Defining your requirements? Let’s start educating those guesses

13 May 2021 3min read

All medical device engineers know that defining your requirements at the very beginning of your project is important. After all, it steers your project and acts as the list you use to judge your project’s success against.

Requirements definition is not without its challenges though, as sometimes it can seem like the answer is having to precede the question.

Your product specification may well be a living document, but nothing feels worse than having to renege some of your headline figures when six months into development you find it just isn’t possible to hit your initial targets. Your stakeholders might not be best pleased either.

The good news is that it doesn’t necessarily have to be this way. Many of us are familiar with Finite Element Analysis (FEA) as a tool for concept selection and development, but what if it could be employed as a tool much earlier in your project?

Let’s consider some hypotheticals for a moment. Perhaps you have conflicting requirements, like a thermal control system that needs both good stability and fast transients? Or maybe you have some material or package size limitations but need a lot of stored mechanical energy?

Whatever conundrum you are tussling with, FEA can be used early on to rapidly assess, at a high level, what existing technologies might be able to achieve your goals, without necessarily constraining your eventual solution. You don’t want exact answers at this stage, just some knowledge of where the limits of the performance envelope might be.

One of the primary benefits of FEA is the ability to eliminate time consuming prototyping cycles, allowing you to quickly flesh out your performance envelope, which refers to the operating ranges of certain characteristics.

You might want to ask:

  • What if the power input was varied by 20%?
  • What if the ramp rate was changed from 5ºC/s to 8?
  • What if we double the spring force?

Simple models, where only a few parameters are of interest, can be set up and iterated much more quickly than you might be used to from a typical, detailed concept selection project. A few days spent early in the project could prove invaluable in getting your initial requirements in the right ball park. Such insights can help you avoid a lot of angst about deciding what aspects of your product needs to give later in the project when your development team drops an unwelcome bombshell.

So, which of your requirements are you unsure about? Perhaps we can help. You never know, it might save you an awkward conversation with your boss in six months’ time.

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