SRESSESNBENDING 85-2 NORMAL STRESS ON THE CROSS SECTION OF THE BEAM IN PLANAR BENDING 1、 NORMAL STRESS ON THE CROSS SECTION OF THE BEAM IN Longitudinal PLANAR BENDING plane of (1 Geometric law of the symmetry eutral 接多多多多 deformation: Neutral 1. Experiment of pure bending of the beam Lateral lines(a b, cd) keep I straight lines and rotate through some angles after deformation, longitudinal straight lines change into curves with M M upper fibers constructed and lower fibers elongated, lateral lines are still normal to longitudinals lines after deformation§5－2 NORMAL STRESS ON THE CROSS SECTION OF THE BEAM IN PLANAR BENDING 1.Experiment of pure bending of the beam Lateral lines(a b、c d）keep l straight lines and rotate through some angles after deformation, longitudinal straight lines change into curves with upper fibers constructed and lower fibers elongated, lateral lines are still normal to longitudinals lines after deformation. （1）Geometric law of the deformation： 1、 NORMAL STRESS ON THE CROSS SECTION OF THE BEAM IN PLANAR BENDING Neutral layer Longitudinal plane of symmetry b d a c a b c d M M