24.4 : 组合载荷下的应力

A bent tube with a circular cross-section subjected to several forces will produce stresses at certain points.

Calculating stresses involves passing a section through specific points and assessing the force-couple system at the centroid, representing internal forces and maintaining the member's equilibrium.

The centric axial force produces normal stresses in the section, while couple vectors cause the member to bend, producing normal stresses. The sum of the normal stresses produced is calculated using Saint-Venant's principles.

The twisting couple and shearing forces generate shearing stresses. The summation of these components is calculated, combined, and then displayed at specific points on the member's surface.

The normal and shearing stresses determine the principal stresses and orientation of the principal planes at these points. The maximum shearing stress at each of these points is then determined.

The superposition principle and Saint-Venant's principle guide stress determination. However, they are valid only if stresses are within the material's proportional limit, deformations from one loading do not affect others, and the analysis section is far from the points of force application.