Inventor In-Depth: Functional Design Gets the Right Designs Done Faster

14 Apr, 2005 By: Kevin Schneider Cadalyst

Autodesk Inventor 10 incorporates intelligent tools that work the way engineers think

One of my earliest introductions to engineering was a grammar-school exercise in building a peanut butter sandwich. The teacher stood in front of us with a loaf of bread, a jar of peanut butter and a knife. The students were to give her instructions for assembly.

We told her to take out two pieces of bread. Next, we told her, "Put peanut butter on one slice."

Following directions, she picked up the jar and balanced it on top of a slice of bread. We hadn't suggested unscrewing the lid or using the knife. We thought this was hilarious, and silly as it was, the exercise was a lesson in one of the primary challenges in product design: abstraction.

The latest release of Autodesk Inventor, launched in March, tackles some of the long-standing constraints that technology has placed on engineers -- constraints that make design work abstract instead of intuitive. Specifically, Autodesk Inventor 10 includes more capabilities for functional design, tools that let engineers start with product performance to get to the right design. I'll review some of these features in this month's column.

Functional Design Works the Way Engineers Think
Take the handheld vacuum. Most likely an engineer conceived the whole first, including function, style and ergonomics: A vacuum that's small and lightweight enough to carry easily, powerful enough to operate at different angles and comfortable to grip.

Next, conventional design technology requires a step of abstraction -- like the instructions for building a sandwich. To use design software, the engineer must abstract his or her idea for the end product into elements such as geometry and features, the number of parts and how they might fit together.

This is not a very intuitive way to work. Users of 2D software spend a lot of time capturing ideas in AutoCAD and then tweaking lines, arcs and circles until calculations indicate the drawings should work. Then they build a prototype and fit the parts together to evaluate function. That's when they discover if the design works as intended. Often it's back to the drawing board.

Enter software capabilities for functional design. Functional design entails a more intuitive approach to design that's congruent with engineers' thought process. Functional design tools help engineers get past the limitations of geometric modeling.

Functional design capabilities are noteworthy because they describe how parts work and what they do, not just their dimensions and physical features. As a result, designs are active, not static; they have built-in intelligence to reflect the actual behavior of the parts they represent -- including the relationship to other parts.

Ultimately, functional design gives engineers the ability to begin the design process with the end-product's performance, and then define relationships among product components rather than their geometry. In functional design, torque and speed characteristics are built into a gear, and the first gear knows it must interact with another gear; it's not just a representation of a disk with a certain number of teeth of specific dimension.

Autodesk Inventor 10 Adds More Functional Design
If you've used Autodesk Inventor Professional, you've experienced functional design by working with tools for automated tube, pipe and wire harness design, and tools for built-in FEA (finite element analysis) from Ansys. Piping design capabilities incorporate user-defined styles, rules, and pipe properties, rather than simply tracing pipe placement (figure 1). FEA mesh and analysis is produced automatically from user-defined loads, revealing how parts perform based on actual characteristics.

Figure 1. Properties are built into piping design elements to reflect their function.

The latest Autodesk Inventor family of applications includes new functional design capabilities. Autodesk Inventor 10 lets engineers simulate the motion or action of a product from within the design application. Engineers can create parts and assemblies based on real-world attributes, using drag-and-drop tools to quickly build 3D models without the abstraction required for parametric design.

  • Design Accelerator automates creation of parts and assemblies based on object properties rather than geometric descriptions. Tools for doing so include the Engineer's Handbook, a comprehensive online reference for engineering formulas and manufacturing; Mechanical Calculators for design and validation of mechanical systems, from weld and solder to fit and tolerance; and Component Generators, which incorporate user-defined conditions -- from power, speed, materials, and torque to working temperatures -- to address mechanical connections between assembly components.
  • Feature Generator lets engineers create parts by dragging and dropping shapes from a library of standard geometry that has built-in intelligence to reflect attributes such as speed, power, and material properties (figure 2). Using 3D Grips, users can edit parametric parts through drag-based action.

Figure 2. Drag-and-drop standard components build a functioning assembly.

  • Autodesk Inventor Studio produces state-of-the-art rendering and animations within the Autodesk Inventor design environment for high-quality, photo-realistic renderings and animation of designs (figure 3).

Figure 3. Animation capabilities within Autodesk Inventor help show a design's function.

Take Less Time to Get to the Right Design
Functional design allows engineers to start with the end-product's performance and move on to the relationships among product components. For example, functional design tools build torque and speed characteristics into a gear, and the drawing element knows it must interact with another gear -- it's not just a representation of a disk with teeth.

That means engineers spend less time trying to master modeling software to get a 2D idea into a 3D representation. Without the drafting tasks and abstract thinking required by conventional design, functional design is faster and more intuitive. Instant insight into components' interaction makes designers more productive: They can optimize designs as they work, modeling product quality and cost trade-offs and reconciling them quickly with fewer prototyping and refinement cycles to get to the right design.

About the Author: Kevin Schneider

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