This post describes the key enhancements introduced in version 68.0 of D-Cubed 2D DCM (2D Dimensional Constraint Manager).
Singular Dimension and Constraint Configurations
A major strength of 2D DCM is its ability to handle a wide range of models, including those which are in mathematically complex configurations. An example of this are models which are singular.
The pictures below give two examples of singular models.
This model becomes singular if h1=h2 and v1=v2. The points will
be coincident and the angle of the line will be undefined.
The model on the left is not singular and all dimensions can be changed independently. The model on the right is singular and it is not possible to find a solution if the dimensions are changed independently.
For most users, models containing singularities are undesirable because their behaviour can be unstable and harder to predict. For example, geometry may be under-defined, but adding any additional dimensions or constraints will make it over-defined. Singular models will also frequently be slower to solve. Typically it is straightforward to get a non-singular configuration by using a different set of dimensions and constraints.
Two new features have been introduced in version 68.0 of 2D DCM related to the handling of singular models and these are described in the following sections.
Sophisticated new techniques have been introduced to determine efficiently and accurately if a model contains singular dimension and constraint configurations. The number of singular regions in the model will be found, together with the dimensions and constraints which are involved in a singularity. Applications can use this information to highlight the issue to users and suggest that the model is changed.
Enhancements to Autodimensioning
2D DCM offers various methods and options for automatically identifying dimensions and constraints which can be added to under-defined geometry. However, as described above, singular dimensioning schemes can degrade stability and performance. The latest release of 2D DCM better analyses dimensions before they are added to determine if they would make a model singular, and will use different dimensions instead.
About D-Cubed 2D DCM
D-Cubed 2D DCM (2D Dimensional Constraint Manager) is widely acknowledged as the leading 2D geometric constraint solver. In addition to driving the sketcher in many CAD products, 2D DCM is used in CAM, CAE and other geometry-based applications.