IMPACT LOADING – MAX. STRESS & ELONGATION – COURSE QUESTION
Impact loading remains one of the topics in Engineering Mechanics that is not expressively discussed. Understanding the dynamics of impact loads, forces and resulting stresses calls for well-crafted and procedural coverage. This work offers a comprehensive solution to a course question on impact stress, that, to this end, had remained unsatisfactorily answered. The question is seemingly an assignment preferred by professors when giving a test in the impact load topic. The question has appeared year after year, mostly in the exact form presented herein, or in a tweaked variation of the same. An 18-ton industrial elevator is supported by a standard steel cable of 3 in.2 cross section and an effective modulus of elasticity of 12 * 106 psi. As the elevator is descending at a constant 500 ft. /min, an accident causes the top of the cable, 80 ft. above the elevator, to stop suddenly.
(a). Estimate the maximum elongation and maximum tensile stress developed in the cable.
(b). Using Excel sheet, Plot the Cable Length (on X axis) vs. Maximum Tensile stress in PSI (on Y axis) for a cable length above the elevator of 1 to 600 feet. Using Excel sheet, Plot the Cable Length (on X axis) vs. Maximum Elongation in Inches (on Y axis) for a cable length above the elevator of 1 to 600 feet. With the help of two plotted curves, comment on the Effect of cable length on the maximum elongation
