The AFM probe in tapping mode is a continuous process of energy dissipation,from moving away from to intermittent contact with the sample surfaces.At present,studies regarding the energy dissipation mechanism of this ...The AFM probe in tapping mode is a continuous process of energy dissipation,from moving away from to intermittent contact with the sample surfaces.At present,studies regarding the energy dissipation mechanism of this continuous process have only been reported sporadically,and there are no systematic explanations or experimental verifications of the energy dissipation mechanism in each stage of the continuous process.The quality factors can be used to characterize the energy dissipation in TM-AFM systems.In this study,the vibration model of the microcantilever beam was established,coupling the vibration and damping effects of the microcantilever beam.The quality factor of the vibrating microcantilever beam under damping was derived,and the air viscous damping when the probe is away from the sample and the air squeeze film damping when the probe is close to the sample were calculated.In addition,the mechanism of the damping effects of different shapes of probes at different tip–sample distances was analyzed.The accuracy of the theoretical simplified model was verified using both experimental and simulation methods.A clearer understanding of the kinetic characteristics and damping mechanism of the TM-AFM was achieved by examining the air damping dissipation mechanism of AFM probes in the tapping mode,which was very important for improving both the quality factor and the imaging quality of the TM-AFM system.This study’s research findings also provided theoretical references and experimental methods for the future study of the energy dissipation mechanism of micro-nano-electromechanical systems.展开更多
A differential equation that is generally effective for squeeze film air damping of perforated plate and non perforated plate as well as in MEMS devices is developed.For perforated plate,the thickness and the dimens...A differential equation that is generally effective for squeeze film air damping of perforated plate and non perforated plate as well as in MEMS devices is developed.For perforated plate,the thickness and the dimensions of the plate are not limited.With boundary conditions,pressure distribution and the damping force on the plate can be found by solving the differential equation.Analytical expressions for damping pressure and damping force of a long strip holeplate are presented with a finite thickness and a finite width.To the extreme conditions of very thin plate and very thin hole,the results are reduced to the corresponding results of the conventional Reynolds' equation.Thus, the effectiveness of the generalized differential equation is justified.Therefore,the generalized Reynolds' equation will be a useful tool of design for damping structures in MEMS.展开更多
A squeeze film damper (SFD) with metal rubber (MR) ring installed on the end and the radial direction of rotor are implemented in this paper. Based on the hypothesis of π film, the description of the new SFD/MR flux ...A squeeze film damper (SFD) with metal rubber (MR) ring installed on the end and the radial direction of rotor are implemented in this paper. Based on the hypothesis of π film, the description of the new SFD/MR flux and nonlinear oil film damping force is derived according to the Reynolds Eq. and Darcy’s law. It proves that the SFD/MR has better damping characteristics than the traditional SFD after comparatively analyzing characteristics of oil film between the traditional short SFD and the SFD/MR.展开更多
