Elastic Moduli of Glasses by a Dynamic Method

The elastic moduli and speed of sound of twenty‐three optical glasses, a series of Na 2 O 3 , CaO 3 , SiO 3 , and B 2 O 3 glasses, and some specimens of fused silica were measured by a dynamic method. Each specimen, in the shape of a prismatic bar, was vibrated in four different ways: longitudinally, flexurally on the wide side, flexurally on the thin side, and torsionally. Good agreement was found on Young's modulus as determined by the first three methods. The torsional mode was used to obtain the shear modulus. Statically and dynamically determined values of Young's modulus for six sample glasses also showed good agreement.