The outer valence electron momentum distributions of benzene are reinvestigated with theoretical calculations involving the vibrational effects.The results are compared with recent experimental measurements[Phys.Rev.A...The outer valence electron momentum distributions of benzene are reinvestigated with theoretical calculations involving the vibrational effects.The results are compared with recent experimental measurements[Phys.Rev.A 98042705(2018)].The significant discrepancies between theories and experiments in previous works have now been interpreted quantitatively,indicating that the vibrational motion in benzene molecule has noticeable influence on its electron momentum distributions.展开更多
It is shown that the introduction of thermal effect, zero-point vibration, and phonon anharmonicity to a high quality and first-principle-Sased force field （atomic potential） results in a significant improvement in ...It is shown that the introduction of thermal effect, zero-point vibration, and phonon anharmonicity to a high quality and first-principle-Sased force field （atomic potential） results in a significant improvement in predict- ing the densities for the α phase crystalline hexahydro-1,3,5-trinitro-l,3,5-triazine （RDX）, and derivation of its high-fidelity Hugoniot locus and Mie-Grfineisen equation of state covering a very wide range of pressures and temperatures. This work can be used to efficiently and accurately predict the thermophysical properties of solid explosives over the pressures and temperatures to which they are subjected, which is a long-standing issue in the field of energetic materials.展开更多
Higher-order shear and normal deformation theory is used in this paper to account thickness stretching effect for free vibration analysis of the cylindrical micro/nano shell subjected to an applied voltage and uniform...Higher-order shear and normal deformation theory is used in this paper to account thickness stretching effect for free vibration analysis of the cylindrical micro/nano shell subjected to an applied voltage and uniform temperature rising.Size dependency is included in governing equations based on the modified couple stress theory.Hamilton’s principle is used to derive governing equations of the cylindrical micro/nano shell.Solution procedure is developed using Navier technique for simply-supported boundary conditions.The numerical results are presented to investigate the effect of significant parameters such as some dimensionless geometric parameters,material properties,applied voltages and temperature rising on the free vibration responses.展开更多
Model test studies based on the similarity theory were conducted to investigate vibration effect and damage evolution characteristics of tunnel surrounding rock under push-type cyclic blasting excavation.The model was...Model test studies based on the similarity theory were conducted to investigate vibration effect and damage evolution characteristics of tunnel surrounding rock under push-type cyclic blasting excavation.The model was constructed with a ratio of 1∶15.By simulating the tunnel excavation of push-type cyclic blasting,the influence of the blasting parameter change on vibration effect was explored.The damage degree of tunnel surrounding rock was evaluated by the change of the acoustic wave velocity at the same measuring point after blasting.The relationship between the damage evolution of surrounding rock and blasting times was established.The research results show that：（1）In the same geological environment,the number of delay initiation is larger,the main vibration frequency of blasting seismic wave is higher,and the attenuation of high frequency signal in the rock and soil is faster.The influence of number of delay initiation on blasting vibration effect cannot be ignored;（2）Under push-type cyclic blasting excavation,there were great differences in the decreasing rates of acoustic wave velocity of the measuring points which have the same distance to the blasting region at the same depth,and the blasting damage ranges of surrounding rock were typically anisotropic at both depth and breadth;（3）When blasting parameters were basically kept as the same,the growth trend of the cumulative acoustic wave velocity decreasing rate at the measuring point was nonlinear under different cycle blasting excavations;（4）There were nonlinear evolution characteristics between the blasting cumulative damage（D）of surrounding rock and blasting times（n）under push-type cyclic blasting loading,and different measuring points had corresponding blasting cumulative damage propagation models,respectively.The closer the measuring point was away from the explosion source,the faster the cumulative damage extension.Blasting cumulative damage effect of surrounding rock had typically nonlinear evolution properties and anisotropic characteristics.展开更多
