Laminated Glass Design Calculator

Omega controls how much the two glass plies act as one stiffer unit versus two independent sheets under sustained load. Standard PVB creeps and softens over long-duration loading, so the calculator conservatively assumes it transfers essentially no shear between plies (omega = 0), while SGP is a much stiffer, more rigid interlayer material that keeps transferring load between plies even under long-term loads, so it's modeled at 0.6 — meaningful but still well short of full monolithic coupling.

Equivalent thickness for deflection and equivalent thickness for stress answer different engineering questions from the same layered-plate formula: the deflection value estimates how much the whole assembly bends under load, while the stress value (calculated only against ply 1) estimates the bending stress that specific outer ply experiences. A laminate can have a comfortable deflection equivalent while still concentrating more stress on one ply than the other, especially with unequal ply thicknesses.

The STC formula adds (interlayerLayers - 1) × 1.5 on top of the base thickness-driven acoustic curve, so each extra 0.38mm PVB or 0.89mm SGP layer both thickens the panel — pushing up the logarithmic base STC term — and earns its own small direct acoustic bonus. Physically this reflects how a thicker, more damped interlayer stack absorbs more sound energy passing through the laminate, though the calculator's per-layer bonus is a simplified estimate rather than a measured lab result.

No. The meetsImpact check is a simplified stand-in that just compares total thickness against a single 7.5mm threshold and classifies area as Category I or II by the 9-square-foot ANSI Z97.1/CPSC 16 CFR 1201 breakpoint — it doesn't run an actual drop-ball or pendulum impact test. Use it for early sizing decisions, and confirm any code-required safety glazing with actual certified test data for your specific glass and interlayer combination.