Glass Types

The NCSEA Glass Design Guide presents a common mathematical model for the strength of fabricated glass. This common model is reflected in the class GlassType.

Much like steel, float glass’s strength properties can be manipulated using heat treatments and chemical processes. Different processes have been quantified and codified. Glass fabricators can produce glass plys that are either:

• annealed

• heat strengthened

• fully tempered

To facilitate these common designations a GlassType can be created using the from_name() and from_abbr() class methods:

from structuralglass import Q_
import structuralglass.glass_types as gt

# Allowable stress FT
ft = gt.GlassType.from_name("Fully Tempered")
allow_stress_ft = ft.prob_breakage_factor(1/1000) \
    * ft.load_duration_factor(Q_(3, "sec")) \
    * ft.surf_treat_factor("None") * ft.stress_edge     # Q_(66.448, "MPa")

# Allowable stress AN
an = gt.GlassType.from_abbr("AN")
allow_stress_an = an.prob_breakage_factor(1/1000) \
    * ft.load_duration_factor(Q_(3, "sec")) \
    * ft.surf_treat_factor("None") * ft.stress_edge     # Q_(12.464, "MPa")

A background registry holds the glass type parameters. New glass type parameters can be added via the register_glass_type() function.

from structuralglass import Q_
from structuralglass import glass_types as gt

gt.register_glass_type(
    name="My Fully Tempered",
    stress_surface=Q_(93.1, "MPa"),
    stress_edge=Q_(73.0, "MPa"),
    duration_factor=47.5,
    coef_variation=0.2,
    surf_factors={
        "None": 1,
        "Fritted": 1,
        "Acid etching": 0.5,
        "Sandblasting": 0.5
    },
    abbr="MyFT"
)

Glass types can be removed via the deregister_glass_type() function. The underlying data can be viewed via the get_glass_types_data() function. The abbreviation mapping can be viewed via the get_abbr_data() function.