34 When you create a 2-D primitive, ANSYS defines an area, along with its underlying lines and keypoints. When you create a 3-D primitive, ANSYS defines a volume, along with its underlying areas, lines and keypoints. Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-35 You can create primitives by specifying their dimensions or by picking locations in the graphics window. –For example, to create a solid circle: Preprocessor > -Modeling- Create > -Areas- Circle > Instructions Picker Pick the center and radius in graphics window... By picking...Or enter values here Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-36 –To create a block: Preprocessor > -Modeling- Create > -Volumes- Block > Instructions Picker Pick the desired locations in graphics window... By picking...Or enter values here Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-37 The “WP” in the prompts and in the picker stands for Working Plane — a movable, 2-D reference plane used to locate and orient primitives. –By default, the WP origin coincides with the global origin, but you can move it and/or rotate it to any desired position. –By displaying a grid, you can use the WP as a “drawing tablet.” –WP is infinite despite the grid settings. WX WY X2 X1 Y2 Y1 WX WY WP (X,Y) width height Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-38 All working plane controls are in Utility Menu > WorkPlane. The WP Settings menu controls the following: –WP display - triad only (default), grid only, or both. –Snap - allows you to pick locations on the WP easily by “snapping” the cursor to the nearest grid point. –Grid spacing - the distance between grid lines. –Grid size - how much of the (infinite) working plane is displayed. Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-39 You can move the working plane to any desired position using the Offset and Align menus. –Offset WP by Increments… Use the push buttons (with increment set by slider). Or type in the desired increments. Or use dynamic mode (similar to pan-zoom-rotate). Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-40 –Offset WP to > This simply “translates” the WP, maintaining its current orientation, to the desired destination, which can be: Existing keypoint(s). Picking multiple keypoints moves WP to their average location. Existing node(s). Coordinate location(s). Global origin. Origin of the active coordinate system (discussed later). Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-41 –Align WP with > This reorients the WP. For example, Align WP with Keypoints prompts you to pick 3 keypoints - one at the origin, one to define the X-axis, and one to define the X-Y plane. To return the WP to its default position (at global origin, on global X-Y plane), click on Align WP with > Global Cartesian. Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-42 Demo: –Clear the database –Display WP and create a few keypoints by picking. Note the coordinates displayed in the picker. –Turn on the grid, change spacing, and activate snap. –Create more keypoints. Note how the cursor snaps to grid points. –Define 2 rectangles — one by picking corners and one by dimensions. –Now offset WP to average of a few keypoints, then rotate in-plane by 30º. –Define 2 more rectangles by picking and by dimensions. Note the change in rectangle orientation. –Align WP with global origin, then define some 3-D primitives. Use picking as well as “By dimensions.” Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-43 Boolean operations are computations involving combinations of geometric entities. ANSYS Boolean operations include add, subtract, intersect, divide, glue, and overlap. The “input” to Boolean operations can be any geometric entity, ranging from simple primitives to complicated volumes imported from a CAD system. add Input entities Boolean operation Output entity(ies) Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-44 All Boolean operations are available in the GUI under Preprocessor > -Modeling- Operate. By default, input entities of a Boolean operation are deleted after the operation. Deleted entity numbers become “free” (i.e., they will be assigned to a new entity created, starting with the lowest available number). Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-45 Add –Combines two or more entities into one. Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-46 Glue –Attaches two or more entities by creating a common boundary between them. –Useful when you want to maintain the distinction between entities (such as for different materials). Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-47 Overlap –Same as glue, except that the input entities overlap each other. Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-48 Subtract –Removes the overlapping portion of one or more entities from a set of “base” entities. –Useful for creating holes or trimming off portions of an entity. Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-49 Divide –Cuts an entity into two or more pieces that are still connected to each other by common boundaries. –The “cutting tool” may be the working plane, an area, a line, or even a volume. –Useful for “slicing and dicing” a complicated volume into simpler volumes for brick meshing. Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-50 Intersect –Keeps only the overlapping portion of two or more entities. –If there are more than two input entities, you have two choices: common intersection and pairwise intersection Common intersection finds the common overlapping region among all input entities. Pairwise intersection finds the overlapping region for each pair of entities and may produce more than one output entity. Common Intersection Pairwise Intersection Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-51 Partition –Cuts two or more intersecting entities into multiple pieces that are still connected to each other by common boundaries. –Useful, for example, to find the intersection point of two lines and still retain all four line segments, as shown below. (An intersection operation would return the common keypoint and delete both lines.) L1 L2 L3 L6 L5 L4 Partition Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-52 Demo: –“Drill” a hole by subtracting a circle from a rectangle (or a cylinder from a block) –Create two overlapping entities, save db, and do the overlap operation. Now resume db and add the entities. Note the difference between the two operations. (Glue is similar to overlap.) –Interesting model: block,-2,2, 0,2, -2,2 sphere,2.5,2.7 vinv,all ! intersection Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-53 Refer to your Workshop Supplement for instructions on: W5F. Pillow Block Chapter 5 – ANSYS Native Commands …Top-Down Modeling
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Training Manual October 30, 2001 Inventory #001569 5-54 Bottom-up modeling begins with a definition of keypoints, from which other entities are “built up.” To build an L-shaped object, for example, you could start by defining the corner keypoints as shown below. You can then create the area by simply “connecting the dots” or by first defining lines and then defining the area by lines. Chapter 5 – ANSYS Native Commands Bottom-Up Modeling
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Training Manual October 30, 2001 Inventory #001569 5-55 To define keypoints: –Preprocessor > -Modeling- Create > Keypoints –Or use the K family of commands: K, KFILL, KNODE, etc. The only data needed to create a keypoint is the keypoint number and the coordinate location. –Keypoint number defaults to the next available number. –The coordinate location may be provided by simply picking locations on the working plane or by entering the X,Y,Z values. How are the X,Y,Z values interpreted? It depends on the active coordinate system. Chapter 5 – ANSYS Native Commands …Bottom-Up Modeling
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Training Manual October 30, 2001 Inventory #001569 5-56 Active Coordinate System Defaults to global Cartesian. Use CSYS command (or Utility Menu > WorkPlane > Change Active CS to) to change it to –global Cartesian [csys,0] –global cylindrical [csys,1] –global spherical [csys,2] –working plane [csys,4] –or a user-defined local coordinate system [csys, n] Each of these systems is explained next. Chapter 5 – ANSYS Native Commands …Bottom-Up Modeling
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Training Manual October 30, 2001 Inventory #001569 5-57 Global Coordinate System The global reference system for the model. May be Cartesian (system 0), cylindrical (1), or spherical (2). –For example, location (0,10,0) in global Cartesian is the same as (10,90,0) in global Cylindrical. Chapter 5 – ANSYS Native Commands …Bottom-Up Modeling
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Training Manual October 30, 2001 Inventory #001569 5-58 Local Coordinate System A user-defined system at a desired location, with ID number 11 or greater. The location may be: –At WP origin [CSWP] –At specified coordinates [LOCAL] –At existing keypoints [CSKP] or nodes [CS] May be Cartesian, cylindrical, or spherical. May be rotated about X, Y, Z axes. X Y X 11 Y 11 X 12 Y 12 Chapter 5 – ANSYS Native Commands …Bottom-Up Modeling
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Training Manual October 30, 2001 Inventory #001569 5-59 Working Plane Coordinate System Attached to the working plane. Used mainly to locate and orient solid model primitives. You can also use the working plane to define keypoints by picking. Chapter 5 – ANSYS Native Commands …Bottom-Up Modeling
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Training Manual October 30, 2001 Inventory #001569 5-60 You can define any number of coordinate systems, but only one may be active at any given time. Several geometry items are affected by the coordinate system [CSYS] that is active at the time they are defined: –Keypoint and node locations –Line curvature –Area curvature –Generation and “filling” of keypoints and nodes –Etc. The graphics window title shows the active system. Chapter 5 – ANSYS Native Commands …Bottom-Up Modeling
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Training Manual October 30, 2001 Inventory #001569 5-61 There are many ways to create lines, as shown here. If you define areas or volumes, ANSYS will automatically generate any undefined lines, with the curvature determined by the active CS. Keypoints must be available in order to create lines. Create > -Lines- Arcs Create > -Lines- Lines Create > -Lines- Splines Operate > Extrude / Sweep Chapter 5 – ANSYS Native Commands …Bottom-Up Modeling
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Training Manual October 30, 2001 Inventory #001569 5-62 Creating areas using bottom-up method requires keypoints or lines to be already defined. If you define volumes, ANSYS will automatically generate any undefined areas and lines, with the curvature determined by the active CS. Create > -Areas- Arbitrary Operate > Extrude Chapter 5 – ANSYS Native Commands …Bottom-Up Modeling
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Training Manual October 30, 2001 Inventory #001569 5-63 Creating volumes using bottom-up method requires keypoints or areas to be already defined. Create > -Volumes- Arbitrary Operate > Extrude Chapter 5 – ANSYS Native Commands …Bottom-Up Modeling
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Training Manual October 30, 2001 Inventory #001569 5-64 Demo: –Clear the database –Create 5 keypoints at (1,2), (3,2), (4,0), (1,1.5), (2.5,0) –Switch to CSYS,1 and create a line “in active CS” between KP4 & KP5 –Switch back to CSYS,0 and create an area “through KP’s.” Notice that the remaining lines were automatically generated lines, all of them straight. –Define two circles: 0.3R, centered at (2.25,1.5) 0.35R, centered at (3.0,0.6) –Subtract the two circles from base area. (We have used a combination of bottom-up and top-down modeling.) –Save as r.db Chapter 5 – ANSYS Native Commands …Bottom-Up Modeling
