Finite Element Modeling

Transcription

1 What s New in FEMAP FEMAP 10.0 and include enhancements and new features in: User Interface on page 3 Meshing on page 23 Mesh Associativity on page 33 Properties on page 33 Functions on page 35 Loads and Constraints on page 35 Connections (Connection Properties, Regions, and Connectors) on page 35 Geometry on page 36 Groups and Layers on page 42 Views on page 42 Output and Post-Processing on page 43 Geometry Interfaces on page 47 Analysis Program Interfaces on page 48 Tools on page 50 OLE/COM API on page 51 Preferences on page 53 FEMAP includes enhancements and new features in: User Interface on page 57 Meshing on page 58 Layups on page 60 Geometry on page 62 Groups and Layers on page 62 Geometry Interfaces on page 62 Analysis Program Interfaces on page 62 Tools on page 63 OLE/COM API on page 63 Preferences on page 64

2 Finite Element Modeling

3 What s New for versions 10.0 and What s New for versions 10.0 and User Interface "Windows Vista", "General", "Menu", "Entity Select", "Toolbars", "Meshing Toolbox", "Model Info tree", "Data Table", "Entity Editor", "API Programming", "Status Bar", "Graphics", "Astroid" Windows Vista General FEMAP is now supported on 32-bit and 64-bit versions of Windows Vista. Many issues from previous unsupported versions of FEMAP with regards to Windows Vista, such as entity picking and proper use of the Model Info tree have been addressed. Renamed Weld Property Element/Property Type to Weld/Fastener to include Fastener Elements Added support to create GIF, Animated GIF, TIFF, and PNG files when using File, Picture, Save command. Improved length-based spacing, distance along, and other length-based curve functions to perform better when highly nonlinear parametric domains exist on curves. Menu Added Tools, Meshing Toolbox command to the Tools menu. See the Meshing section for more information on this dockable pane. Added Geometry, Curve - From Surface, Split at Locations; Geometry, Curve - From Surface, Offset Curve/ Washer; Geometry, Curve - From Surface, Pad; Geometry, Curve - From Surface, Point to Point; Geometry, Curve - From Surface, Point to Edge; and Geometry, Curve - From Surface, Edge to Edge commands to Geometry menu. See the Geometry section for more information on these commands. Deleted Geometry, Curve - From Surface, Split at Points. See the Geometry section for more information on these commands. Replaced by Geometry, Curve - From Surface, Split at Locations. Added Geometry, Surface, NonManifold Add and Geometry, Surface, Recover Manifold Geometry commands to the Geometry menu. See the Geometry section for more information on these commands. Added Geometry, Midsurface, Offset Tangent Surfaces command to the Geometry menu. See the Geometry section for more information on this command. Added Modify, Associativity, Automatic command to the Modify menu. See the Mesh Associativity section for more information on this command. Added Modify, Update Other, Solid Facetting command to the Modify menu. Entity Select Added Combined Curves options (Default, All Points/Curves, Points/Curves Eliminated by Combined Curves, and Combined Curves Only) to the Pick Menu in the standard Entity Selection dialog box. Only one mode can be selected at any given time. Added Boundary Surfaces options (Default, All Curves/Surfaces, Curves/Surfaces Eliminated by Boundary, and Boundary Surfaces Only) to the Pick Menu in the standard Entity Selection dialog box. Only one mode can be selected at any given time.

4 Finite Element Modeling Toolbars Added Add Connected Fillets option to the Pick Menu in the standard Entity Selection dialog box. Allows you to quickly add connected fillets to the selection list by first choosing any number of surfaces which represent fillets in your geometry. This is a helpful picking tool when using Geometry, Solid, Remove Face or the Feature Removal Tool set to Surfaces in the Meshing Toolbox to try and remove fillets from geometry. Only visible when selecting surfaces. Added Add Tangent Surfaces option to the Pick Menu in the standard Entity Selection dialog box. Allows you to add surfaces based on their relationship to surfaces which have already been selected. In this case, surfaces tangent to any number of surfaces already in your selection list will be added to the list. This is a helpful command when you would like to pick all of the surfaces on one side of a part. Only visible when selecting surfaces. Updated direction of mouse wheel for Query Pick list to follow direction of mouse wheel. Added Meshing Toolbox icon to Panes Toolbar. Added Curve Washer, Curve Pad, Split Between Points, Split Point to Edge, and Split Edge to Edge icons to Curves on Surface Toolbar. Improved Select Related mode of the Select Toolbar to include coordinate systems used as definition coordinate systems for other selected Coordinate Systems and include reference nodes on beams when the nodes are related to elements, properties, or materials. Meshing Toolbox The Meshing Toolbox is completely new for FEMAP 10 and contains several individual tools which can be very helpful during the meshing process. There are tools which allow you to simplify geometry; create combined geometric entities for meshing purposes using several underlying geometric entities; change the mesh size, biasing, and other options on any number of curves interactively; move any number of nodes dynamically while seeing the mesh update; and plot the element quality in the graphics window. The Meshing Toolbox also contains the Entity Locator, which can be used to locate Curves or Surfaces in your model which meet certain search criteria (for example, short curves or sliver surfaces which may cause problems during meshing). Once the Locator identifies entities, you can then cycle through all of the located entities in the model one at a time and take action using the Geometry Tools in the Meshing Toolbox, when appropriate. Meshing Toolbox Icons Mesh Quality Toggle Select Entity Entity Locator Remesh Modes Dialog Select Toggle Tools Toggle Tools menu - By default, all 7 of the tools will be visible in the Meshing Toolbox. Using the drop-down menu from this icon, you can make all of the tools visible or hidden at once using Toggle All Tools, individually toggle them on and off by choosing the individual tool name (for example, Feature Suppression) from the menu, or decide to show only one set of tools at a time by selecting the appropriate tool set name (for example, Geometry Tools). When a tool is visible, there will be a check mark next to it in the list. Here is a short description of each set of tools: Geometry Tools Feature Suppression - Basically, this tool allows you to use the same options available in the Mesh, Mesh Control, Feature Suppression command interactively. You may suppress loops (curves of internal holes on surfaces and solids, base curves of bosses and extrusions on solids), curves (usually relatively small in size), and surfaces (usually sliver surfaces, not fillets or chamfers). Suppressed geometry still exists in the model and can be restored at any time. See "Feature Suppression Tool"

