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STRESS RELEASE IN GLASS A PHENOMENON INVOLVING VISCOSITY AS A VARIABLE WITH TIME *
Author(s) -
Lillie Howard R.
Publication year - 1936
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1936.tb19794.x
Subject(s) - power law , thermodynamics , viscosity , materials science , stress (linguistics) , glass transition , composite material , annealing (glass) , modulus , law , mathematics , polymer , physics , linguistics , statistics , philosophy , political science
This paper contains a discussion of the well‐known Adams and Williamson annealing law which makes the rate of release of stress in glass proportional to the second power of the stress and points out certain fundamental objections to such a law. A new expression free from these objections and taking into consideration the change of viscosity with time at constant temperature is given as ‐df/dt = Mfφ, where M is a modulus and φ the instantaneous fluidity. Experiments made with an ordinary lime glass show that this law holds for the release of mechanical stresses imposed on strain‐free glass as well as for the release of thermal stresses in chilled samples. The value of M found for these two types of stress at two different temperatures is 5.9 (±0.5) × 10 10 dynes/cm. 2 .