Mechanical properties of glass
Glasses – Properties and applications

At room temperature, far from the glass transition temperature, glass has a viscosity greater than 10¹⁹ Pa.s (or 10¹⁹ Pl). It can be considered a solid. Under the effect of an increasing tensile stress σ, deformation varies in proportion to the stress, and this until breakage occurs. Breakage occurs abruptly, and cannot be detected beforehand. Glass is said to be a brittle material. It has no macroscopic plasticity.

In fact, the tension experiment can only be carried out correctly for small-diameter fibers. In most cases, Young's modulus E is obtained by static three-point or four-point bending tests. Glass behaves like a Hooke solid: