I am new to solid work, and would like help on how to analyse a 2m steel cable with a point load in the middle. basically i would like to know how much tension there will be in the cable once the point load is applied. Thanks in advance.
You could probably do this with a beam element and large-displacement formulation, but you need to define cross-section properties for it, which will be difficult for a steel cable (given the individual strands in it). However, it'd be much easier to do this with Newton's 2nd Law and some simple calculus.
can you please explain what sort of cross section properties i will have to define as i am really new to solidworks simulation, i have already defined cable as 4mm round bar. Thanks again for quick reply.
I'm not really sure how'd you define them. In Eulerian or Timoshenko beam theory, the shear stress (VQ/It) arises because it is assumed that "layers" of the beam cannot slip relative to each other, but this is not entirely the case with a steel cable. If you compared the stiffness of several layers of plywood that are not glued together against the same number of layers of the same plywood that are glued together, the glued plywood will be stiffer because the glued interface allows the transfer of shear loads. In fact, the more I think about it, the more I think that a beam model would be a poor choice.
You might get a more realistic model of a cable by using a discrete number of mass and spring elements, but it'd be rather time consuming to do (I'm not sure if SW can do it either, but I'm not an expert with it so I'll let someone else answer that).
If you don't mind me asking, why are you trying to simulate this? As I said before, this is an easy hand calculation to do; using the FEM to do this is overkill (and will potentially give you very inaccurate results if you don't model it correctly).
Shaun, first of all thanks for your reply, but if i knew how to do hand calculation to the problem I have (see my picture below) i would never think of simulating. if its possible can you give me a tip on how to do this calculation by hand like a example or somthing? thanks
how will you define tension?
and as shaun mentioned, is there multiple elements making up your cable or is it just one cable. (is 2m the length or diameter)
for simplicty for now its just a round 4mm diameter bar subject to point load in the middle. i understand its a non-linear problem as only thing stoping cable to defelect is tension in it. which is what i am try to simulate.
are you saying that your question is "how do i add pretension" before you apply your load?
the analysis as you described it is pretty straight forward, fix both ends of the wire, add your point load, run
if you need to pretension, you'll need to use nonlinear to add the pretension first.
then measuring "tension" will be based on the stresses in the wire
Thanks for your promp reply again, i really aprecite your help. my question is how much pretension i will need for the cable to not deflect too much under the given point loadin y & z direction. I have attached a picture of what i need to do. Thanks again.
do you have simulation premium?
i would start with just getting the non tensioned version to work the way you want
if you have simulation premium, before you add your load you can pull to create tension
if you don't have simulation premium you might be able to do something with compressing a part with a temperature to generate the preload, btu then it would be applied at the same time as the tension, that is probably ok for your static case
Jared, thanks very much again for reply, i do have solidworks premium at my work place, can you please give me a tip on how you think i can best simulate it as i am new to simulation. like what study i should chosee static or non-linear? i notice non-linear also have two types dynamic and 2d? and also what sort of fixtures i should put? thanks
hi saqib, see above
if you need to add pretension you need to use force or displacement to generate it
this is what i have to design, as you can see i am trying to simulate cable part of the project. thanks
looks like there is no pretension in those wires
is this sort of analysis posible using solidworks?
To see how they hang?
yes, to see how much they will diflect under given point load. thanks
going back over the thread, i think the concensus is yes it can be done. where are you stuck? would it be best to outsource this analysis at first and then use that as a source of education?
Hello Jared, my concern is that solidworks simulation doesnt have a cable element, from my understanding the only way to simulate this analysis on solidworks is to define a cable as a solid with similar properties to cable. this might give me similar results but wont help me difine the geometry of the cable. for example the real cable will sag under its own weight as a pre-condition and then will probable sag further under the 1.5kN load. how do you simulate the sag under its own weight? i will be more confident of doing this analysis if the horizontal members were steel rods and not cable as i am not sure if solidworks simulation can analysis cable? in the end for this structure to work i have to make sure the cables doesnt deflect more than 25mm under the load. thanks
Gravity is a boundary condition option. Ie a load that would be in addition to the force.
Idealizing the cable as a solid is based on what Shaun and I have described.
Idealising a solid to behave like cable is what I am finding hard to do. If I can somehow do that then I will be confident in modelling the rest. Thanks
How do your equations treat them?
I am not doing any hand calculations. But if I did i would use cable cross section area and E value to predict deflection. But I think it's a very difficult hand calculation.
This is the same approach fea would use.
Because the cable is made of separate wires wound in a spiral it is more flexible than a similarly sized piece of steel. You need to estimate how it will react to the stresses being applied to it. If you have access to an Instron type of tester, you could measure the change in length under tension to get an equivalent Young's Modulus. You could measure the deflection under gravity in your picture and come up with another equivalent Young's Modulus. If they are pretty close to the same, you could have a little faith in your FEA.
Simulia ABAQUS has special elements to simulate steel cables and ropes (check attached paper).
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