5 Meshing Toolbox Feature Removal - Most of the functionality in this tool, which is used to permanently remove geometric entities to simplify geometry, is offered in other FEMAP commands. This tool brings them together in one place where they can be used interactively. Removing Loops basically mimics the functionality of the Geometry, Surface, Remove Hole command, while removing Surfaces essentially uses the same process as Geometry, Solid, Remove Face. Finally, removing Curves uses portions of the Geometry, Solid, Cleanup command along some other methodology to try and remove redundant curves. In the case of Aggressive Removal, localized geometry around the selected curve may be slightly altered to accommodate the curve no longer being part of the geometry. See "Feature Removal Tool" Combined/Composite Curves - In some cases, combining several smaller curves along the edge of a surface will allow you to create a higher quality mesh on the surface. This tool allows you to combine curves by choosing the curves themselves or a point that two curves share. A Composite Curve will be created in FEMAP, which will be used for mesh sizing purposes instead of the underlying curves. There are also options for splitting a composite curve at a selected point or removing any of the underlying curves. See "Combined/Composite Curve Tool" Combined/Boundary Surfaces - Much like creating composite curves to improve mesh quality, it may be a good idea to combine several surfaces into a Boundary Surface. This tool uses the same concept as the Geometry, Boundary Surface, From Surfaces on Solid command. This can be especially helpful when there are sliver surfaces next to a much larger surface. By combining the selected surfaces into one boundary surface, all of the internal curves can be ignored during the meshing process. Boundary surfaces can be created by selecting a curve shared by multiple surfaces or choosing the surfaces themselves. Also, any underlying surface can be removed from a boundary surface or split along a chosen curve. See "Combined/Boundary Surface Tool" Meshing Tools Mesh Sizing - Combines the options used to set mesh sizing and node spacing on curves (Mesh, Mesh Control, Size on Curve) with the Add, Subtract, and Set To functionality of the Mesh, Mesh Control, Interactive command. When using the Auto Remesh option in the Meshing Toolbox you will be able to see the mesh update on the fly after each change to sizing or node spacing, while you also monitor the element quality update (Mesh Quality Toggle On ). There are also options for matching any number of selected curves to a Master Curve, as well as setting biasing and length based sizing without changing the number of elements on the curve. See "Mesh Sizing Tool" Mesh Editing Tools Mesh Locate - There may be times when you would like to make small changes to an existing mesh simply by moving one or several nodes without changing the number of elements. This tool will allow you to do this while making sure that as you move the node or nodes dynamically, they remain attached to specified solid(s), surface(s), and curve(s), or if you have no geometry, follow the overall topology of the selected standalone mesh. There are also options to move the selected nodes by a defined amount, continually smooth the mesh as the nodes are moved, and allow the moved nodes to no longer be attached to surfaces or curves. Much like the Mesh Sizing tool, you can also turn on the Mesh Quality Toggle and monitor the element quality real time as the nodes are moved. See "Mesh Locate Tool" Mesh Quality - Creating a mesh with high quality elements is essential to the accuracy of a Finite Element model. When the Mesh Quality Toggle in the Meshing Toolbox is set to on, this tool allows you to graphically see an element quality value plotted on each element similar to a contour/criteria plot. There are several different element quality types which can be selected and each type has default automatic values, but user-defined values can also be specified. Also, the minimum and maximum distortion values for the specified quality type are listed in the bottom fields of the tool. See "Mesh Quality" Entity Locator menu - The Entity Locator is very helpful in finding Short Edges and Sliver/Small Surfaces which may be causing meshing issues. It may also make it easier to locate free edges in troublesome geometry. This menu contains commands for toggling the Entity Locator on and off, cycling through the entities currently in the Entity Locator, removing the current entity from the Entity Locator or clearing it entirely, as well as creating a group from the entities currently in the Entity Locator or sending them to the Data Table. Toggle Entity Locator - When this icon is toggled on, the Entity Locator is ready to be filled with entities and the Locator fields will be available in the Meshing Toolbox. Depending on which entity type is selected in the Search For drop-down list, Curves or Surfaces, the Locator fields change. The Locate Options and Show