A disc-pad friction system is modelled as that two moving pads act symmetrically on an annular beam with flexible boundary condition.Simulation procedure is proposed to deal with the moving interactions and calculatio...A disc-pad friction system is modelled as that two moving pads act symmetrically on an annular beam with flexible boundary condition.Simulation procedure is proposed to deal with the moving interactions and calculation is carried out by using the finite difference method,which shows that only the first-order mode vibration of the beam can be induced.Then the partial differential equation of motion of the disk is reduced to a first-order mode vibration system with time-varying stiffness.As the disk speed is decreased below the critical speeds,the relative equilibrium of the pad on the disk loses its stability and stick-slip type limit cycle vibrations are resulted in all directions′movements.Acceleration of the disk motion on the frictional instability is also investigated.The period of stick-slip vibration with large amplitude will be shortened with higher moving deceleration.展开更多
The rapid development of high-speed railway networks requires advanced methods for analysing vibration and sound radiation characteristics of a fast rotating train wheel subject to a vertical harmonic wheel-rail force...The rapid development of high-speed railway networks requires advanced methods for analysing vibration and sound radiation characteristics of a fast rotating train wheel subject to a vertical harmonic wheel-rail force. In order to consider the rotation of the wheel and at the same time increase the computational efficiency, a procedure is adapted in this paper taking advantage of the axial symmetry of the wheel. In this procedure, a recently developed 2.5D finite element method, which can consider wheel rotation but only requires a 2D mesh over a cross section containing the wheel axis, is used to calculate the vibration response of the wheel. Then, the vibration response of the wheel is taken as acoustic boundary condition and the 2.5D acoustic boundary element method, which only requires a 1D mesh over the boundary of the above cross section, is utilised to calculate the sound radiation of the wheel. These 2.5D methods and relevant programs are validated by comparing results from this procedure with those from conventional 3D analyses using commercial software. The comparison also demonstrates that these 2.5D methods have a much higher computational efficiency. Using the 2.5D methods, we study the wheel rotation speed influences on the factors including the vertical receptance of the wheel at wheel-rail contact point, sound pressure level at a pre-defined standard measurement point, radiated sound power level, directivity of the radia- tion, and contribution of each part of the wheel. It can be concluded that the wheel rotation speed splits most peaks of the vertical receptance at the wheel-rail contact point, sound pressure levels at the field, and the sound power level of the wheel into two peaks. The directivity and power contribution of the wheel are also significantly changed by the wheel rotation speed. Therefore, the rotation of a train wheel should be taken into account when calculating its vibration and sound radiation.展开更多
In order to deal with the non-stationary characteristics of blasting vibration signals and the end issue in the empirical mode decomposition(EMD), an improved endpoint continuation method is proposed. First, the linea...In order to deal with the non-stationary characteristics of blasting vibration signals and the end issue in the empirical mode decomposition(EMD), an improved endpoint continuation method is proposed. First, the linear continuation method of extreme points is used to determine the extremum of the signal endpoint fast. Secondly, the extreme points of transition section outside the signal ends are obtained by a mirror continuation method of extreme points, and then the envelope and continuation curve of the transition section of the signal are constructed. Lastly, the sinusoid of the stationary section outside the signal is constructed to achieve the continuation curve from the transition section to the stationary section. Based on the "singular extreme points" phenomenon of blasting vibration signal, the negative maxima and positive minimum are eliminated, then the maximum and minimum are guaranteed to appear at intervals. Thus,the number of iterations is reduced and the instability of EMD decomposition is improved. The calculation formula of amplitude, cycle and initial phase are given for the transition section and stationary section outside the signal. The endpoint processing effect of the simulated signal and the measured blasting vibration signal show that the improved endpoint continuation method can suppress the signal endpoint effect well.展开更多