The elimination of rotor vibration is usually achieved by applying additional damping to the system.Squeeze film dampers are widely used in various aerospace and turbine equipments.The research is carried out on flow ...The elimination of rotor vibration is usually achieved by applying additional damping to the system.Squeeze film dampers are widely used in various aerospace and turbine equipments.The research is carried out on flow characteristics in the integral squeeze film dampers(ISFDs).The dynamic response to the operation condition is investigated through the computational fluid dynamics(CFD) model of ISFD.Due to the large pressure loss at the oil inlet,the oil film force only changes slightly with the increase of oil supply pressure,and the damping increases slightly.The vibration amplitude only affects the film force,but has no effect on the damping.The oil film force and damping show an upward tendency with the decrease of thickness of the end seal clearance.展开更多
The squeeze-film air damping exists in a lot of micro-electronic-mechanical system (MEMS) devices unavoidably. The effects of air damping in traditional inertial switch with spring-mass system can be ignored for its l...The squeeze-film air damping exists in a lot of micro-electronic-mechanical system (MEMS) devices unavoidably. The effects of air damping in traditional inertial switch with spring-mass system can be ignored for its large volume and mass. But, many properties of MEMS switch, such as sensitivity, resolution and contact time, are affected by the air damping caused from the squeezed air film between two parallel plates moving relatively. Based on the conservation laws for mass and flux and the nonlinear Reynolds equation, the coefficient of squeeze-film damping was derived. The dynamic responses of the inertial switch with and without squeeze-film damping were simulated by using software ANSYS. The simulated results show that the sensitivity and contact time of the switch descend by about 5% and 15%, respectively, when the effects of squeeze-film damping are considered.展开更多
Based on the energy transfer model(ETM) proposed by Bao et al.and the Monte Carlo(MC) model proposed by Hutcherson and Ye, this paper proposes an efficient molecular model(MC-S) for squeeze-film damping(SQFD) in raref...Based on the energy transfer model(ETM) proposed by Bao et al.and the Monte Carlo(MC) model proposed by Hutcherson and Ye, this paper proposes an efficient molecular model(MC-S) for squeeze-film damping(SQFD) in rarefied air by releasing the assumption of constant molecular velocity in the gap.Compared with the experiment data, the MC-S model is more efficient than the MC model and more accurate than ETM.Besides, by using the MC-S model, the feasibility of the empirical model proposed by Sumali for SQFD of different plate sizes is discussed.It is proved that, for various plate sizes, the accuracy of the empirical model is relatively high.At last, the SQFD of various vibration frequencies is discussed, and it shows that, for low vibration frequency, the MC-S model is reduced to ETM.展开更多
航空发动机转子系统通常在支承处设置挤压油膜阻尼器(squeeze film damper,SFD)来实现系统减振设计,与定心SFD相比,非定心SFD结构简单紧凑,减振效果良好,但是具有更强的非线性特征,动力特性更为复杂。以某航空发动机动力涡轮转子为研究...航空发动机转子系统通常在支承处设置挤压油膜阻尼器(squeeze film damper,SFD)来实现系统减振设计,与定心SFD相比,非定心SFD结构简单紧凑,减振效果良好,但是具有更强的非线性特征,动力特性更为复杂。以某航空发动机动力涡轮转子为研究对象,建立了多支点高速柔性转子-非定心SFD系统非线性动力学模型,考虑了非定心SFD静偏心的影响,采用数值方法求解转子系统响应,结合系统不平衡响应特征、分岔图、庞家莱截面、频谱等,开展了系统非线性动力学特性研究,并通过了转子试验验证。研究结果表明,非定心SFD油膜间隙较大时,转子系统存在较强的非线性运动,频率成分丰富,减小油膜间隙能够使系统在跨临界后为单周期运动,降低系统的非线性不平衡响应;但过小的油膜间隙将导致转子系统峰值响应和对应的转速显著增大,转子可工作转速范围变小,合理的油膜间隙可以兼顾非线性振动响应和峰值转速较小,实现转子系统在大转速范围内长时间运行。展开更多
为了对齿轮轴系进行减振降噪,提出了一种新型integral squeeze film damper(ISFD)弹性阻尼支撑结构。设计并加工了4套实验用ISFD弹性阻尼支撑结构,搭建了开式一级直齿轮实验台,并通过对比主、从动轴分别安装刚性支撑、弹性支撑及弹性阻...为了对齿轮轴系进行减振降噪,提出了一种新型integral squeeze film damper(ISFD)弹性阻尼支撑结构。设计并加工了4套实验用ISFD弹性阻尼支撑结构,搭建了开式一级直齿轮实验台,并通过对比主、从动轴分别安装刚性支撑、弹性支撑及弹性阻尼支撑后轴系的振动幅值,来验证其减振降噪效果。实验结果表明,该ISFD弹性阻尼支撑结构能够较好地改善齿轮啮合的冲击振动,并对齿轮啮合传动中大部分频率成分的振动都有良好的减振效果,平均降幅达50%以上,并且减振频带宽。展开更多
鉴于二甲基硅油较高的黏度及良好的热稳定性,考虑将其作为整体式挤压油膜阻尼器(Integral squeeze film damper,ISFD)的阻尼液,研究ISFD阻尼液黏度对齿轮轴系减振特性的影响规律。建立了ISFD弹性阻尼支承系统力学模型和齿轮传动有阻尼...鉴于二甲基硅油较高的黏度及良好的热稳定性,考虑将其作为整体式挤压油膜阻尼器(Integral squeeze film damper,ISFD)的阻尼液,研究ISFD阻尼液黏度对齿轮轴系减振特性的影响规律。建立了ISFD弹性阻尼支承系统力学模型和齿轮传动有阻尼单自由度振动模型,证明了ISFD用于齿轮轴系减振的有效性。搭建一级直齿轮传动轴系实验台,对比了齿轮轴系分别安装刚性支承和不同阻尼液黏度ISFD弹性阻尼支承的振动。研究发现,以二甲基硅油作阻尼液的ISFD可以有效抑制齿轮轴系振动,且减振效果良好,降幅可达50%以上;在一定黏度范围内,随着ISFD阻尼液黏度的增加,齿轮轴系的振动降幅增大;以二甲基硅油作阻尼液的ISFD具有优良的阻尼减振性能,可以有效抑制大部分频率成分的振动,保证齿轮系统平稳工作。展开更多
