Why does elasticity of modulus go up as the cable gets more "sag"

[tugni925]

Imagine a cable like this pinned at each end; I am looking at a table and it says the temporary elasticity modulus is about E_i = 35GPa, while the permanent is E_p = 50 GPa. Should this not be the other way around? I would imagine as the cable has just been installed and is extra stiff and gradually loses its stiffness as time goes on and there is more sag (d) in the cable? Not that it gains more stiffness as it hangs there. Perhaps I have misunderstood something here?

 

[Compositepro]

"Perhaps I have misunderstood something here?"

Probably. But we can't help with that based on the information you have provided.

 

I think you are confusing elasticity modulus [sic] E with the bulk stiffness of the equipment, which is a function of a number of design variables including E.
When a cables sags (as cables do), it is not because E has changed. We were all taught it is a constant after all.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[dik]

The effective E for a cable is slightly reduced from a solid section. This is due to the twisted construction of the cable. As it is more loaded, some of the 'twist effect' disappears, but some still remains.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik