I Required Strength of a Strap connecting 2 Rolls

[anima]

TL;DR Summary

Hello, I am trying to figure the strength (in lbs) of a strap needed to attach 2 Rolls together without breaking. Each wheel has a weight of 1000lbs and a diameter of 30in. Assume each roll is a perfect circle.

Hello, I am trying to figure the strength (in lbs) of a strap needed to attach 2 Rolls together without breaking. Each wheel has a weight of 1000lbs and a diameter of 30in. If there is required information missing, let me know.

 

[russ_watters]

Welcome to PF!

We need to know what they are and what they are doing. If they are just sitting there, for example, Scotch Tape will work.

 

[anima]

Welcome to PF!

We need to know what they are and what they are doing. If they are just sitting there, for example, Scotch Tape will work.

They are big rolls of plastic sheets. They are usually sitting there but I wanted to know the breaking strength of the straps (in lbs) needed in order to prevent them from separating as they will eventually be shipped via trucks.

 

[berkeman]

They are big rolls of plastic sheets. They are usually sitting there but I wanted to know the breaking strength of the straps (in lbs) needed in order to prevent them from separating as they will eventually be shipped via trucks.

What would cause any side-to-side motion that would stress the strap? How are the rolls packaged for lifting into the trucks? Why do you need to join pairs of them instead of crating several all together? How are they unloaded at the destination? Have you discussed this with the trucking company to get their ideas?

 

[anima]

What would cause any side-to-side motion that would stress the strap? How are the rolls packaged for lifting into the trucks? Why do you need to join pairs of them instead of crating several all together? How are they unloaded at the destination? Have you discussed this with the trucking company to get their ideas?

Understood. Without external forces, anything would hold them together. Now, what if the question was changed where there is a third wheel stacked on top of the other two. What forces would be acting on each wheel on the bottom.

 

[berkeman]

We would prefer to get right to the actual application, instead of playing 20 questions. Please outline the project parameters and give all of the details so we can try to help you do this safely. Also, what is your background in Engineering, Math and Physics? Knowing that will help us to help you. Thank you.

 

[russ_watters]

Let me try this way: describe a specific scenario you expect would cause them to separate if not strapped together.

 

[Lnewqban]

The worst-case scenario could be one roll hanging in the air from the next one located at certain angle.

If that angle is estimated to be 45 degrees, the force on each leg of the strap should reach 707 lbs.
If that angle is estimated to be 60 degrees from vertical, the force on each leg of the strap should reach 1000 lbs.

The length of each roll should be above 33 inches.
Do you have a suitable flexible strap that can be wrapped around a length of above 130 inches (11 feet)?

 

[berkeman]

The worst-case scenario could be one roll hanging in the air from the next one located at certain angle.

You forgot to draw the little stick figure person below that roll with a very scared look on their face...

 

[russ_watters]

The worst-case scenario could be one roll hanging in the air from the next one located at certain angle.

I was thinking something similar, but I don't know shipping: is there an impact scenario where they have to remain attached? What if they are shipped by air, and the g-forces from the plane have to be included?

 

[Baluncore]

If there is required information missing, let me know.

The material and the wrapping are very important.

Analyse the system as a pair of meshed gears. If one can rotate, the other must rotate backwards on the storage surface.

The coefficient of friction, CoF, is important. If the rolls are low CoF against each other, then they should first be wrapped in a high CoF material. For example, steel-steel should become steel-paper against paper-steel.

The strap must hold the rolls together, so friction between rolls is greater than the friction due to the weight of one roll on the storage surface.

An alternative would be to strap three rolls together, locked in an equilateral triangle, so the storage surface no longer plays a part in preventing rolling. Strap tension should prevent the two lower rolls separating due to the weight of the upper roll.