Volume 29, Issue 6 (November 2001)
Yield Strength in Relation to Cyclic Loading
The yielding phenomenon under cyclic loading has been investigated for low-carbon steel. Under various loading ratios, the surface state of the specimen was observed with the naked eye, using the Lüders band as an indicator for the yield point elongation. The stress-strain curve was measured simultaneously. The results show that both the surface states and the cyclic stress-strain characteristics vary depending on the load ratio. This makes it questionable to use the yield strength evaluated under monotonic loading to describe the mechanical properties of the specimen material for fatigue tests, though it is a prevailing practice recommended by ASTM. The result of this study also indicates that the Lüders band can be used as a smart sensor to investigate the yield phenomenon.