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Stress and Structural Relaxation in Tempering Glass
Author(s) -
NARAYANASWAMY O. S.
Publication year - 1978
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.1151-2916.1978.tb09259.x
Subject(s) - tempering , viscoelasticity , relaxation (psychology) , stress relaxation , materials science , residual stress , stress (linguistics) , thermal , composite material , thermodynamics , creep , physics , psychology , social psychology , linguistics , philosophy
Temper stresses are brought about, primarily, by a partial relaxation of transient stresses generated by rapid cooling of the glass. Stress relaxation under nonisothermal conditions is competently handled by a mathematical tempering model, in which glass is treated as a simple viscoelastic material. However, this model proved inadequate in some respects since the properties of glass depend not only on its instantaneous temperature but also on its prior thermal history. A tempering model was therefore developed that incorporates both stress and structural relaxation. Predictions of this structural model are compared with experimental data on tempering and contrasted with predictions of the viscoelastic model. Such comparisons revealed that, typically, structural relaxation accounts for approximately 24% of the total residual temper stresses.