<P> In mechanics, the neutral plane or neutral surface is a conceptual plane within a beam or cantilever . When loaded by a bending force, the beam bends so that the inner surface is in compression and the outer surface is in tension . The neutral plane is the surface within the beam between these zones, where the material of the beam is not under stress, either compression or tension . </P> <P> As there is no lengthwise stress force on the neutral plane, there is no strain or extension either: when the beam bends, the length of the neutral plane remains constant . Any line within the neutral plane parallel to the axis of the beam is called the deflection curve of the beam . </P>

What is the neutral surface of a bending rod
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