Multibody Design for Beginners

Written By: Dave Martin
  • 6/3/2020
  • Read Time : 3 min
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One of the biggest enhancements in Creo Parametric 7.0 – and to Creo Parametric in years – is the addition of multibody modeling. This is a game changer for product design in Creo Parametric for parts, assemblies, and top-down design. You’re going to want to adopt this as soon as possible – good thing it’s so easy to learn. So, let’s jump in.

What Is Multibody Modeling?

In the 1990s, Pro/ENGINEER (the predecessor of Creo Parametric) introduced Skeletons and data-sharing features like Copy Geometry to help manage the design of interdependencies between parts. This is essentially the core of top-down design.

In Pro/ENGINEER version 1 through Creo Parametric 6.0, when solid geometry intersected existing solid geometry in a part, the exterior surfaces and interior volumes were merged. If you wanted to avoid this behavior, you had to model with surfaces.

The introduction of multibody modeling to Creo Parametric simplifies part design and top-down design.

Bodies are containers for solid geometry. Starting in Creo Parametric 7.0, when solid geometry from a feature intersects other solid geometry in the part, you can choose for that new geometry to not merge and be in its own separate body.

How Do You Use Multibody?

When you create a new part or open an existing part in Creo Parametric 7.0, you see a Bodies folder in the Model Tree. All parts have a default body called Body 1. If you open a part from an earlier version, Body 1 contains all the solid geometry.

Multibody part geometry and model tree in Creo 7.0.

Image: Bodies now appear as part of the model tree.

You can create new bodies and set which body to be the default body. When you create new features with solid geometry, you can choose whether it goes into the default body or a new body.

The power of Multibody comes largely from the actions you can perform on bodies:

  • Merge combines two or more bodies into a single body.
  • Subtract uses one or more bodies to remove geometry from a body.
  • Intersect creates the union of two or more bodies.

A single body can even be split into two bodies using a datum plane, a surface, or a quilt. Also a selected disjoint geometric volume can be split off from a body.

Using a body to subtract geometry from a part.
Image: A body is used as a subtractive tool to create a pattern on a part.

A body can be converted to sheetmetal. In this case, you will have both a Sheetmetal tab and Model tab for mixed modeling in the part. You can also set a body to be construction, in which it won’t contribute to your mass properties.

You can assign different appearances, materials, and parameters to bodies. You can create a “Bill of Materials” to list different bodies and their properties on drawings.

With appropriate licenses, you can create a separate part from a body and can control whether changes to the source part are propagated to the extracted part.

These tools are simple to use but provide enormous design capability.

When Should You Use Multibody?

PTC has identified multiple use cases for the initial release of Creo Parametric 7.0, but quite simply, Multibody should be used anytime you want to simplify the design process. It can be used when you want to design:

  • Interdependencies between parts, especially in assemblies with a low number of components, without having to use Skeletons and Data-Sharing Features.
  • A solid part and split it into multiple parts.
  • A part with multiple materials.

Multibody is also used extensively in Topology Optimization, Generative Design, and Additive Manufacturing. Creo 7.0 combines multiple technologies for the next stage in computer-aided engineering.

 
  

What’s Next for Multibody?

Martin Neumueller, the product manager for Multibody, continues to work on larger enhancements for Creo Parametric 8.0 and beyond along with a number of smaller enhancements in maintenance releases of Creo 7.0.

If you want to help influence the future direction of Multibody Modeling in Creo Parametric, propose your ideas on the PTC Community website and get involved in the Creo 8.0 multibody working group.

This is an exciting time for modeling in Creo Parametric. Multibody is part of the core functionality, so all you have to do is install Creo 7.0 to start using it. Give it a test drive today – it will revolutionize and transform your approach to modeling.

To learn more about using Multi-body design in Creo Parametric, replay Martin Neumueller’s recent virtual presentation and follow his multibody blog on the PTC Community site.

Replay: Multibody Design Use Cases in Creo 7.0

Tags:
  • CAD

About the Author

Dave Martin

Dave Martin is a former Creo, Windchill, and Mathcad instructor and consultant. After leaving PTC, he was the Creo specialist for Amazon; and a mechanical engineer, Creo administrator, and Windchill administrator for Amazon Prime Air. He holds a degree in Mechanical Engineering from MIT and currently works as an avionics engineer for Blue Origin. 


Martin is the author of the books Design Intent in Creo Parametric and Top Down Design in Creo Parametric--both available at www.amazon.com. He can be reached at dmartin@creowindchill.com.

Multibody Design for Beginners | PTC
With multibody design, bodies are containers for solid geometry. As an example, you can use intersecting geometry to create a separate body. Learn more.