Microstructural Effects During Crackling Noise Phenomena

Crackling noise phenomena typically exhibit scale-free statistical distributions (e.g., power law) of the measured variables. Such a universal behavior reveals little information regarding the physical mechanisms and microstructures that are either responsible and/or affect crackling behavior. Here, we address this issue and show three physical systems in which the distributions of certain variables are centered around a most probable value, which is related to a characteristic size of the internal microstructure. These variables represent microstructural-related events. At the same time, each microstructural-related event proceeds through a multitude of smaller mesoscopic events that span several orders of magnitude. Statistical analyses of other variables, which are associated with the mesoscopic events, follow a scale-invariant power law distribution. The origins for the co-existence of events at different scales and their different statistical distributions are discussed in light of the physical characteristics of the investigated systems.