Author

Tien Yu Hsieh

Document Type

Thesis - Open Access

Award Date

1970

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

Abstract

The pioneer A. A. Griffith (1921), led by Inglis' idea (1913) of stress distribution around an elliptical void, set up the fundamental theory of rupture and flow in solids for the contemporary scientists in the field of fracture mechanics. Today his theory is the well known Griffith fracture criterion extensively used in investigation and explanation of fracture phenomena. Two of the recent researchers who contributed substan-tially to the field of fracture mechanics are I. N. Sneddon (1946) and R. Sack (1948). They have both derived expressions for the critical stress around a three dimensional penny-shaped crack. In addition, Sneddon found the equations for stress distribution around a penny-shaped crack and succeeded in expressing them in an asymptotic form valid when the distance from the crack tip is small. Mott (1948), in a study of the fracture process in a solid from the energy viewpoint, found that the kinetic energy of a propagating crack should be in the form of kf(f2 t2v 2/2E2, where the k is a numerical constant. This formula has been extensively used by the later researchers. J.P. Berry (1960) who was interested in the behavior of a moving crack, has employed the kinetic consideration of the Griffith criterion to consider the crack propagation and has succeeded in obtaining the equations of motion under constant force and constant strain as well. However, those researchers all treat the crack problems under the assumption that the material surrounding the crack is an ideal elastic solid. In recent years it has been found that the fracture mechanism is much more involved than the Griffith theory implies. The reason for this is that there are few materials which behave in a perfectly brittle manner, as is assumed by the early theory. Most solids exhibit a certain amount of yielding around the crack tips before the fracture can start.

Library of Congress Subject Headings

Fracture mechanics

South Dakota State University Theses

Format

application/pdf

Number of Pages

104

Publisher

South Dakota State University

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