SYMPOSIA PAPER Published: 01 January 1977
STP27393S

Computation of Crack Propagation and Arrest by Simulating Microfracturing at the Crack Tip

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This paper describes the initial development stages of a computational capability for fast fracture and arrest, based on treatment of plastic flow and microfracturing at the crack tip. The approach is to model the events occurring within the process zone, compute the associated energies, and thereby determine the fracture toughnesses of propagating and arresting cracks.

The model treats crack propagation as occurring by the nucleation, growth, and coalescence of microfractures in the plastically deforming material at the crack tip. It uses as input actual measurements from specimens fractured under stress wave loads. The dynamic stress history experienced by this material is calculated by a two-dimensional wave propagation code.

The approach was demonstrated by performing a computational simulation of a Battelle double-cantilever-beam crack arrest experiment and calculating the energies absorbed in plastic flow and microfracturing. Plastic work accounted for about 95 percent of the fracture toughness, but microfracture activity controls the amount of plastic work that is done and hence governs the toughness. Agreement between computed and observed crack velocity and arrest length is not yet satisfactory but should improve when a finer computational grid is used.

The approach offers an avenue for understanding fracture toughness on a micro-level by linking micromechanical material response to continuum toughness parameters.

Author Information

Shockey, DA
Shock Physics and Geophysics Group, Poulter Laboratory, Stanford Research Institute, Menlo Park, Calif.
Seaman, L
Shock Physics and Geophysics Group, Poulter Laboratory, Stanford Research Institute, Menlo Park, Calif.
Curran, DR
Shock Physics and Geophysics Group, Poulter Laboratory, Stanford Research Institute, Menlo Park, Calif.
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Details
Developed by Committee: E08
Pages: 274–285
DOI: 10.1520/STP27393S
ISBN-EB: 978-0-8031-4700-3
ISBN-13: 978-0-8031-0341-2