Combined Stress of Cable Around Pulley

AI Thread Summary
The discussion focuses on analyzing the combined stresses in a cable used with a small pulley for lifting an object. Key stress types to consider include axial stress, bending stress from the cable around the pulley, and bearing stress where the cable contacts the pulley. Initial calculations were unclear, prompting a need for a clearer method to determine these stresses, particularly the tensile stress in the cable. The user emphasizes that while bending stresses are often considered negligible, they should still be calculated based on the pulley radius and cable thickness. Understanding these combined stresses is crucial for ensuring the cable can safely hold the load.
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I have an application where I'm trying to lift an object by using a pulley and pulling on the cable. We were forced to use a pretty small pulley and thin cable, so my question is how to analyze the total stress of the cable? I should be looking for axial stress, bending stress (cable around pulley), and bearing stress (cable onto pulley)?

I did some initial calculations and they didn't seem to make sense. Note the cable we are using is a McMaster multi-strand flexible cable, so I know it's pretty easy to physically bend it around. How would I go about calculating these?
 
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I think the main factor (about the cable) is the tensile stress in the cable. This will tell if it can hold the load.
There is also the stress in the bar or cable that supports the pulley. And if the pulley is really flimsy you may bend its axis so you may need to look at the bending stress in the axis too..
 
I'm not concerned about the pulley or bolt/pin that supports it, those are easy checks and I'm plenty good there.

My question is how to actually calculate the combined stresses in the cable. What methods are used?
 
It is usually assumed that the bending stresses in a cable are negligible. Take the cable and see what kind of bending stresses you calculate based on the radius of the pulley and the thickness of the cable.
 

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