The Experimental Studies Of Thermal Strain Of Laminated Glass By Moire Interferometry Method

Military aircrafts flying at high speed in low latitude, the problem of bird impacting is concerned by aviation circle, specially the parts against the wind as laminated glass as the windshield of aircraft, the radar covering etc. are impacted by birds at high probability. Various kinds of laminated glass are researched in our country. Not only has laminated glass as the windshield of aircraft high strength, but it can work in the environment of rapidly changed temperatures. Laminated glass as the windshield of aircraft is an important part of aircraft, andit is composed of two or more layers of silicate glass and PMMA. Because of the different coefficient of temperature expansion of every layer, it will produce temperature stresses caused by expanding with heat and contracting with cold and interlaminar restrainting. To offer references of choosing the fit structure, moire interferometry method is used to study thermal deformations of laminated glass in this paper.First of all, experimental systems of high temperature moire interferometry are built and debugged, and thermal strain of laminated glass is studied using the systems. By the methods of real time observation and fringe pattern collection systems recording fringe patterns at special temperature, thermal strain distribution of unsymmetric laminated structure is analyzed.When the temperature is changed, the deformations of prepreg layer are important for the steadiness of the whole laminated glass structure. The above techniques are also applied to the study of the change of thermal strains and distribution of prepreg layer. If only thinking the influence ofinterlaminar shear strains, laminated glass structure of the thickness of 1.25mm prepreg layer is superior to the one of 0.63mm prepreg layer.The study in this paper shows that moire interferometry can be used to investigate thermal strains of laminated glass.