Thin-walled aluminum alloy tube numerical control （NC） bending with small bending radius is a complex process with multi-factor coupling effects and multi-die constraints. A significance-based optimization method of...Thin-walled aluminum alloy tube numerical control （NC） bending with small bending radius is a complex process with multi-factor coupling effects and multi-die constraints. A significance-based optimization method of the parameters was proposed based on the finite element （FE） simulation, and the significance analysis of the processing parameters on the forming quality in terms of the maximum wall thinning ratio and the maximum cross section distortion degree was implemented using the fractional factorial design. The optimum value of the significant parameter, the clearance between the tube and the wiper die, was obtained, and the values of the other parameters, including the friction coefficients and the clearances between the tube and the dies, the mandrel extension length and the boost velocity were estimated. The results are applied to aluminum alloy tube NC bending d50 mm×1 mm×75 mm and d70 mm×1.5 mm×105 mm （initial tube outside diameter D0 × initial tube wall thickness t0 × bending radius R）, and qualified tubes are produced.展开更多
Although reviewers of Tremblay＇s play For the Pleasure of Seeing Her Again （1998） focus on the monologues of the angry mother who rants about everyday concerns for the well-being of her child, a character much like...Although reviewers of Tremblay＇s play For the Pleasure of Seeing Her Again （1998） focus on the monologues of the angry mother who rants about everyday concerns for the well-being of her child, a character much like the one who initiated Tremblay＇s career （the old song）, the author will focus on how the narrator＇s memory of his mother stage by stage in his life enacted before our eyes, permits Tremblay to self-consciously explain that his artistry reaches far beyond bringing the people he knew best in his youth, who had no knowledge of theater history, acting, and directing and staging, to the stage. His growth as an artist and his ＂new songs＂ are a result of his own continuous development of that knowledge展开更多
The cyclic rotating−bending(CRB)processes under different deformation conditions were carried out to refine the microstructure and improve the mechanical properties of the 65Cu−35Zn brass tubes.The microstructure and ...The cyclic rotating−bending(CRB)processes under different deformation conditions were carried out to refine the microstructure and improve the mechanical properties of the 65Cu−35Zn brass tubes.The microstructure and the mechanical properties in the axial direction of the tubes after the CRB process were studied with the OM,EBSD and conventional tensile test.To obtain the accumulated effective plastic strain of the tube during the CRB process,the FEM simulation was also executed.The results show that the average grain size decreases with the increase of rotation time at RT,and with the decrease of bending angle at 200℃.With the increase of accumulated effective plastic strain during the CRB process,the reduction rate of average grain size of the brass tube increases,the tensile strength of the brass tube increases in wave shape and the elongation increases first and then sharply decreases.展开更多
The blend ratio and tensile properties are vital important characteristics of blended fibre bundles. Fibre-bundle tensile behaviour has been measured by means of the Sirolan-Tensor in order to derive a typical specifi...The blend ratio and tensile properties are vital important characteristics of blended fibre bundles. Fibre-bundle tensile behaviour has been measured by means of the Sirolan-Tensor in order to derive a typical specific stress — extension curve. According to the typical tensile curve, the relationships between the blend ratio and the tensile parameters are discussed and established. Two new algorithms, so-called the strength method and the work method, have been developed for the blend-ratio estimation of blended fibre bundles. The relevant blend-ratios and calculations of the two methods are defined in detail. Also, the characteristics have been explained for every calculation and compared to each others. The experimental results show that the blend ratios estimated from the theoretical methods are high coincidence with the measured results. Meanwhile, the specific stress — extension curve of blended fibre bundles depends directly on the blend ratios of the fibre bundles.展开更多
This investigation focused on the analysis of using the M-cycle （Maisotsenko cycle） to improve the efficiency of a gas turbine engine. By combining the M-cycle with an open Brayton cycle, a new cycle, is known as th...This investigation focused on the analysis of using the M-cycle （Maisotsenko cycle） to improve the efficiency of a gas turbine engine. By combining the M-cycle with an open Brayton cycle, a new cycle, is known as the MCTC （Maisotsenko combustion turbine cycle）, was formed. The MCTC used an indirect evaporative air cooler as a saturator with a gas turbine engine. The saturator was applied on the side of the turbine exhaust （M-cycle#2） in the analysis. The analysis included calculations and the development of an EES （engineering equation solver） code to model the MCTC system performance. The resulting performance curves were graphed to show the effects of several parameters on the thermal efficiency and net power output of the gas turbine engine. The models were also compared with actual experimental test that results from a gas turbine engine. Conclusions and discussions of results are also given.展开更多
In order to obtain a basic understanding of the unwanted distortions in the pipe wall during the press cutting process, the deformation of a thin-walled round pipe to form a curvilinear end was numerically and experim...In order to obtain a basic understanding of the unwanted distortions in the pipe wall during the press cutting process, the deformation of a thin-walled round pipe to form a curvilinear end was numerically and experimentally studied. Vector analysis was used to study the relationship between the punch shape and the collapse of the cut-end. Stamping experiments on AISI 1020 steel pipe were conducted using different angles a and β defining the shape of the punch. The elasto-plastic finite element method that allows consideration of a ductile fracture was also employed to study the process. The results show that the deformation of the pipe end after press cutting is inβuenced mostly by the shape of the punch. A satisfactory quality of the curvilinear end of the pipe can be obtained if the appropriate geometric parameters of the punch are chosen. The pipe-wall collapse in the upper part of the section is decreased when a and β increase. The recommended values for a and β lie within 30°-50°. The hole on the underside of the punch has less inβuence on the quality of the cut-end, and the wall distortion and the generation of burr on the cut-end can be satisfactorily simulated using the fracture criterion of Brozzo or the normalized criterion of Cockcroft and Latham.展开更多
基金Projects (50905144, 50875216) supported by the National Natural Science Foundation of ChinaProject (09-10) supported by the State Key Laboratory of Materials Processing and Die & Mould Technology, ChinaProject (JC201028) supported by the Northwestern Polytechnical University Foundation for Fundamental Research, China
文摘Thin-walled aluminum alloy tube numerical control （NC） bending with small bending radius is a complex process with multi-factor coupling effects and multi-die constraints. A significance-based optimization method of the parameters was proposed based on the finite element （FE） simulation, and the significance analysis of the processing parameters on the forming quality in terms of the maximum wall thinning ratio and the maximum cross section distortion degree was implemented using the fractional factorial design. The optimum value of the significant parameter, the clearance between the tube and the wiper die, was obtained, and the values of the other parameters, including the friction coefficients and the clearances between the tube and the dies, the mandrel extension length and the boost velocity were estimated. The results are applied to aluminum alloy tube NC bending d50 mm×1 mm×75 mm and d70 mm×1.5 mm×105 mm （initial tube outside diameter D0 × initial tube wall thickness t0 × bending radius R）, and qualified tubes are produced.