6 Finite Element Modeling Options can be used to modify how the Entity Locator searches for entities and then displays them. Also, the entities loaded in the Entity Locator update after each change made in the Locator fields, unless Auto Locate is turned off in the Locate Options section. Once entities are loaded into the Entity Locator, use the following commands to move from entity to entity. By default, the current entity in the Entity Locator will be highlighted in the graphics window using the display options currently set in the Style portion of the Windows, Show Entities command (See Section , "Window, Show Entities..."). There are other options for automatically rotating the model and zooming in to get a better view of the entity. See the Locate Options and Show Options sections in the Locator section for more information. Next - Makes the next entity in the Entity Locator the current entity. Previous- Makes the previous entity in the Entity Locator the current entity. Once either Next or Previous has been selected, the icon will persist at the top of the Entity Locator menu in the Meshing Toolbox. This enables you to easily go to the next or previous entity simply by clicking the icon. When you reach the last entity in the Entity Locator, the Next icon will automatically become the Previous icon and vice versa. Current - Re-highlights the current entity in the Entity Locator. This can be helpful if you have regenerated or rotated the model. First - Makes the first entity in the Entity Locator the current entity. When using Search Methods based on physical size, the smallest located entity will be the first entity. Last - Makes the last entity in the Entity Locator the current entity. When using Search Methods based on physical size, the largest located entity will be the last entity. Do Not Locate - Places the current entity into a group which is then automatically specified in the Not In Group field of the Locate Options. Remove - Removes the current entity from the Entity Locator until cleared or new search criteria are entered. Clear Locator - Simply clears the Entity Locator of all entities. Create Group - Creates a new group with all of the entities currently in the Entity Locator or adds/removes/ excludes those entities from an existing group. Add to Data Table - Adds all entities currently loaded in the Entity Locator to the Data Table. The Data Table needs to be open in the User Interface and unlocked for the command to be available. Search For - Indicates the entity type, Curves or Surfaces, the Entity Locator will currently be able to locate in the model. Depending on the entity type, different Locator fields become available. Locator fields and buttons when Search For is set to Curves: Search Method - Specifies the method the Entity Locator uses to find, then load itself with specific Curves in the model. Depending on the Search Method, other options may become available. Here are descriptions of the different Search Methods:

7 Meshing Toolbox Short Edges - Short edges will be loaded into the Entity Locator using criteria specified in the current Based On option. When Based On is set to: Global Mesh Size - Curves whose length is shorter than the specified % of Mesh Size (default) will be loaded into the Entity Locator. Curve Length - Curves will only loaded into the Entity Locator which are Shorter Than a user-specified value. You may type the value in directly or specify the value by clicking the Select Curve to Set Length icon button, then choosing any curve on the screen. Shortest Curves - Finds the shortest specified % of All Curves in the model (For example, if set to 5, it will find the bottom 5% of curves, based on length) and loads them into the Entity Locator. This value can be set from 0 to 25 using the slider bar or a value can be entered directly (if value is higher than 25, loads all curves satisfying that criteria into the Entity Locator, then returns to 25). Free Edges - Locates all edges in a Solid which are not stitched to another surface. Free Edges in a Solid usually indicate gaps or holes in the geometry, meaning the Solid does not fully enclose a volume and is probably not viable for solid meshing (tet or hex). If multiple surfaces are stitched together but do not enclose a volume (Sheet Solid) or joined using the Geometry, Surface, Non- Manifold Add command (General Bodies), then free edges may also indicate gaps or holes between surfaces. Of course, free edges in this type of geometry may be internal holes/loops or the outside edge of the stitched/joined part, which are normal. Free Edges of set of surfaces Stitched together Free Edges of surfaces joined using NonManifold Add NonManifold Edges - Locates all NonManifold edges in the geometry. Only geometry that has been joined using the Geometry, Surface, NonManifold Add command (General Bodies) will have any of these edges. Typical NonManifold Edges are found where surfaces come together at T-junctions or a surface has been Non- Manifold added to a Solid. Two Examples of NonManifold Edges Surfaces joined using NonManifold Add Surface and Solid joined using NonManifold Add From Group - Loads all Curves in a specified Group into the Entity Locator.

