Approximate energy loss ratio in mechanical springs

[Faris ARSLAN]

Hi!.. As known, a certain amount of energy is applied for compressing a mechanical spring. Thus mechanical spring is charged with energy and it stores it as elastic-potential energy. But whole energy, applied for compressing spring, can not be converted into potential energy. The reason is internal friction of spring which causes heat loss during the compressing process. Thus some energy is wasted as heat and retain energy is stored as elastic potential energy. If we assume:

Applied Energy for compressing=Eapp

Wasted Energy due to heat loss=Ewast

Stored Elasto-potential Energy =Epot

We can formulate Stored Elasto-potential Energy as:

Epot = Eapp - Ewast

So what is the Ewast / Eapp ratio? In other words, what is the approximate Energy loss percentage for springs made of steel? And can u suggest to me any source as website, book, etc..

 

[Baluncore]

If the spring can be arranged to oscillate, the oscillation will be damped by the very small losses per cycle.
https://en.wikipedia.org/wiki/Q_factor
https://en.wikipedia.org/wiki/Q_factor#Mechanical_systems

 

[jrmichler]

I'm not aware of anything published on energy loss in springs. Energy loss comes from the spring mounting and spring material hysteresis. The material hysteresis is usually small. I do know that a particular part made from one aluminum alloy would audibly ring for a full minute, while the identical part made from a different aluminum alloy would damp immediately. The only difference was the material hysteresis.

The end turns of an extension spring that has seen a lot of use will many times show wear where they contact the mounting. The end turns of a compression spring will wear against the mounting, or wear a circular groove in the mounting. That wear is the result of friction, which is wasted energy.

Springs at high speeds can surge. The surging wastes energy.

There are so many variables that it is impractical to look for a simple energy loss percentage. The two best sources of spring information are:

The SMI Handbook of Spring Design: https://smihq.org/store/ViewProduct.aspx?id=8525988

And THE book on springs is Mechanical Springs by Wahl: https://www.amazon.com/dp/0070677050/?tag=pfamazon01-20

 

[Dr.D]

@ jrmichler had mentioned energy losses at the ends as well as internal losses due to hysteresis. Of the two, I'd feel pretty save in saying that end effects cause more losses than hysteresis. End effects include both friction between the end of the spring and the support and also end flexibility. The truly rigid support never exists, so there is always some energy carried away in the support structure.