In this paper, a dynamic model on a rigid rotor sliding bearing system with a SFD is established. The stability and bifurcation behaviors of the system are studied. On the basis of the differential equations of fluid...In this paper, a dynamic model on a rigid rotor sliding bearing system with a SFD is established. The stability and bifurcation behaviors of the system are studied. On the basis of the differential equations of fluid momentum and mass continuity, the distribution pressure function is derived by taking oil film inertia force into consideration. Damping force, clearance excitation force, interference force of different frequencies and static load are also considered in the model. Finally, the governing equations of the stability and bifurcation behaviors of the system are solved by Floquet theory. Simulation of dynamic model shows that the rigid rotor sliding bearing system can maintain stability and exhibit a Hopf bifurcation phenomenon in a certain range.展开更多
A dynamic model of a flexible rotor-sliding bearing system ( FRSBS ) with asqueeze film damper ( SFD) is established. Considered in the model are oil film inertia force,damping farce, clearance excitation force, inter...A dynamic model of a flexible rotor-sliding bearing system ( FRSBS ) with asqueeze film damper ( SFD) is established. Considered in the model are oil film inertia force,damping farce, clearance excitation force, interference force of different frequencies and staticload, as opposed to previous research. On the basis of this model, the optimal design of the systemis deeply studied. Simulation shows that the system optimization design can effectively improve thesystem stability.展开更多
In this paper, the chaotic response of a rotor system with crack supported on the squeeze film damper (SFD) is studied. Baesd on the short bearing approximation and π film assumption, the film force is expressed as a...In this paper, the chaotic response of a rotor system with crack supported on the squeeze film damper (SFD) is studied. Baesd on the short bearing approximation and π film assumption, the film force is expressed as a function of speed and displacement of the bearing in the X and Y directions. The result shows that the film force can suppress the non synchronous response effectively if an SFD is designed well. The increase of the bearing parameter can suppress chaos. When the bearing parameter is s...展开更多
In this study we describe an FEM-based methodology to solve the coupled fluid-structure problem due to squeeze film effects present in vibratory MEMS devices, such as resonators, gyroscopes, and acoustic transducers. ...In this study we describe an FEM-based methodology to solve the coupled fluid-structure problem due to squeeze film effects present in vibratory MEMS devices, such as resonators, gyroscopes, and acoustic transducers. The aforementioned devices often consist of a plate-like structure that vibrates normal to a fixed substrate, and is generally not perfectly vacuum packed. This results in a thin film of air being sandwiched between the moving plate and the fixed substrate, which behaves like a squeeze film offering both stiffness and damping. Typically, such structures are actuated electro-statically, necessitating the thin air gap for improving the efficiency of actuation and the sensitivity of detection. To accurately model these devices the squeeze film effect must be incorporated. Extensive literature is present on mod- eling squeeze film effects for rigid motion for both perforated as well as non-perforated plates. Studies which model the plate elasticity often use approximate mode shapes as input to the 2D Reynolds Equation. Recent works which try to solve the coupled fluid elasticity problem, report iterative FEM-based solution strategies for the 2D Reynolds Equation coupled with the 3D elasticity Equation. In this work we present a FEM-based single step solution for the coupled