The Experimental Studies And Numerical Analysis Of Thermal Deformation Of Laminated Glass

Airplane in high-speed flight, the aerodynamic heat and ambient temperature's change caused the surface temperature of the windshield to rise suddenly. Bending deformation was caused by the change of temperature and the temperature gradient of the existence of the windshield. So the windshield of displacement and stress were affected. High strength of aircraft windshield are necessary. The dramatic changes of temperature was common in use.Aircraft windshield was a laminated glass. Laminated glass unit consists of two or more than two apparent materials with very high elasticity modulus, which was formed by bounding together an elastomeric polymer called Polyvinyl Buytral (PVB) or PU with very low shear modulus. Behavior of laminated glass was affected by temperature since the shear modulus of PVB or PU interlayer exhibits great changes with respect to temperature, increasing with falling temperature and decreasing with rising temperature. In addition, because between each material the thermal-expansion coefficient had the very great difference, therefore the temperature change can cause the very great the interlayer shear stress. The interlayer shear stress has very important influence on the windshield of the mechanics. Therefore, the research aircraft windshield under temperature load the interlayer shear stress distribution is of great significance.In this paper, Thermal strain experiment of the windshield of a specimen were performed by moire interferometry method. From 20℃to warm up to 50℃, each increased 10℃record moire fringes. The high sensitive moire fringes were obtained in fine resolution and high quality. Interlayer shear stress was calculated by moire fringes. Distribution of the interlayer shear stress along longitudinal direction were obtained by numerical stimulation by the structure nonlinear dynamics program LS-DYNA. The results were compared. Tendency of change are same. Interlayer shear stress gradually increasing from center of symmetry to edge, which of center is zero and of edge is maximum value. If the load of the temperature on the impact of interlayer shear stress was only considered, transparent material is same, the more adhesive layer thickness is the greater, the more smaller the shear should be. When the thickness of the adhesive layer is homological, The greater difference the thermal expansion coefficient of materials has the greater the shear stress. Thermal stress distribution of unsymmetrical laminated structure composed by the materials with great difference in expansion coefficient and under uniform temperature variation was analyzed. The study provides an investigation and theoretic basis for feasibility of laminated glass as the windshield of aircraft.