Statistical features of magnetic noise in mixed-type impact fracture

TL;DR

This study analyzes the statistical properties of magnetic noise during mixed-type impact fracture in steel, revealing power law distributions and asymmetries linked to crack dynamics and stress localization.

Contribution

It introduces a detailed analysis of magnetic noise features in mixed fracture, highlighting power law behaviors and pulse shape asymmetries not previously characterized.

Findings

Peak height, duration, area, and energy follow power law distributions.

Crossover between two regimes of different exponents due to mixed fracture.

Micro-cracking pulse shape is parabolic with right-handed asymmetry.

Abstract

We study the statistical features of magnetic noise accompanying the dynamic fracture of steel samples during mixed type fracture, where the overall ductile character of crack propagation is interrupted by a sudden brittle jump. The structure of the voltage time series is investigated by identifying discrete peaks which correspond to elementary steps of the jerky cracking process. We show that the height, duration, area, and energy of peaks have power law distributions with exponents falling close to the corresponding values of pure ductile fracture. For single peaks a power law correlation of the height and area with the width is evidenced, however, the mixed nature of fracture gives rise to a crossover between two regimes of different exponents. The average pulse shape of micro-cracking events has a parabolic form with a right handed asymmetry similarly to quasi-static fracture propagation. The asymmetry emerges due to stress localization at the advancing crack front.