A support rod for the landing gear of a private airplane is subjected to a tensile load during landing. The loads are predicted to be as high as 40,000 pounds. Because the rod is crucial and failure could lead to a loss of life, the rod is to be designed with a factor of safety of 4 (that is, designed so that the rod is capable of supporting loads four times as great as expected). The operation of the system also produces loads that may induce cracks in the rod. Our non-destructive testing equipment can detect any crack greater than 0.02 in. deep. Based on the materials given in the following Table 7-1, design the support rod and the material, and justify your answer.
Design Against Fluctuating Loads
Machine elements are subjected to varieties of loads, some components are subjected to static loads, while some machine components are subjected to fluctuating loads, whose load magnitude tends to fluctuate. The components of a machine, when rotating at a high speed, are subjected to a high degree of load, which fluctuates from a high value to a low value. For the machine elements under the action of static loads, static failure theories are applied to know the safe and hazardous working conditions and regions. However, most of the machine elements are subjected to variable or fluctuating stresses, due to the nature of load that fluctuates from high magnitude to low magnitude. Also, the nature of the loads is repetitive. For instance, shafts, bearings, cams and followers, and so on.
Design Against Fluctuating Load
Stress is defined as force per unit area. When there is localization of huge stresses in mechanical components, due to irregularities present in components and sudden changes in cross-section is known as stress concentration. For example, groves, keyways, screw threads, oil holes, splines etc. are irregularities.
A support rod for the landing gear of a private airplane is subjected to a tensile load during landing. The loads are predicted to be as high as 40,000 pounds. Because the rod is crucial and failure could lead to a loss of life, the rod is to be designed with a factor of safety of 4 (that is, designed so that the rod is capable of supporting loads four times as great as expected). The operation of the system also produces loads that may induce cracks in the rod. Our non-destructive testing equipment can detect any crack greater than 0.02 in. deep. Based on the materials given in the following Table 7-1, design the support rod and the material, and justify your answer.
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