Modelization of Crack Growth in Brittle, Disordered Materials

TL;DR

This thesis investigates crack growth in brittle, disordered materials through experimental, modeling, and numerical methods, focusing on fractal fracture surfaces, scaling laws, and hydraulic fracturing in heterogeneous solids.

Contribution

It provides new numerical insights into fracture scaling, extends existing models, and explores fractal crack patterns in hydraulic fracturing of heterogeneous materials.

Findings

Fractal patterns can develop in cracks during hydraulic fracturing.

Scaling laws for fracture stress are characterized in non-disordered materials.

Elastic stress fields and crack opening volumes are quantified for experimental validation.

Abstract

The thesis consists of four main chapters. In Ch.2 we discuss experimental results concerning the scaling behavior and fractality of fracture surfaces. In Ch.3 continuum and discrete models for fracture mechanics are reviewed and partially extended. In Ch.4 we present numerical results for a finite size scaling of the macroscopic fracture stress in the absence of any disorder in the material. We discuss in Ch.5, the main chapter, the technological important problem of hydraulic fracturing of heterogeneous solids. We have performed intensive computer simulations on this problem and discuss the conditions under which the resulting cracks may develop fractal patterns. We also determine the opening volume of the crack and the elastic stress field in the bulk, quantities that are accessible experimentally. postscript file 'ft_phd93.ps.gz' (1.9Mb) only via ftp server 'ftp.gkss.de'.Login as 'ftp', password: 'your-email', cd /pub/doc, binary mode, get ft_phd93.ps.gz, quit, and then decompress with 'gunzip ft_phd93.ps.gz'. The uncompressed postscript file is around 25Mb large, but you can easily preview it with 'ghostview' for example. Hardcopy upon request.