8 Finite Element Modeling Show # Curves button - By default, when you initially place Curves in the Entity Locator, ALL of the found Curves will be highlighted in the graphics window using the display options currently set in the Style portion of the Windows, Show Entities command (See Section , "Window, Show Entities..."). Like Windows, Show Entities and the Show When Selected capabilities of the Data Table and Model Info tree, once the view has been redrawn or regenerated the highlighting is removed and the view is restored to how it appeared before the show command. If you want to highlight the curves again, simply click the Show # Curves button. Locator fields and buttons when Search For is set to Surfaces: Search Method - Specifies the method the Entity Locator will use to search and locate specific Surfaces in the model. Depending on the Search Method, other options may become available. Here are descriptions of the different Search Methods: Surface Geometry - This method is used in conjunction with any combination of the Small Surfaces, Slivers, Spikes, and By Area options. If none of these options are turned on (checked), no surface geometry will be loaded into to the Entity Locator. Small Surfaces (Fit In Radius value) - Surfaces which completely fit inside a sphere with a specified radius (defined by Fit In Radius value) will be loaded into the Entity Locator. Enter the Fit In Radius value directly or click the Measure Distance icon button to specify the sphere radius by picking two locations graphically. Default value is equal to the default Merge Tolerance in the model. Slivers (Sliver Tolerance value) - Surfaces which have high aspect ratios and small areas are known as Slivers. Examining a surface s maximum width is often a good indication of whether a surface is a sliver or not. Surfaces with a maximum width smaller than the Sliver Tolerance will be loaded into the Entity Locator. Enter the Sliver Tolerance value directly or click the Measure Distance icon button and choose two locations graphically to specify a distance. Default value is equal to the default Merge Tolerance in the model. Spikes (Spike Width value) - Much like slivers, Surfaces with spikes also have high aspect ratio and small area. The main difference is that only a portion of the surface fits this criteria, not the entire surface. When this option is on and a spike on a surface is detected (smaller than Spike Width), FEMAP will try and remove the spike, while keeping the rest of the surface intact. Enter the Sliver Tolerance value directly or click the Measure Distance icon button and choose two locations graphically to specify a distance. Default value is equal to the default Merge Tolerance in the model. By Area (Area Less Than value) - Surfaces which have an Area Less Than the specified size will be loaded into the Entity Locator. Enter the Area Less Than value directly or click the Measure Area of Surface icon button to specify an area by choosing a surface graphically. Default value is equal to 1/1000 of the model box diagonal. From Group - Loads all Surfaces in a specified Group into the Entity Locator. Show # Surfaces button - By default, when you initially place Surfaces in the Entity Locator, ALL of the found Surfaces will be highlighted in the graphics window using the display options currently set in the Style portion of the Windows, Show Entities command (See Section , "Window, Show Entities..."). Like Windows, Show Entities and the Show When Selected capabilities of the Data Table and Model Info tree, once the view has been redrawn or regenerated the highlighting is removed and the view is restored to how it appeared before the show command. If you want to highlight the curves again, simply click the Show # Surfaces button. Locate Options: Only In Group - The Locator will only attempt to locate entities which meet the specified criteria in the selected group. Not In Group - The Locator will only attempt to locate entities which meet the specified criteria and are NOT in the selected group. A group based on any number of solids can be generated directly from the Locator by clicking the Select Solids for Group with Related Entities icon button next to the Only In Group or Not In Group drop-down list. Ignore If - Instructs the Locator to ignore entities which meet the specified criteria which are either Suppressed or Combined. If you want to change the options, simply expand the Ignore If portion of the Locate Options and check or uncheck Suppressed or Combined accordingly.

9 Meshing Toolbox Auto Locate - When this option is on, the Locator will automatically be loaded with the entities that meet the criteria currently specified. If it is turned off, you will need to click the Locate button which is now visible. Update Selector - If this option is checked, the Selection List (usually created using the Select Toolbar) will be cleared, then updated with the entities currently placed in the Locator. If you have entities currently in the Selection List before the Locator is filled with entities, they will be cleared and replaced once the Locator is filled with entities. Show Options: Show All On Locate - When on, entities loaded into the Locator will be highlighted on the screen immediately. The highlighting is controlled by the options currently set in the Style portion of the Windows, Show Entities command (See Section , "Window, Show Entities..."). If this is set to off, you will have to click the appropriate Show button to highlight the entities in the graphics window. Auto Rotate - When this option is on, the view will be automatically rotated to align the current entity in the Locator on the screen. For surfaces, the view will align so the normal of the surface is pointing out of the screen and centered about the CG of the surface. For curves, the vector tangent to the curve, at the curve s midpoint, will be used to align the view to the horizontal screen axis. The midpoint of the curve will be centered in the view and the normal vectors of all the surfaces to which the current curve is attached will be averaged together and that averaged normal will point out of the screen. Auto Zoom- If this option is checked, FEMAP will zoom in to the current entity in the Locator a specified amount. The size of the current entity is used in conjunction with the Zoom Factor, which is a percentage of graphics window size, to determine how far FEMAP zooms in to the entity. The Zoom Factor can be set from 1 to 100 (using the slider bar or entering a value directly), with 1 essentially zooming in as far as possible, while still being able to see the entire entity in the graphics window, and 100 making the length of the entity 1/100 the width of the graphics window. If the Entity Locator is filled with very small entities, FEMAP may only be able to zoom in so far before it reaches the magnification limit, which is 1/10000 of model box size. Mesh Quality Toggle - Toggles a plot of mesh quality on and off for all of the currently visible elements. Please see the section regarding the Mesh Quality tool below for more information on the different quality types and plotting options. Jacobian check shown with 2 distortion levels Jacobian check shown with 4 distortion levels Elements shown in red are above the specified Max Allowable Value for the Jacobian distortion check set to 0.4 Remesh Modes menu - This menu contains several modes for remeshing the model when using all tools except the Mesh Locate tool. There are three separate modes : Auto Remesh, Disable Remesh, and Track Meshing Changes. The fourth option on the menu, Remesh Entities, is only used when using the Track Meshing Changes mode. Essentially, only one mode can be active at any given time. When Auto Remesh is on, the mesh will be updated every time a change is made using one of the tools in the Meshing Toolbox. Once Disable Remesh or Auto Remesh has been chosen, the icon will persist at the top of the Remesh Modes menu. You can now toggle back and forth between these two modes by simply clicking the icon.

