Enter the load or pressure, length of the glass panel, modulus of elasticity, and moment of inertia into the calculator to determine the deflection of the glass panel.

Glass Deflection Formula

The following formula is used to calculate the deflection of a glass panel.

D = (P * L^3) / (48 * E * I)

Variables:

  • D is the deflection of the glass panel (mm)
  • P is the load or pressure on the glass (N)
  • L is the length of the glass panel (mm)
  • E is the modulus of elasticity of the glass (Pa)
  • I is the moment of inertia of the glass panel (mm^4)

To calculate the deflection of a glass panel, multiply the load or pressure on the glass by the cube of the length of the glass panel. Divide this result by the product of 48, the modulus of elasticity of the glass, and the moment of inertia of the glass panel.

What is a Glass Deflection?

Glass deflection refers to the bending or warping of a glass surface under pressure or load. This can occur in windows, doors, or other structures made of glass when subjected to wind pressure, temperature changes, or physical force. The amount of deflection depends on factors such as the thickness of the glass, the size of the pane, and the type of load applied. Excessive deflection can lead to glass breakage or damage to the surrounding frame.

How to Calculate Glass Deflection?

The following steps outline how to calculate the Glass Deflection using the given formula:


  1. First, gather the values of the variables: D, P, L, E, and I.
  2. Next, substitute the values into the formula: D = (P * L^3) / (48 * E * I).
  3. Calculate the value of D using the formula.
  4. Finally, check your answer with the calculator or by comparing it with other known values.

Example Problem:

Use the following variables as an example problem to test your knowledge:

D: deflection of the glass panel (mm) = 0

P: load or pressure on the glass (N) = 500

L: length of the glass panel (mm) = 1000

E: modulus of elasticity of the glass (Pa) = 2.1 x 10^11

I: moment of inertia of the glass panel (mm^4) = 5000