The free vibration analysis of a rotating sandwich conical shell with a reentrant auxetic honeycomb core and homogenous isotropic face layers reinforced with a ring support is studied.The shell is modeled utilizing th...The free vibration analysis of a rotating sandwich conical shell with a reentrant auxetic honeycomb core and homogenous isotropic face layers reinforced with a ring support is studied.The shell is modeled utilizing the first-order shear deformation theory(FSDT)incorporating the relative,centripetal,and Coriolis accelerations alongside the initial hoop tension created by the rotation.The governing equations,compatibility conditions,and boundary conditions are attained using Hamilton’s principle.Utilizing trigonometric functions,an analytical solution is derived in the circumferential direction,and a numerical one is presented in the meridional direction via the differential quadrature method(DQM).The effects of various factors on the critical rotational speeds and forward and backward frequencies of the shell are studied.The present work is the first theoretical work regarding the dynamic analysis of a rotating sandwich conical shell with an auxetic honeycomb core strengthened with a ring support.展开更多
A lumped parameter-rigid elastic coupled dynamic model of two-stage planetary gears for a hybrid car is established through the inter-stage coupled method,in which the supports of the ring gear of planet set Ⅱ are re...A lumped parameter-rigid elastic coupled dynamic model of two-stage planetary gears for a hybrid car is established through the inter-stage coupled method,in which the supports of the ring gear of planet set Ⅱ are represented as an elastic foundation with radial and tangential uniform distributed stiffness,and the ring gear of planet set Ⅱ is modeled as an elastic continuum body. The natural frequencies based on the eigenvalue problem of dynamic model of planetary transmission are solved and the associated vibration modes are discussed. The rules are revealed which are the influences of the ring gear elastic supports stiffness and rim thickness on natural frequencies of planetary transmission. The theoretical analysis indicates that the vibration modes of planetary transmission with thin-walled ring gear on elastic supports are classified into seven types: Ⅰ/Ⅱ stage coupled rotational mode,Ⅰ stage translational mode,Ⅰ stage planet mode,Ⅱ stage translational mode,Ⅱ stage degenerate planet mode,Ⅱ stage distinct planet mode and purely ring gear mode. For each vibration mode, its properties are summarized. The numerical solutions show that the elastic supports stiffness and rim thickness of the ring gear of planet set Ⅱ have different influences on natural frequencies.展开更多
振动抑制是保障武器装备安全运行的重要基础,在航空发动机中广泛使用弹性环挤压油膜阻尼器(Elastic Ring Squeeze Film Dampers,ERSFD)抑制转子系统振动响应。针对多支点支承的悬臂动力涡轮转子,通过有限元分析和敏感度评估,阐明了ERSF...振动抑制是保障武器装备安全运行的重要基础,在航空发动机中广泛使用弹性环挤压油膜阻尼器(Elastic Ring Squeeze Film Dampers,ERSFD)抑制转子系统振动响应。针对多支点支承的悬臂动力涡轮转子,通过有限元分析和敏感度评估,阐明了ERSFD在不同转子特性下的减振效果。研究结果表明,合理的结构及刚度设计能够有效提升ERSFD的动力特性,为高速转子系统提供更优的抑振效果。不同弹性环支承阻尼对悬臂转子响应的幅值抑制敏感性有所不同,受转子振型等特征影响,对于双支点支承的悬臂动力涡轮,远离动力涡轮支点(5#支点)应用阻尼结构,有利于降低轴段弯曲振型下振动响应;而靠近悬臂动力涡轮支点(6#支点)的阻尼结构,对动力涡轮摆动振动响应抑制效果更显著,可实现振动响应衰减超过70%。通过有针对性地开展弹性环支承阻尼设计,可实现对多支点悬臂动力涡轮转子多阶振型下振动响应抑制。展开更多
The China-type cubic press(CCP)is widely used in the high-pressure field because of its simple operation and low cost.However,the low ultimate pressure inside the cavity of CCP has limited its application.In order to ...The China-type cubic press(CCP)is widely used in the high-pressure field because of its simple operation and low cost.However,the low ultimate pressure inside the cavity of CCP has limited its application.In order to improve the ultimate pressure of the cavity,this paper simulates the pressure transfer efficiency and the Von Mises stress(VMS)of the tungsten carbide(WC)anvil.We find that the effect of the pretightening force of the WC anvil can be changed by changing the angle of the steel supporting ring.When the angle of the steel supporting ring is 1.2°,the pretightening force of the WC anvil is the most uniform,and the support effect of the WC anvil is the best.At the same time,this paper designs a double-beveled WC(D-WC)anvil.The D-WC anvil can not only improve the ultimate pressure of the cavity,but also ensure the stability of the cavity and the durability of the WC anvil.The design in this paper can also be used with the first-stage pressurization assembly to achieve better pressurization effect.展开更多
文摘The free vibration analysis of a rotating sandwich conical shell with a reentrant auxetic honeycomb core and homogenous isotropic face layers reinforced with a ring support is studied.The shell is modeled utilizing the first-order shear deformation theory(FSDT)incorporating the relative,centripetal,and Coriolis accelerations alongside the initial hoop tension created by the rotation.The governing equations,compatibility conditions,and boundary conditions are attained using Hamilton’s principle.Utilizing trigonometric functions,an analytical solution is derived in the circumferential direction,and a numerical one is presented in the meridional direction via the differential quadrature method(DQM).The effects of various factors on the critical rotational speeds and forward and backward frequencies of the shell are studied.The present work is the first theoretical work regarding the dynamic analysis of a rotating sandwich conical shell with an auxetic honeycomb core strengthened with a ring support.
