Chapter 12. Constitutive Model for Damaged Borosilicate Glass

Summary

An experimental technique developed in a previous paper, and consisting of testing a predamaged specimen inside a steel sleeve, is used to obtain the data to develop the constitutive equations (elastic and plastic behavior) for Borofloat® 33 glass. The glass was chosen as the specimen because it is easy to fail in that configuration. This paper first briefly summarizes the experimental technique and then shows that, if the specimen follows a Drucker-Prager plasticity model it is possible to determine, with the help of an analytical model, the elastic and plastic constants from the slopes of the axial stress vs. axial strain and axial stress vs. hoop strain curves measured in the laboratory tests. The paper determines the constants and shows how the model compares with the test data available so far. The analytical model is verified with the help of LS-DYNA in 2-D and 3-D numerical simulations. The analytical and numerical models allow a double check of different assumptions and confirm that the experimental technique is a valid procedure to determine the elastic and plastic constants. The constants can then be used in very different computations like ballistic penetration.