problem at hand, using only one type of element (27 node 3D brick). The structure is modeled with 27 node brick elements of which the lowest layer of nodes is also treated as the fluid domain (2D) and the integrals over fluid domain are evaluated for these nodes only. We also apply an electrostatic loading to our model by considering an equivalent electro-static pressure load on the top surface of the structure. Thus we solve the coupled 2D-fluid-3D-structure problem in a single step, using only one element type. The FEM results show good agreement with both existing analytical solutions and published experimental data.展开更多
This paper aims at investigating the effectiveness of squeeze oil film in suppressing the longitudinal vibration of propulsion shaft systems through a novel integral axial squeeze film damper(IASFD).After designing th...This paper aims at investigating the effectiveness of squeeze oil film in suppressing the longitudinal vibration of propulsion shaft systems through a novel integral axial squeeze film damper(IASFD).After designing the IASFD,a propulsion shafting test rig for the longitudinal vibration control is built.Longitudinal vibration control experiments of the propulsion shafting are carried out under different magnitude and frequency of the excitation force.The results show that both IASFD elastic support and IASFD elastic damping support have excellent vibration attenuation characteristics,and can effectively suppress the longitudinal vibration of the shaft system in a wide frequency range.However,IASFD elastic damping support has a more significant vibration reduction effect than the other supports,and increasing the damping of the system has obvious effect on reducing the shafting vibration.For an excitation force of 45 N,the maximum reduction of the vibration amplitude is 89.16%.Also,the vibration generated by the resonance phenomenon is also significantly reduced.展开更多
考虑挤压油膜阻尼器(squeeze film damper,SFD)非线性油膜力建立了转子的运动微分方程,将转子在冲击载荷下的振动响应分解为谐响应和冲击响应,分别建立了谐响应、冲击响应的有限元模型,并开展了振动响应计算分析。在振动台上开展了航空...考虑挤压油膜阻尼器(squeeze film damper,SFD)非线性油膜力建立了转子的运动微分方程,将转子在冲击载荷下的振动响应分解为谐响应和冲击响应,分别建立了谐响应、冲击响应的有限元模型,并开展了振动响应计算分析。在振动台上开展了航空发动机转子在不同脉宽的垂向冲击载荷下的振动特性试验研究,获取了转子在冲击瞬时的振动响应,并与计算结果进行对比分析。研究结果表明:在一定范围内,转子的振动响应随冲击脉宽变大而变小;与试验结果相比,振动响应计算误差在10.44%~20.00%。研究为冲击载荷下航空发动机转子振动响应分析和试验提供了方法,具有重要的工程应用价值。展开更多
基金the National Natural Science Foun-dation of China(Grant No.11572031).
文摘The AFM probe in tapping mode is a continuous process of energy dissipation,from moving away from to intermittent contact with the sample surfaces.At present,studies regarding the energy dissipation mechanism of this continuous process have only been reported sporadically,and there are no systematic explanations or experimental verifications of the energy dissipation mechanism in each stage of the continuous process.The quality factors can be used to characterize the energy dissipation in TM-AFM systems.In this study,the vibration model of the microcantilever beam was established,coupling the vibration and damping effects of the microcantilever beam.The quality factor of the vibrating microcantilever beam under damping was derived,and the air viscous damping when the probe is away from the sample and the air squeeze film damping when the probe is close to the sample were calculated.In addition,the mechanism of the damping effects of different shapes of probes at different tip–sample distances was analyzed.The accuracy of the theoretical simplified model was verified using both experimental and simulation methods.A clearer understanding of the kinetic characteristics and damping mechanism of the TM-AFM was achieved by examining the air damping dissipation mechanism of AFM probes in the tapping mode,which was very important for improving both the quality factor and the imaging quality of the TM-AFM system.This study’s research findings also provided theoretical references and experimental methods for the future study of the energy dissipation mechanism of micro-nano-electromechanical systems.
