True integration puts system-level simulation into component-focused CAD

NASA Tech Briefs, Oct 2000 by Wegienka, Alan

Mechanical design simulation tools that are truly CAD-integrated deliver advanced simulation technology at an affordable price.

Savvy manufacturers competing in a global marketplace undoubtedly have invested in a myriad of software and hardware systems for computer-aided design, manufacturing, and engineering (CAD/CAM/CAE), as well as product data management (PDM) and enterprise resource planning (ERP).

Those same manufacturers probably have also spent tens of thousands of dollars on training, support, and maintenance of these computer resources - all with the aim of reducing time to market and improving quality in new product development.

In the design-for-manufacturing realm, an engineering team is likely deploying the latest mechanical design automation tools. New products are now created using realistic 31) solid models, which allow engineers to investigate the form and the fit of a design long before bending any metal or cutting any plastic in the prototyping phase.

This computer-aided approach already should be reaping important benefits for manufacturers. When a physical prototype of a design is finally built and tested, the parts usually fit, assembly interferences are less of a problem, and getting it right the first time is a realistic goal.

But after investing all of this time and money on the technology and support resources required, there's at least one critical question about a new mechanical system design that must wait to be answered by hardware prototypes: Does it work?

A new product that jams, breaks, or fails even after undergoing extensive design, testing, and production procedures is an expensive mistake that can cause a manufacturer to miss a critical window of market opportunity.

Getting Answers Early

Consider just these two new product examples: seat restraints for next year's vehicle designs and the latest cellular phone models. These products must meet mission-critical design requirements and stringent production schedules. If a manufacturer can't deliver quality products on time to demanding customers, there are plenty of competitors who can, and who will. And this cold, hard reality probably holds for most manufacturing industries.

Why let it happen? The smart approach is to address issues of functional performance early in the design cycle - at the same time the form and fit of a design is investigated and perfected. In this way, design mistakes can be found and corrected when the cost of addressing them remains low.

The bottom line is this: If one has the right tools to investigate the functional performance of a design at the same time its form and fit is evaluated, one would have all of the pieces needed to start truly realizing the long-promised time-saving, cost-cutting, and quality-improving benefits of digital product development.

Proven Simulation Technology

Available today is CAD-embedded mechanical design simulation technology that's fully up to the task of answering the "does it work?" question. The most sophisticated of these software solutions also provide information needed to answer another important question about a design: Will it break?

The underlying technology for these products was developed more than two decades ago and has gained widespread acceptance by large companies' engineering teams developing complex products such as automobiles, aircraft, and space vehicles. These organizations have learned that by investigating the functional aspects of their designs on the computer, before building expensive physical prototypes, they can deliver better new products to market faster. At the same time, they have been able to reduce their overall development costs while evaluating many more design alternatives than before.

Today's mechanical design simulation products take design geometry created in CAD in the form of wireframe, surfaces, and solids that represent an assembly of moving parts. The user can then add special motion-related items such as joints, springs, motion generators, and forces to produce a complete motion model. The user simulates the assembly's motion over a period of time, calculating the displacement, velocity, acceleration, and reaction forces for each part in the assembly. This information can be used to produce animations and calculate interference ("Does it work?").

Mechanical design simulation also can generate operating loads needed for structural analysis ("Will it break?") using finite element analysis (FEA) software. In this way, the technology serves as a valuable complement to FEA.

CAE tools that are truly CAD-integrated - not just stitched on through clumsy interfaces for exchanging design geometry between software packages deliver the same advanced simulation technology at a price affordable by even the smallest manufacturing organization or engineering workgroup.

What's more, since designers call up the simulation software's functionality from directly within their familiar CAD environment, they get answers to their design performance questions without having to learn new software or taking extra steps to transfer data.