MONITORED BALLISTIC TESTS ON SHOCKPROOF SANDWICH GLASSES IN DIFFERENT CONDITIONS

The locomotive windshields adopted by the Italian Railroad for high speed trains are made of shockproof glass which has a multilayer structure (tempered glass with high stiffness and PVB or polycarbonate with high elasticity); as already reported. Among the acceptance tests for these panels, the most important is the ballistic impact one: a projectile of 1 kg mass is fired into the panel at velocities of 360 or 460 km/h. As the sandwich glass is approved if it is not pierced by the projectile, useful information for the manufacturers, and the for the purchasers, can be obtained monitoring the panel during the ballistic tests with piezoelectric accelerometers and strain gages. Only the experimental analysis can explain the local behavior of the panel. Some references 2,3 concern elastic and plastic phenomena during composite impacts, not possible failures. The applicability of piezoelectric accelerometers and strain gages to the glasses has been already shown. 4,5 Moreover, the sensors can be used also for impulsive elastic tests before the ballistic ones and reference values can be obtained from these tests. As several kinds of glasses can be adopted by the Italian Railroad (as by other railroads), the sensor outputs, both during the impulsive and the ballistic tests can help in choosing the best panel. In addition, the phenomena ' that occur during the impact can be usefully investigated ' firing the projectile at different velocities.