Impact Behavior Of Monolithic And Multi-Layered Polymer Windshields For Light Helicopters

Many helicopter windshields that fulfill bird strike requirements according to FAR 29.631 are heavy and have no complex shapes. Some transparent polymers, either monolithic or as multi-layered composites, are promising materials to significantly reduce the weight. In this paper it is investigated whether their mechanical properties are sufficient also to resist a bird strike. This includes tensile tests of monolithic specimens under different conditions and 3-point bending tests of multi-layer samples. Impact and bird-strike tests have been performed to study the fracture and failure mechanics of these polymers. Also simulation results are presented. Finally, results from a full scale bird strike test on a prototype windshield are shown. It can be concluded that some transparent polymers have sufficient mechanical properties to be used for designing light weight impact resistant windshields. However, further research is necessary to manufacture windshields with complex shapes in the required optical quality with these materials.