Calculate the maximum +ve and –ve moments.5-13 Example 5-2.Wire bent around a drum Oįor the beam shown determine the maximum tensile and compressive stresses in the beam. For beam design we can calculate the required section modulus and then select.įIG. Where S=section modulus and is a geometric factor. symmetric in the z and y directions, the neutral axis will be at the center of the beam. Taking moments about the neutral z-axis (for each small slice the force is stress x area and the distance from the z-axis is y) Rememberĭoubly symmetric cross-sectional shapesIf a beam is doubly symmetric (i.e. The beams shown have non-symmetric cross-sections and the neutral axis is therefore not at the center. For positive curvature compression occurs at the top surface. Positive curvature results from positive applied moments. Normal stresses in a beam of linearly elastic material: (a) side view of beam showing distribution of normal stresses, and (b) cross section of beam showing the z axis as the neutral axis of the cross section To determine the normal stress in a beam subjected to bending we need to know the moment acting at that point the distance from the neutral axis and the moment of inertia of the beam.
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