calculation of residual bending tensions

[RonaldoBS]

hello to all, I am doing a job on the bending of pipes, I should determine the residual tensions to continue in my project.

I read that the residual tensions are equal to the sum of tensions due at the time applied to bend the tube, minus the tensions due to the elastic return.

In addition, these residual tensions act only in plastically deformed areas.

I have very high voltages of 1200 mpa at the external radius and about 100 mpa at the beginning of plasticization. Moreover these tensions are of traction in the extremity, and of compression in the intradox, but I wonder, should they not be opposite?
i.e. piego the tube, the extended will be plastically deformed for traction, the intradox for compression. the part of undeformed beams4 tends to realline horizontally, so in the deformed area for traction the tensions here agents because of this phenomenon are compression, and vice versa in the deformed zone for compression. according to my reasoning are these residual tensions, and not as the formula tells me, is it correct? So they are induced by this elastic moment of return in the original configuration, right?
I ask you why I have no examples, a text or exercises where we talk about these tensions, except two theoretical lines that explain the phenomenon, so I would like to ask you confirmation?
Thank you.

 

[Fulvio Romano]

1200mpa tensions? What kind of material is it?

I'd say that's what you say. in plasticized traction zones will remain compression tensions, and vice versa.

 

[RonaldoBS]

Hello fulvio
I attach the characteristics
sy=99,96 mpa (aluminum)
bending radius r0 to machine 40 mm
k=r0/rf= 0.982 where rf is the final bending radius due to the elastic return phenomenon post bending
and = 70001 mpa
outer radius of the tube 6,350 mm
thickness pipe 1,02 mm
distance (long radius) from the neutral axis of the zone in which the plasticized zone begins ye=0,057 mm (which obviously extends up to r)

the formula is sigma_res= sigma_application - y*e*(1/ro-1/rf)
with 0< = =
I have to calculate the maximum and minimum sigma_res

 

[RonaldoBS]

help:frown:

 

[Jack_Landis]

Good evening,

I have to make a similar calculation on a folded pipe that I have to check. Could you please give me some reference where you can find the formulas you're talking about?

Thank you so much!