The vibration problem of a fluid conveying cylindrical shell consisted of newly developed multi-scale hybrid nanocomposites is solved in the present manuscript within the framework of an analytical solution.The consis...The vibration problem of a fluid conveying cylindrical shell consisted of newly developed multi-scale hybrid nanocomposites is solved in the present manuscript within the framework of an analytical solution.The consistent material is considered to be made from an initial matrix strengthened via both macro-and nano-scale reinforcements.The influence of nanofillers’agglomeration,generated due to the high surface to volume ratio in nanostructures,is included by implementing Eshelby-Mori-Tanaka homogenization scheme.Afterwards,the equivalent material properties of the carbon nanotube reinforced(CNTR)nanocomposite are coupled with those of CFs within the framework of a modified rule of mixture.On the other hand,the influences of viscous flow are covered by extending the Navier-Stokes equation for cylinders.A cylindrical coordinate system is chosen and mixed with the infinitesimal strains of first-order shear deformation theory of shells to obtain the motion equations on the basis of the dynamic form of principle of virtual work.Next,the achieved governing equations will be solved by Galerkin’s method to reach the natural frequency of the structure for both simply supported and clamped boundary conditions.Presenting a set of illustrations,effects of each parameter on the dimensionless frequency of nanocomposite shells will be shown graphically.展开更多
This paper puts forward the concept of double semi-active vibration isolation systemutilizing the 'on-off' active damper and the 'on-off' active spring. Applying KBM Asympto-tic method, the vibration ...This paper puts forward the concept of double semi-active vibration isolation systemutilizing the 'on-off' active damper and the 'on-off' active spring. Applying KBM Asympto-tic method, the vibration of the system in case of weak semi-active control is studied. ln pcactice, there are two types of vibration isolation. One is to isolate the transmitting of the cyclicunbalanced force generated by the revolving machine to the surroundings. The other is to isolatethe transmitting of the vibration displacement of the surroundings to precise equipment. Deduc-ing the influence of the roadway unflatness on vehicles also belongs to this type. For the firsttype of isolation system, the damper always dissipates energy, and the total work done by the spring in a vibration cycle is zero. For the second type of isolation system, the work done by the damper sometimes is positive, and sometimes negative. The damper dissipates less energy. The work done by the spring in a vibration cycle isn't zero, and it is usually positive. ln thispaper, the vibration isolation is refered to the second type. .展开更多
Fracture and ground vibration of rock subjected to different decoupling decked charges are investigated based on the numerical simulation. The dynamic pressure value is studied, which demonstrates that simulation of f...Fracture and ground vibration of rock subjected to different decoupling decked charges are investigated based on the numerical simulation. The dynamic pressure value is studied, which demonstrates that simulation of fracture zone is feasible. Attenuation index of dynamic pressure is 2.06, 2.05 and 1.93 for air, water and sand intervals respectively. The small attenuation of sand in- terval results in the large ground vibration. The predicted vertical vibration waveform and peak parti- cle velocities （PPV） in far-field are in agreement with the monitoring results. The results show that the air and water decked charges can improve the effect of rock fracture in near-field and reduce ground vibration in far-field.展开更多
The influence of temperature on mode coupling effect in piezoelectric vibrators remains unclear.In this work,we discuss the influence of temperature on two-dimensional(2D)mode coupling effect and electromechanical cou...The influence of temperature on mode coupling effect in piezoelectric vibrators remains unclear.In this work,we discuss the influence of temperature on two-dimensional(2D)mode coupling effect and electromechanical coupling coefficient of cylindrical[001]c-poled Mn-doped 0.24PIN-0.46PMN-0.30PT piezoelectric single-crystal vibrator with an arbitrary configuration ratio.The electromechanical coupling coefficient kt decreases with temperature increasing,whereas k33 is largely invariant in a temperature range of 25℃-55℃.With the increase of temperature,the shift in the‘mode dividing point’increases the scale of the poling direction of the piezoelectric vibrator.The temperature has little effect on coupling constantΓ.At a given temperature,the coupling constantΓof the cylindrical vibrator is slightly greater than that of the rectangular vibrator.When the temperature changes,the applicability index(M)values of the two piezoelectric vibrators are close to 1,indicating that the coupling theory can be applied to piezoelectric vibrators made of late-model piezoelectric single crystals.展开更多
The vibrational motions are usually neglected when calculating(e,2e) triple differential cross sections(TDCSs) of molecules. Here, multi-center distorted-wave method(MCDW) has been modified by including molecular vibr...The vibrational motions are usually neglected when calculating(e,2e) triple differential cross sections(TDCSs) of molecules. Here, multi-center distorted-wave method(MCDW) has been modified by including molecular vibrations. This vibrational MCDW method is employed to calculate the TDCSs of 1b3gorbital of ethylene at low(100 eV) and medium(250 eV) incident electron energies in coplanar asymmetric kinematic condition. The results show that molecular vibrations significantly influence the angular distributions of the TDCSs, especially in the binary region along momentum transfer near the Bethe ridge.展开更多
