We suppose that in order to maintain high accuracy of holes and to lower residual stresses after cold expansion of thick-walled cylinders, which undergo cross-section plastic deformation, it is necessary to perform ax...We suppose that in order to maintain high accuracy of holes and to lower residual stresses after cold expansion of thick-walled cylinders, which undergo cross-section plastic deformation, it is necessary to perform axial plastic compression and subsequent cold expansion with small interferences. To test this hypothesis, we studied hoop, radial and axial residual stresses in cylinders made of carbon steel AISI 1050 with hole diameter of 5 mm, outer diameter of 15 mm and length of 30 mm by Sachs method as well as accuracy of expanded holes. It is found that double cold expansion with total interference equal to 5.1% generates hoop residual stresses with largest absolute value equal to 284 MPa and ensures high holes accuracy(IT7). After plastic compression with strain equal to 0.5 and 1% the mentioned stresses reduced to 120 and 75 MPa respectively,and accuracy of the holes reduced as well. Subsequent cold expansion with small interference equal to 0.9% helps to restore holes accuracy(IT7)gained by double cold expansion and ensure that absolute value of hoop residual stresses(177 MPa) is lower compared to double cold expansion.展开更多
Log house is a traditional type of vernacular dwelling in Chinese cold area. It contains distinct regional characteristics and architectural cultures. In recent years,log house has come into vogue softly with the deve...Log house is a traditional type of vernacular dwelling in Chinese cold area. It contains distinct regional characteristics and architectural cultures. In recent years,log house has come into vogue softly with the development of wood techniques. However,log houses expend too much wood materials. There are also many negative aspects of this type of wood building which go against the criteria of energy conservation,and its high prime cost hinders the application as well. To solve these problems, the paper emphasizes using more environmental standardized techniques which save cost at the same time,and put forward technical strategy to improve the log walls. The optimization schemes are mainly divided into two categories: internal insulation and filled insulation. Each type of insulation is respectively derived two schemes through changing the thickness of main structure layers and insulation layer. Firstly,we use Weto software to calculate the timber volume of the four schemes,and it concludes that all the optimizations can save more timber than the prototype log wall with the section of 200 mm × 200 mm. Secondly,thermal comfort of each scheme is insulated in Design Builder.The results show that thermal insulation of filling type represents better than the other schemes. At last,we use thermal calculating formula to calculate thermal resistance of every scheme. Contrast to the energy efficiency standards of Heilongjiang Province, the data show that the four schemes meet the requirements of the specification.展开更多
This paper aims at solving the problems of low thermal collection rate,inconvenient maintenance,hindering indoor using during the application of passive solar technologies in rural houses in severe cold region.All the...This paper aims at solving the problems of low thermal collection rate,inconvenient maintenance,hindering indoor using during the application of passive solar technologies in rural houses in severe cold region.All these defects prevent the passive solar houses' further development. This paper chooses trombe wall,which has higher thermal efficiency of the passive solar house,as research object. The traditional vent is improved into a new type of ventilation device. This improvement overcomes the shortcoming,which traditional vent loses huge heat,and simplifies the construction of vent. Comparing with traditional trombe wall,the energy saving rate is 15. 69%.展开更多
In this paper, the suitability and construction technology of self-insulation walls were studied under the specific climatic conditions and regional resources of Hanzhong and Ankang in the hot summer and cold winter z...In this paper, the suitability and construction technology of self-insulation walls were studied under the specific climatic conditions and regional resources of Hanzhong and Ankang in the hot summer and cold winter zone of Southern Shaanxi. Through the calculation of heat transfer coefficient and thermal inertia index, combined with the specifications of the shale hollow brick and aerated concrete block of Hanzhong and Ankang in southern Shaanxi, the thermal performance and suitable thickness of the external wall using self-insulation materials that meet the Design Standard for Energy Efficiency of Residential Buildings(DBJ61-65-2011) in Shaanxi Province were obtained. The results showed that the self-insulation wall had technical suitability in the hot summer and cold winter zone. The research results provide not only a theoretical basis for the external wall insulation design of urban residential buildings in the hot summer and cold winter zone of southern Shaanxi, but also a reference for designers to carry out energy-saving design of external walls of residential buildings in other similar climate zones.展开更多
