| Building external wall insulation technology originated earlier.Since then,people have made continuous improvements in insulation technology and insulation materials,bringing about the rapid spread of external thermal insulation throughout the country.At present,most urban high-rise buildings are installed external insulation board as building insulation materials.Insulation decorative panel is usually made of materials like face brick.If the installation is not reliable,or it suffers from long-term erosion of complex environment,it will fall off,thus causing great hidden danger.Therefore,it is of great significance to study some environmental factors on,such as environmental temperature and solar radiation.This paper firstly introduces the thermal insulation structure of building exterior wall and common thermal insulation materials,then analyze the possible factors that cause the hidden danger of insulation structure.Next,the panel is considered as a two-dimensional plane,and its energy balance equations under the single and coupled effects of ambient temperature and radiation can be derived;the equations are transformed in S-Domain,and the temperature signal solutions of the three equations are obtained,among which the transfer functions are included;the temperature decoupling equation is constructed by virtue of the transfer functions;then the temperature signal is substituted into the two-dimensional thermal stress equation of displacement expression;finally,a strain decoupling equation can be established by combining the directional strain and the maximum elongation line strain formula,and a decoupling test method about the coupling of ambient temperature-radiation can be obtained.This method can calculate the result of coupling effects according to the separate effects of ambient temperature and radiation on the decorative panel,thus providing a theoretical thesis for the coupling test.Meanwhile,it resolves the problem that large environmental silos do not have the coupling test conditions.This paper also uses the finite difference method to verify the correctness of the decoupling method.Secondly,in this experiment,there are several working conditions such as the effects of ambient temperature alone,non-shielded radiation and sheltered radiation respectively,and the coupling effect of non-shielded or sheltered ambient temperature-radiation.The environmental temperature and radiation from 4:00 to 20:00 in Beijing are substituted into MATLAB program for numerical simulation.The results show that under the temperature action alone,the strain and shear strain in the X and Y directions of the decorative panel are positive when the temperature decreases,and negative when the temperature rises;the strain value at the center point is the largest.When the temperature changes from heating to cooling at about 14:00,the maximum elongation line strain changes abruptly,and the decorative panel is easy to fall off.While under the action of solar radiation alone,when the weakening ambient temperature is added without shielding,the temperature and the maximum elongation line strain at the test point delays reaching the peak value,which becomes larger.When the decoration panel is half shielded and no weakening ambient temperature is not added,the temperature of the radiation zone and non-radiation zone will reach the peak at the maximum radiation point.After adding the weakening ambient temperature,the peak time of all points is delayed.The addition of the weakening ambient temperature has little effect on the maximum elongation line strain.At 12: 00 noon,the strain difference between the radiation zone and the non-radiation zone is the largest,and the radiation zone is easy to fall off at this time.Then,experiments on the effects of ambient temperature and radiation on thermal insulation decorative panel are carried out by using the high and low temperature environmental chamber and the disaster coupled environment laboratory.The results show that the effect of ambient temperature on the decorative panel is similar to that of the simulation in the real situation,the negative strain increases with increasing temperature and decreases with decreasing temperature.However,what is different from the simulation is that there is no strain mutation.The strain in the short side direction is slightly larger than that in the long side direction.The smaller the radiation angle is,the smaller the temperature change of the decorative panel caused by the radiation is and the smaller the strain value is.To be shielded or not has a great impact on the temperature and strain of the shielded part,but it has little impact on the unshielded radiation area.When the inclination angle is 30 °,namely the 60 ° radiation angle,the maximum elongation line strain at the same radiation point of the panel is the largest,and it is easier to fall off.Finally,the maximum elongation line strain under the coupling of ambient temperature and radiation is measured by changing the aspect ratio and thickness of the decorative panel.The results show that under the two coupling factors,the optimum size ratio of thermal insulation decorative panel is 1: 2.2.The smaller the thickness of decorative panel,the larger the maximum elongation line strain and it is easier to fall off.The selection of decorative layer thickness should be combined with the local climate conditions.The paper has also investigated several decorative materials of thermal insulation decorative integrated board,and given suggestions on the selection of decorative materials.It is suggested that water-inwater sand should be selected as the thermal insulation finishing material in the area with bad environmental conditions.Figure [ 61 ] Table [ 3 ] References [ 58 ]... |
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