Apolo79,

What is a parametric mode?

You need to design a spring element, taking advantage of many plastics' flexibility.

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JHG

There's many articles on the web for plastic snap fit design. I'm sure some have equations you could plug into Excel for a parametric study. Not quite sure how yours works.

....Parametric model, for example

there is nothing about these snap-fit. Are about simple snap-fit

A snap fit means having the ability to distort enough to fit past an obstacle without permanently damaging the part.

In models that means an FEA to determine factors such as how much contact pressure there is, how much strain there is, and from the strain, determine if the material will break from the resulting stress. There's no formula for any of those.

That picture doesn't look like a good snap fit solution - it appears to require far too much distortion to deflect without breaking.

Take a bunch of things that have snap fits apart and see how they work. You can measure to see the required distortion and measure the force required to produce that distortion to get an idea of the material properties involved.