Fire Induced Thermal Fields in Window Glass II - Experiments.
Fire Induced Thermal Fields in Window Glass II -
Joshi, A. A.; Pagni, P. J.
Fire Safety Journal, Vol. 22, No. 1, 45-65, 1994.
Sponsor:National Institute of Standards and Technology,
glass; windows; computer models; fire models;
mathematical models; radiation; thermal stresses; vents;
equations; temperature profiles; heat flux
The authors' previously presented model determines the
time to breakage of window glass exposed to a
compartment fire. The physical and mechanical properties
of glass and the history of the compartment fire are
required. Among the mechanical properties of glass, the
breaking stress is the least well known. Here,
experiments on 59 plate glass samples using the
four-point flexure method are described to determine the
breaking stress distribution. This distribution is by a
three-parameter cumulative Weibull function with
parameters. A breaking stress of 40 M Pa (5800 psi) was
determined to be a reasonable value to use in breaking
calculations for ordinary window glass. The breaking
patterns of the test specimens suggest that fractures
initiate at edge imperfections rather than at surface
flaws. Some experiments to estimate the heat transfer
coefficient inside the compartment and the emissivity of
the hot layer are also described and values are
suggested for use in the model.