![]() The equation basically states that when a crack is able to propagate enough to fracture a material, that the gain in the surface energy is equal to the loss of strain energy, and is considered to be the primary equation to describe brittle fracture. His theory described the behavior of crack propagation of an elliptical nature by considering the energy involved. This concentration would allow the stress to reach E/10 at the head of the crack long before it would seem to for the material as a whole.įrom this work Griffith formulated his own theory of brittle fracture, using elastic strain energy concepts. This was because any void in a solid concentrates stress, a fact already well known to machinists at the time. Griffith discovered that there were many microscopic cracks in every material, and hypothesized that these cracks lowered the overall strength of the material. However it was well known that those materials would often fail at 1000 times less than this predicted value. At the time it was generally taken that the strength of a material was E/10, where E was the Young's modulus for that material. Griffith is more famous for a theoretical study on the nature of stress and failure in metals. This method, and similar ones, were used well into the 1990s when computer power became generally available that could do the same experiment numerically. Using this method a soap bubble is stretched out between several strings representing the edges of the object under study, and the coloration of the film shows the patterns of stress. Taylor suggested the use of soap films as a way of studying stress problems. Some of Griffith's earlier works remain in widespread use today. ![]() ![]() In 1915 he was accepted by the Royal Aircraft Factory as a trainee, before joining the Physics and Instrument Department the following year in what was now been renamed as the Royal Aircraft Establishment (RAE). Griffith took a first in mechanical engineering, followed by a Master’s Degree and a Doctorate from Liverpool University. Alan Arnold Griffith (13 June 1893 – ) was an English engineer, who, among many other contributions, is best known for his work on stress and fracture in metals that is now known as metal fatigue, as well as being one of the first to develop a strong theoretical basis for the jet engine.Ī. ![]()
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