Geometric Modeling in StressCheck

To access geometric modeling in StressCheck, select Class > Geometry or navigate to the Geometry tab in the Input dialog. The construction of 2D and 3D geometry in StressCheck is based on the Parasolid geometric modeling kernel from Unigraphics Solutions.

While there are a few construction methods for point and curve/wireframe objects, most of the Parasolid functionality is related to the construction of solid geometry, and the various operations used for creating three dimensional solid bodies using boolean and blend operations.

This functionality fits quite easily into the familiar Class/Action/Object/Method (C/A/O/M) command paradigm, and all objects may be created in parametric form. The implementation supports the construction of solid geometry such as:

• Solid Primitives: Box, Sphere, Cylinder, Cone, Torus
• Solid Booleans: Union, Subtraction, Intersection
• Clip Operations: Clip-Front, Clip-Back
• Blend Operations: Rolling Ball, Chamfer, Variable Radius
• Body-Solid Operations: Sweep, Spin, Thicken, Extrude
• Body-Copy Operations: Child, Orphan

StressCheck automatically trims the surfaces affected by boolean operations, and automatically constructs all intersection curves and points of intersection for use in construction of the finite element mesh.

Geometry (CAD) Importation

Not only can you construct solid geometry in StressCheck, it is also possible to import CAD geometry that was created by third party CAD tools such as CATIA, SolidEdge or Creo. It is also possible to import files which were exported from a CAD system using the IGES or STEP standards. Although imported geometry is essentially a static snapshot of a part, it may be modified within StressCheck through the addition of new solid objects, and the application of boolean or blend operations. Additionally, as of StressCheck v12.0 imported solids will maintain their original color definitions. For more detailed discussion of CAD model importation, refer to Importing Model Inputs.

After importation, it is possible to copy CAD geometry to another location for convenience and/or global-local analysis. For a step by step workflow, refer to How Do I Move My Imported CAD to A Different Location?

Terminology

There are a few important terms and concepts that should be understood before navigating further:

• Point – A one dimensional geometric object defined primarily in terms of an X,Y,Z location in 2D or 3D space. For example, a point, node, or local coordinate system.
• Curve – A two dimensional geometric object defined in terms of a single variable (e.g. P1) in 2D or 3D space. For example, a line, circle, ellipse, spline curve, or surface curve.
• Surface – A three dimensional geometric object defined in terms of two variables (e.g. P1, P2) in 3D space. A surface object has no volume or thickness. For example, a plane, sphere, cylinder, cone, torus, tabulated cylinder, surface of revolution, spline surface, etc.
• Solid Body – A three dimensional topological object representing a volume bounded by a collection of bounding faces (trimmed surfaces) edges (trimmed curves) and vertices (points).
• Sheet Body – A three dimensional topological object composed of a single face (trimmed surface), edges (trimmed curves) and vertices (points). The sheet body does not represent a bounded volume. NOTE: In StressCheck, when we talk about creating a surface, we really mean a sheet body.
• Wire Body – A two dimensional topological object composed of one or more trimmed curves. NOTE: In StressCheck, when we talk about creating a curve, we really mean a wire body.
• General Body – A three dimensional topological object composed of one or more faces (trimmed surfaces), edges (trimmed curves) and vertices (points). The general body does not represent a bounded volume. A general body is created by applying a boolean or face blending operation to one or more sheet bodies.
• Boolean operation – The union, subtraction, or intersection of one or more solid or sheet bodies. If all objects which are components of the boolean operation are solids, the result is a solid topology. If one or more of the components are sheet bodies, the result is considered to be a general body (not necessarily a solid).
• Blend operation – The application of a fillet (rolling ball, chamfer, or variable radius) to a solid body.
• Body – A topological entity which is either a primitive or the result of any boolean, blend, or clipping operation. A body may be a solid, a sheet, or a general topology.
• Target – In a boolean, clip or blend operation, the first object selected is considered to be the target, and is generally the object which remains after the operation is complete.
• Tool – In a boolean, clip or blend operation, the objects selected after the target which do not survive after the operation is complete.
• Implicit associativity – The result of a boolean or blend operation is a collection of faces (trimmed surfaces), edges (trimmed curves) and vertices (points). The edges represent the curves of intersection between neighboring faces. The vertices represent the points of intersection between the coincident edges. Since these relationships are automatically created by the various modeling operations, their relationship (associativity) is considered to be implicit. The user is free to make changes to solid objects without regard for the resulting changes in implicit associative relationships.
• Explicit associativity – It is sometimes necessary to create new explicit associative relationships in a model. For example, attaching a point as an offset, a midoffset, or a projection to a surface or curve, or as an intersection of 2 or more curves. This explicit associativity will prevent the future application of a boolean or blend operation to a solid body. As a consequence, explicit associative relationships should not be added to a body unless it is certain that no future boolean or blend operations will be necessary for the corresponding body (i.e. its faces, edges or vertices).

