The Brainstorm is the section in Product Design & Development where we talk with industry leaders to get their perspective on critical issues in the design engineering marketplace. In this issue, we ask: Simulation Software vs. Performing an Actual Test: When is it appropriate to choose one over the other?
This is an interesting question that continues to be relevant in all areas of product development. My particular perspective is the transition from design in CAD to the physical world with manufacturing. The CAD world has made some astounding transformations over the last 20 years, and one would expect this trend to continue. The future holds the critical transition point of where the virtual world and the physical world cross in their useful application to product development.
The virtual world is excellent at providing complicated assessments of the product, how it will work, potential issues that may arise and efficient optimizations to make the “best product possible.” As these technologies continue, we would expect the output of CAD, and their respective technologies, to produce the optimum product for the given purpose. This is particularly true with regards to designing for manufacturing and product cost optimization.
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In the near future, the transition point will continue to exist when there is a need for human interaction with the product, and the engineers, managers, customers, suppliers, marketers and others need to have and hold the product for their respective jobs. While virtual reality-based systems are cool, they still don’t replace the tactile sensation of picking up a product.
Whether this is just a carry over of the old days of “touchy-feely” or the baseline for the future, it will be fascinating to watch. However, as long as products continue to be developed to be used by the end-user, there will always be some point where the transition from the virtual world to the real world is imminent.
 Richard Bush
Siemens PLM Software
Director of NX Simulation Marketing
www.siemens.com |
With inexpensive and easy-to-use simulation tools now available, you should always simulate first to save time and money. For most companies, simulation in the design phase answers basic questions about which design is better. Actual testing may or may not be appropriate for validation.
Today extensive simulation capabilities enable larger model simulation and more physics studies. Yet FEA models are still an approximation of reality. Material property, loading, mass, damping, joint stiffness, and component interaction are very complex issues and can cause analysis results to differ from an actual test. Testing has improved too, but multiple tests may still give different results, especially for large complex assemblies.
Some companies have effectively replaced testing with simulation on certain models once they have validated, consistently, that the simulation results match actual test results. Yet increased competitive pressures often require re-engineering to reduce material or resolve problems caused in new usage scenarios, so there may be fewer tests in one area, but more in another.
An ideal combination is FEA models correlated with actual tests — investigate a broader range of test conditions in less time and for less money. Correlation shows how well the model represents the test. It does not imply what to change to improve it so engineer expertise is still needed.
 Randall Restle BSEE, MS
Newark
Technical Marketing Manager
www.newark.com
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It makes the most sense to perform an actual test for simple, inexpensive systems, or when it is difficult to have a complete and accurate model of a system. For example, S-parameters of an RF circuit are commonly tested. It is difficult to know the value of all the parasitics of such a system, and there might be danger in wrongly characterizing parameters.
Simulation software tools can be expensive and developing an accurate model is time-consuming – especially when learning the simulation tool. This delays discovery of errors until the model is made, and the model still might not represent the final system.
However, because simulation software requires designers to build models of their systems, they will certainly gain a better understanding of them, and models do serve to teach others. This can be invaluable.
Modeling also improves system robustness. Subjecting models to severe inputs (provided they are accurate) reveals weaknesses. These inputs might not even be possible in the real world. Design teams can thus increase design margin before their systems are built.
Controllability and the ability to observe are key parameters in testing. A system whose nodes are 100 percent controllable and observable is said to be fully testable. Simulation has the edge, because internal nodes are easily controlled and observed.
A relatively new advance in simulation is Hardware-in-the-Loop (HIL) simulation whereby internal signals are brought out and made real where they can interact with hardware. This allows you to model either the plant or the controller. Watch out for this.
 Paul Reynolds, Ph.D., PZFlex
Associate, Weidlinger Associates
www.pzflex.com
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When designing and developing any product there is a crucial factor to consider when contemplating the use of simulation: What is the cost of the simulation compared to the cost of an actual test? Answer that question, and the choice is clear. Of course, nothing is ever that simple, and 'cost' is dependent on a wide range of factors, varying depending on the needs of the designer. But it's critical for users to answer that question.
