Steady State Analysis for Dynamic Crack Propagation in Gas Pipelines

International audience Dynamic crack propagation in elastomer membranes is investigated; the focus is laid on cracks reaching the speed of shear waves in the material. The specific experimental setup developed to measure crack speed is presented in details. The protocol consists in (1) stretching an elastomer membrane under planar tension loading conditions, then (2) initiating a small crack on one side of the membrane. The crack speed is measured all along the crack path in both reference and actual configurations, including both acceleration and deceleration phases, i.e. non steady-state crack propagation phases. The influence of the prescribed stretch ratio on crack speed is analysed in the light of both these new experiments and the few previously published studies. Conclusions previously drawn for steady-state crack growth are extended to non steady-state conditions: stretch perpendicular to the crack path governs crack speed in intersonic crack propagation regime, and the role of the stretch in crack direction is minor.

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Dynamic steady-state analysis of crack propagation in rubber-like solids using an extended finite element method

Computational Mechanics ◽

10.1007/s00466-011-0630-5 ◽

2011 ◽

Vol 49 (1) ◽

pp. 73-86 ◽

Cited By ~ 5

Author(s):

Martin Kroon

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Steady State ◽

Crack Propagation ◽

Extended Finite Element Method ◽

Extended Finite Element ◽

Steady State Analysis ◽

Element Method ◽

State Analysis

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Micro-mechanical Insights Into the Dynamics of Crack Propagation in Snow Fracture Experiments

10.21203/rs.3.rs-242220/v1 ◽

2021 ◽

Author(s):

Grégoire Bobillier ◽

Bastian Bergfeld ◽

Jürg Dual ◽

Johan Gaume ◽

Alec Herwijnen ◽

...

Keyword(s):

Steady State ◽

Crack Propagation ◽

Field Experiments ◽

Process Zone ◽

Crack Tip ◽

Dynamic Crack Propagation ◽

Dynamic Crack ◽

Stress Concentrations ◽

Weak Layer ◽

Mountainous Regions

Abstract Dry-snow slab avalanches result from the propagation of compacting shear bands in highly porous weak layers buried within a stratified and metastable snowpack. While our understanding of slab avalanche mechanisms improved with recent experimental and numerical advances, fundamental micro-mechanical processes remain poorly understood due to a lack of non-invasive monitoring techniques. Using a novel discrete micro-mechanical model, we reproduced crack propagation dynamics observed in field experiments, which employ the propagation saw test. The detailed microscopic analysis of weak layer stresses and bond breaking allowed us to define the crack tip location of closing crack faces, analyze its spatio-temporal characteristics and monitor the evolution of stress concentrations and the fracture process zone both in transient and steady-state regimes. Results highlight the occurrence of a steady state in crack speed and stress conditions for sufficiently long distances of crack propagation (> 4 m). Crack propagation without external driving shear force is possible due to the local mixed-mode shear-compression stress nature at the crack tip induced by slab bending and weak layer volumetric collapse. Our result shed light into the microscopic origin of dynamic crack propagation in snow slab avalanche release that eventually will improve the evaluation of avalanche release sizes and thus hazard management and forecasting in mountainous regions.

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Micro-mechanical insights into the dynamics of crack propagation in snow fracture experiments

Scientific Reports ◽

10.1038/s41598-021-90910-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Grégoire Bobillier ◽

Bastian Bergfeld ◽

Jürg Dual ◽

Johan Gaume ◽

Alec van Herwijnen ◽

...

Keyword(s):

Steady State ◽

Crack Propagation ◽

Field Experiments ◽

Process Zone ◽

Crack Tip ◽

Dynamic Crack Propagation ◽

Dynamic Crack ◽

Stress Concentrations ◽

Weak Layer ◽

Mountainous Regions

AbstractDry-snow slab avalanches result from crack propagation in a highly porous weak layer buried within a stratified and metastable snowpack. While our understanding of slab avalanche mechanisms improved with recent experimental and numerical advances, fundamental micro-mechanical processes remain poorly understood due to a lack of non-invasive monitoring techniques. Using a novel discrete micro-mechanical model, we reproduced crack propagation dynamics observed in field experiments, which employ the propagation saw test. The detailed microscopic analysis of weak layer stresses and bond breaking allowed us to define the crack tip location of closing crack faces, analyze its spatio-temporal characteristics and monitor the evolution of stress concentrations and the fracture process zone both in transient and steady-state regimes. Results highlight the occurrence of a steady state in crack speed and stress conditions for sufficiently long crack propagation distances (> 4 m). Crack propagation without external driving force except gravity is possible due to the local mixed-mode shear-compression stress nature at the crack tip induced by slab bending and weak layer volumetric collapse. Our result shed light into the microscopic origin of dynamic crack propagation in snow slab avalanche release that eventually will improve the evaluation of avalanche release sizes and thus hazard management and forecasting in mountainous regions.

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