Important Limitations

Some basic rules and limitations must be kept in mind while constructing solids-based finite element models in StressCheck.

• StressCheck is not intended to be used as a general purpose CAD system. It is a solids-based analysis system.
• There is no solid modeling history tree maintained in StressCheck. This means that you cannot edit a previous operation to change the type of solid modeling operation that was performed. For example, if you create a box, a cylinder and a sphere, then union the box with the sphere, then subtract the cylinder, you may not edit the history to change the union operation to a subtraction operation. To accomplish this, you must delete all objects and operations that were performed after the step that you wish to change, make the change, then manually retrace your modeling steps. However, you may edit dimension information for objects in your model, as long as the modification does not change the topological structure of the model.
• You may not perform a boolean or blend operation on an object which has explicit associative relationships. For example, you may not attach a point as an offset to a surface which is part of a solid body, then attempt to apply a blend to the same body. The blend operation effectively deletes the original definition of the body and replaces it with the blended representation. The deletion is not possible if there is an explicitly associated object.

Creating New Geometric Objects

The options under Geometry provide for the definition of the solution domain using points, lines, circles, ellipses, rectangles, boxes, cylinders, boolean operations, etc. StressCheck lets you separate the definition of boundaries from the definition of the finite element mesh. Separation of geometric objects from mesh objects provides for a great deal of flexibility in modeling.

Geometric objects may be defined parametrically or by formula expression so that the domain may be easily changed by adjusting individual design variables. Since boundary conditions may be attached to geometric boundaries, the finite element mesh may be easily changed/re-meshed without affecting boundary condition definitions. The following describes the creation of new geometric objects via the C/A/O/M options in the Geometry tab.

Action Combo-Box

In order to create a new object by a specific method, you must first set the action to Create in the Action (first) combo-box of the C/A/O/M. Once the action is set to Create, the Object and Method combo-boxes of the C/A/O/M will automatically populate with the available options, and the Input dialog will provide more details about the expected inputs. Additionally, the mouse cursor will reflect the Create action (). The default when the action is set to Create is Create > Point > Locate. The object type can then be changed, followed by the creation method, by selecting new options in the Object and Method combo-boxes, respectively.

Data/Index Subtabs

At the bottom of the Geometry tab are two subtabs: Data and Index. The Data subtab allows for specification and modification of geometric input data (e.g. X,Y,Z coordinates, ellipse radii, box dimensions), while the Index subtab provides a scrolling list of existing geometric objects for selection, modification and deletion (Figure 2).

Note: the scrolling list of objects in the Index subtab is determined by the object type specified in the Object combo-box of the C/A/O/M. If no objects exist for the selected object type, then the Index subtab will be empty. See the “Index Subtab Filters & Options” section below for more information.

To create new 2D or 3D geometric objects, select the Data subtab at the bottom of the Geometry tab in the Input dialog, set the Action combo-box of the C/A/O/M to Create, and the Object and Method combo-boxes the desired object type and creation method. Then, provide the geometric input data by screen selection of objects (if applicable) or by entering the input data in the available input fields (see the following for more detail).