基金Innovation Funded Project of Fujian Province,China(No.2015C0030)Natural Science Foundation of Guangdong Province,China(No.S2013020013855)
文摘A lumped parameter-rigid elastic coupled dynamic model of two-stage planetary gears for a hybrid car is established through the inter-stage coupled method,in which the supports of the ring gear of planet set Ⅱ are represented as an elastic foundation with radial and tangential uniform distributed stiffness,and the ring gear of planet set Ⅱ is modeled as an elastic continuum body. The natural frequencies based on the eigenvalue problem of dynamic model of planetary transmission are solved and the associated vibration modes are discussed. The rules are revealed which are the influences of the ring gear elastic supports stiffness and rim thickness on natural frequencies of planetary transmission. The theoretical analysis indicates that the vibration modes of planetary transmission with thin-walled ring gear on elastic supports are classified into seven types: Ⅰ/Ⅱ stage coupled rotational mode,Ⅰ stage translational mode,Ⅰ stage planet mode,Ⅱ stage translational mode,Ⅱ stage degenerate planet mode,Ⅱ stage distinct planet mode and purely ring gear mode. For each vibration mode, its properties are summarized. The numerical solutions show that the elastic supports stiffness and rim thickness of the ring gear of planet set Ⅱ have different influences on natural frequencies.
文摘振动抑制是保障武器装备安全运行的重要基础,在航空发动机中广泛使用弹性环挤压油膜阻尼器(Elastic Ring Squeeze Film Dampers,ERSFD)抑制转子系统振动响应。针对多支点支承的悬臂动力涡轮转子,通过有限元分析和敏感度评估,阐明了ERSFD在不同转子特性下的减振效果。研究结果表明,合理的结构及刚度设计能够有效提升ERSFD的动力特性,为高速转子系统提供更优的抑振效果。不同弹性环支承阻尼对悬臂转子响应的幅值抑制敏感性有所不同,受转子振型等特征影响,对于双支点支承的悬臂动力涡轮,远离动力涡轮支点(5#支点)应用阻尼结构,有利于降低轴段弯曲振型下振动响应;而靠近悬臂动力涡轮支点(6#支点)的阻尼结构,对动力涡轮摆动振动响应抑制效果更显著,可实现振动响应衰减超过70%。通过有针对性地开展弹性环支承阻尼设计,可实现对多支点悬臂动力涡轮转子多阶振型下振动响应抑制。
基金supported by the National Natural Science Foundation of China(Grant Nos.52272210 and 51872112)the Natural Science Foundation of Jilin Province of China(Grant Nos.20220101005JC and SKL202302007).
文摘The China-type cubic press(CCP)is widely used in the high-pressure field because of its simple operation and low cost.However,the low ultimate pressure inside the cavity of CCP has limited its application.In order to improve the ultimate pressure of the cavity,this paper simulates the pressure transfer efficiency and the Von Mises stress(VMS)of the tungsten carbide(WC)anvil.We find that the effect of the pretightening force of the WC anvil can be changed by changing the angle of the steel supporting ring.When the angle of the steel supporting ring is 1.2°,the pretightening force of the WC anvil is the most uniform,and the support effect of the WC anvil is the best.At the same time,this paper designs a double-beveled WC(D-WC)anvil.The D-WC anvil can not only improve the ultimate pressure of the cavity,but also ensure the stability of the cavity and the durability of the WC anvil.The design in this paper can also be used with the first-stage pressurization assembly to achieve better pressurization effect.