10 Finite Element Modeling Disable Remesh does not track any of the changes made using the tools in the Meshing Toolbox. Any changes made with the tools are applied to the model, but you will need to delete and remesh the model using the commands on the Mesh, Geometry... menu or switch to Auto Remesh mode and make a change with any tool. Having the model Auto Remesh after every single change may not be the efficient way to use the tools in the Meshing Toolbox, especially for larger models. You may want to use the Disable Remesh mode, make changes to your model using the Meshing Toolbox, then remesh the model. Track Meshing Changes will track all of the changes made using the different tools in the Meshing Toolbox, but the model will only be remeshed by clicking the icon for the Remesh Entities command, which will be at the top of the Remesh Modes menu whenever you are in Track Meshing Changes mode. Sometimes in larger models, tracking the meshing changes can be quite computationally intensive. You may want to turn Track Meshing Changes off, which is accomplished by going to Disable Remesh. Select Entity - Many of the tools in the Meshing Toolbox require you to select entities. Depending on which tool is currently active and how the options for that tool are currently set, will determine the type of entity you will be able to select when Select Entity is toggled on. When on, you can graphically choose entities from the graphics window one at a time or use box/circle picking to select multiple entities (hold down the Shift key to make a pick box or the Ctrl key to make a circular picking area). Depending on which tool you are using and the current Remesh Mode set, you will be able to see the mesh update real time as you choose entities. For example, if you are using the Add Operation in the Mesh Sizing tool, and have Auto Remesh on, every time you select a curve or curves (box/circle pick) in the graphics window, the mesh will be updated real time. Dialog Select - Very similar to Select Entity, except it allows you to use the typical Entity Selection dialog box to choose entities. See Section 4.3.1, "Entity Selection" of the FEMAP User Guide for more information on the different selection methods available. Feature Suppression Tool This tool allows you to use the manual options available in the Mesh, Mesh Control, Feature Suppression command interactively. You may suppress loops, curves (usually relatively small in size), and surfaces (usually sliver surfaces, not fillets or chamfers). Suppressed geometry still exists in the model and can be restored at any time. Feature Type - Choose which entity type you would like to suppress/restore. When using Select Entity or Dialog Select in the Meshing Toolbox, only the selected entity type will be available for selection. Loops - Usually curves of internal holes on surfaces and solids or base curves of bosses and extrusions on solids. Curves - In this case, curves usually refers to curves which are relatively small in size compared to the rest of the geometry. Surfaces - Like curves, surfaces to be suppressed are usually small in size compared to the rest of the geometry, thus creating the possibility of meshing issues. Action - This option specifies what action will take place when entities are selected using Select Entity or Dialog Select. When either Suppress or Restore is set, all entities selected will either be suppressed or restored. When Toggle Suppression is set, selecting an existing entity the first time will suppress the entity, while selecting it again will restore the entity. Limit Size - When used, this option limits the entities which can be chosen based on size. Only loops that are Smaller Than the specified size, curves that are Shorter Than the specified length, and surfaces with Area Less Than the specified area will be available to suppress/restore. This can be helpful to filter what is included when choosing multiple entities with Select Entity or Dialog Select.

11 Meshing Toolbox Update Colors - When a loop, curve, or surface is suppressed, the color of the entity will be changed to the color specified here. This allows you to easily see which entities have been suppressed. Click the Color Wheel icon button to bring up the Color Palette dialog box to choose different colors for suppressed entities. Show Suppressed (Curves and Surfaces buttons) - Highlights either suppressed curves or suppressed surfaces in the graphics window using the display options currently set in the Style portion of the Windows, Show Entities command (See Section , "Window, Show Entities..."). Like Windows, Show Entities and the Show When Selected capabilities of the Data Table and Model Info tree, once the view has been redrawn or regenerated the highlighting is removed and the view is restored to how it appeared before the show command. Restore All (In Solids and In Model buttons) - Restores all features on either selected solids by clicking the In Solids button or all the features in the model by click in the In Model button. For example Original Solid Part with stepped hole Curve chosen for loop to Suppressed Resulting Solid Mesh See Section , "Mesh, Mesh Control, Feature Suppression..." for additional examples Feature Removal Tool This tool is used to permanently remove geometric entities interactively to simplify geometry. Most of this tool s functionality is offered in other FEMAP commands. Removing Loops basically mimics the functionality of the Geometry, Surface, Remove Hole command, while removing Surfaces essentially uses the same process as Geometry, Solid, Remove Face. Finally, removing Curves uses portions of the Geometry, Solid, Cleanup command along some other methodology to try and remove redundant curves. Feature Type - Choose which entity type you would like to remove. When using Select Entity or Dialog Select in the Meshing Toolbox, only the selected entity type will be available for selection. Loops - Usually curves of internal holes on surfaces and solids or base curves of bosses and extrusions on solids. Curves - In this case, curves usually refers to curves which are relatively small in size compared to the rest of the geometry. Surfaces - Surfaces to remove can be all the surfaces of a hole, fillets, chamfers, and cutouts. In some cases, you may have to remove more then one surface at a time for this command to be successful. Limit Size - When used, this option limits the entities which can be chosen based on size. Only loops that are Smaller Than the specified size, curves that are Shorter Than the specified length, and surfaces with Area Less Than the specified area will be available to remove. This can be helpful to filter what is included when choosing multiple entities with Select Entity or Dialog Select. Aggressive Removal - If you have attempted to remove a curve or surface and FEAMP was not successful, then you may want to try using this option. For curves, Aggressive Removal uses functionality from the Parasolid Bodyshop to try and remove curves and then heal the geometry, which may change the topology of the geometry.