以双层隔振系统为研究对象,建立双层隔振系统的三维有限元模型。在给定的刚度范围内,单独改变设备隔振器刚度值或者底座隔振器刚度值时发现,任意一层隔振器刚度的变化对各级隔振均产生一定的影响。从底座隔振器与设备隔振器刚度比的角...以双层隔振系统为研究对象,建立双层隔振系统的三维有限元模型。在给定的刚度范围内,单独改变设备隔振器刚度值或者底座隔振器刚度值时发现,任意一层隔振器刚度的变化对各级隔振均产生一定的影响。从底座隔振器与设备隔振器刚度比的角度出发,对两层隔振器的刚度进行适配,研究结果表明:在刚度适配时,可能出现振动传递过程中振动放大的情况;当刚度比相同时,在刚度值较小的工况下传递到底座上的振动加速度级比刚度值较大的工况小,同时其整体隔振效果也更好;在所计算的工况中,最优刚度适配工况下的整体隔振效果比最差刚度适配工况提高9.8 dB,传递到底座的振动加速度级降低12.3 d B,辐射声功率级总值降低12.8 dB。展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0402300).
文摘The outer valence electron momentum distributions of benzene are reinvestigated with theoretical calculations involving the vibrational effects.The results are compared with recent experimental measurements[Phys.Rev.A 98042705(2018)].The significant discrepancies between theories and experiments in previous works have now been interpreted quantitatively,indicating that the vibrational motion in benzene molecule has noticeable influence on its electron momentum distributions.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11372053,11402031,11221202 and 11172044the Opening Project of the State Key Laboratory of Explosion Science and Technology under Grant No KFJJ14-06M
文摘It is shown that the introduction of thermal effect, zero-point vibration, and phonon anharmonicity to a high quality and first-principle-Sased force field （atomic potential） results in a significant improvement in predict- ing the densities for the α phase crystalline hexahydro-1,3,5-trinitro-l,3,5-triazine （RDX）, and derivation of its high-fidelity Hugoniot locus and Mie-Grfineisen equation of state covering a very wide range of pressures and temperatures. This work can be used to efficiently and accurately predict the thermophysical properties of solid explosives over the pressures and temperatures to which they are subjected, which is a long-standing issue in the field of energetic materials.
基金The authors would like to thank the Iranian Nanotechnology Development Committee for their financial support.
文摘Higher-order shear and normal deformation theory is used in this paper to account thickness stretching effect for free vibration analysis of the cylindrical micro/nano shell subjected to an applied voltage and uniform temperature rising.Size dependency is included in governing equations based on the modified couple stress theory.Hamilton’s principle is used to derive governing equations of the cylindrical micro/nano shell.Solution procedure is developed using Navier technique for simply-supported boundary conditions.The numerical results are presented to investigate the effect of significant parameters such as some dimensionless geometric parameters,material properties,applied voltages and temperature rising on the free vibration responses.
基金Supported by the National Natural Science Foundation of China(51064009,51464015)the Natural Science Foundation of Guangdong Province of China(2016A030313121)+1 种基金the Higher School Talent Introduction Project of Guangdong Province(A413.0210)the Science and Technology Project of Huizhou City of Guangdong Province of China(2014B020004018)
文摘Model test studies based on the similarity theory were conducted to investigate vibration effect and damage evolution characteristics of tunnel surrounding rock under push-type cyclic blasting excavation.The model was constructed with a ratio of 1∶15.By simulating the tunnel excavation of push-type cyclic blasting,the influence of the blasting parameter change on vibration effect was explored.The damage degree of tunnel surrounding rock was evaluated by the change of the acoustic wave velocity at the same measuring point after blasting.The relationship between the damage evolution of surrounding rock and blasting times was established.The research results show that：（1）In the same geological environment,the number of delay initiation is larger,the main vibration frequency of blasting seismic wave is higher,and the attenuation of high frequency signal in the rock and soil is faster.The influence of number of delay initiation on blasting vibration effect cannot be ignored;（2）Under push-type cyclic blasting excavation,there were great differences in the decreasing rates of acoustic wave velocity of the measuring points which have the same distance to the blasting region at the same depth,and the blasting damage ranges of surrounding rock were typically anisotropic at both depth and breadth;（3）When blasting parameters were basically kept as the same,the growth trend of the cumulative acoustic wave velocity decreasing rate at the measuring point was nonlinear under different cycle blasting excavations;（4）There were nonlinear evolution characteristics between the blasting cumulative damage（D）of surrounding rock and blasting times（n）under push-type cyclic blasting loading,and different measuring points had corresponding blasting cumulative damage propagation models,respectively.The closer the measuring point was away from the explosion source,the faster the cumulative damage extension.Blasting cumulative damage effect of surrounding rock had typically nonlinear evolution properties and anisotropic characteristics.
