Experimental Research on the Shear Behavior of Laminated Glass with PVB Film Under Different Temperature

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1 2017 Asia-Pacific Engineering and Technology Conference (APETC 2017) ISBN: Experimental Research on the Shear Behavior of Laminated Glass with PVB Film Under Different Temperature Qing Su and Zhixiong Tao ABSTRACT The shear modulus of PVB film with different thickness used in different temperatures has been investigated by shearing test. The results indicate that shear stress-strain curve has been changed with different thickness of PVB film. The bigger of thickness, the smaller of shearing modulus will be. Change of Temperature leads obvious variation of the shear modulus which decreases quickly with the increasing of temperature. 1 INTRODUCTION With rapid development of glass curtain wall, laminated glass has been increasing widely used in high rise buildings as a kind of safety glass. Laminated glass is such kind of composite glass that one or more layers transparent polyvinyl butyral film (PVB) are sandwiched in two or more pieces of glasses by heated and pressure bond[1]. It is a typical composite plates and the shear stiffness of interlayer film has greatly influence on its performance. Just as shown in Fig.1, the bending capacity of laminated glass falls in between the separation section and the whole section [2,3]. When shear stiffness of PVB film nearly infinite, it seems that the workability of laminated glass equivalent to an overall cross-section, and the results will be accepted as the upper limit of its bearing capacity. Contrarily, the lower limit will occur when the shear stiffness of PVB film is zero, and its performance seems equivalent to a simple superposition of the separate section. Herein, it should be emphasized is that the composite section in Figure 1 always occur in reality. Figure 1. Schematic of laminated glass. Qing SU 1, a and Zhixiong TAO 2,b 1 WhChang University of Technology, Wuhan China 2 CITIC General Institute of Architectural Design and Research Co., Ltd. Wuhan China a ss_q2004@163.com 1, b Zhixiogntao@163.com 2032

performance of laminated glass, it is necessary to study the shear resistance of PVB film.

refer to experimental methods overseas [4] and Sandwich constructions or cores Shear Test

and thickness is (6mm+1.14mmPVB+6mm), (6mm+2.28mmPVB+6mm).

laminated glass, which shown in Fig.2 and Fig.3.

and then the average shear stress and shear strain will be calculated by stress-strain

Schematic of sensor location. Test phenomenon.

2 SHEAR TEST PROCEDURE Specimen design. The shear test has not been carried out to investigate the shear modulus of PVB film in domestic so far. As mentioned above, the shear performance of PVB is a crucial factor affected the performance of laminated glass, it is necessary to study the shear resistance of PVB film. Some interesting results listed in this paper are got from the shear test of PVB,in which refer to experimental methods overseas [4] and Sandwich constructions or cores Shear Test Method (GB/T ). The panel dimension of specimen used for shear test is 150mm 273mm. and thickness is (6mm+1.14mmPVB+6mm), (6mm+2.28mmPVB+6mm). In order to measure the shear deformation of film under load, two sensors are fixed on laminated glass, which shown in Fig.2 and Fig.3. The relative displacement of these two sensors is defined as the shear displacement of film, and then the average shear stress and shear strain will be calculated by stress-strain function. measure point displacement meter No2 No1 Figure 2. Test set-up (mm). Figure 3. Schematic of sensor location. Test phenomenon. In order to make the shear deformation visible, a straight line was scored in the cross section of the laminated glass. With the developing of deform, the straight line will be polyline, just like shown in Fig.4 and Fig.5. Start Loading Limit state Figure 4. The process of shear test in 20. Destroy Start Loading Limit state Figure 5. The process of shear test in 40. Destroy 2033