12 Finite Element Modeling For surfaces, instead of using the process used by Geometry, Solid, Remove Face, the Aggressive Removal option instructs FEMAP to take a completely different approach. The chosen surface is deleted from the model and the remaining surfaces are stitched together using a stitch tolerance which is slightly larger the chosen surface. Selecting relatively large surfaces while the Aggressive Removal option is on can have very adverse effects on the geometry. Because the stitch tolerance is set so high, other surfaces may be removed during the stitching process and the resulting solid may not really be very similar to the original solid. There may also be times when this process creates an invalid solid. Examples Here is an example of removing Loops from a surface. Choose one curve on each interior hole and all of the curves making up the loop will be found and removed from the surface All internal holes have been removed from the surface Surface with several interior holes In this example, the hole feature is removed differently from this solid geometry by choosing different Loops. Original Solid Part with stepped hole Curve chosen for loop in Remove Face Resulting Solid Geometry Original Solid Part with stepped hole Curve chosen for loop in Remove Face Resulting Solid Geometry

13 Meshing Toolbox In this example, the features can be removed from this solid geometry by either removing Loops or Surfaces. Original solid geometry The holes in the solid along with the boss and the post can be removed from the geometry by removing loops and choosing one curve on each feature. Alternatively, the features can be removed by selecting all of the surfaces of each individual feature. Geometry shown with holes and boss removed Here is an example of removing a curve with the Aggressive Removal option turned on. Original solid geometry Small curve to Remove Modified geometry without curve

14 Finite Element Modeling Here is an example of removing a surface with the Aggressive Removal option turned on. Original solid geometry Modified geometry without surface Small surface to Remove Combined/Composite Curve Tool In some cases, combining several smaller curves along the edge of a surface will allow you to create a higher quality mesh on the surface. This tool allows you to combine curves by choosing the curves themselves or a point that two curves share. A Composite Curve will be created in FEMAP, which will be used for mesh sizing purposes instead of the underlying curves. Action - This option specifies how individual curves may be combined to form Composite Curves (Add by Point or Add Curves) and how Composite Curves can be partitioned (Split At and Remove). You can also delete Composite Curves completely using Delete, which may be more convenient than using Delete, Geometry, Curve. Add by Point - Combines two curves connected to a selected point into a Composite Curve. If you are creating a Composite Curve along the edge of a surface with many small curves, you can watch the Composite Curve grow simply by starting at one end and choosing the points in sequence. Combine Surfaces - When this option is checked, a Boundary Surface will automatically be created from the surfaces connected to the underlying curves. As additional curves are added to the Composite Curve by choosing points, more surfaces will be combined into Boundary Surfaces. Add Curves - Creates a Composite Curve by allowing you to choose individual curves. There are also several options which can be used to make the process of creating Composite Curves more automatic. Merge to Existing - When checked, each curve selected will be added to an existing Composite Curve, unless the selected curve is not within Max Tangent Angle to the existing Composite Curve. Add Short Curves - Automatically includes any Curve Shorter Than the specified length that is adjacent to a selected curve in the Composite Curve. You may type the value in directly or specify the value by clicking the Select Curve to Set Length icon button, then choosing any curve on the screen. Add to Branch - Allows you to choose one curve and have a Composite Curve created by simply branching out from that curve until it reaches the corner of a surface. Combine Surfaces - When this option is checked, a Boundary Surface will automatically be created from the surfaces connected to the underlying curves. As additional curves are added to the Composite Curve, more surfaces will be combined into Boundary Surfaces Split At - Allows you to choose points to partition/break a single Composite Curve into two.

15 Meshing Toolbox Remove - Allows you to remove any of the underlying curves from a Composite Curve. It you remove a curve from the end, the Composite Curve will get shorter, but otherwise remain intact. If you a curve is removed from the middle, the Composite Curve will be split into two with a gap in between. The appearance of Composite Curves can be controlled via the Combined Curve option in the Labels, Entities and Color category of the View, Options command (See Section , "View, Options..."). Original Surface (9 individual curves on front edge of surface) Small curves on edge of surface create a skewed mesh The 9 curves of the front edge have been combined to create one Composite Curve. The quality of the mesh has been improved by using a Composite Curve. Delete - Allows you to delete a Composite Curve completely from FEMAP. The underlaying curves of the Composite Curve will be available for picking again once it has been deleted. Combined/Boundary Surface Tool Much like creating composite curves to improve mesh quality, it may be a good idea to combine several surfaces into a Boundary Surface. This tool uses the same concept as the Geometry, Boundary Surface, From Surfaces on Solid command. This can be especially helpful when there are sliver surfaces next to a much larger surface. By combining the selected surfaces into one boundary surface, all of the internal curves can be ignored during the meshing process. Action - This option specifies how individual curves may be combined to form Boundary Surface (Add by Curve or Add Surfaces) and how Boundary Surface can be partitioned (Split Along and Remove). You can also delete Boundary Surface completely using Delete, which may be more convenient than using Delete, Geometry, Surface. Add by Curve - Combines two surfaces sharing a single curve into a Boundary Surface. If you select a curve that a regular surface shares with a Boundary Surface, the regular surface will simply be added as another underlying surface for the existing Boundary Surface. Add Surfaces - Creates a Boundary Surface by allowing you to choose individual surfaces. Using the Merge to Existing Split Along - Allows you to choose curves to partition/break a single Boundary Surface into two. Remove - Allows you to remove any of the underlying surfaces from a Boundary Surface.