文摘A differential equation that is generally effective for squeeze film air damping of perforated plate and non perforated plate as well as in MEMS devices is developed.For perforated plate,the thickness and the dimensions of the plate are not limited.With boundary conditions,pressure distribution and the damping force on the plate can be found by solving the differential equation.Analytical expressions for damping pressure and damping force of a long strip holeplate are presented with a finite thickness and a finite width.To the extreme conditions of very thin plate and very thin hole,the results are reduced to the corresponding results of the conventional Reynolds' equation.Thus, the effectiveness of the generalized differential equation is justified.Therefore,the generalized Reynolds' equation will be a useful tool of design for damping structures in MEMS.
文摘A squeeze film damper (SFD) with metal rubber (MR) ring installed on the end and the radial direction of rotor are implemented in this paper. Based on the hypothesis of π film, the description of the new SFD/MR flux and nonlinear oil film damping force is derived according to the Reynolds Eq. and Darcy’s law. It proves that the SFD/MR has better damping characteristics than the traditional SFD after comparatively analyzing characteristics of oil film between the traditional short SFD and the SFD/MR.
基金Supported by the National Science and Technology Major Project (No.2017-ⅠV-0010-0047)China Postdoctoral Science Foundation Funded Project (No.2020M6701 13)Fundamental Research Funds for the Central Universities (No.JD2003)。
文摘The elimination of rotor vibration is usually achieved by applying additional damping to the system.Squeeze film dampers are widely used in various aerospace and turbine equipments.The research is carried out on flow characteristics in the integral squeeze film dampers(ISFDs).The dynamic response to the operation condition is investigated through the computational fluid dynamics(CFD) model of ISFD.Due to the large pressure loss at the oil inlet,the oil film force only changes slightly with the increase of oil supply pressure,and the damping increases slightly.The vibration amplitude only affects the film force,but has no effect on the damping.The oil film force and damping show an upward tendency with the decrease of thickness of the end seal clearance.
文摘The squeeze-film air damping exists in a lot of micro-electronic-mechanical system (MEMS) devices unavoidably. The effects of air damping in traditional inertial switch with spring-mass system can be ignored for its large volume and mass. But, many properties of MEMS switch, such as sensitivity, resolution and contact time, are affected by the air damping caused from the squeezed air film between two parallel plates moving relatively. Based on the conservation laws for mass and flux and the nonlinear Reynolds equation, the coefficient of squeeze-film damping was derived. The dynamic responses of the inertial switch with and without squeeze-film damping were simulated by using software ANSYS. The simulated results show that the sensitivity and contact time of the switch descend by about 5% and 15%, respectively, when the effects of squeeze-film damping are considered.
基金Project supported by the National Natural Science Foundation of China(Grant No.51375091)
文摘Based on the energy transfer model(ETM) proposed by Bao et al.and the Monte Carlo(MC) model proposed by Hutcherson and Ye, this paper proposes an efficient molecular model(MC-S) for squeeze-film damping(SQFD) in rarefied air by releasing the assumption of constant molecular velocity in the gap.Compared with the experiment data, the MC-S model is more efficient than the MC model and more accurate than ETM.Besides, by using the MC-S model, the feasibility of the empirical model proposed by Sumali for SQFD of different plate sizes is discussed.It is proved that, for various plate sizes, the accuracy of the empirical model is relatively high.At last, the SQFD of various vibration frequencies is discussed, and it shows that, for low vibration frequency, the MC-S model is reduced to ETM.
