Product: ABAQUS/CAE
Benefits: You can control the geometry in a sketch and create parametric equations to relate pieces of geometry. Several new tools and options are available, and the functionality of many existing sketch creation and editing tools has been enhanced.
Description: Constraints, dimensions, and parameters control sketch geometry by creating relationships within a sketch. Constraints create logical relationships, dimensions create numerical relationships, and parameters create mathematical relationships between entities—Sketcher constraints include all three types of controls. Use the following tools to add and edit Sketcher constraints:
Use the constraint tool 
to add coincident, concentric, equal length, equal radius, fixed, horizontal, midpoint, parallel, perpendicular, symmetry, tangent, or vertical constraints to a sketch.
Use the auto-constrain tool 
to allow ABAQUS/CAE to constrain selected geometry automatically. You can use the sketcher options to control the types of constraints and the tolerances within which constraints will be added.
Use the dimension tool 
to add dimensions to a sketch. You can use this new interactive tool to add horizontal, vertical, radial, angular, and oblique dimensions to your sketch without switching tools for each dimension type. ABAQUS/CAE uses your geometry selections and the cursor position to determine the type of dimension that you want to add.
Use the auto-dimension tool 
to allow ABAQUS/CAE to dimension selected geometry automatically. You can use the sketcher options to control the types of dimensions that can be added.
Use the dimension modification tool 
to edit dimensions, convert dimensions into reference dimensions, or associate dimensions with parameters.
Use the Parameter Manager 
to add, organize, rename, and edit parameters and to access the Expression Builder to create parametric equations.
Use the Sketcher customization options 
to select the types of constraints and dimensions available for use with the auto-constrain and auto-dimension tools, the constraint solution methods used for editing geometry, whether parameter values or names are displayed in the sketch, and other aspects of a sketch's appearance.
) and a symmetry constraint (a line with a circle on each side) are applied to the top bolt hole to show that it cannot be moved and that it is symmetric with the bottom bolt hole (the horizontal construction line is the line of symmetry). The holes also have an equal radius constraint (a long dash through the edge of the circles) so that any change in size affects all of the holes. ABAQUS/CAE colors fully constrained entities green to indicate that they cannot be modified without changing the associated controls. Unconstrained or partially constrained entities are displayed in yellow. If objects are overconstrained—where the number of controls exceeds the number of degrees of freedom—they remain yellow, but ABAQUS/CAE displays the symbols of the conflicting constraints in magenta. There is an overconstraint in Figure 4–1 because in addition to the equal radius constraint two of the bolt holes are dimensioned (the dimension 2. on the holes on the positive X-axis and in the lower left quadrant)—with the equal radius constraint only one hole's radius should be dimensioned.The image is animated to show the resolution of the overconstraints by converting the lower left radius dimension to a reference dimension. Reference dimensions indicate the size of the entity without controlling it. The reference dimension for the flange base feature and the dimension for one of the holes have been associated with parameters. The Parameter Manager is shown in Figure 4–2. A parametric equation relates the position of the hole to the size of the flange. The flange radius is a reference dimension since the size of this reference geometry cannot be changed within the sketch for the bolt holes. Other additions and changes to the Sketcher include the following:
You can query a sketch to indicate the entities associated with a constraint or to list the total number of geometries, constraints, dimensions, and unconstrained degrees of freedom.
You can drag individual vertices, edges, construction lines, and dimension text to new locations.
Separate tools are available for translating, rotating, scaling, and mirroring entities. Each tool allows you to choose whether you want to move or copy the selected entities.
Drag and move operations are controlled by the constraint solver settings in the Sketcher options and the applied Sketcher constraints.
If the grid and sketch cursor coordinates are different (for example, if you change the grid origin or add a saved sketch such that ABAQUS/CAE realigns the grid), the grid coordinates are displayed in the upper-left corner of the Sketcher and the sketch coordinates are displayed in the upper-right corner.
Sketch module: AddAuto-Constrain, Constraint, Auto-Dimension, Dimension Edit
