Siemens Boosts PLM with D-Cubed Update 

Digital manufacturing offers clear advantages over traditional methods, particularly in the area of prototyping. There, product lifecycle management (PLM) software can act as an extension of a designer's and engineer's imagination to create a product that reflects its inspiration down to the pixel.

At the core of many PLM offerings, including popular products from Autodesk and Solid Edge, are Siemens' 3D D-Cubed software components, which have recently been updated to version 46.0.

The components are comprised of Siemens' 3D Dimensional Constraint Manager (3D DCM), Hidden Line Manager (HLM), Collision Detection Manager (CDM) and the Assembly Engineering Manager (AEM). Each of these parts plays a key role in enabling the highly-precise workflow that PLM is known for, whether it be constructing an object itself, enhancing the user interface or preventing accidental collisions during a products physical assembly.

One critical advantage of employing computers to model objects and carry out simulations is that the end user can create physical conditions not normally possible, but this freedom means that it becomes easy to lose sight of what is and isn't physically possible when constructing a model.

This is where Siemens' first 3D D-Cubed component, the 3D Dimensional Constraint Manager, is designed to come in.

Ideally, a model created through CAD software is considered “well-defined” once it is done, meaning that the rules provided by the user leave no room for interpretation. Not only that, but the rules should result in each angle and plane meshing together to create a structure that is geometrically possible. Similarly, multiple objects designed to interlock should be physically be able to do so.

But when a user incorrectly adds one constraint too many, creating a conflict with the other design requirements, 3D DCM is designed to provide diagnostics that identify what is over- (or under-) defined, and recommend dimensions that would make it well-defined.

To tackle the over-defined model problem, Siemens has included in this update additional equation solvers to provide a more robust defense against constraint conflicts.

An additional feature that is essential to a successful PLM offering is the effective visualization of 3-dimensional shapes on a 2-dimensional drawing.

Neil Howarth, business development manager at Siemens PLM explained that creating effective drawings for manufacturing applications necessitates the effective translation of 3D content to a 2D medium. “Once you project that x, y and z, you just get the kind of drawing someone would work from in a manufacturing context.”

A common problem in achieving this is being able to teach the program how to hide lines that should not be visible when viewing a design from a given perspective.

A popular example of this problem is the Necker Cube illusion. Here, the wire frame of a cube is drawn by overlapping two equally sized squares and connecting their corresponding corners with diagonal lines. If no other depth cues (such as dotted lines) are given, either plane could be perceived as being in front of the other.

This same problem can also confound digital designs, which is where Siemens' Hidden Line Manager comes in. HLM has been designed to calculate which planes and edges are hidden from a particular position, such that those lines can be altered to create a sense of depth. The component specializes in computing visible, hidden, occluded and silhouetted edge segments within a drawing, helping designers and engineers to create clearer, more effective visualizations.

In Version 46.0, HLM's reflection transform tool has been enhanced by improving users' ability to reposition repeated instances of parts.

Next -- Geometry Meets Physics in Object Collision >

As far as the manufacturing process itself, ensuring that the moving parts' assemblies do not accidentally collide is essential. So rather than locking up an expensive machine tool, the Collision Detection Manager is designed to compute exactly where and how a collision will occur along a given path. It is also capable of providing clearance calculations among various moving parts.

By using exact models of the assembly design process in tandem with motion simulation, the software is able to identify the precise location where motion would be impeded. Because there are no approximations involved, manufacturers are then able to consolidate an otherwise expensive prototyping process.

Where precision engineering is key, using an exact model like that of CDM has clear benefits, as collisions that result in model approximation error no longer occur. However, CDM is also capable of using faceted model formats for applications where pinpoint accuracy is not a concern.

Siemens' final 3D D-Cubed component, the Assembly Engineering Manager is an example of where technologies have built upon one another to take basic physics engines normally seen in video games to a more accurate (and practical) level in order to predict what happens when objects come into contact with one another.

What AEM is designed to address are the complex physics simulations of the interactions that occur between objects being assembled, which requires the geometric-constraint data from HLM, the collision algorithms from the CDM, as well as specific physics equations that predict not only where a collision occurs, but what that collision looks like.

Howarth commented that there are more advanced motion solvers out there that do physics, but contact between B-rep solids (the objects created within PLM software that are defined by their boundaries) is one area that other companies have shied away from.

“It's one of our least-used components (relative to the prevalence of the geometric constraint solvers), but it's probably our more sophisticated component, given that it combines two of the other components plus a lot of additional technology.”

As for whether or not you'll be seeing these updates in your own PLM software, that depends. Although Siemens 3D D-Cubed components are featured in a vast number of CAD and CAM offerings from various companies, when they pick up specific updates from Siemens depends on their own development cycles.