โ Scribed by Pekka Ruuskanen; Pentti Kettunen
No coin nor oath required. For personal study only.
The amplitude spectrum of the magnetoelastically induced voltage u~ was studied during cyclic stressing of polycrystalline iron and nickel. Test specimens were loaded with a sinusoidaily varying stress with a frequency of 25 Hz. The amplitude spectrum of voltage u~ is a typical harmonic spectrum consisting of numerous harmonic components. The fundamental frequency of the spectrum was 25 Hz, the same as the loading frequency. The amplitude of the high frequency components of the spectrum increased in the beginning of stress cycling and decreased towards the fracture of the test specimen. This indicates that the cyclic plastic deformation has an effect on the micromagnetization of the material. An increase in the amplitude of the harmonics were observed even at stress amplitudes where no plastic deformation can be measured with an extensometer. The present results show that the magnetic measurements can be used to study the changes in the material microstructure and fatigue caused by cyclic stressing.
๐ SIMILAR VOLUMES
Recent results reported by Lukfg and coworkers raise questions about the differences in the cyclic stress-strain curves (CSSCs) of polycrystalline copper reported by many workers. In order to differentiate the effects on the CSSC of grain size and the ramp-loading mode of initiating a test in cyclic