16 Finite Element Modeling Delete - Allows you to delete a Boundary Surface completely from FEMAP. The underlaying surfaces of the Boundary Surface will be available for picking again once it has been deleted. The appearance of Boundary Surfaces can be controlled via the Boundary option in the Labels, Entities and Color category of the View, Options command (See Section , "View, Options..."). Original Geometry (11 individual surfaces make up the bump ) Quad mesh on the individual surfaces of the bump Boundary Surface created using all 11 individual surfaces of the bump Quad mesh on boundary surface Mesh Sizing Tool Combines the options used to set mesh sizing and node spacing on curves (Mesh, Mesh Control, Size on Curve) with the Add, Subtract, and Set To functionality of the Mesh, Mesh Control, Interactive command. When using the Auto Remesh option in the Meshing Toolbox you will be able to see the mesh update on the fly after each change to sizing or node spacing, while you also monitor the element quality update (Mesh Quality Toggle On ). There are also options for matching any number of selected curves to a Master Curve, as well as setting biasing and length based sizing without changing the number of elements on the curve.

17 Meshing Toolbox Sizing Option - This switch is used to specify which method, Size Curve(s) or Match Curve(s), is currently set for updating the mesh size on curves. Size Curves - When selected, this method uses the option currently set in Operation along with the specified Spacing options to dynamically change the mesh sizing on curves. With Select Entity on in the Meshing Toolbox, every time you click on a curve the Mesh Size will be updated. You can also change the size on multiple curves all at once using a box pick or Dialog Select. Match Curves - With this method, a Master Curve ID may be entered directly or selected graphically after clicking the Select Master Curve icon button. Once the Master Curve is specified, turn on Select Entity in the Meshing Toolbox to match curves to the Master Curve one at a time by selecting them or change multiple curves all at once with a box pick or using Dialog Select. Operation - Allows you to select the current operation for the Mesh Sizing tool. You can choose to Add or Subtract the specified Number of Nodes from the selected curve(s), update the sizing on any curve(s) to the Number of Nodes using Set To, or simply change the Spacing options ( Bias and if Length Based Sizing should be used) without changing the number of nodes along the curve(s) with Set Spacing Options. Manual Update - When this option is on, the specified Operation and other options will not be used to update the mesh size and spacing until the Apply Operation button is pressed. Using a box pick while Select Entity is active or using Dialog Select in the Meshing Toolbox, is a very efficient method to update multiple curves at one time. Pressing the # Curve(s) Selected button will highlight the selected curves in the graphics window. Pressing Clear Selection sets the number of selected curves currently ready to be updated to 0. Spacing - This drop-down allows you to specify biasing options. By default, this option is set to Equal, which will place a uniform distance between each node along a curve. The other options allow you to bias the mesh size and the level of biasing will be controlled by the Bias Factor. here is a breakdown of the biasing options: Biased using Pick Location - The node spacing on the curve is biased using the location of the cursor when the curve is selected. The smaller distances between nodes will be positioned by the selection location. When working in a model that is not planar, which is quite common, it is a good idea to have the snap mode set to either Snap to Node or Snap to Point. This will allow FEMAP to use the point or node related to the curve closest to pick location to determine where the biasing should occur. When the snap mode is set to Snap to Point, you will only be able to bias towards one end of the curve or the other. When it is set to Snap to Node, you will be able to bias towards either end of the curve or towards the center, much like you can using Biased Small at Center in the Spacing options. Biased Small at Ends - The smaller distances between nodes will be positioned at each end of the curve with the larger distances between nodes being at the center. Biased Small at Center - The smaller distances between nodes will be positioned at the center of the curve with the larger distances between nodes being at the at each end of the curve. Bias Factor - This factor is a ratio of the largest distance between nodes to the smallest distance between nodes along a given curve. For example, when it is set to 2, the largest distance equals the smallest distance multi-

18 Finite Element Modeling plied by 2. All of the distances between the other nodes along the curve are defined using a linear interpolation of the large and small distances. Mesh Elements = 10 Bias Small towards this end Bias Factor = 3 Mesh Elements = 10 Bias Small towards this end Bias Factor = 4 Mesh Elements = 10 Bias Small at Ends Bias Factor = 2 Mesh Elements = 10 Bias Small at Ends Bias Factor = 2 Mesh Elements = 8 Bias Small at Center Bias Factor = 3 Mesh Elements = 8 Bias Small at Center Bias Factor = 2 Mesh Elements = 10 Bias Small towards this end Bias Factor = 3 Mesh Elements = 10 Bias Small towards this end Bias Factor = 4 Length Based Sizing - Allows you to choose whether mesh locations will be located in parametric or length coordinates along the curve. For lines, arcs and circles, these options make no difference since the parametric and length coordinates are equivalent. For spline curves however, parametric coordinates are typically much different. In most cases, choosing parametric spacing is the preferred method. It results in a finer mesh in areas of high curvature, which is often desirable. However, if you have two spline curves side by side, which happen to have different parametric coordinates, checking Length Based Sizing will allow you to match the meshes on those two curves (this can also be accomplished using a matched custom mesh size on one of the curves - see Section , "Mesh, Mesh Control, Custom Size Along Curve...". Propagate Mapped Approach - This option, which is on by default, will update the mesh sizing accordingly on all appropriate curves of a surface which has a mapped approach set using Mesh, Mesh Control, Approach on Surface, in order for the approach to remain valid. Also, any other surfaces with a mapped approach which would be effected by changing the size will also have their sizing updated as well. For more information on setting mesh approaches, see Section , "Mesh, Mesh Control, Approach On Surface". If this option is turned off, there is a good chance that changing the mesh sizing on only one curve of the surface will create inappropriate sizing for FEMAP to create a mapped mesh on the surface. For Example, this geometry is three surfaces stitched together. Each surface has a Mapped-Four Corner meshing approach specified and has been sized with the default mesh size. 3 Surfaces with Mapped - Four Corner Approaches Set Mesh using default Mesh Size 2 Nodes Added to sizing on either of these Curves Two Subtracted from this Curve Three Nodes Added from this Curve Change is Propagated through entire Model as all surfaces effected by new mesh size. Changes only Propagated locally to individual surface where meshing sizing was changed. Show Free Edges - Simply highlights the nodes of any free edges in your model. This can be helpful for confirming the mesh is still fully connected after sizing has been updated.

