Bending Strength of Glass Materials under Strong Dynamic Impact and Its Strain Rate Effects

Based on the structural characteristics of the high-speed loading tester, a four-point bending test device was designed to carry out the four-point bending strength test of glass under the action of static load and different impact velocities, and the formulae for calculating the maximum dynamic stress and strain rate of glass specimens under the action of impact loads were derived. The experimental results show that the bending strength values of the glass under dynamic impact loading are all higher than those under static loading. With the increase of impact speed, the bending strength value of glass specimens generally tends to increase, and the bending strength value increases more obviously when the impact speed exceeds 0.5 m/s or higher. By increasing the impact velocity, higher tensile strain rate of glass specimens can be obtained because the load action time becomes shorter. The bending strength of the glass material increases with its tensile strain rate, and when the tensile strain rate is between 0 and 2 s-1, the bending strength of the glass specimen grows more obviously with the strain rate, indicating that the glass bending strength is particularly sensitive to the tensile strain rate in this interval. As the strain rate increases, the number of cracks formed after glass breakage increases significantly, thus requiring more energy to drive the crack formation and expansion, and showing the strain rate effect of bending strength at the macroscopic level. The results of the study can provide a reference for the load bearing and structural design of glass materials under dynamic loading.