A hydraulic steel tube of diameter 10mm and wall thickness 1.5mm has been bent to a radius of 100mm. Calculate the reverse radius of curvature that needs to be applied to straighten the tube. M/I= σ/Y = E/R I am really struggling on the above question. I think I need to read off the stress/strain graph for steel to try and work the formula backwards. I believe that the material will also see the Bauschinger effect which will further complicate the working? Any help would be greatly appreciated.