Deformation analysis of insulating glass sealing u

2022-09-23
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Analysis of the deformation of insulating glass sealing unit under the action of ambient temperature

insulating glass is the most widely used energy-saving glass in door, window and curtain wall of energy-saving buildings in China. The insulating glass is composed of two or more pieces of glass, separated by aluminum spacer frame with desiccant in the middle, and sealed with sealant up to 3.5m around. The durability and reliability of insulating glass mainly depend on the health and integrity of the edge sealing unit. Once the sealing unit fails, it will not only affect the energy-saving effect of insulating glass, but also bring hidden dangers to the use safety of insulating glass

the insulating glass edge sealing unit is composed of the first sealant and the second sealant. The first sealant has these properties, including flexural strength and flexural modulus of elasticity butyl rubber, which, together with the aluminum spacer strip, plays the role of isolating moisture; The second sealant is mostly silicone sealant or polysulfide sealant, which plays the role of structural bonding at the edge of insulating glass. At present, researchers generally pay more attention to the influence of material properties, construction technology and air tightness in the manufacturing process of insulating glass on the performance of insulating glass sealing unit, that is, the quality problem of insulating glass itself. However, the adverse effect of environmental temperature change on the performance of insulating glass sealing unit in the application process of insulating glass is ignored

during the service process of insulating glass, due to the cyclic action of environmental temperature changes, indoor and outdoor temperature differences and other factors, its edge sealing unit will produce a certain expansion and dislocation deformation. Excessive deformation will lead to the extrusion of the first sealant, resulting in insufficient width and thickness of the first sealant, and even degumming and breaking, which will seriously affect the performance and service life of insulating glass, and even cause complete failure of insulating glass. In the actual curtain wall project, it is very common that the first sealant of insulating glass is extruded, causing the first sealant to break and the aluminum frame strip to be exposed. This situation is not caused by the quality problem of insulating glass itself, but by the change of ambient temperature. Moreover, with the increasing size of insulating glass, the dislocation deformation of insulating glass edge caused by ambient temperature is also increasing, and the impact on the failure of insulating glass sealing unit is also increasing

the deformation of insulating glass sealing unit caused by the temperature difference between the inner and outer sheets of insulating glass

in the application process of insulating glass, it must be affected by the temperature difference between indoor and outdoor. In the cold winter in the north, the temperature difference between indoor and outdoor even reaches more than 60 ℃. The effect of indoor and outdoor temperature difference can produce the temperature difference between the inner and outer glass sheets of the insulating glass caused by fatigue, resulting in obvious expansion and deformation difference between the inner and outer glass sheets, and then causing stress and deformation of the insulating glass sealing unit: the glass at the low temperature side shrinks, while the glass at the high temperature side extends. Such edge dislocation and deformation will cause the dislocation of the first sealant at the edge of the insulating glass and be extruded

in this case, the dislocation deformation of the insulating glass edge sealing unit decreases with the increase of the width of the second sealant and increases with the increase of the thickness of the sealant (the thickness of the hollow layer). However, because the shear modulus of the structural adhesive itself is several orders of magnitude smaller than the elastic modulus of the glass, the constraint of the two sealing structural adhesives on the deformation of the glass is relatively limited, and the deformation difference between the two pieces of glass caused by the temperature difference between the inner and outer pieces of the insulating glass plays a decisive role in the dislocation deformation of the sealing unit at the edge of the insulating glass. New materials for insulating glass household appliances will also usher in more opportunities and challenges. The dislocation deformation of sealing units is basically linear with its long side size. Therefore, for super large insulating glass structures (the maximum side length of existing insulating glass products is more than 15m), the dislocation deformation of insulating glass edges is relatively large, and its impact on the dislocation deformation of the first sealant needs more attention

the deformation of the insulating glass sealing unit under the action of environmental temperature difference

the sealed gas in the insulating layer of insulating glass will produce a "breathing" effect under the action of environmental temperature changes. When the operating ambient temperature of insulating glass is lower than the production ambient temperature, the insulating glass will be concave, causing the overflow of the first sealant; When the ambient temperature of the insulating glass is higher than the production ambient temperature, the insulating glass will bulge. Once the bulge deformation of the glass is too large, the first sealant will be pulled open and degummed. The reciprocating cycle of the above conditions, especially the combined action of the ambient temperature and the temperature difference between the inner and outer sheets, has accelerated the failure of the first sealant at the edge of the insulating glass

under the effect of ambient temperature changes, the air pressure difference between the internal cavity of the insulating glass and the external air is generated, and the glass is bent into a sphere under the uniformly distributed pressure difference. In this case, the edge deformation of large-size insulating glass is smaller than that of small-size insulating glass, and the maximum deformation of edge sealing unit is only micron level

it can be seen that in addition to the quality of insulating glass itself, ambient temperature also has an important impact on the durability and reliability of insulating glass performance. The influence of the temperature difference between the inner and outer sheets on the insulating glass is mainly the dislocation deformation of the edge sealing unit. The dislocation deformation increases with the increase of the size of insulating glass, and the relationship is approximately linear. Therefore, the edge dislocation deformation of large-size insulating glass has a greater impact on its performance. The deformation of the first sealant at the edge caused by the "breathing" effect of insulating glass under the action of ambient temperature is only within the range of microns, and decreases with the increase of the size of insulating glass

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