How do you calculate the mech.stiffness of a multilayered circular structure, for example a telecoms cable?
The circular structure is about 1000um diameter and has three concentric layers of different material with a bundle of 4 circular members around the centre.
depends whether the layers are bonded together or slide alongside each other. if they are bonded you have to use calculus to find the sum of the flexibility constants. As for the 4 internal cables these slide inside the concentric outer and unless they are (the sum of all 4 stiffness or inverse of the sum of the flexibility constants) are stiffer than the exterior have minimal impact on the overall stiffness.
then again you could do what cable manufacturers do.. Make the cable then take a physical measurement of its flexibility. Stiffness being the inverse of its flexibility constant.
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February 18th, 2010 at 11:37 am
depends whether the layers are bonded together or slide alongside each other. if they are bonded you have to use calculus to find the sum of the flexibility constants. As for the 4 internal cables these slide inside the concentric outer and unless they are (the sum of all 4 stiffness or inverse of the sum of the flexibility constants) are stiffer than the exterior have minimal impact on the overall stiffness.
then again you could do what cable manufacturers do.. Make the cable then take a physical measurement of its flexibility. Stiffness being the inverse of its flexibility constant.
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February 18th, 2010 at 12:27 pm
If this is for government work just assume that the space between the wires is neglibable and then just calc the stiffness for one wire of the total combined wires diameter. its in micrometers so I think this assumption maybe valid.
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February 18th, 2010 at 1:17 pm
Why would you calculate and get an answer with a lot of tolerance buildup in it when you could just test it? But if you must, model it in CATIA, UG, SolidWorks (or others) and use mechanica (or other programs) to calculate it for you. Also once it’s modeled you can change it if it doens’t meet some of your specs.
I must admit I never liked Calculus. Maybe I got an overdose.
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February 18th, 2010 at 1:31 pm
the mech. stiffness can be caculated through passing a electrical current.
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