Unless you’ve lived in a cave for these past 40+ years, you’re certainly aware of the leading (literally) role that analysis, or simulation, plays in new product development. Fueled with real-world test data, CAD models are put through their paces in the early upstream development stages to determine product integrity, performance and longevity. Today analysis is used to help ensure profitability before raw materials are even ordered.
But what about equipment currently used in the field? What role does analysis play in solving mechanical or structural failures and ensure that companies can maximize their investment in costly machinery? We talked with Six D Testing & Analysis engineers Steve Biel and Likith Nagaraja to learn more.
How does the 6D testing and analysis approach differ from the traditional applications of both testing and analysis?
Likith: In many failure investigation cases, we use Finite Element Analysis as a first step to assess the dynamics of the structure. We do various static, modal G-loading, response analysis to determine if there’s something we can attribute to the problem. These hints from FEA helps us shortlist the tests we want to do and the transducer map. Sometimes it may be more of an application/customer usage/handling related issue. We also take into account these considerations. All these information shall be used in the development of a test plan. If we have high suspicion on a certain root cause, we also try to develop a fix for those issues in our FE model before the testing, this way when we determine the root cause during the testing we could implement the fix and validate it.
So analysis is employed after testing?
Biel: Yes, in many cases analysis is used to evaluate and disprove or validate solution alternatives. However, we also employ analysis tools to guide testing. After creating a model of the system analysis is performed to help identify areas of concern or probable problem areas. This helps accelerate the problem-solving process to get equipment back into operation more quickly.
Can you elaborate on this?
Analysis is a versatile technology and should be leveraged as such. Testing tends to be more precisely focused on specific areas while analysis provides a more broad system-wide approach. When dealing with complex systems a crack, for example, may be the result of vibration emulating from a seemingly unrelated component. Pretesting analysis helps identify probable cause areas and determine where testing should be focused, where to lay strain gauges, place accelerometers and so on.
Do you have an example of this?
Likith: When equipment is down or operating at less than full capacity, the customer is losing money. As a result many of our troubleshooting projects require us to arrive on-site with a solution in hand. There is an example of an off-shore oil platform experiencing genset failure. Obviously it was cost-prohibitive to fly half way around the world, helicopter out to the platform, collect data, return to the office to run an analysis, engineer a fix, and make the return trip to fix the problem. Instead what we did was to analyze a model in advance of a site visit. This allowed us to highly suspect two probable areas of concern. We were able to arrive on site equipped to implement either solution. After quickly collecting operating data we were confident in the solution and implemented the fix. What’s more the client was able to replicate the solution in gensets across its multiple oil platforms to avoid similar failure. This literally saved them millions of dollars.
So analysis in 6D’s approach might differ from traditional uses?
Biel: Yes, think of it as Just-in-Time Analysis. We know that our clients don’t have the time or money for long analysis projects. We use our analysis tools to provide quick answers or guidance to help engineer practical solutions.
What analysis tools do you use; and how have they changed in the past 40 years?
Biel: We currently use NX I-DEAS, NX Nastran, and LS Dyna. Let’s be honest. While there have certainly been advancements in usability and features, the underlying math on which analysis is based has been around since the 1700s. Software providers have simply digitized these calculations over the years. But it’s safe to say that these and other tools will continue to become more robust and user-friendly.
Do you foresee a day when testing and analysis will not be needed together?
Likith: There are a lot of advancements in the world of analysis. Many companies use virtual testing and Hybrid Simulation to develop a robust model during the design phase. With all the latest tools and of course with experience, one could develop high confidence in their design/model. But there are also non-linearities, complex loading conditions which cannot be simulated very accurately in the model. I’d say testing and analysis will be used jointly at least for the next 10-15 years.
I’ve read where simulation is becoming more democratized; that is being made more accessible to non-analysts. How might this affect its role in testing and analysis?
Biel: As Likith mentioned, today’s equipment and structures are becoming more complex. But this also applies to simple structures. For example, brackets are being manufactured with fewer welds. Pinpointing areas of high stress and weakness are less obvious and require a certain level of expertise and experience to make good judgement calls. Democratized simulation is useful in a new product development scenario where simulation templates or simulation applications can be used to evaluate a number of design alternatives. But in the “fix it yesterday” world of troubleshooting experience is vital.
About Steve & Likith
Steve Biel is a professional engineer with more than 25 years of design, analysis, testing, and project management experience in the automotive, machine tool and consumer product industries. He provides engineering and finite element analysis expertise to clients in the areas of design, development and testing.
Likith Nagaraja is a Test and Analysis Engineer. He is a masters graduate from University of Cincinnati specializing in Structural Dynamics and Vibration. Likith’s roles include testing, data analysis and FEA projects. He is experienced with modal analysis, rotating machinery vibration analysis and fatigue concepts. Previously Likith worked for Cummins, Godrej & Boyce Mfg. Co Ltd and Volvo Construction Equipment.