Belt elongation over time

[htngwilliam]

Hi

Is there any way to calculate belt elongation over time assuming you have a fixed load? I am thinking of doing some experiment but end of the day, I wonder how I can measure the elongation considering the belt doesnt have a fixed shape.

 

[MikeHalloran]

Stretch it between two guided pulleys and measure the center distance at a fixed load... wait and repeat...

Since most belts are composite materials, good luck calculating anything.



Mike Halloran
Pembroke Pines, FL, USA

 

[unclesyd]

Why are you needing to measure the elongation?

Are you looking at the sag of the belts either running or at rest?

 

[htngwilliam]

I need to know the elongation over time. ie, how much the belt will get elongated over time so that I can decide whether I need a tension idler or I can have a fix idler

 

[unclesyd]

Still more questions

Is this a single belt or multibelt drive.

What is the size?

 

[htngwilliam]

It is a single belt. 9mm width.

 

[unclesyd]

They make a measuring device that once was used by most auto parts stores to compare belts. It consisted to two half circles one fixed and the other sliding that you could use to get measurements.

The reason I asked some of the questions is that most small V-belts normally don't use a tension pulley while nearly all poly-V belts use one. On small belts you would use tension measuring device periodically to measure the deflection or how tight the belt was or wait until it stared squealing to tighten it up or spray it with rubber lube. Most of the time the drive end was fixed while the driven end was adjustable.

 

[MikeHalloran]

Some other variables, so far unrevealed, might affect the belt's behavior, among them:

belt technology, length, center distance(s), pulley size, number of pulleys, speed, load, whether reversing or unidirectional, whether the curvature is the same sign everywhere, how many loads are driven, whether and how any are driven from the backside, how many such drives you will make in a year, operating temperature range, design lifetime, environmental considerations (presence of oil, water, ozone, shock loads, etc.), and probably more.

Given a relatively complete summary of the problem you face, this group, or preferably the belt manufacturer, could advise you on the need for an automatic tensioner.

If you're going to dispense factoids one or two at a time, then an experiment might well turn out to be quicker... unless you need it to be statistically significant.



Mike Halloran
Pembroke Pines, FL, USA