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Training Manual October 30, 2001 Inventory #001569 5-65 Boolean operations are available for entities created by both top- down and bottom-up modeling approaches. Besides Booleans, many other operations are available: –Extrude –Scale –Move –Copy –Reflect –Merge –Fillet Chapter 5 – ANSYS Native Commands …Bottom-Up Modeling
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Training Manual October 30, 2001 Inventory #001569 5-66 Extrude To quickly create volumes from existing areas (or areas from lines, and lines from keypoints). If the area is meshed, you can extrude the elements along with the areas. Four ways to extrude areas: –Along normal — creates volume by normal offset of areas [VOFFST]. –By XYZ offset — creates volume by a general x-y-z offset [VEXT]. Allows tapered extrusion. –About axis — creates volume by revolving areas about an axis (specified by two keypoints) [VROTAT]. –Along lines — creates volume by “dragging” areas along a line or a set of contiguous lines [VDRAG]. Chapter 5 – ANSYS Native Commands …Bottom-Up Modeling
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Training Manual October 30, 2001 Inventory #001569 5-67 Scaling is typically needed when you want to convert the geometry to a different set of units, say from inches to millimeters. To scale a model in ANSYS: –First save the database -- Toolbar > SAVE_DB or SAVE command. –Then Main Menu > Preprocessor > Operate > Scale > Volumes (choose the highest-level entity available in the model) [Pick All] to pick all volumes Then enter desired scale factors for RX, RY, RZ and set IMOVE to “Moved” instead of “Copied” –Or use the VLSCALE command: vlscale,all,,,25.4,25.4,25.4,,,1 Chapter 5 – ANSYS Native Commands …Bottom-Up Modeling
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Training Manual October 30, 2001 Inventory #001569 5-68 Move To translate or rotate an entity by specifying DX,DY,DZ offsets. –DX,DY,DZ are interpreted in the active CS. –To translate an entity, make the active CS Cartesian. –To rotate an entity, make the active CS cylindrical or spherical. –Or use the commands VGEN, AGEN, LGEN, KGEN Another option is to transfer coordinates to a different system. –Transfer occurs from the active CS to a specified CS. –This operation is useful when you need to move and rotate an entity at the same time. –Or use the commands VTRAN, ATRAN, LTRAN, KTRAN Transfer from csys,0 to csys,11 Rotate -30° Chapter 5 – ANSYS Native Commands …Bottom-Up Modeling
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Training Manual October 30, 2001 Inventory #001569 5-69 Copy To generate multiple copies of an entity. Specify the number of copies (2 or greater) and the DX,DY,DZ offset for each copy. DX,DY,DZ are interpreted in the active CS. Useful to create multiple holes, ribs, protrusions, etc. Copy in local cylindrical CS Create outer areas by skinning Chapter 5 – ANSYS Native Commands …Bottom-Up Modeling
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Training Manual October 30, 2001 Inventory #001569 5-70 Reflect To reflect entities about a plane. Specify the direction of reflection: –X for reflection about the YZ plane –Y for XZ plane –Z for XY plane All directions are interpreted in the active CS, which must be a Cartesian system. What is the direction of reflection in this case? Chapter 5 – ANSYS Native Commands …Bottom-Up Modeling
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Training Manual October 30, 2001 Inventory #001569 5-71 Merge To attach two entities together by removing coincident keypoints. –Merging keypoints will automatically merge coincident higher-order entities, if any. Usually required after a reflect, copy, or other operation that causes coincident entities. Merge or glue required Reflect Chapter 5 – ANSYS Native Commands …Bottom-Up Modeling
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Training Manual October 30, 2001 Inventory #001569 5-72 Subtract from base area Fillet Line fillet requires two intersecting lines with a common keypoint at the intersection. –If the common keypoint does not exist, do a partition operation first. –ANSYS does not update the underlying area (if any), so you need to either add or subtract the fillet region. Area filleting is similar. Create fillet Create area Chapter 5 – ANSYS Native Commands …Bottom-Up Modeling
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Training Manual October 30, 2001 Inventory #001569 5-73 Demo: –Resume r.db (if necessary) –Create two keypoints for the axis, at (0,0) and (0,1), then extrude the area by revolving about the axis 60º –Resume r.db –Make copies of the rib radially about the Y-axis: Create a local cylindrical CS at global origin, with THYZ = -90 Generate 7 total copies (6 new ones) with DY=15 –Create the three outer “skin” areas using ASKIN,P –Resume r.db –Create a 0.5R fillet between the top and right lines. (Notice that the lines attached to the area have been modified. This is allowed in some cases.) –Create the triangular fillet area by lines (AL,P), then subtract it from the main area. Chapter 5 – ANSYS Native Commands …Bottom-Up Modeling
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Training Manual October 30, 2001 Inventory #001569 5-74 Refer to your Workshop Supplement for instructions on: W5G. Connecting Rod – Bottom-Up Approach W5H. Connecting Rod – Importation/Clean-up Chapter 5 – ANSYS Native Commands …Bottom-Up Modeling
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