Simple Bending Theory OR Theory of Flexure for Initially Straight Beams

The assumptions made in the Theory of Simple Bending are as follows:

• The material of the beam that is subjected to bending is homogenous (same composition throughout) and isotropic(same elastic properties in all directions).
• The beams have a symmetrical cross-section and they are subjected to bending only in the plane of symmetry.
• The beam is made up of a number of fibers that run longitudinally to each other and are all straight initially. On bending, they do so in the form of circular arcs, with a common center of curvature.
• The effect of Shear stresses is neglected. The beam is subjected to pure bending.
• No warping of the cross-section takes place. That is, transverse sections through the beam taken normal to the axis of the beam remain plane after the beam is subjected to bending.
• The dimensions of the beam are very small as compared to the radius of curvature of the beam.