![]() ![]() For the loading shown here, just as the deformation is uniform, so the internal bending moment is uniform, equal to the moment applied by each hand. Between the thumbs, the strip has deformed into a circular arc. The couples of the two hands must be equal and opposite. Each hand applies a couple or moment (equal and opposite forces a distance apart). Take a flexible strip, such as a thin ruler, and apply equal forces with your fingers as shown. Pure bending ( Theory of simple bending) is a condition of stress where a bending moment is applied to a beam without the simultaneous presence of axial, shear, or torsional forces. The material obeys Hooke's law (it is linearly elastic and will not deform plastically). The structural element is assumed to be such that at least one of its dimensions is a small fraction, typically 1/10 or less, of. The material is isotropic (or orthotropic) and homogeneous. In applied mechanics, bending (also known as flexure) characterizes the behavior of a slender structural element subjected to an external load applied perpendicularly to a longitudinal axis of the element. Shear force at any X- section is zero and the normal. This means that the shear force is zero, and that no torsional or axial loads are present. Furthermore, even when the cross-sections warp, the final results of the classical beam bending theory stay valid as long as the axial and the shear forces remain constant 70, which is often the case. In flexural bending (pure bending), constant bending moment acts along the entire length of the beam. More in depth explanation of sign convention can be found here Pure Bending Stresses caused by the bending moment are known as flexural or bending stresses. Typically for flexure elements the height is kept significantly smaller than the length, and therefore Bernoulli’s assumptions hold. Whenever a part deforms in this way, we say that it acts like a “beam.” In this chapter, we learn to determine the stresses produced by the forces and how they depend on the beam cross-section, length, and material properties. When the fingers apply forces, the ruler deflects, primarily up or down. ![]() ![]() This wood ruler is held flat against the table at the left, and fingers are poised to press against it. Pure Bending Take a flexible strip, such as a thin ruler, and apply equal forces with your fingers as shown. ![]()
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