Why do tubes have a tendency to buckle when bent? Experiment with a straight soda straw, and describe your observations. Recall that, in bending of any section, one-half of the cross section is under tensile stresses and the other half under compressive stresses. Also,

compressing a column tends to buckle it, depending on its slenderness. Bending of a tube

subjects it to the same state of stress, and since most tubes have a rather small thickness compared to their diameter, there is a tendency for the compression side of the tube to buckle.

Thus, the higher the diameter-to-thickness ratio, the greater the tendency to buckle during

bending.