Abstract
Square plate of laminated glass, whose interlayer is the polyvinyl butyral, are impacted transversely by a circular steel ball. The impact critical energies Uc and Up which are the energy to initiate a crack in the outerlayer glasses and penetration energy of the ball, are measured by changing the dropping height of the ball. The static bending strength and Uc are depending on the total thickness T of glass in the laminated glass. But, Up is independent of T and depends on the thickness of the interlayer. The penetration fracture of the laminated glasses consists of three steps. The first step is until initial cracks initiate in the outerlayer glasses, the second fracture is the bending fracture of the laminated glass and the third is the fracture due to shearing the interlayer. Considering the relationships mentioned above and material properties of the laminated glasses, we can propose the penetration formula for estimating Up. The validity of this formula is discussed in terms of the results of experimental and theoretical examination.
