Design Of Police Broken Window Device And Application Of Cutting Laminated Glass

In the background of modern terrorism into or disaster relief, police broken window device has a wide range applications. It is a kind of special equipment working to break the glass for entering the building or mandatory vehicle, which has the characteristics of simple operation and high hidden efficient. Based on the research results about copper tube linear shaped charge cutter, a new type of police broken window device was designed, and the contained elements were introduced. Additionally, the software of ANSYS/LS-DYNA is employed to simulate device.The police broken window device works like this: the jet flow formed by shaped-charge that initiated by detonation button impact the laminated glass and which leads failure destructions and crack, even broken of glass finally. The operators adjust the scale length and hand lever so that this device can attach the targets closely then the shaped charge was initiated to break the glass. The main parameters of broken window device contain of batteries, electric detonator, action bars, and liner cutter, which is used for breaking laminated glass and tempered glass.The final failure mode of laminated glass and tempered glass isn`t same as the PVB layer existing in former glass which would not form a regular notch geometry under the situation of shock and impact. The PVB film in the middle of glass used in automobiles has no a unified standard about thickness, so a simplification to actual issue was presented to discuss the failure mechanism of laminated glass. The cutting process of laminated glass with various PVB thickness(0.38mm~3.04mm) created by conventional liner shaped charge cutter was simulated and the crack generated and final failure mode of laminated glass was studied. The main influence of variation in PVB thickness on the differences of crack growth and final failure pattern was explained from the energy absorption, the stress wave propagation and the elastic energy accumulated. It shows that the presented police broken window device can break the commonly used laminated glass of automobiles effectively when the thickness of PVB is 1.52 mm and smaller than it. The cutter designed as rectangle(with a 90 o corner angle) was simulated and the result shows that the cutter of police windows broken device can be designed as various shapes to meet the different requirements of counter-terrorism needs...