The machine tool equipped with the dual-drive servo feed system could realize high feed speed as well as sharp precision. Currently, there is no report about the thermal behaviors of the dual-drive machine, and the cu...The machine tool equipped with the dual-drive servo feed system could realize high feed speed as well as sharp precision. Currently, there is no report about the thermal behaviors of the dual-drive machine, and the current research of the thermal characteristics of machines mainly focuses on steady simulation. To explore the influence of thermal characterizations on the precision of a jib boring machine assembled dual-drive feed system, the thermal equilibrium tests and the research on thermal-mechanical transient behaviors are carried out. A laser interferometer, infrared thermography and a temperature-displacement acquisition system are applied to measure the temperature distribution and thermal deformation at different feed speeds. Subsequently, the finite element method （FEM） is used to analyze the transient thermal behaviors of the boring machine. The complex boundary conditions, such as heat sources and convective heat transfer coefficient, are calculated. Finally, transient variances in temperatures and deformations are compared with the measured values, and the errors between the measurement and the simulation of the temperature and the thermal error are 2 ~C and 2.5 pm, respectively. The researching results demonstrate that the FEM model can predict the thermal error and temperature distribution very well under specified operating condition. Moreover, the uneven temperature gradient is due to the asynchronous dual-drive structure that results in thermal deformation. Additionally, the positioning accuracy decreases as the measured point became further away from the motor, and the thermal error and equilibrium period both increase with feed speeds. The research proposes a systematical method to measure and simulate the boring machine transient thermal behaviors.展开更多
This paper studies the thermal effect of the cable-stayed bridge tower based on full time accurate measurement and finite element analysis on Xiantao Hanjiang River Highway Bridge. The measured results and the displac...This paper studies the thermal effect of the cable-stayed bridge tower based on full time accurate measurement and finite element analysis on Xiantao Hanjiang River Highway Bridge. The measured results and the displacement variation of top tower show that the tower rotates periodically when it is exposed in sunshine. But the tower column will not decline when there is no sunshine. In spite of in winter or in summer, the period when the tower column changed smallest is from 0∶00 am to 5∶00 am. The time period when the tower column has maximum deviation lags behind the time when the tower column has maximum temperature difference, and this phenomenon is obvious in winter. The conclusions also have directive value in predicting the tower deformations and their directions in construction control of cable-stayed bridge, and in verifying the finite element program.展开更多
In this study, an etched-SiO-film grating fabrication technique based on solute-solvent separation soft lithography is developed. By using this new technique, high temperature grating with frequency of 600 lines/mm is...In this study, an etched-SiO-film grating fabrication technique based on solute-solvent separation soft lithography is developed. By using this new technique, high temperature grating with frequency of 600 lines/mm is successfully fabricated on the surface of thermal barrier coatings(TBCs). During the fabrication process, the microstructure and chemical compositions of ceramic coating before and after polishing is analyzed with a digital microscope and the energy dispersive X-ray spectroscope(EDS) in scanning electron microscope(SEM). And then the grating on TBCs is heated at the temperature ranging from 300℃ to 1000℃ for examining the high temperature resistance. In the practical application, the displacement and strain field around the crack on the ceramic surface are investigated with geometry phase analysis(GPA). The successful results verify that the etched-SiO-film grating has a good oxidation resistance and can be applied to high temperature deformation measurement of TBCs.展开更多
基金Supported by National Hi-tech Research and Development Program of China(863 Program,Grant No.2012AA040701)
文摘The machine tool equipped with the dual-drive servo feed system could realize high feed speed as well as sharp precision. Currently, there is no report about the thermal behaviors of the dual-drive machine, and the current research of the thermal characteristics of machines mainly focuses on steady simulation. To explore the influence of thermal characterizations on the precision of a jib boring machine assembled dual-drive feed system, the thermal equilibrium tests and the research on thermal-mechanical transient behaviors are carried out. A laser interferometer, infrared thermography and a temperature-displacement acquisition system are applied to measure the temperature distribution and thermal deformation at different feed speeds. Subsequently, the finite element method （FEM） is used to analyze the transient thermal behaviors of the boring machine. The complex boundary conditions, such as heat sources and convective heat transfer coefficient, are calculated. Finally, transient variances in temperatures and deformations are compared with the measured values, and the errors between the measurement and the simulation of the temperature and the thermal error are 2 ~C and 2.5 pm, respectively. The researching results demonstrate that the FEM model can predict the thermal error and temperature distribution very well under specified operating condition. Moreover, the uneven temperature gradient is due to the asynchronous dual-drive structure that results in thermal deformation. Additionally, the positioning accuracy decreases as the measured point became further away from the motor, and the thermal error and equilibrium period both increase with feed speeds. The research proposes a systematical method to measure and simulate the boring machine transient thermal behaviors.
文摘This paper studies the thermal effect of the cable-stayed bridge tower based on full time accurate measurement and finite element analysis on Xiantao Hanjiang River Highway Bridge. The measured results and the displacement variation of top tower show that the tower rotates periodically when it is exposed in sunshine. But the tower column will not decline when there is no sunshine. In spite of in winter or in summer, the period when the tower column changed smallest is from 0∶00 am to 5∶00 am. The time period when the tower column has maximum deviation lags behind the time when the tower column has maximum temperature difference, and this phenomenon is obvious in winter. The conclusions also have directive value in predicting the tower deformations and their directions in construction control of cable-stayed bridge, and in verifying the finite element program.
基金financially supported by the National Natural Science Foundation of China(11672153,11232008)
文摘In this study, an etched-SiO-film grating fabrication technique based on solute-solvent separation soft lithography is developed. By using this new technique, high temperature grating with frequency of 600 lines/mm is successfully fabricated on the surface of thermal barrier coatings(TBCs). During the fabrication process, the microstructure and chemical compositions of ceramic coating before and after polishing is analyzed with a digital microscope and the energy dispersive X-ray spectroscope(EDS) in scanning electron microscope(SEM). And then the grating on TBCs is heated at the temperature ranging from 300℃ to 1000℃ for examining the high temperature resistance. In the practical application, the displacement and strain field around the crack on the ceramic surface are investigated with geometry phase analysis(GPA). The successful results verify that the etched-SiO-film grating has a good oxidation resistance and can be applied to high temperature deformation measurement of TBCs.
