ABSTRACT
In testing the material strength, the focus is generally directed toward determining material response to tension.Most strength tests are performed by simplymeasuring the elongation of a rod as a function of an axial tensile load. Homogeneous and isotropic materials (particularly metals) are then assumed to have similar strength properties when compressed. Compression tests are thus often not conducted. Even though Hooke’s law (with a linear stress-strain relation) is generally found to be valid for both tension and compression, compression loading often produces changes in structural geometry, which can then lead to buckling even before a yield stress is reached. In this chapter, we look at the phenomenon of buckling and the associated concepts of stability of beams, rods, columns, and panels.
Consider a long, slender rod or bar subjected to an axial compressive loading as in Figure 15.1. If the geometry is ideal and the loads are centered on the bar axis, the bar will simply shorten due to the loading. If, however, the geometry is not perfect, the bar may bend and buckle as represented in Figure 15.2. As the bar buckles, the greatest deflection will occur at midspan as indicated.
