Griffith glasses

Ernsberger, F.M. (1963) Current status of the Griffith crack theory of glass strength, in Progress in Ceramic Science, vol. 3, ed. Burke, J.E. (Pergamon, Oxford) p. 58. 

Griffiths, D. R. (1980), The Deterioration of Ancient Glass, B.Sc. thesis, Univ. Wales, Cardiff. 

Griffith derived his relationship for glass where R consists only of surface energy. In the case of metals, R is mainly plastic energy associated with the formation of a crack tip plastic zone. It is obvious from Eq. 9 that, for plane stress,... 

Many decades ago, Griffith (1919,1920) described the white (laboratory) rat s response to cats. From the age of 3 weeks, rats huddle in corners, freeze, and crouch when presented with a cat. They tremble, twitch their muscles, whine, and cease to feed and nurse. A cloth with cat scent or an arena with cat scent sufficed to trigger these responses. Anosmic rats or those confronted with a cat in a glass jar remained unaffected. Hence, the critical cue proved to be odor (Griffith, 1919). Cat feces, urine, heart, or other tissues did not elicit these fright reactions (Griffith, 1920). 

Today, 29% of the total number of boats built are constructed of reinforced polymers. Water absorption represents an important property. J. R. Griffith, A. Sands, and J. E. Cowling describe reduction of water absorption through the use of halogenated epoxies in glass fiber reinforced composites. 

The second method of developing surface cracks is to expose the surface to hot sodium vapour.1 With various kinds of glass, this treatment produces visible markings (Fig. 45). It is interesting that neither the metallic films nor the sodium vapour show scratches or drawing marks etching with hydrofluoric acid, on the other hand, shows scratches, but does not show the Griffith cracks,2 as Andrade has called them. 

Griffith, J. H., and B. G. RA.nby Dilatometric measurements on poly (4-methyl-l-pentene), glass and melt transition temperatures, crystallization rates and unusual density behavior. J. Polymer. Sci. 44, 369—381 (1960). 

In one sense, this is an easy topic. All of the interactions of light with matter can be described with Maxwell s equations (Griffiths, 1981). However, for the materials chemist faced with the problem of designing a glass lens that does not reflect visible light. Maxwell s equations, in their native state, do not appear to offer a straightforward solution. Fortunately, Maxwell s equations have been solved for most of the problems encountered in materials design. Here, one such case is examined. 

Griffith attempted to check the validity of his formula for cracks on the surface of a solid. He took thin round tubes and spherical bulbs made of glass, and introduced (surface) cracks of fixed lengths (in the range 4 to 23 mm.) with a glass cutter. The specimens (with the above-mentioned cracks)... 

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