[Editor’s note. Traditionally, a company that wanted an analysis of a product design left it to the simulation experts—people who specialized in FEA and CFD. But with the introduction of in-CAD simulation technology (like Creo Simulate), design engineers can run their own studies on their models. The question is, should they?
We asked our simulation expert to weigh in on when to engage an expert, when to do it yourself, and how to make the most of any consultant you hire.]
Carrying out Finite Element Analysis (FEA) on a CAD model can represent quite a learning curve. Do you need an expert to help you? Well it depends on how deep you are diving!
The level of effort required for analysis will, in turn, depend on how important the analysis is within your design process. For example, , if you are designing a part to meet airworthiness, vehicle safety, or maritime certification you may have formal requirements that are going to be stringent. Essentially, anything that includes safety compliance will require formal simulation analysis and justification. It wouldn’t be wise to attempt an analysis to these levels of sophistication without a fair bit of experience.
On the other hand, you may be carrying out a product improvement to meet your own in-house requirements for reliability and performance. It is still a very useful exercise to document what your objectives are going to be and how you will attempt to meet them using simulation. However, you will be doing this outside a formal justification process.
Alternatively, you may be using simulation purely as an awareness exercise. Can you get a feel for the relative strength and stiffness of the different designs that are evolving? This is a very useful approach that I see many designers taking. It gives great insight into the cause-and-effect of the design process.
Whichever level of simulation effort you are anticipating, one possible way to speed up the learning curve is to use a simulation expert. This is essential for a formal safety justification. However, it may be considered a “nice to have” if you are exploring the structural performance of your designs in a more informal way.
And a word of caution for do-it-yourselfers: Example problems from the user manuals and carefully selected training videos can be very useful. However, if you use publicly available demo videos, for example from YouTube, be careful of those that emphasize pure software menu workflows on simplistic models (i.e., button pushing) as they tend to include very poor modelling practice.
You may commission a simulation expert to undertake the complete planning and execution of the project, and to teach you the steps along the way. The advantage then is that you can move more quickly up the learning curve with minimum risk to the project.
The key stages the consultant will be going through will include reviewing the brief, assessing the analysis implications and reporting requirements, planning the work, and finally executing the work and writing a report.
One of the important things to assess here is the level of technology transfer that the expert is prepared to provide. Some consultants keep their skills close to their chests! Others take a more enlightened view and consider technology transfer as part of the service. You will obviously want to avoid the first option.
Alternatively, you could opt for a mentoring approach, whereby the consultant guides you through this process, but you carry out the actual work. I have used this approach; however, it can get cumbersome because a typical FEA project is an evolution. Taking wrong directions in the early stages of a project assessment and then making course corrections is normal. When the client is doing the work, it is difficult to monitor this path, which is why I personally prefer that clients closely shadow my work. The process is then analogous to flight school, the first project is carried out dual and the next project can be carried out solo.
You may be surprised to find that your consultant uses little or no reference to deep-level theory on finite element analysis. The emphasis is instead on best practice. This includes standard methodologies for carrying out the analysis and a good understanding of the implications of loads and boundary conditions.
The analysis methods need to match the physics of the component and its loading environment as closely as possible. Stress convergence is also a dominating factor; are the elements sufficiently small and well-shaped to allow an accurate solution? Other metrics will be used to check that the solution makes sense from a numerical point of view.
A good briefing on each stage of this process will help you understand how the consultant is looking to improve confidence in the model, and hence that of the reviewer or checker.
It is a good idea to engage a consultant who is familiar with the concept of technology transfer. You don’t want a complicated report that snows you under with jargon and gives little insight. The best approach is a series of briefing milestones based around a clear set of objectives. At each stage you will be able to ask questions as to the methodology, the key metrics, and decisions taken.
The deliverables need to be clearly defined. This will include the certification report and any supplementary information you will need. As a final kicker, I would always recommend requesting a copy of the analysis file, which you can run subsequently. This is a stringent requirement for the consultant, and you may get pushback. However, if contractually possible, this will give you a great resource to experiment with and develop your understanding further.
So, at the end of this process you should have a satisfied certification authority and have gone up that learning curve in a significant way!
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