基金Lyudmila Petrova for invaluable metrological support. A.I.D. also thanks RFBR grant no. 15-08-01511a
文摘We suppose that in order to maintain high accuracy of holes and to lower residual stresses after cold expansion of thick-walled cylinders, which undergo cross-section plastic deformation, it is necessary to perform axial plastic compression and subsequent cold expansion with small interferences. To test this hypothesis, we studied hoop, radial and axial residual stresses in cylinders made of carbon steel AISI 1050 with hole diameter of 5 mm, outer diameter of 15 mm and length of 30 mm by Sachs method as well as accuracy of expanded holes. It is found that double cold expansion with total interference equal to 5.1% generates hoop residual stresses with largest absolute value equal to 284 MPa and ensures high holes accuracy(IT7). After plastic compression with strain equal to 0.5 and 1% the mentioned stresses reduced to 120 and 75 MPa respectively,and accuracy of the holes reduced as well. Subsequent cold expansion with small interference equal to 0.9% helps to restore holes accuracy(IT7)gained by double cold expansion and ensure that absolute value of hoop residual stresses(177 MPa) is lower compared to double cold expansion.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51478137)the Sub Task of Science and Technology Support Program in China(Grant No.2012BAJ06B04-02)
文摘Log house is a traditional type of vernacular dwelling in Chinese cold area. It contains distinct regional characteristics and architectural cultures. In recent years,log house has come into vogue softly with the development of wood techniques. However,log houses expend too much wood materials. There are also many negative aspects of this type of wood building which go against the criteria of energy conservation,and its high prime cost hinders the application as well. To solve these problems, the paper emphasizes using more environmental standardized techniques which save cost at the same time,and put forward technical strategy to improve the log walls. The optimization schemes are mainly divided into two categories: internal insulation and filled insulation. Each type of insulation is respectively derived two schemes through changing the thickness of main structure layers and insulation layer. Firstly,we use Weto software to calculate the timber volume of the four schemes,and it concludes that all the optimizations can save more timber than the prototype log wall with the section of 200 mm × 200 mm. Secondly,thermal comfort of each scheme is insulated in Design Builder.The results show that thermal insulation of filling type represents better than the other schemes. At last,we use thermal calculating formula to calculate thermal resistance of every scheme. Contrast to the energy efficiency standards of Heilongjiang Province, the data show that the four schemes meet the requirements of the specification.
基金Sponsored by the National Science-Technology Support Plan Projects (Grant No.2011BAJ08B06-2)
文摘This paper aims at solving the problems of low thermal collection rate,inconvenient maintenance,hindering indoor using during the application of passive solar technologies in rural houses in severe cold region.All these defects prevent the passive solar houses' further development. This paper chooses trombe wall,which has higher thermal efficiency of the passive solar house,as research object. The traditional vent is improved into a new type of ventilation device. This improvement overcomes the shortcoming,which traditional vent loses huge heat,and simplifies the construction of vent. Comparing with traditional trombe wall,the energy saving rate is 15. 69%.
文摘In this paper, the suitability and construction technology of self-insulation walls were studied under the specific climatic conditions and regional resources of Hanzhong and Ankang in the hot summer and cold winter zone of Southern Shaanxi. Through the calculation of heat transfer coefficient and thermal inertia index, combined with the specifications of the shale hollow brick and aerated concrete block of Hanzhong and Ankang in southern Shaanxi, the thermal performance and suitable thickness of the external wall using self-insulation materials that meet the Design Standard for Energy Efficiency of Residential Buildings(DBJ61-65-2011) in Shaanxi Province were obtained. The results showed that the self-insulation wall had technical suitability in the hot summer and cold winter zone. The research results provide not only a theoretical basis for the external wall insulation design of urban residential buildings in the hot summer and cold winter zone of southern Shaanxi, but also a reference for designers to carry out energy-saving design of external walls of residential buildings in other similar climate zones.
