Improved Laminated Windshields by Energy-Controlled Breakout

A recently developed laminated windshield offers amazing improvement in safety performance compared to conventional laminated windshields by energy-controlled breakout at the fixed edge, working at an impact speed of more than 20 mph. The performance of the head impact against the windshield as well as the energy reaction between the head and the screen were studied in some 70 tests. The impact velocity was raised from 15 to 37 mph, and the temperature of the windshields was varied between 278-308 K, in order to analyze the effect of velocity and temperature upon the parameters influencing the safety performance. All results are compared with those of a similar investigation on conventional laminated windshields (0.03 in HPR-interlayer) obtained earlier.

With the newly designed windshields, resulting head decelerations are not essentially lower than those of the conventional type, but there is a smoother rise of the deceleration time-history due to breakoff at the edge. Above all, there are hardly any penetrations or long ruptures of the interlayer, compared to more than 50% with normal types. The very low amount of residual kinetic energy of the head after its impact onto the windshield indicates the improved safety performance, and this in fact results in preventing or at least minimizing head injuries during a following impact against outer body parts.