19 Meshing Toolbox Mesh Locate Tool There may be times when you would like to make small changes to an existing mesh simply by moving one or several nodes without changing the number of elements. This tool will allow you to do this while making sure that as you move the node(s) dynamically, they remain attached to specified solid(s), surface(s), and curve(s). If you have no geometry, there is an option to have the nodes follow the overall topology of the selected standalone mesh as they are moved. There are additional options to move the selected nodes by a defined amount, continually smooth the mesh as the nodes are moved, and allow the moved nodes to no longer be projected to a surface or remain along a curve. Much like the Mesh Sizing tool, you can also turn on the Mesh Quality Toggle and monitor the element quality real time as the nodes are moved. Finally, once the mesh locations have been updated, you have the choice to Save the new mesh or Discard the updated mesh and revert to the original mesh. Select Mesh to Edit - Limits the elements whose nodes will be allowed to move in this command. Simply choose an option, then click the... icon button to choose the entities. Only elements and nodes connected to the selected entities will be visible and available for update of nodal locations. You must use the Select Mesh to Edit first in order for the other options in this tool to become available. Attached to Surface - Allows you to choose surfaces in the model to limit the nodes and elements for possible update. Attached to Solid - Allows you to choose solids in the model in the model to limit the nodes and elements for possible update. Standalone Mesh - When no geometry is available, this option allows you to choose any number of elements from the model and use the overall topology of the selected mesh to limit where the nodes can be moved, when the Project option is on. To create the overall topology, the existing mesh is facetted, much like a surface. This allows the node(s) to be projected back onto pseudo geometry in order to maintain the general shape of the model. Locate Multiple - When this option is checked, it enables you to move more than one node at a time. To select multiple nodes to move, turn on Select Entity in the Meshing Toolbox and then choose the nodes one at a time, with a box pick (hold down Shift key), or circle pick (hold down Ctrl key). Once the nodes are selected, they will move in unison based on the chosen Locate Method. Press the X icon button to choose different nodes to move. Locate Method - You may choose to move the node(s) dynamically, based on screen position, or manually, using a vector. If you have the Mesh Quality Toggle on, you will likely want to use the Dynamic option and move the node(s) around until the attached elements reach the desired quality. On the other hand, if you would like to move the nodes a precise distance, it is probably better to use the Manual, Vector option. Original Mesh Dynamically modified Mesh with improved Jacobian element quality values When using the Dynamic method, simply choose the node(s) using Entity Select in the Meshing Toolbox and then drag the node(s) to the desired location. It is best to have the Snap Mode set to Snap to Screen when using the Dynamic method to allow for smooth movement of the selected node(s). This allows the most flexibility when positioning the node(s).

20 Finite Element Modeling When using the Manual, Vector method, the Move Along Vector fields will appear. You may use the Select Vector icon button to choose a vector graphically using any method available in the Select Vector dialog box. Another option is to enter a Base Point for the vector or use the Select Coordinates icon button to pick it graphically, then enter the distances in each direction (dx, dy, and dz) manually. Once the vector has been specified, click the Apply Vector button to complete the move to the new location. Smooth - When this option is checked, the selected mesh will constantly be smoothed as nodal locations are updated. If you want to only have the elements directly connected to the selected node(s), turn this option off. Project - When this option is enabled, the selected nodes are constantly projected back to the surface to which they are attached. When the Standalone Mesh option for Select Mesh to Edit is used, the nodes are projected back to pseudo geometry created using the overall topology of the selected elements. Constrain to Curve - Nodes which are attached to curves will only be allowed to move along the attached curve, when this option is on. This is the default configuration and is usually the desired behavior, as it attempts to prevent undesired holes from accidentally being introduced into the mesh. Save and Discard buttons - Once the mesh locations have been updated, you have the choice to Save the new mesh or Discard the updated mesh and revert to the original mesh. If you choose to use the Undo command (Tools, Undo or Ctrl+Z) after pressing the Save button, ALL changes to the mesh since the Save button was last used will be undone, not the movement of individual nodes. Also, if you use Undo before choosing Save or Discard, the original mesh will be restored. Mesh Quality When the Mesh Quality Toggle in the Meshing Toolbox is set to on, this tool allows you to graphically see element quality values plotted on each element similar to a contour/criteria plot. There are several different element quality types which can be selected and each type has default automatic values. User-defined values can also be specified. Also, the minimum and maximum distortion values for the specified quality type are listed in the bottom fields of the tool. Quality Type - There are 8 different types of element quality checking available through the Meshing Toolbox. They correspond to the element distortion checks of the Tools, Check, Distortion command. The element checks are: Aspect Ratio Taper Alternate Taper Internal Angles Warping Nastran Warping Jacobian Combined Quality See Section , "Tools, Check, Distortion..." for more details on the individual element checks.