基金supported by the National Natural Science Foundation of China (Nos.51575378, 11272228 and 11332008)
文摘A disc-pad friction system is modelled as that two moving pads act symmetrically on an annular beam with flexible boundary condition.Simulation procedure is proposed to deal with the moving interactions and calculation is carried out by using the finite difference method,which shows that only the first-order mode vibration of the beam can be induced.Then the partial differential equation of motion of the disk is reduced to a first-order mode vibration system with time-varying stiffness.As the disk speed is decreased below the critical speeds,the relative equilibrium of the pad on the disk loses its stability and stick-slip type limit cycle vibrations are resulted in all directions′movements.Acceleration of the disk motion on the frictional instability is also investigated.The period of stick-slip vibration with large amplitude will be shortened with higher moving deceleration.
基金the support to this work from the Ministry of Science and Technology of China (2016YFE0205200)China Railway (2015Z003-B)Scientific Research Foundation of State Key Laboratory of Traction Power (2017TPL_T01)
文摘The rapid development of high-speed railway networks requires advanced methods for analysing vibration and sound radiation characteristics of a fast rotating train wheel subject to a vertical harmonic wheel-rail force. In order to consider the rotation of the wheel and at the same time increase the computational efficiency, a procedure is adapted in this paper taking advantage of the axial symmetry of the wheel. In this procedure, a recently developed 2.5D finite element method, which can consider wheel rotation but only requires a 2D mesh over a cross section containing the wheel axis, is used to calculate the vibration response of the wheel. Then, the vibration response of the wheel is taken as acoustic boundary condition and the 2.5D acoustic boundary element method, which only requires a 1D mesh over the boundary of the above cross section, is utilised to calculate the sound radiation of the wheel. These 2.5D methods and relevant programs are validated by comparing results from this procedure with those from conventional 3D analyses using commercial software. The comparison also demonstrates that these 2.5D methods have a much higher computational efficiency. Using the 2.5D methods, we study the wheel rotation speed influences on the factors including the vertical receptance of the wheel at wheel-rail contact point, sound pressure level at a pre-defined standard measurement point, radiated sound power level, directivity of the radia- tion, and contribution of each part of the wheel. It can be concluded that the wheel rotation speed splits most peaks of the vertical receptance at the wheel-rail contact point, sound pressure levels at the field, and the sound power level of the wheel into two peaks. The directivity and power contribution of the wheel are also significantly changed by the wheel rotation speed. Therefore, the rotation of a train wheel should be taken into account when calculating its vibration and sound radiation.
基金Supported by the National Natural Science Foundation of China(51374212)
文摘In order to deal with the non-stationary characteristics of blasting vibration signals and the end issue in the empirical mode decomposition(EMD), an improved endpoint continuation method is proposed. First, the linear continuation method of extreme points is used to determine the extremum of the signal endpoint fast. Secondly, the extreme points of transition section outside the signal ends are obtained by a mirror continuation method of extreme points, and then the envelope and continuation curve of the transition section of the signal are constructed. Lastly, the sinusoid of the stationary section outside the signal is constructed to achieve the continuation curve from the transition section to the stationary section. Based on the "singular extreme points" phenomenon of blasting vibration signal, the negative maxima and positive minimum are eliminated, then the maximum and minimum are guaranteed to appear at intervals. Thus,the number of iterations is reduced and the instability of EMD decomposition is improved. The calculation formula of amplitude, cycle and initial phase are given for the transition section and stationary section outside the signal. The endpoint processing effect of the simulated signal and the measured blasting vibration signal show that the improved endpoint continuation method can suppress the signal endpoint effect well.
