You are called as an expert witness to analyze the fracture of a sintered silicon carbide plate that was fractured in bending when a blunt load was applied to the plate center. Measurement of the distance between the fracture origin and the mirror/mist boundary on the fracture surface gives a radius of 0.796 mm. You are given three pieces of the same SiC to test, and you determine that the mirror radius is 0.603, 0.203, and 0.162 mm for bending failure stress levels of 225, 368, and 442 MPa, respectively. What is your estimate of the stress present at the time of fracture for the original plate?
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.
You are called as an expert witness to analyze the
fracture of a sintered silicon carbide plate that was fractured
in bending when a blunt load was applied to the plate center.
Measurement of the distance between the fracture origin and
the mirror/mist boundary on the fracture surface gives a
radius of 0.796 mm. You are given three pieces of the same
SiC to test, and you determine that the mirror radius is 0.603,
0.203, and 0.162 mm for bending failure stress levels of 225,
368, and 442 MPa, respectively. What is your estimate of the
stress present at the time of fracture for the original plate?
Trending now
This is a popular solution!
Step by step
Solved in 4 steps with 4 images
