4. The figure shows a riveted lap joint with cover plates connecting two steel plates. Each rivet has diameter of 12 mm and the thickness of each steel plate is 15 mm. (a) Compute the shear stress (MPa) in each rivet due to a force of 10.2 kN applied to the plates. (b) If the bearing stress in the steel plates is limited to 40 MPa, what is the allowable load P (kN)? (c) If the width of the steel plates is 100 mm what is the allowable load P (kN) for a limited normal stress of 20 MPa? rivet cover plate Steel plate cover plate Elevation View Plan View
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.
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