A novel spiral non-circular bevel gear that could be applied to variable-speed driving in intersecting axes was proposed by combining the design principles of non-circular bevel gears and the manufacturing principles ...A novel spiral non-circular bevel gear that could be applied to variable-speed driving in intersecting axes was proposed by combining the design principles of non-circular bevel gears and the manufacturing principles of face-milling spiral bevel gears.Unlike straight non-circular bevel gears,spiral non-circular bevel gears have numerous advantages,such as a high contact ratio,high intensity,good dynamic performance,and an adjustable contact region.In addition,while manufacturing straight non-circular bevel gears is difficult,spiral non-circular bevel gears can be efficiently and precisely fabricated with a 6-axis bevel gear cutting machine.First,the generating principles of spiral non-circular bevel gears were introduced.Next,a mathematical model,including a generating tooth profile,tooth spiral,pressure angle,and generated tooth profile for this gear type was established.Then the precision of the model was verified by a tooth contact analysis using FEA,and the contact patterns and stress distributions of the spiral non-circular bevel gears were investigated.展开更多
The stability of underground excavations is influenced by discontinuities interspaced in surrounding rock masses as well as the stress condition. In this work, a numerical study was undertaken on the failure behavior ...The stability of underground excavations is influenced by discontinuities interspaced in surrounding rock masses as well as the stress condition. In this work, a numerical study was undertaken on the failure behavior around a circular opening in a rock mass having non-persistent open joints using PFC software package. A parallel-bond stress corrosion(PSC) approach was incorporated to drive the failure of rock mass around the circular opening, such that the whole progressive failure process after excavation was reproduced. Based on the determined micro parameters for intact material and joint segments, the failure process around the circular opening agrees very well with that obtained through laboratory experiment. A subsequent parametric study was then carried out to look into the influence of lateral pressure coefficient, joint dip angle and joint persistency on the failure pattern and crack evolution of the rock mass around the circular opening. Three failure patterns identified are step path failure, planar failure and rotation failure depending on the lateral pressure coefficient. Moreover, the increment of joint dip angle and joint persistency aggravates the rock mass failure around the opening. This study offers guideline on stability estimation of underground excavations.展开更多
为提高分插机构的设计效率,缩短设计开发周期,该文以偏心齿轮-非圆齿轮后插旋转式分插机构为基础,并以三维软件UG6.0为设计平台,利用可视化编程语言VB.NET定制用户界面,采用NX Open for.NET的UG二次开发技术,建立该分插机构的三维参数...为提高分插机构的设计效率,缩短设计开发周期,该文以偏心齿轮-非圆齿轮后插旋转式分插机构为基础,并以三维软件UG6.0为设计平台,利用可视化编程语言VB.NET定制用户界面,采用NX Open for.NET的UG二次开发技术,建立该分插机构的三维参数化设计系统。利用该系统,通过用户界面输入主要设计参数,即可快速生成偏心齿轮-非圆齿轮后插旋转式分插机构的零件(包括非圆齿轮)和装配三维模型,实现该分插机构的三维参数化设计。展开更多
基金Project(52175361)supported by the National Natural Science Foundation of ChinaProject(2019 CFA 041)supported by the Natural Science Foundation of Hubei Province,ChinaProject(WUT:202407002)supported by the Fundamental Research Funds for the Central Universities,China。
文摘A novel spiral non-circular bevel gear that could be applied to variable-speed driving in intersecting axes was proposed by combining the design principles of non-circular bevel gears and the manufacturing principles of face-milling spiral bevel gears.Unlike straight non-circular bevel gears,spiral non-circular bevel gears have numerous advantages,such as a high contact ratio,high intensity,good dynamic performance,and an adjustable contact region.In addition,while manufacturing straight non-circular bevel gears is difficult,spiral non-circular bevel gears can be efficiently and precisely fabricated with a 6-axis bevel gear cutting machine.First,the generating principles of spiral non-circular bevel gears were introduced.Next,a mathematical model,including a generating tooth profile,tooth spiral,pressure angle,and generated tooth profile for this gear type was established.Then the precision of the model was verified by a tooth contact analysis using FEA,and the contact patterns and stress distributions of the spiral non-circular bevel gears were investigated.
基金Project(2013CB036003)supported by the National Basic Research Program of ChinaProjects(51374198,51134001,51404255)supported by the National Natural Science Foundation of ChinaProject(BK20150005)supported by the Natural Science Foundation of Jiangsu Province for Distinguished Youth Scholar,China
文摘The stability of underground excavations is influenced by discontinuities interspaced in surrounding rock masses as well as the stress condition. In this work, a numerical study was undertaken on the failure behavior around a circular opening in a rock mass having non-persistent open joints using PFC software package. A parallel-bond stress corrosion(PSC) approach was incorporated to drive the failure of rock mass around the circular opening, such that the whole progressive failure process after excavation was reproduced. Based on the determined micro parameters for intact material and joint segments, the failure process around the circular opening agrees very well with that obtained through laboratory experiment. A subsequent parametric study was then carried out to look into the influence of lateral pressure coefficient, joint dip angle and joint persistency on the failure pattern and crack evolution of the rock mass around the circular opening. Three failure patterns identified are step path failure, planar failure and rotation failure depending on the lateral pressure coefficient. Moreover, the increment of joint dip angle and joint persistency aggravates the rock mass failure around the opening. This study offers guideline on stability estimation of underground excavations.
文摘为提高分插机构的设计效率,缩短设计开发周期,该文以偏心齿轮-非圆齿轮后插旋转式分插机构为基础,并以三维软件UG6.0为设计平台,利用可视化编程语言VB.NET定制用户界面,采用NX Open for.NET的UG二次开发技术,建立该分插机构的三维参数化设计系统。利用该系统,通过用户界面输入主要设计参数,即可快速生成偏心齿轮-非圆齿轮后插旋转式分插机构的零件(包括非圆齿轮)和装配三维模型,实现该分插机构的三维参数化设计。
