This paper investigates the multiaxial fatigue life of the roller in rolling contact with wheels with respect to axis line deflection. The multiaxial fatigue criteria proposed by Wang and Brown, together with the raln...This paper investigates the multiaxial fatigue life of the roller in rolling contact with wheels with respect to axis line deflection. The multiaxial fatigue criteria proposed by Wang and Brown, together with the ralnflow counting method and Miner- Palmgren＇s rule, are applied to the cumulative damage estimation and life prediction. As the axis line deflection of overlong kilns generally results in asymmetric load distribution on each roller, the load ratio is introduced to describe the deflection for quantitative stress analyses. The stress analyses are performed within the finite element code ANSYS. The tangential friction stress is calculated in terms ：of the condition of the rolling contact area. By taking one roller as an example, the plotted fatigue life versus load ratio curve discovers how the axis line deflection affects the fatigue life. This study is significant to prevent the fatigue failure of the roller and can provide basis to adjust and optimize the axis line of the rotary kiln.展开更多
Qingdao Jiaozhou Bay subsea tunnel is the second self-built tunnel in China with the designed service life over 100 years.The durability of lining concrete are one of an important factors to determinate the service li...Qingdao Jiaozhou Bay subsea tunnel is the second self-built tunnel in China with the designed service life over 100 years.The durability of lining concrete are one of an important factors to determinate the service life of tunnel.Considering the main environmental loads and mechanical loads of subsea tunnel,the durability properties of lining concrete under combined action of compressive load and carbonation has been studied through the critical compressive load test,accelerated carbonation test,natural carbonation test and capillary suction test.The tests results show that critical compressive load apparently accelerates the carbonation and deteriorates the anti-permeability of concrete.Under the combined action of critical compressive load and carbonation,the durability of lining concrete decreases.Based on the carbonization life criteria and research results,for the high-performance concrete with proposed mix ratio,the predicted service life of lining concrete for Jiaozhou bay subsea tunnel is about 80 years which fails to reach the required service life.It is necessary to adopt other measurements simultaneously to improve the durability of lining concrete.展开更多
A series of improvements in prolonging the AOD refractory lining life in Baosteel are introduced and analyzed in this paper,including modification of the AOD shell shape, adjustment of the top slag components and sele...A series of improvements in prolonging the AOD refractory lining life in Baosteel are introduced and analyzed in this paper,including modification of the AOD shell shape, adjustment of the top slag components and selection of the side-blowing tuyeres. Firstly,the layout of side-blow tuyeres was altered with the angle between each two tuyeres being 22.5° instead of the original 18° ,and the connection of the outside steel shell in the side-blow area was modified from the former platform shape with great stress concentration into a new smooth circle shape. Secondly,the slag components were changed from the former CaO-FeO-SiO： system to the CaO-MgO-SiO2 system. Besides, the basicity of the top slag was kept higher than 1.8 ,and the MgO content in the slag was kept within the range of 8% - 12%. Finally,tuyeres with an inner diameter 13% smaller than that of the original tuyeres were used. Based on these research and optimization work,the thermodynamics and kinetics in the AOD refining bath has been improved markedly, and the campaign of the AOD has been prolonged from 45 heats at the beginning of its start-up to the current 185 heats. Meanwhile,the yield of chromium alloy and the decarburization efficiency have also been improved.展开更多
基金Project supported by the National High-Tech Research and Development Program of China (863Program) (No. 2007AA04Z415)the National Natural Science Foundation of China (No. 50675066)the Scientific Research Fund of Hunan Provincial Education Department (No. 09C407)
文摘This paper investigates the multiaxial fatigue life of the roller in rolling contact with wheels with respect to axis line deflection. The multiaxial fatigue criteria proposed by Wang and Brown, together with the ralnflow counting method and Miner- Palmgren＇s rule, are applied to the cumulative damage estimation and life prediction. As the axis line deflection of overlong kilns generally results in asymmetric load distribution on each roller, the load ratio is introduced to describe the deflection for quantitative stress analyses. The stress analyses are performed within the finite element code ANSYS. The tangential friction stress is calculated in terms ：of the condition of the rolling contact area. By taking one roller as an example, the plotted fatigue life versus load ratio curve discovers how the axis line deflection affects the fatigue life. This study is significant to prevent the fatigue failure of the roller and can provide basis to adjust and optimize the axis line of the rotary kiln.
基金Funded by the National Key Basic Research and Development Plans-973 Plans(2009CB623203)the Key Project of National Natural Science Foundation of China (50739001)+2 种基金the National Natural Science Foundation of China (50878109)the National Key Technology R & D Program (2007BAB27B03)the Education Ministry Doctor Foundation of China (20070429001)
文摘Qingdao Jiaozhou Bay subsea tunnel is the second self-built tunnel in China with the designed service life over 100 years.The durability of lining concrete are one of an important factors to determinate the service life of tunnel.Considering the main environmental loads and mechanical loads of subsea tunnel,the durability properties of lining concrete under combined action of compressive load and carbonation has been studied through the critical compressive load test,accelerated carbonation test,natural carbonation test and capillary suction test.The tests results show that critical compressive load apparently accelerates the carbonation and deteriorates the anti-permeability of concrete.Under the combined action of critical compressive load and carbonation,the durability of lining concrete decreases.Based on the carbonization life criteria and research results,for the high-performance concrete with proposed mix ratio,the predicted service life of lining concrete for Jiaozhou bay subsea tunnel is about 80 years which fails to reach the required service life.It is necessary to adopt other measurements simultaneously to improve the durability of lining concrete.
文摘A series of improvements in prolonging the AOD refractory lining life in Baosteel are introduced and analyzed in this paper,including modification of the AOD shell shape, adjustment of the top slag components and selection of the side-blowing tuyeres. Firstly,the layout of side-blow tuyeres was altered with the angle between each two tuyeres being 22.5° instead of the original 18° ,and the connection of the outside steel shell in the side-blow area was modified from the former platform shape with great stress concentration into a new smooth circle shape. Secondly,the slag components were changed from the former CaO-FeO-SiO： system to the CaO-MgO-SiO2 system. Besides, the basicity of the top slag was kept higher than 1.8 ,and the MgO content in the slag was kept within the range of 8% - 12%. Finally,tuyeres with an inner diameter 13% smaller than that of the original tuyeres were used. Based on these research and optimization work,the thermodynamics and kinetics in the AOD refining bath has been improved markedly, and the campaign of the AOD has been prolonged from 45 heats at the beginning of its start-up to the current 185 heats. Meanwhile,the yield of chromium alloy and the decarburization efficiency have also been improved.