Index Subtab Filters & Options

The Index sub tab is specific to the Geometry and Mesh class tabs, and contains options for sorting, filtering and object ID lookups for the object type specified by the Object combo-box. For example, if the input class is set to Geometry and the A/O/M configuration is set to Select > Plane > Locate, the following column options are available within the Index subtab (Figure 3):

• Columns may be sorted in ascending/descending order by clicking on the column headers.
• Right-clicking on the “#” column will display the “Go to ID…” button:
  • Clicking “Go to ID…” allows the user to enter a specific object number in the “Scroll to ID:” field.
  • Clicking “OK” will then scroll the user to the specified object number in the Index.
• Right-clicking on the “Type” column will display a filter option list for associated object types.
  • For example, if the Object combo is set to “Any Boundary” and the model contains a variety of different boundary types (e.g., cylinders, planes, spheres, etc.), the following filter option list would display on right-click:
  • By default, all object types are included in the Index rows (“All”).
  • Selecting one or more object types from the filter option list will include only objects of the selected object type(s) in the Index rows.
• Right clicking on the “Status” column will display a filter option list for object statuses.
  • The filter options are All, None, Selected, Hidden and Ignore:
  • By default, all object statuses are included in the Index rows (“All”).
  • Selecting one or more object statuses from the filter option list will include only objects of the selected object status(es) in the Index rows.

Surface/Curve Selector

In the Geometry tab of the Input interface, there is a button between the Action and Object combo boxes, which controls whether the object combo presents a list of point/curve/wireframe objects (Figure 4):

or point/surface/solid objects (default, as shown in Figure 5):

Point and system objects are included under both settings for convenience.

Surface/Solid Toggle

For boxes, spheres, cones, cylinders and torus there is also a button which identifies whether they should be created as surfaces or solids. Solid (default) will result in solid bodies with finite volume, whereas Surface will result in a collection of trimmed surface (sheet) bodies (Figure 6):

Screen/Text Input Toggle

By default, all input fields in the Input dialog are inactive and the checkbox above the input fields will read Screen:. Screen: assumes the model input data will be based on screen left-clicks or left-click + drag actions, with the inactive input fields reflecting the mouse cursor location/movement in the Model View (Figure 7):

For example, you may create a circle using Create > Circle > Locate, with Screen: displayed and all input fields inactive. Then, hover your mouse cursor in the Model View, left-click + hold to establish the X,Y,Z location of the circle center, and while holding the left mouse button, drag the mouse cursor to establish the circle radius. Note all input fields populate based on the cursor location and movement. Then, release the left mouse button to create the circle.

Individual input fields can be activated for manual text input by checking the corresponding checkbox next to the input field. All input fields can be activated by checking the checkbox next to Screen:. The checkbox label will change to Input:, and all input fields will be active for text input. Unchecking the checkbox will deactivate all input fields and the checkbox label will change back to Screen:.

Note: in some cases, it may be useful to leave one or more input fields inactive for screen input, and activate the remaining input fields for manual text input. As discussed previously, the inactive input fields will be populated once the mouse cursor hovers over the Model View, or a left-click + drag action is completed in the Model View.

Specifying Geometric Inputs

The geometric input data requirements will depend on the Object and Method specified by the user in the C/A/O/M combo-boxes. Some geometric input data will require screen selection (e.g. intersection of two curves, a midpoint between two objects, selection of an object for projection to a boundary), entering the data into the provided input fields (e.g. circle radius, box size), or a combination.

When input fields are available, the input may be constant, parametric or formula-based. Note: input fields are currently limited to 15 alphanumeric characters. Below is an example of the input fields for Create > Box > Locate:

Constant Input

Simply enter the value in floating point (e.g. 12345) or scientific notation (e.g. 1.2345e4) in the input field. If the constant value is to be evaluated based on a simple expression, such as “5*1.2345e4” then an “=” must precede the expression so it as written as “=5*1.2345e4”. As shown in the below animation, hitting the tab key will evaluate the expression in the input field:

Parametric Input

Simply enter the parameter name, or an expression containing constants and parameter names, in the input field. Parameter autofill and validation check features are available as of StressCheck v12.0 to assist in parameter selection. For example, if there is a parametric model dimension (e.g. “dim1”) to be modified by a parametric scale factor (e.g. “scalefactor”), an expression can be written in the input field as “dim1*scalefactor”. Changing the “scalefactor” parameter value will result in an automatic model update.

