| With the improvement of building energy efficiency standards of our country, organic insulation materials are widely used because of high insulation properties. But organic insulation materials are so flammable that they has led to several serious fire in recent years. Therefore the state issued the relevant law, and clearly defined the scope of application of organic insulation materials. So the application of organic insulation materials is limited. Urea-formaldehyde resin foam which is a new organic insulation materials imported from abroad is not only excellent insulation properties, low price, but also non-flammabilitywith anti-flame fire rating to B1 level. So it has a wide range of applications and market prospects. At present, domestic applications and researchof Urea-formaldehyde resin foam is still in its initial stage,and it's only applies to sandwich wall and roof insulation. But it has not yet been used in exterior wall external insulationwhich is widely applied in our country. This paper design a new exterior wall external insulation system according to the characteristics of urea-formaldehyde resin foam, which is referred to CUFFI insulation system. Analyze the thermal performance through experiments, theoretical and finite element simulation method. Then analyze the Mechanical behavior of CUFFI insulation system by finite element simulation method.Firstly, the impact on the thermal performance of CUFFI insulation system of the C-shaped steelconnectorsare analyzed by the experimental methods of temperature box-heat flow meter and thermal imager. The results of experimental and theoretical calculations and ABAQUS simulation are analyzed to obtainsome conclusions. The applicationof connectors reduces the insulation resistance and adversely affect the insulation properties of the system because its thermal conductivity is higher than other materials. But the degree of influence within an acceptable range.When the insulation layer is composed of two materials whose thermal conductivityaresignificantly different, the theoretical calculation method is not suitable. The results of finite element analysis and experimental results are similar, so the finite element analysis of thermal performance is feasible.Secondly, in order to reduce the adverse effects of C-shaped steel connectors for thermal insulation, using ABAQUS finite element software to analyze plate thickness and opening size of holes on the connectorsincluding: horizontal and vertical spacing, horizontal and vertical margins, width. The analysis shows that more and thiner holes are beneficial toreduce equivalent thermal conductivity of the C-shaped steel connectors, while the plate thickness almost has no effect on it. The equivalent thermal conductivity and the size of holes of different lengths are calculated.Thirdly, finite element analysis model of CUFFI insulation system is built based on the calculated data of size. According to the weather conditions in Harbin evalute and analyze the overall thermal performance of the CUFFI insulation system. The maximum temperature gradient in the insulation layer indicates that the thermal insulation properties of Urea-formaldehyde resin foam is much more better than other materials of this insulation system. And the insulation layer thickness required by residential building of different height and facades are calculated out according to the heat transfer coefficient given by relevant regulations. The minimum temperatures of interior surface are above the dew point temperature, so it will not produce condensation and mildew because of thermal bridges caused by the C-shaped steel connectorswhen the thickness of the insulation layer meets the limits of heat transfer coefficient.Finally, based on the finite element software ABAQUS,simulate and analyze the CUFFI insulation system's mechanical properties loaded by weight and wind. Depending on the material characteristics of each member, choose three control parameters as following: maximum principal stress and lateral displacement of the trim board and maximum mises stress of the C-shaped steel connectors. Through changing the layout and plate thickness of the C-shaped steel connectors and thickness of trim board to study the relationship between these variables and control parameters.Maximum lateral displacement and principal stress of the trim board are effected mainly by its own thickness, and has no effect with the plate thickness of connectors. However, connectors and trim board has equivalent effect on the maximum Mises stress of connectors, but both of their thickness increasing are unfavorable. Encrypting the arrangement of connectors is the most effective method on reducing the stress and diaplacement. According to the control parameter values, determine the components size of CUFFI insulation system required by different heights residential building in harbin. |
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