DETERMINATION OF SIMPLE CONSTITUTIVE MODELS FOR BOROSILICATE GLASS USING PENETRATION-VELOCITY DATA FROM BALLISTIC EXPERIMENTS

Constitutive models for brittle materials such as glass can be very complex as they are dependent on strains, strain rates, pressures, temperatures, damage and other parameters. There may also be significant (pressure‐dependent) strength after failure such that the constitutive response is much different for intact material and failed material. A large number of laboratory tests is required to develop a comprehensive constitutive model. Another approach is to develop simple models by using penetration‐velocity data obtained from ballistic experiments. Here various functional forms of simple models (with a limited number of constants) can be used to (computationally) match the penetration velocity over a range of impact velocities. This allows for the determination of the most important parameters and it provides an approximation of the stresses that occur during penetration. This article presents several simple computational models for borosilicate glass, including single‐state models and dual‐state models (that include an intact strength and a failed strength).