If an input field has focus, using Alt+P will result in a popup containing a scrolling list of parameter names (Figure 8). Parameter names are not case sensitive. For more details on parameters, refer to Parameters & Rules Overview.

Formula Input

Simply enter the formula name in the input field. Formula autofill and validation check features are available as of StressCheck v12.0 to assist in formula selection. Valid formula names will appear in purple text, and are preceded by a pipe symbol “|”. No additional characters, such as “-“, should precede the formula name. To reverse the sign of a formula, or to scale the formula expression, modify the formula expression directly in the formula definition.

If an input field has focus, using Alt+F will result in a popup containing a scrolling list of formula names (Figure 9). Formula names are not case sensitive. For more details on formulae, refer to Formula Overview.

Repeating Geometric Objects

When objects are to be created at regular intervals (i.e. repeated), it can be helpful to make use of the Repeat function in the Input dialog (Repeat # =, as shown in Figure 10). This functionality is available for constant and parametric intervals.

Note: the Repeat toggle is automatically switched off when the Accept button is clicked, but not when the left mouse button is clicked in the Model View.

Constant Repeat

To repeat the creation of geometric objects using constant intervals, first toggle the input fields you wish to repeat (e.g. X:, Width:, Depth:). Then, check the Repeat #= checkbox. A “+” symbol followed by an interval input field will appear to the right each active input field. The Repeat input box will also be active, and you may enter the number of desired repetitions as an integer value (N). Next, input the initial values for the geometric object repetition in the left-hand input fields.  Enter the interval values in the corresponding right-hand input fields. Note: leave interval values as “0” if you do not wish to modify the initial values. Below is an example of Create > Box > Locate with N=5 (Figure 11):

Finally, click Accept and five (5) solid boxes will be created with the offsets provided in Figure 11.

Repeated object creation can be very useful with other creation methods also. For example, if you wish to create 8 points at evenly-spaced intervals of 45 degrees around a wireframe circle object, you can use Create > Point > Offset with the Repeat field set to “8”, and specify the offset interval as “45” (degrees). Then, click on the wireframe circle object to automatically generate the points. Note: the number of objects repeated should be equal to the value in the Repeat input box (N), with the first object created having the properties of the initial values and the last object created having the properties of the initial values + (N-1)*interval values.

Parametric Repeat

To repeat the creation of geometric objects using parametric intervals, first toggle the input fields you wish to repeat (e.g. X:, Width:, Depth:). Then, enter expressions in the active input fields containing parameter names, arithmetic operators and the symbol “#”. The symbol “#” will act as an index variable incrementing from 0 to N-1, where N is the value entered into the Repeat input box. Next, check the Repeat #= checkbox and enter the number of desired repetitions as an integer value (N). Below is an example of Create > Box > Locate with N=5 and the parameter “scalefactor” in expressions of arithmetic operators “*”, “/” and “+” and the symbol “#” (Figure 12):

Finally, click Accept and five (5) solid boxes will be created with intervals ranging from #=0 to #=5-1=4. Note: the number of objects repeated should be equal to the value in the Repeat input box (N), with the first object created having the properties when #=0 and the last object created having the properties when #=N-1.

Associative Object Creation

Associativity is an important feature of any design tool which is to be used for parametric analysis. Associativity is simply a geometric relationship among objects. This relationship is maintained as the underlying objects are modified. For example, lines may be defined associatively with respect to 2 endpoints. If one or both endpoint locations are changed, the definition of the associated line is automatically updated. Similarly, a circle may be associated with either a local coordinate system, or with 3 points. If the locations of these underlying objects are changed, the definition of the circle is updated automatically.

