We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Variation of microplastic limit during cyclic loading
Summary
This study investigated how the microplastic limit of ferromagnetic steel changes during cyclic loading, using magnetic permeability measurements to detect the stress threshold at which dislocation pile-ups begin forming in the metal microstructure. Tracking changes in the microplastic limit during fatigue cycling provides insight into cumulative damage accumulation below the conventional fatigue limit.
The microplastic limit (MPL) can be considered to be a stress (strain) at which plastic strains begin to occur in some micro-volumes of metal. The occurrence of these strains can not be determined by common methods but they can be detected by means of monitoring changes in magnetic permeability of a ferromagnetic material during application of mechanical load to a specimen [1]. Microplastic strains occur below the fatigue limit, namely as a result of dislocation movement in favourably oriented microregions in the metal lattice. With increasing load the dislocations are gradually piling-up at obstacles, firstly at grain boundaries, and due to that they form short-distance stress fields which obstruct magnetic domains to rotate to the direction of the acting load (strain).