Where can I find this..

[MJFellow]

A report refers to:
From classical laminate analysis theory
Fs=3M/2Rbt
where M is the applied bending moment
R is radius of curvature
b is plate width
t is plate thickness
Can someone help me to find the source of the equation.

 

[RPstress]

Links wrong.

Looks like the Brazier radial stress formula for a curved isotropic plate.

Fs would be the maximum radial tension (if moment is 'opening' radius) or compression. It occurs not far from the neutral axis.

M is total moment on plate not moment per unit width (because of presence of 'b').

This is a small approximation for a laminated plate. It's unlikely to be more than a percent or three wrong.

Also, it is an over-estimate if the inside bend angle of the radius is more than about 120°. As you reach the tan points is effect drops off markedly. It also doesn't apply so well to thick sheels.

As for who developed the original, it was Brazier.

When and where, I found this by Googling a bit:
'Brazier, L.G., "On the Flexure of Thin Cylindrical Sheels and Other 'Thin' Sections," Proceedings on the Royal Society, Series A, London, Vol. 116, pp. 104–114, 1927.'

It has been adapted for laminated plates.

 

[SWComposites]

Yes, is a classical curved beam formula; it has nothing specific related to laminated composites. Should be able to find a reference in one of the common Strength of Materials textbooks.

 

[MJFellow]

Thank you fellow Stressers, you have confirmed my doubt, now I can go back to the organisation who submitted the report.
Sorry the link is for the smile, and didn't work