Windshield Material Constitutive Relation

When an aircraft flies at a high speed in the low altitude, bird impact possiblyoccurs. The bird strike is similar to adding a high velocity rate loading to the aircraftwndshield, and thus results in the Wndshield's high stain rate deformation. It's we1lknown that the windshield material is an organic material. It shows visco-plasticbehavior Which is that the stress-strain curve, the yield stress and the limited stfessvaried with the material deformation rate. At the same time, the environmenttemperature affects it. The windshield propefties varied obviously at differenttemperatWes, are constrained by material's constitute equation. All these st fain rateand temperature dependence which is the basic paraxneter of the windshield design.So, the study of the windshield material's constitllte equation is important .It can notonly offer the basic parameter to the design of the windshield's resistance to the birdstfike, but also has importam significance to guarantee the safety of the aircraft and' the pilot.In the paPer, the dynamic response of aircraft wtndshield material over widerange stfain rates is investigated from the vieWPoillt of impact dynamics. Theexperimental results of the aeronatical PMMA #3 at the st fain-rates of l0--3s--lto l0's--' and the temperatllres of l6.5'C to l00"C are given. An apparentnonlinear elastic-plastic constitlltive equation is suggested.