Elastic hysteresis in thin wall cylindrical shell

[dep4611]

I am looking for information related to the permanent deformation of thin-wall cylindrical shells that require precise diameter bores. I am told a rule of thumb states that if the ratio of wall thickness to diameter is too small, say less than 5%, then excessive deformation may occur if these shells are laid horizontal. Calculations show that the stresses due to self weight are well below the elastic limit so some other small-strain mechanism must be responsible. Does anyone know where I might locate some representative single-quadrant (+stress, +strain) elastic hysteresis curves for carbon steels? Are there other rules of thumb used in industry? Thanks.

 

[MagBen]

Is that at room temperature, not due to creep? I can not imagine anything else except self weight cause the deformation.

Are you sure the calculations of stress by weight are correct? It sounds not a simple calculation. To get the stress for deformation (half way of the cycline would deform horizontally first), you will have to get the horizontal force vector by weight, determine the load area.

You may use yield strength (.2%) as a primary criteria for permenanet deformation although the elastic (proportional limit) could be much smaller than yield