All associative relationships are based on the order of creation of the associated objects. It is possible to create points which are associatively attached to boundaries, lines parallel to lines which are normal to other lines, etc. The associative relationships are evaluated strictly in the order of object creation. Therefore, if you wish to change an existing object definition in such a way that it depends on another object which was created later than itself, it may not be possible. The program will attempt to revise the order of evaluation to accommodate the desired change, but it may not be possible. In this case, you must delete the object you wish to change, and recreate it.

Checking Object Dependencies

If the Input class is set to Geometry or Mesh, and an object is currently selected, directly below the input toggles, fields, combo-boxes & options area will be 1) a label box containing the selected object’s type & number and 2) an object associativity list box containing references to the selected object’s dependencies. If the selected object has no object dependencies, then the object associativity list box will read: “No associativity”.

For example, selecting a plane object (via the A/O/M configuration of Select > Plane > Locate) created by the 3-Pt. Plane method will return the selected plane’s number (e.g. Plane = PLN3) and the three (3) associated point numbers used to define the plane (Points = 6,7,4, as shown in Figure 13):

To visually confirm object dependencies, first select the objects of interest. Then click the “Assoc.” button. All objects that depend on the initially selected objects will also be selected.

For more details on object associativity, refer to StressCheck Tutorial: Object Associativity and Why Do I Receive An Error Message About Associativity When Creating or Deleting Geometry?

Geometric Object Types

StressCheck supports the creation of 2D and 3D geometric object types. Click on the below links to learn more about geometric object creation:

• 2D Primitive Geometry Objects
• 3D Primitive Geometry Objects
• Sheet Body Operations
• 3D Solid Body Operations

Primitive Geometry Creation Methods

StressCheck supports a variety of creation methods for primitive geometric object types. For more details, refer to Primitive Geometry Creation Methods.

Selecting/Editing Geometric Objects

So far, we have described how to create geometric objects by setting the Action combo-box to Create. It is very important to be able to select, manipulate, edit, examine and/or update objects after they have been created. The Action combo-box of the C/A/O/M combo-boxes in the Geometry input class contains the following additional actions:

• Select – selection of objects from the screen.
• Edit – selection of an object from the screen or the Data subtab’s Object Identifier (OI) listbox for revision of input data.
• Move To – selection of an object from the screen for redefinition of the creation method and/or input data.
• Check – selection of an object to query properties like location/dimensions/distance from another object.

Additionally, when the Action is set to Select or Edit two buttons are available at the bottom of the Input dialog for revising selected objects:

• Move – increment object location/dimensions.
• Replace – overwrite object location/dimensions.

These actions are summarized as follows:

Select

Set the Action combo-box to Select to identify an object for manipulation by some other command. You may then set the Object combo-box to the desired object type (e.g. Point, Cylinder, Any Body, Any Object). Each time you select an object from the Model View, the location and dimension information will appear automatically in the input fields which have been set for screen input. If a field has been set for manual data input, the current manual input data will be retained. Figure 14 shows the location information from the selection of a point via Select > Point > Locate:

By default, each selection operation automatically cancels the selection of other objects. Pressing the Shift key while selecting an object will enable the selection of multiple objects. Pressing the Ctrl key will allow you to cancel a particular selected object without affecting other selected objects. The Cancel Highlighted Objects icon in the Edit Toolbar or right-clicking in the Model View may be used to cancel all selected objects, regardless of type. The Cancel Specific Object Type icon in the Edit toolbar may be used to cancel the selection of all objects of the current object type.

Note: the coordinate location is always given in Global coordinates when using Select. Set the Action combo-box to Edit to obtain actual input definitions of an object. See the discussion below on the use of the Replace and Move buttons with objects which have been selected.

Edit

Set the Action combo-box to Edit to identify an object so that you may examine and/or revise its definition. You may then set the Object combo-box to the desired object/operation type (e.g. Point, Cylinder, Ellipse, Blend Edge, Body-Sheet, Body-Solid). Select an object from the Model View or the Object Identifier (OI) listbox under the C/A/O/M, and the input fields associated with that object’s type and creation method will appear in the Input dialog.

An example OI list for cylinder objects is shown below in Figure 15:

Once the object is selected for edit, the OI listbox status will show the object as “Selected” and the current object data will appear automatically in the input fields which have been set for screen input. If a field has been set for manual data input, the current manual input data will be retained during object editing.

To revise the object data associated with an input field, enable the checkbox next to the input field and modify the input data. Then, you may click the Replace or Move button (see the discussion below on the use of the Replace and Move buttons for an object being edited). For example, if you Edit a point defined at a parametric Global location via Edit > Point, the input fields will populate with that point’s X, Y, Z coordinates (in this case they are parameter names). Enable the checkbox next to the X: input field (current value is Tlug/2), and enter a new value (Tlug/2*100, as shown in Figure 16):

Then, click Replace to revise the point definition. If the object is associative then those objects on which it depends are also highlighted in the Model View. For example, if you Edit a point defined as an intersection of three curves (Method: Intersection-Multi), the three intersecting curves will be highlighted and listed in the Input dialog to indicate the associativity condition (Figure 17):

The following animation demonstrates how to use Edit > Cylinder to edit a hole radius from 1.0 to 2.0:

Note: when you select the object on the screen or from the OI listbox, the method by which the object was originally defined will appear in the Input dialog. You should not change the method when using Edit. Use Move To for this purpose.

Move To

Set the Action combo-box to Move To to change the definition of an existing object while keeping its object number intact. This action is intended for direct manipulation of an object with the mouse cursor. When you edit the object, it will be highlighted, and the method by which the object was created will be highlighted in the Method combo-box. Additionally, the mouse cursor will change to the Create cursor ().

To revise the definition of the object, simply redefine it as though it were a new object. You may change the creation method (such as switching from Projection to Offset), select new associative objects from the Model View, and/or supply new coordinate or dimension information manually in the input fields. When you are ready to apply your changes, click the left mouse button in the Model View, or click the Replace button. Using the Replace button will preserve any coordinate or dimension information from the original object definition corresponding to input fields which are turned off.

The following animation demonstrates how Move To was used to convert a system from the 3-Pt. Plane method to the Projection method:

Note: if you use the cursor to activate the revision, the appropriate coordinate, dimension, or associativity information will be determined by the proximity of your cursor pick location.

Check

Set the Action combo-box to Check to perform various query operations on the geometry or mesh. Check may be used to obtain object definition information, to compute the location of a Point, Node, or System object, or compute the distance between two Point, Node or System objects.

For example, set the C/A/O/M to Check > Point > Locate and select a point to return its location in Global coordinates. Next, set the C/A/O/M to Check > Point > Distance and select any two points to return the distance between the two points. When used with coplanar lines in particular, the distance will be computed between parallel lines, or the angle between nonparallel lines.

Note: the Check action is also available in the Mesh tab to identify distorted elements and free edges.

Replace and Move Buttons

The Replace and Move buttons can be used to change the definition of all selected objects. If you have identified an object using the Select, Edit, or Move To actions, you may manually change a coordinate or dimension value in the input area using the Replace or Move buttons.

• Replace will change the coordinate or dimension of the selected object to the one given.
• Move will increment the coordinate or dimension by the magnitude given in the input field.

Only the coordinate or dimension values selected for manual entry will be affected during the Replace or Move operation.

For example, if you select 5 different points, then turn on only the X: coordinate input toggle and enter a new value, a Replace operation will assign the same X coordinate to all points whereas a Move operation will translate all selected points by the magnitude of the value in the X: coordinate input field.

Hiding/Showing Geometric Objects

To hide objects from the Model View temporarily, use the Select action to identify the object(s) to be hidden and then use the Hide Objects icon in the Edit Toolbar, Display > Selection > Hide from the main menu, or the Hide option in the right-click context menu. The selected objects will then be hidden from the Model View. To restore (unhide) the hidden objects, click on the Unhide Objects icon in the Edit Toolbar, Display > Selection > Unhide from the main menu, or the Unhide option in the right-click context menu. The hidden objects will then be displayed in the Model View.

For more information on hiding/showing objects, refer to How Do I Use the Edit Toolbar to Select, DeSelect, Blank and Unblank Objects?

