Falling through the cracks: energy storage along segmented brittle crack fronts

2025-07-25

AI Summary

In brittle fracture propagation, stepped crack fronts and connecting ligaments frequently emerge, significantly perturbing the singular stress field and influencing crack stability—yet their quantitative mechanical mechanisms remain unclear. This study integrates thin-laser-sheet scanning with embedded tracer particles for three-dimensional motion tracking, enabling, for the first time, in situ, high-precision 3D deformation-field measurements across stepped cracks and ligament regions in hydrogels. We observe intense localization of strain-energy density within ligaments; moreover, the apparent fracture energy scales linearly with ligament strain energy. These findings uncover an energy-localization mechanism governing discontinuous crack fronts, providing a novel theoretical foundation and experimental paradigm for reconstructing singular fields and analyzing crack stability in fracture mechanics.

Technology Category

• Intelligent Robots: Localization, Mapping, and Navigation
• Search and Optimization: Local Search
• Computer Vision: Motion & Tracking

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Web Mining and Content Analysis: Web data provenance, reliability, and authenticity
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs

Abstract

During brittle crack propagation, a smooth crack front curve frequently becomes disjoint, generating a stepped crack and a material ligament that unites the newly formed crack fronts. These universal features fundamentally alter the singular field structure and stability of propagating cracks; however, a quantitative analysis of their mechanics is lacking. Here, we perform in-situ 3D measurements to resolve the deformation field around stepped cracks, and crucially, within the ligament feature. The 3D kinematic data are obtained by scanning a thin laser sheet through the brittle hydrogel samples, while recording the scattered intensity from the embedded tracer particles. We find that the ligament concentrates the strain energy density, and moreover, the apparent fracture energy increases proportionally to the strain energy within the ligament.

Problem

• Quantify mechanics of stepped cracks and material ligaments
• Measure 3D deformation fields around brittle crack features
• Analyze strain energy concentration in crack ligaments

Innovation

• In-situ 3D measurements of stepped cracks
• Laser sheet scanning for kinematic data
• Strain energy concentration in ligaments