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Snap-Fit - Material selection for fatigue

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New Member
Joined: 13 years ago

Dear members of PolymerFEM!

Enclosed you can find a predesign of snap-fit connection.This is very small component, which have to survive at least 100 000 cycles. The part will work at room temperature. One cycle (open/close) will take 3 [s] and the opening/closing forces are about 50N.

I have selected polyamid 66 (PA 66) for this application. As plastic analysis is not my daily work I want to ask you if this would be a good choice.

If you know better material at reasonable costs with a good behaviour in fatigue and wear, please recommend me it. Please consider only the materials for which you have S-N fatigue data.

It is generally a problem to get S-N diagramm from online resources. In case of 100 000 cycles I would assume for PA 66 the allowable stress at 50MPa (according to material data yield stress is 80MPa). If I am wrong, please correct me.

Thanks a lot for your support!

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Posts: 3998
Joined: 5 years ago

PA66 sounds like a fine material choice. It has good mechanical properties and fatigue life. Note, however, the mechanical response of many PA resins degrade if exposed to water.


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