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Do I Need to Hire an FEA Expert?
When exposed to a need for engineering simulation, whether it be to investigate a part failure, meet a regulatory requirement or make a more robust design, organizations are often forced to choose among the following three options:
- Physical testing
- In-house simulation
- Outside consultants
All three options have value and, if time and budget were not an issue, performing a combination of all three might be the most valuable solution. Unfortunately, companies rarely have this luxury, and thus must often select the best option of the three. To aid in this selection process, I have listed some pros and cons from my 35 years of engineering simulation experience.
Pros of Physical Testing:
1. Engineers can see the product break and capture a failure mode of actual geometry and materials under physical loads.
2. Results can be easily explained to outsiders. As the saying goes, a picture is worth a thousand words. I would suggest one could add a cliché that a broken part impact is worth a thousand pictures!
Cons of Physical Testing:
1. Testing takes a lot of time and money and multiple tests are not scalable like simulation. Running 100 tests costs close to 100 times the initial experiment, where 5 to 10 additional simulations might be performed for the same cost of the first analysis.
2. Testing can be affected by errors that might not always be obvious. For example, even for a simple dog bone material tensile test, I have seen cases where the slipping of clamps lead to a significant underestimation of material stiffness.
3. Testing can sometimes lead to misleading conclusions, since it is often not possible to model the real life problem.You aren’t going to build a dam for physical testing. Models used in experiments often present scalability issues. For example, keeping stiffness properties consistent with a shaker table test typically requires the engineer to choose either axial (N^2) or flexure (N^4) correlation.
4. Testing is not predictive – the part must be designed and built before it is tested. Design changes are very expensive to make after the fact.
Pros of In-House Simulation:
1. Engineers have knowledge of the parts including material properties, connections and physical application.
2. Costs are limited to the software and salary of current employees.
3. Repurposing existing calculations can provide fast and valuable engineering insight.
4. Knowledge regarding simulation methods and processes is developed as a core competency of the engineering team.
Cons of Simulating In-House
1. The engineer might not have the experience to intuitively spot simulation results that don’t look right. For this reason, errors in simulations occur much more often due to the inexperience of the analyst. Selecting an efficient process of checks to perform verification and validation takes experience. This blog post provides a great initial go-to check list, but without knowing when to perform which checks it is likely to be cost and time prohibitive to complete the entire list. Thus, with the inexperienced engineer, some of the most important checks might never get done.
2. Time of the solution. The in-house engineer usually wears many hats and thus might not be able to dedicate enough time to perform the solution. They also will spend more time developing the model, creating a reasonable mesh, boundary conditions etc. than the expert consultant.
3. Potential lack of understanding of the detailed physics. For complex problems, it can be very dangerous to have the engineer run simulations without a complete understanding of the physics. For example, assuming a linear stress analysis is not sufficient where material plasticity and/or permanent creep strains cannot be neglected.
4. Will they honestly recognize their own limits? Are they encouraged to leverage the knowledge of internal or consulting professional analysts?
Pros of Hiring a Consultant:
1. Analysis is all they do, so their experience can narrow the focus, speed and accuracy of the simulation to provide an efficient robust simulation.
2. Getting an outsider involved can provide a fresh look at the problem without the bias of the “we do this because we have always done this” analysis process.
3. With sound engineering knowledge and experience they can intuitively spot simulation results that don’t look right.
4. They can educate the in-house staff to better utilize the software tool to make them better analysts.
5. They have experience in the field and have past projects that may mirror the project at hand. This helps to give you peace of mind knowing that your simulation is being guided by an expert who has seen your situation before.
6. It may be cheaper than hiring a new employee, where having to pay for benefits, work space, technology and training may not always be justified.
Cons of Hiring a Consultant:
1. If they are not qualified, they could be missing the point. It is important to find a consultant that understands the engineering physics and also has experience that is easily transferable to the problem at hand.
2. The consultant might approach the job with a one-size-fits-all mentality and thus is unable to meet the cost and time deadlines by utilizing engineering judgement in developing the best modeling methods and solutions to meet the customer’s needs.
3. The consultant may share only the final results, and not how they were obtained, thereby depriving the engineering team of true insight into the problem and getting them no further along the learning curve towards tackling similar problems on their own.
There is no single option which is best all the time. The decision depends on many factors which will be unique, not only within each organization, but in different situations. The value of the simulation expert comes from their experience in solving complex problems quickly and accurately. If you find a consultant that is also willing to share their knowledge and mentor your team, that will be a significant added benefit. What is your experience with FEA consultants? I would love to hear other pros and cons on this difficult decision process.
by: Chris Mesibov
by: Chris Mesibov
by: Chris Mesibov
by: Chris Mesibov
by: Peter Barrett
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