You have been given the following test sample data following mechanical testing of 15 test pieces of a modified Alumina. What is the Weibull modulus of this material? Would you advise the use of this material over one with a Weibull Modulus of 19.6 and a mean failure stress of 270 MPa, if you anticipate that the peak stress on the material could be 255 MPa? Sample 1 2 3 4 5 6 7 68 9 10 11 12 13 45 14 15 Failure Stress (MPa) 297 293 270 300 260 286 265 295 A 293 280 288 263 290 298 275
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.
Step by step
Solved in 3 steps with 3 images