文摘Although reviewers of Tremblay＇s play For the Pleasure of Seeing Her Again （1998） focus on the monologues of the angry mother who rants about everyday concerns for the well-being of her child, a character much like the one who initiated Tremblay＇s career （the old song）, the author will focus on how the narrator＇s memory of his mother stage by stage in his life enacted before our eyes, permits Tremblay to self-consciously explain that his artistry reaches far beyond bringing the people he knew best in his youth, who had no knowledge of theater history, acting, and directing and staging, to the stage. His growth as an artist and his ＂new songs＂ are a result of his own continuous development of that knowledge
基金the National Natural Science Foundation of China(No.51304046)the Grant-in-Aid for Young Scientists(B)of Japan Society for the Promotion of Science of Japan(No.25870594)。
文摘The cyclic rotating−bending(CRB)processes under different deformation conditions were carried out to refine the microstructure and improve the mechanical properties of the 65Cu−35Zn brass tubes.The microstructure and the mechanical properties in the axial direction of the tubes after the CRB process were studied with the OM,EBSD and conventional tensile test.To obtain the accumulated effective plastic strain of the tube during the CRB process,the FEM simulation was also executed.The results show that the average grain size decreases with the increase of rotation time at RT,and with the decrease of bending angle at 200℃.With the increase of accumulated effective plastic strain during the CRB process,the reduction rate of average grain size of the brass tube increases,the tensile strength of the brass tube increases in wave shape and the elongation increases first and then sharply decreases.
文摘The blend ratio and tensile properties are vital important characteristics of blended fibre bundles. Fibre-bundle tensile behaviour has been measured by means of the Sirolan-Tensor in order to derive a typical specific stress — extension curve. According to the typical tensile curve, the relationships between the blend ratio and the tensile parameters are discussed and established. Two new algorithms, so-called the strength method and the work method, have been developed for the blend-ratio estimation of blended fibre bundles. The relevant blend-ratios and calculations of the two methods are defined in detail. Also, the characteristics have been explained for every calculation and compared to each others. The experimental results show that the blend ratios estimated from the theoretical methods are high coincidence with the measured results. Meanwhile, the specific stress — extension curve of blended fibre bundles depends directly on the blend ratios of the fibre bundles.
文摘This investigation focused on the analysis of using the M-cycle （Maisotsenko cycle） to improve the efficiency of a gas turbine engine. By combining the M-cycle with an open Brayton cycle, a new cycle, is known as the MCTC （Maisotsenko combustion turbine cycle）, was formed. The MCTC used an indirect evaporative air cooler as a saturator with a gas turbine engine. The saturator was applied on the side of the turbine exhaust （M-cycle#2） in the analysis. The analysis included calculations and the development of an EES （engineering equation solver） code to model the MCTC system performance. The resulting performance curves were graphed to show the effects of several parameters on the thermal efficiency and net power output of the gas turbine engine. The models were also compared with actual experimental test that results from a gas turbine engine. Conclusions and discussions of results are also given.
基金Project(CDJZR10110029)supported by the Fundamental Research Funds for the Central Universities in China
文摘In order to obtain a basic understanding of the unwanted distortions in the pipe wall during the press cutting process, the deformation of a thin-walled round pipe to form a curvilinear end was numerically and experimentally studied. Vector analysis was used to study the relationship between the punch shape and the collapse of the cut-end. Stamping experiments on AISI 1020 steel pipe were conducted using different angles a and β defining the shape of the punch. The elasto-plastic finite element method that allows consideration of a ductile fracture was also employed to study the process. The results show that the deformation of the pipe end after press cutting is inβuenced mostly by the shape of the punch. A satisfactory quality of the curvilinear end of the pipe can be obtained if the appropriate geometric parameters of the punch are chosen. The pipe-wall collapse in the upper part of the section is decreased when a and β increase. The recommended values for a and β lie within 30°-50°. The hole on the underside of the punch has less inβuence on the quality of the cut-end, and the wall distortion and the generation of burr on the cut-end can be satisfactorily simulated using the fracture criterion of Brozzo or the normalized criterion of Cockcroft and Latham.
