A custom-built miniature tensile testing apparatus was used to study the propagation of cracks through the articular cartilage matrix at various loading rates and initial crack lengths. The crack propagation mechanism was observed to be significantly dissimilar to that normally seen in traditional fracture mechanics opening mode, where fracture propagates through the thickness of samples or perpendicularly to the applied load. Instead, an artificially initiated microcrack in the surface layer of an articular cartilage sample grew laterally in the direction of the applied load, stretching about the crack tip, whose initial position remained unchanged throughout the fracture process. A progressive upward pull of the bottom layer toward the surface, which resulted in necking of the specimen, was observed. Our analysis revealed that the rate of necking was the same as that of the lateral stretch of the growing crack. We hypothesize that necking is due to the response of the collagen meshwork especially in the deep zones of the matrix to the tensile load. Our samples exhibited unstable fracture growth immediately after each microcrack grew to the base of the articular surface layer, with very fast crack propagation to failure, thereby indicating that the fracture toughness of the articular cartilage matrix is significantly determined by the toughness of its articular surface.

Item Type:	Refereed Article
Keywords:	articular cartilage, cartilage fracture mechanism, crack growth, fracture propagation, surface cracks, tissue matrix damage
Research Division:	Engineering
Research Group:	Biomedical engineering
Research Field:	Biomechanical engineering
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in engineering
UTAS Author:	Stok, K (Dr Kathryn Stok)
ID Code:	133038
Year Published:	2003
Web of Science® Times Cited:	14
Deposited By:	Menzies Institute for Medical Research
Deposited On:	2019-06-04
Last Modified:	2019-07-29
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