Costs come from a few simple components — time, labor, and materials — and designers must ask themselves where their critical needs are. For a professional engineer in a large company tasked with delivering a new product to beat the competition, it's time to market that carries the premium.
If a one-hour simulation can replace two weeks of constructing and testing a prototype, then the choice of simulation is clear. For university research groups, labor and time are usually less of a cost issue than materials, and simulation is almost always a good choice, concentrating all the design, construction and testing roles to the simulation realm, under the control of the student.
Our aim is to address these key costs for our varied customer base. Our recent alliance with SolidWorks enables tight integration of our package with a world class solid modeling tool for design and drawings, cutting development time. By systematically targeting the cost bottlenecks that customers face, simulation software providers can ensure that for more and more users the answer is always 'simulation'.
When it comes to safety, simulation software is vital. When products can impact human health and safety, it’s smarter to use software that will simulate a test first – to identify potential problems early in the design process – so that people experience little or no adverse consequences during final product testing, and overall time-to-market and costs are reduced.
Many types of products must meet a host of U.S. Federal government testing requirements, such as a choke test – a common test for toys. In designing toys, a typical scenario is that a concept model is developed; then prototyped, and used for testing. If the toy fails the test, the design must be modified, another prototype made, and more tests conducted. This cycle repeats until the design passes the test.
Using a software simulation early in the design phase can help streamline this process. For example, a software-simulated choke test can help product designers conduct tests as soon as conceptual models are developed. Using 3-D touch-enabled modeling software, designers can develop digital models of toys and a virtual gauge to represent the mouth of a small child.
To test, designers grasp the digital models and attempt to pass them through the virtual gauge. If the models pass through, they present a potential hazard. Designers can then quickly modify their digital models and re-test, before producing a prototype.
While physical tests may still be mandated, this software-simulated test helps product designers create safer toys. It also enables them to arrive at acceptable final designs faster, and reduce the number of physical prototypes needed.
With the recent advancements in computing and software, I can’t think of too many situations when you would commit to metal and plastic without doing some type of modeling and simulation first. For the past 20 or more years, software companies have been slaving away building virtual tools to provide safe, cheap, simulated, options.
Software today is incredibly easy to use and becoming cheaper with every year. Even a basic spreadsheet will give you some insight into your widget, while more sophisticated, yet still very affordable, analysis tools will help you weigh many options early.
Even if your material and fabricating labor costs were very cheap, bypassing the simulation is still a very myopic view. A company that doesn’t constantly think about how to make their products work a bit better, cost a bit less, and be a bit more robust, will eventually succumb to a company that does.
The right modeling and simulation strategy is the platform that lets you explore concepts frequently and — once your organization is past the learning curve — the cost/benefit ratio shifts dramatically as simulations become easier to set up. Bonus benefits of the right simulation strategy also include easy-to-manage archives of your designs, intellectual property as well as a much deeper knowledge of how your widget works.
Nothing helps an engineer understand the inner-workings of a widget than having to develop good, robust, accurate simulation models. So, better designs, long-term lower costs, well-managed design archives, deeper understanding of your products and designs … do I need to go on?
 Keith Perrin
Autodesk, Manufacturing Division
Industry Solutions Manager
www.autodesk.com |
This seems to be a question on the mind of every engineering firm today. I would argue, though, that the real issue isn’t choosing between simulations and performing actual tests, but has to do with knowing how to best complement the physical world with the digital one.
There is no doubt that the ability to simulate and create a digital prototype is key in product development. Digital prototyping helps simplify product development because it allows manufacturers to optimize and validate their ideas before creating a physical product. Even a recent AberdeenGroup report says best-in-class manufacturers use more digital prototypes than physical prototypes. However, it is important to note that good engineering is not simply about using simulation to eliminate physical prototypes.
Rather, innovative companies are adopting new strategies to combine their digital and physical processes and calibrating their digital prototyping processes with physical testing.
By comparing the physical and digital models, companies are able to mirror the real world in the digital one. This kind of collaboration allows critical analysis and testing to take place early in the development lifecycle. Simulation testing helps save time and money that would otherwise be spent on multiple physical tests.