Machine Design And Shop Practice (MDSP) Inhouse Practice Exam

The most important stresses in a wire rope are axial tension along its length and bending when the rope follows a curve. When the rope is loaded, the wires carry the load in tension, so each wire experiences tensile stress. As the rope passes over pulleys or drums, it bends, causing fibers on the outer side of the bend to be stretched more than those on the inner side, which creates bending stress across the rope’s cross-section. Together, these two stresses—tensile and bending—define the primary stress state in a wire rope. Pure shear or crushing stress aren’t the dominant internal stresses in normal rope operation, though contact with a drum does introduce some surface pressure; that’s not the main internal stress state. Relying on tensile stress alone ignores the bending effects that occur when the rope bends around sheaves.