3 RESULTS AND DISCUSSION Influence of temperature. The result of tensile test confirms that the laminated glass possesses viscoelasticity, so it will be prominent that the influence of temperature change on the mechanical behavior. In the view of the service environment, the 20 and 40 is set as shear test temperature to represent Northern and Southern. According to the results shown in Fig.6 and Fig.7, it is easy to see that the shear modulus of PVB film, whether thickness of 1.14mm or 2.28mm,decreases quickly with the temperature increasing from 20 to 40. Fig.6 The strain-stress relationship of shear test with thickness of 1.14mm Fig.7 The strain-stress relationship of shear test with thickness of 2.28mm Influence of thickness. The behavior of specimen with PVB film thickness of 1.14mm and 2.28mm was investigated by tensile and shear test in this paper. And the results of shear test dotted in Fig.8 and Fig.9 corresponding to temperature of 20 and 40, respectively. The results indicate that the shear modulus of laminated glass specimen with thickness of 2.28mm is less than that of 1.14mm, and the difference between these two is so small as to be neglected. Figure 8. The shear strain-stress relationship in 20. Figure 9. The shear strain-stress relationship in 40. CURVE FITTING OF SHEAR STRAIN-STRESS RELATION OF PVB FILM IN LAMINATED GLASS Curve fitting of shear strain-stress relation of PVB film in 20. According to the test results of shear test in 20, the shear stress-train curves of laminated glass PVB film will be fitted into line model, the line preceding part of the shear modulus is 1.1MPa, posterior part of the shear modulus is 1.5MPa.The basement of above inferences may be sum up as two points. The first is the fact that the increasing of shear modulus is corresponded to shear stress, which has been proved by some examples in reality. Secondly, as we all know the main factor affected the bearing capacity of laminated glass is deflection under uniform loading. The glass will be broken immediately though the glass has not been toughened yet. The 2034

4 laminated glass can bear more strength for the reason that stress of glass not exceeds limitation when the glass toughened, whereas, the shear capacity of PVB significantly enhanced, just shown in Fig.10 and Fig.11. On the basis of literature study, the slope of shear strain-stress curve achieved by foreign researchers [5], just same as the results in this paper, and the first half fully coincides, which also prove the reliability of these results. Figure 10. Curve fitting of shear strain-stress relation in 20. Figure 11. Curve fitting of shear strain-stress relation in 40. The shear strain-stress relation shown in Fig.11 can be formulated in function (1) (1) Where: τ is the shear stress of PVB film [MPa], γ is shear strain of PVB film, G1 is the shear modulus of PVB film when γ range between 0 and 0.2, G2 is the shear modulus of PVB film when γ range between 0.2 and 0.4. Curve fitting of shear strain-stress relation of PVB film in 40. The analysis of test results in 40 show that the laminated glass PVB film shear stress-strain curves can also be fitted into one pair of line model, shown in Fig.12. The line preceding part of the shear modulus of 0.45MPa, when the shear strain range from 0 to 0.2, and posterior part of the shear modulus 0.8MPa with the strain come within 0.2 to 0.4. The shear strain-stress relation of laminated glass tested in 40 can be formulated in function (2), in which the meaning of parameters are same as function(1) G (2) CONCLUSION In this contribution, the influences of thickness of PVB film and temperature on the shear behavior of laminated glass were studied by shear test. And some conclusions can be drawn as following. 1)Based on the results of tensile test, the tensile strain-stress relationship of PVB film in temperature from 20 to 40 is ( 0 0.2) and E ( ) E 1.31 E ( )

5 The results indicate that the shear modulus of laminated glass specimen, with thickness of 1.14mm and 2.28mm, the latter is less, and the difference between these two is so small as to be neglected. 2)The temperature change plays an important role in the shear strain-stress relationship of PVB film, the shear modulus decrease quickly with the temperature increasing from 20 to 40. It is recommended that the shear modulus of PVB film is 1.10MPa at 20 and 0.45MPa at 40, respectively. And the shear strain-stress relation is shown as following ( 0 0.2) ( ), and ( 0 0.2) ( ) ACKNOWLEDGEMENT The author would like thank the support of Science and technology plan project of Hubei Province. REFERENCES [1] Belis, J., Depauw, J., Callewaert, D., Delincé, D., Impe, R.V., Failure mechanisms and residual capacity of annealed glass/sgp laminated beams at room temperature, Engineering Failure Analysis, [2] Zhang Qilin. Structure of glass certain wall [M].Shandong Science Press, 2007(in Chinese) [3] JGJ , Technical code for glass curtain wall engineering [S]. (in Chinese) [4] C.V. Girija Vallabhan, Y.C. Das, Manjunatha Ramasamudra. Properties of PVB interlayer used in laminated glass. Journal of materials in Civil Engineering, 1992, Vol. 4 (1): [5] Ferry, J.D. Viscoelastic properties of polymers, 3rd Ed., John Wiley & Sons,New York, N.Y.,

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