文摘航空发动机转子系统通常在支承处设置挤压油膜阻尼器(squeeze film damper,SFD)来实现系统减振设计,与定心SFD相比,非定心SFD结构简单紧凑,减振效果良好,但是具有更强的非线性特征,动力特性更为复杂。以某航空发动机动力涡轮转子为研究对象,建立了多支点高速柔性转子-非定心SFD系统非线性动力学模型,考虑了非定心SFD静偏心的影响,采用数值方法求解转子系统响应,结合系统不平衡响应特征、分岔图、庞家莱截面、频谱等,开展了系统非线性动力学特性研究,并通过了转子试验验证。研究结果表明,非定心SFD油膜间隙较大时,转子系统存在较强的非线性运动,频率成分丰富,减小油膜间隙能够使系统在跨临界后为单周期运动,降低系统的非线性不平衡响应;但过小的油膜间隙将导致转子系统峰值响应和对应的转速显著增大,转子可工作转速范围变小,合理的油膜间隙可以兼顾非线性振动响应和峰值转速较小,实现转子系统在大转速范围内长时间运行。
文摘为了对齿轮轴系进行减振降噪,提出了一种新型integral squeeze film damper(ISFD)弹性阻尼支撑结构。设计并加工了4套实验用ISFD弹性阻尼支撑结构,搭建了开式一级直齿轮实验台,并通过对比主、从动轴分别安装刚性支撑、弹性支撑及弹性阻尼支撑后轴系的振动幅值,来验证其减振降噪效果。实验结果表明,该ISFD弹性阻尼支撑结构能够较好地改善齿轮啮合的冲击振动,并对齿轮啮合传动中大部分频率成分的振动都有良好的减振效果,平均降幅达50%以上,并且减振频带宽。
文摘鉴于二甲基硅油较高的黏度及良好的热稳定性,考虑将其作为整体式挤压油膜阻尼器(Integral squeeze film damper,ISFD)的阻尼液,研究ISFD阻尼液黏度对齿轮轴系减振特性的影响规律。建立了ISFD弹性阻尼支承系统力学模型和齿轮传动有阻尼单自由度振动模型,证明了ISFD用于齿轮轴系减振的有效性。搭建一级直齿轮传动轴系实验台,对比了齿轮轴系分别安装刚性支承和不同阻尼液黏度ISFD弹性阻尼支承的振动。研究发现,以二甲基硅油作阻尼液的ISFD可以有效抑制齿轮轴系振动,且减振效果良好,降幅可达50%以上;在一定黏度范围内,随着ISFD阻尼液黏度的增加,齿轮轴系的振动降幅增大;以二甲基硅油作阻尼液的ISFD具有优良的阻尼减振性能,可以有效抑制大部分频率成分的振动,保证齿轮系统平稳工作。
文摘In this paper, a dynamic model on a rigid rotor sliding bearing system with a SFD is established. The stability and bifurcation behaviors of the system are studied. On the basis of the differential equations of fluid momentum and mass continuity, the distribution pressure function is derived by taking oil film inertia force into consideration. Damping force, clearance excitation force, interference force of different frequencies and static load are also considered in the model. Finally, the governing equations of the stability and bifurcation behaviors of the system are solved by Floquet theory. Simulation of dynamic model shows that the rigid rotor sliding bearing system can maintain stability and exhibit a Hopf bifurcation phenomenon in a certain range.
文摘A dynamic model of a flexible rotor-sliding bearing system ( FRSBS ) with asqueeze film damper ( SFD) is established. Considered in the model are oil film inertia force,damping farce, clearance excitation force, interference force of different frequencies and staticload, as opposed to previous research. On the basis of this model, the optimal design of the systemis deeply studied. Simulation shows that the system optimization design can effectively improve thesystem stability.