Deleting Geometric Objects

There are several ways to delete geometric objects from within the Geometry tab:

• Screen selection of objects in the Model View, then clicking the Delete button.
• Selection of an object number or numbers from the Index subtab scrolling list, then clicking the Delete button.
• Selection of a specific object from the Data subtab’s OI listbox under the C/A/O/M combo-boxes when Action to Edit, then clicking the Delete button.
• Clicking the DeLast button.

When Action to Select and the Object combo-box  is set to “Any Object” in the C/A/O/M combo-boxes, then any object type can be selected for deletion. To select and delete objects of a specific object type, such as circles, set the Object combo-box to the object type you wish to delete (in this case, “Circle”). Then, only circles can be selected and deleted.

If attempting to delete objects from a model, it may be necessary to first delete objects that have associative relationships that depend on the object that you wish to delete. To determine object dependencies, first select the objects of interest. Then click the “Assoc.” button. All objects that depend on the initially selected objects will also be selected. At this point you may perform the Delete operation.

For more information about identifying and fixing associativity issues, refer to Why Do I Receive An Error Message About Associativity When Creating or Deleting Geometry?

Note: if you delete an object by mistake, select Edit > Undo from the Main Menu Bar or use the Undo button in the Edit Toolbar to retrieve the deleted object. More on DeLast vs. Undo in the following.

Screen Selection

First, in the C/A/O/M combo-boxes set Action to Select and the Object combo-box to the desired object type (e.g. Point, Cylinder, Any Body, Any Object). Left-click on an object in the Model View, or hold the Shift key and left-click on multiple objects, or marquee select a group of objects by left-click + drag, to highlight the object(s) to be deleted. Then, click Delete to remove the object(s).

If selecting a single object of a specific object type for deletion, then you may also set Action to Edit and select an object in the Model View. The object can now be deleted by clicking the Delete button.

Index Subtab List Selection

First, in the C/A/O/M combo-boxes set Action to Select and the Object combo-box to the desired object type (e.g. Point, Cylinder, Any Body, Any Object). Then, change from the Data to the Index subtab. A scrolling numbered list containing objects of the selected object type (or all objects if the Object combo-box was set to “Any Object”) will appear. Left-click on the list items you wish to delete, then click the Delete button.

If selecting a single object of a specific object type for deletion, then you may also set Action to Edit and select an object from the scrolling list. The object can now be deleted by clicking the Delete button.

Data Subtab OI Listbox Selection

In a similar way that an object can be edited/replaced, in the C/A/O/M combo-boxes first set Action to Edit and the Object combo-box to the desired object type (e.g. Point, Cylinder, System). An OI listbox containing objects of the selected object type will appear under the C/A/O/M combo-boxes. Then, you may select the object you wish to delete from the OI listbox, and then click the Delete button.

DeLast Button

If you wish to delete the last object created, simply click the DeLast button to the right of the Delete button. The object will be removed from the screen, the OI listbox on the Data subtab if Action to Edit, and the scrolling list in the Index subtab.

DeLast vs. Undo

The DeLast button can be very useful to retrace several creation operations. But, be aware that DeLast is NOT the same as an Undo operation. It only deletes the last object created. Once an object is deleted, it can be recovered using Undo. Repeating DeLast will continue to delete objects in the reverse order of creation until all objects have been deleted.

StressCheck also provides an Undo operation. Undo reverses the outcome of the previous object or data operation. If an object was created, Undo will remove the object. If an object was deleted, Undo will recover the deleted object. If an object was moved, the object will be returned to its original location. Undo does not have any effect on display operations such as rotation, translation, selection, cancellation, etc.

Note: If your session contains data from a finite element solution, this data will be destroyed by an Undo operation. After an Undo operation, the Redo operation will reverse the effect of the Undo. The Undo can be repeated to retrace all object or data related operations back to the start of the current StressCheck session. Redo can be used to reverse all Undo operations. As soon as a new operation is requested other than an Undo, the possibility of a Redo is eliminated.

For more information on DeLast vs Undo, refer to What’s the Difference Between DeLast and Undo?

