Spring impact

[AustProjEng]

I'm designing a spring as a fall arrest but my mechanical design side is rusty. Mainly work on pumps and piping

Spring is attached to a beam above the person. Person slips and falls off a ledge 3m (static elongation due to mass applied statically?).

I apply the Fe = W (1 + t ( 1 + 2h/static deflection))

My question is, is this correct?

Does this include the weight force OR must the weight force then be added to Fe. ie. F = Fe + Fw

Also, what force does the lug that the spring at the top see. Is it just the weight force and the spring extension 'removes' the Potential/kinetic energy. OR does the support see both the Impact force, Fe and weight force Fw.

If someone could point me to a book with an example or anywhere that would help. Thanks in advance.

 

[Jboggs]

All I can say is if I were a company designing something as critical to human safety as a fall arrest system, I would not hire a pump and piping guy to design it. Just as I would not hire a mechanical systems guy to design a complex piping system. I would make sure that all parties involved knew EXACTLY what they were doing... And I would make sure my liability insurance was fully paid up.

Do you really want to put yourself in the position of telling your boss, "Well some guys on the internet said it should work."?

 

[MintJulep]

An extension spring as a fall arrest?

Bad idea.

 

[desertfox]

Hi

If you use a spring as a fall arrest ask yourself this question:

When the spring exerts sufficient force to arrest someone's fall what then happens to the energy stored in the spring.

 

[rb1957]

bungie jump ? though of course there are many ways to contorl the energy absorbed ... details that the OP hasn't shared ...

of course i know to control the absorbed energy ... there's a pawl and ratchet, so the entended spring won't spring back ...

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