基金National Natural Science F oundationAeronautical Science Foundation of China(0 0 C5 3 0 2 4)
文摘In this paper, the chaotic response of a rotor system with crack supported on the squeeze film damper (SFD) is studied. Baesd on the short bearing approximation and π film assumption, the film force is expressed as a function of speed and displacement of the bearing in the X and Y directions. The result shows that the film force can suppress the non synchronous response effectively if an SFD is designed well. The increase of the bearing parameter can suppress chaos. When the bearing parameter is s...
文摘In this study we describe an FEM-based methodology to solve the coupled fluid-structure problem due to squeeze film effects present in vibratory MEMS devices, such as resonators, gyroscopes, and acoustic transducers. The aforementioned devices often consist of a plate-like structure that vibrates normal to a fixed substrate, and is generally not perfectly vacuum packed. This results in a thin film of air being sandwiched between the moving plate and the fixed substrate, which behaves like a squeeze film offering both stiffness and damping. Typically, such structures are actuated electro-statically, necessitating the thin air gap for improving the efficiency of actuation and the sensitivity of detection. To accurately model these devices the squeeze film effect must be incorporated. Extensive literature is present on mod- eling squeeze film effects for rigid motion for both perforated as well as non-perforated plates. Studies which model the plate elasticity often use approximate mode shapes as input to the 2D Reynolds Equation. Recent works which try to solve the coupled fluid elasticity problem, report iterative FEM-based solution strategies for the 2D Reynolds Equation coupled with the 3D elasticity Equation. In this work we present a FEM-based single step solution for the coupled problem at hand, using only one type of element (27 node 3D brick). The structure is modeled with 27 node brick elements of which the lowest layer of nodes is also treated as the fluid domain (2D) and the integrals over fluid domain are evaluated for these nodes only. We also apply an electrostatic loading to our model by considering an equivalent electro-static pressure load on the top surface of the structure. Thus we solve the coupled 2D-fluid-3D-structure problem in a single step, using only one element type. The FEM results show good agreement with both existing analytical solutions and published experimental data.
基金Supported by the National Science and Technology Major Project(No.2017-Ⅳ-0010-0047)Key Laboratory Fund for Ship Vibration and Noise(No.614220406020717)+1 种基金China Postdoctoral Science Foundation Funded Project(No.2020M670113)the Fundamental Research Funds for the Central Universities(No.JD2003)。
文摘This paper aims at investigating the effectiveness of squeeze oil film in suppressing the longitudinal vibration of propulsion shaft systems through a novel integral axial squeeze film damper(IASFD).After designing the IASFD,a propulsion shafting test rig for the longitudinal vibration control is built.Longitudinal vibration control experiments of the propulsion shafting are carried out under different magnitude and frequency of the excitation force.The results show that both IASFD elastic support and IASFD elastic damping support have excellent vibration attenuation characteristics,and can effectively suppress the longitudinal vibration of the shaft system in a wide frequency range.However,IASFD elastic damping support has a more significant vibration reduction effect than the other supports,and increasing the damping of the system has obvious effect on reducing the shafting vibration.For an excitation force of 45 N,the maximum reduction of the vibration amplitude is 89.16%.Also,the vibration generated by the resonance phenomenon is also significantly reduced.
文摘考虑挤压油膜阻尼器(squeeze film damper,SFD)非线性油膜力建立了转子的运动微分方程,将转子在冲击载荷下的振动响应分解为谐响应和冲击响应,分别建立了谐响应、冲击响应的有限元模型,并开展了振动响应计算分析。在振动台上开展了航空发动机转子在不同脉宽的垂向冲击载荷下的振动特性试验研究,获取了转子在冲击瞬时的振动响应,并与计算结果进行对比分析。研究结果表明:在一定范围内,转子的振动响应随冲击脉宽变大而变小;与试验结果相比,振动响应计算误差在10.44%~20.00%。研究为冲击载荷下航空发动机转子振动响应分析和试验提供了方法,具有重要的工程应用价值。