Geometry Disassociation

StressCheck modeling relies heavily upon associative relations to create geometry. At times, typically when performing Boolean or other solid modeling operations, it may be required to change an associative object type to a global or disassociated object type in order to complete a task. A disassociate button (Disassoc.) is available in the Geometry tab of the Input dialog to allow users to do this quickly for a limited number of scenarios.

To use this feature a supported object must be selected from the Model View and then the Disassoc. button is pressed. Once the action has been completed the object type will be changed to a global object and will no longer be associated to other geometric entities (no dependencies). The disassociate implementation is applicable to the following geometric objects:

• Points – Become global and are transformed to the Locate method.
• Systems – Become global and are transformed to the Locate method.
• Lines – Become “2-Point” lines with two global points automatically created using the Locate method.

Any of the above object types can be selected and disassociated by using the Select, Check, or Edit action. To use the Disassociate feature the following rules must be observed:

• Only one object may be selected at a time to disassociate.
• Objects that are implicitly associated may not be disassociated. Examples of implicit associations are vertex points on a box and points resulting from solid modeling operations.
• Only explicitly associated objects may be disassociated.

Once an object has been disassociated it may be re-associated by pressing the Undo button. It should be noted that the Assoc. button will not re-associate objects. Despite the similarity in the name, the Assoc. button only visually indicates what other objects are associated to/depend on the selected object. To re-associate objects, it is recommended to use the Move To action.

Example: Creating, Editing & Deleting Point Objects

Point Creation at Global Locations

Suppose we wish to construct a geometric point in Global coordinates (i.e. Method: Locate). The most straightforward method would be to set the C/A/O/M in the Geometry tab to Create > Point > Locate, check the checkboxes next to the X:, Y: and Z: input fields, and once the input fields are enabled, supply the desired X, Y, and Z coordinates. For example:

• X: 1.0
• Y: 2.0
• Z: 0.0

Then, click the Accept button at the bottom of the Input dialog. Assuming the Point display in the Display Objects toolbar is enabled, the point will appear in the Model View at the appropriate Global location (1,2,0). Alternatively, you could have left-clicked once in the Model View to create the point. You should now see a point represented in the Model View by a mark similar to a plus sign [+]. Try changing the value in the X: input field and pressing Accept again. Now change the Y: input field value and press Accept again. You should now see three points in the Model View. If you don’t, it may be because the coordinates you entered were outside the current range of the Model View. Click the Center Model icon to bring all points into view.

The point creation steps are demonstrated in the below animation:

Editing Point #1’s Location

Suppose you wish to edit the X: value of point #1. Set the C/A/O/M combo-boxes to Action to Edit and Object: Point, and make sure all input fields are inactive. Then, select point #1 from the Model View or from the OI listbox. The point’s number (Point=1) and properties (X, Y, Z inputs) will appear in the Input dialog. Activate the X: input field, and type “2”. Then, click the Replace button. The point location should now be (2,2,0).

The point edit steps are demonstrated in the below animation:

Deleting a Point

Now, suppose you wish to delete last point created. There are several ways of completing this task:

DeLast Button

The simplest way would be to press the DeLast button to delete the last object created. The user can click DeLast as long as there are objects to be deleted, and objects are deleted in order of newest to oldest. Click DeLast, and the last point will be removed from the model.

Screen Selection

If the point is visible or easy to identify, the C/A/O/M could be changed to Select > Point, and the last point created could be selected from the Model View. Left-clicking on the point will cause the associated [+] of the point number to highlight red. Click Delete, and the last point will be removed from the model.

Index Selection

If the point is not visible or difficult to identify, the C/A/O/M could be changed to Select > Point, and the Geometry subtab could be changed from Data to Index. The last point number may be selected from the scrolling list of point numbers. The associated [+] of the point number will highlight red, and the row number in the scrolling list will highlight blue with Status “Select”. Click Delete, and the last point will be removed from the model. Select the Data subtab to go back to the model data inputs.

The below animation demonstrates how the point was selected in the Index subtab and deleted:

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