- #1

Cyrus

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I am studying the statics of cable systems and I find it to be very interesting. I REALLY like statics. Such an interesting subject, anyways.

My first question is this:

When we have a system of cables supporting weights, say like traffic lights, we can assume the cables to be straight line segments if the cable is of negligible weight. But in all the examples, we had known dimensions, in order to determine the tensile forces in each cable. Is it possible to say given an arrangement of ropes, and suspended masses, this will be the angle, and that will be the tension. Can we predict how the system will look as an end result? I say no, as there are now too many unknowns. I ask this because I wonder how a shipping company that is concerned with rigging would go about designing a system where the can know how the pulleys and cables will be positioned as not to interfere with one another.

Question number 2:

Lets say we have a cable that has a significant weight. The proof of that is readily simple for a given continuous loading; however, how would we derive an equation to describe the curve of the cable given a discontinous change in mass, Like tieing a heavy rope to a lighter rope somewhere along the length.

Question number 3:

How about if we have a cable that has a distributed load w.r.t x and a distributed load due to its own weight, w.r.t. arc length s. How would we go about describing that curve? I would say superposition, assume that the cable sags under its own weight, and then find that curve. Then find the curve if the weight is negligible and then add the two resulting curves to get the new total deflection curve. But this is based on a hunch, and I want to prove it formally.

Question number 4:

What if either of the two types of distributed forces also has a concentrated force somewhere along the way? How could we adjust the proofs to account for that?

These are very difficult to anwser, so if I figure any of it out ill post the solution. If you already know the solution or can provide me a website that has one, I will forever be in your debt .

Thanks,

Cyrus

My first question is this:

When we have a system of cables supporting weights, say like traffic lights, we can assume the cables to be straight line segments if the cable is of negligible weight. But in all the examples, we had known dimensions, in order to determine the tensile forces in each cable. Is it possible to say given an arrangement of ropes, and suspended masses, this will be the angle, and that will be the tension. Can we predict how the system will look as an end result? I say no, as there are now too many unknowns. I ask this because I wonder how a shipping company that is concerned with rigging would go about designing a system where the can know how the pulleys and cables will be positioned as not to interfere with one another.

Question number 2:

Lets say we have a cable that has a significant weight. The proof of that is readily simple for a given continuous loading; however, how would we derive an equation to describe the curve of the cable given a discontinous change in mass, Like tieing a heavy rope to a lighter rope somewhere along the length.

Question number 3:

How about if we have a cable that has a distributed load w.r.t x and a distributed load due to its own weight, w.r.t. arc length s. How would we go about describing that curve? I would say superposition, assume that the cable sags under its own weight, and then find that curve. Then find the curve if the weight is negligible and then add the two resulting curves to get the new total deflection curve. But this is based on a hunch, and I want to prove it formally.

Question number 4:

What if either of the two types of distributed forces also has a concentrated force somewhere along the way? How could we adjust the proofs to account for that?

These are very difficult to anwser, so if I figure any of it out ill post the solution. If you already know the solution or can provide me a website that has one, I will forever be in your debt .

Thanks,

Cyrus

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