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Cable Length and Strength
Name: Duane
Status: student
Grade: 9-12
Location: FL
Country: N/A
Date: 1/4/2006
Question:
A few friends and I were talking about cable length
and strength. Our question is: Does the length of chain, cable or
rope degrade the overall strength? Longer=stronger? or
shorter=stronger? and most importantly, WHY?
Replies:
This is an engineering question.
Generally, a chain, cable, rope, or any long object under stress, will get
less strong with increasing length. Not always, but usually.
For any long object under stress, there is always a "weakest link" which
fails first. Once the bad link of a chain, or one bad section of rope
fails, then the whole thing comes apart.
The longer an object is, the greater the chance of getting a "weak" or "bad"
link present. If the factory always made chain links or rope absolutely
perfectly, then there would never be any weak links, and length would not
matter.
This principle can be applied to other areas as well. For example, a
machine with a lot of parts is expected to be less reliable than one with
few parts, because chances are that one of those many parts will have a
problem.
Bob Erck
Hi Duane
Cable strength is determined by properties of the material out of
which the cable is made and the cross-sectional area. Cables come in
different configurations of bundles and stranding, but that is done
primarily for flexibility. The overall length of a cable really has
no bearing on the strength, however, it will affect how much the
cable will stretch under a load. If you consider defects that may
contribute to premature failure, statistically the longer the cable
is, the more likely there will be something that may contribute to
failure.
Hope this helps.
Bob Froehlich
As whatever tension you place upon a rope or chain is shared equally down
its length, its strength should remain the same whether it is very short or
very long.
In practice, it is worth noting that rope and chain both have characteristics
of their own. If you suspend something from a great length of chain, the
weight of all that extra chain must be added in, reducing your useful load.
Also, the longer a piece of rope or chain is, the greater the chance of some
imperfection reducing its strength.
Ryan Belscamper
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