文摘The vibration problem of a fluid conveying cylindrical shell consisted of newly developed multi-scale hybrid nanocomposites is solved in the present manuscript within the framework of an analytical solution.The consistent material is considered to be made from an initial matrix strengthened via both macro-and nano-scale reinforcements.The influence of nanofillers’agglomeration,generated due to the high surface to volume ratio in nanostructures,is included by implementing Eshelby-Mori-Tanaka homogenization scheme.Afterwards,the equivalent material properties of the carbon nanotube reinforced(CNTR)nanocomposite are coupled with those of CFs within the framework of a modified rule of mixture.On the other hand,the influences of viscous flow are covered by extending the Navier-Stokes equation for cylinders.A cylindrical coordinate system is chosen and mixed with the infinitesimal strains of first-order shear deformation theory of shells to obtain the motion equations on the basis of the dynamic form of principle of virtual work.Next,the achieved governing equations will be solved by Galerkin’s method to reach the natural frequency of the structure for both simply supported and clamped boundary conditions.Presenting a set of illustrations,effects of each parameter on the dimensionless frequency of nanocomposite shells will be shown graphically.
文摘This paper puts forward the concept of double semi-active vibration isolation systemutilizing the 'on-off' active damper and the 'on-off' active spring. Applying KBM Asympto-tic method, the vibration of the system in case of weak semi-active control is studied. ln pcactice, there are two types of vibration isolation. One is to isolate the transmitting of the cyclicunbalanced force generated by the revolving machine to the surroundings. The other is to isolatethe transmitting of the vibration displacement of the surroundings to precise equipment. Deduc-ing the influence of the roadway unflatness on vehicles also belongs to this type. For the firsttype of isolation system, the damper always dissipates energy, and the total work done by the spring in a vibration cycle is zero. For the second type of isolation system, the work done by the damper sometimes is positive, and sometimes negative. The damper dissipates less energy. The work done by the spring in a vibration cycle isn't zero, and it is usually positive. ln thispaper, the vibration isolation is refered to the second type. .
文摘Fracture and ground vibration of rock subjected to different decoupling decked charges are investigated based on the numerical simulation. The dynamic pressure value is studied, which demonstrates that simulation of fracture zone is feasible. Attenuation index of dynamic pressure is 2.06, 2.05 and 1.93 for air, water and sand intervals respectively. The small attenuation of sand in- terval results in the large ground vibration. The predicted vertical vibration waveform and peak parti- cle velocities （PPV） in far-field are in agreement with the monitoring results. The results show that the air and water decked charges can improve the effect of rock fracture in near-field and reduce ground vibration in far-field.
基金Project supported by the Basic Scientific Research Foundation of College and University in Heilongjiang Province,China(Grant No.2018QNL-16)the Guiding Science and Technology Project of Daqing City(GSTPDQ),China(Grant No.zd-2019-03)the National Natural Science Foundation of China(Grant Nos.11304061 and 51572056).
文摘The influence of temperature on mode coupling effect in piezoelectric vibrators remains unclear.In this work,we discuss the influence of temperature on two-dimensional(2D)mode coupling effect and electromechanical coupling coefficient of cylindrical[001]c-poled Mn-doped 0.24PIN-0.46PMN-0.30PT piezoelectric single-crystal vibrator with an arbitrary configuration ratio.The electromechanical coupling coefficient kt decreases with temperature increasing,whereas k33 is largely invariant in a temperature range of 25℃-55℃.With the increase of temperature,the shift in the‘mode dividing point’increases the scale of the poling direction of the piezoelectric vibrator.The temperature has little effect on coupling constantΓ.At a given temperature,the coupling constantΓof the cylindrical vibrator is slightly greater than that of the rectangular vibrator.When the temperature changes,the applicability index(M)values of the two piezoelectric vibrators are close to 1,indicating that the coupling theory can be applied to piezoelectric vibrators made of late-model piezoelectric single crystals.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12004370 and 12127804)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB34020000)。
文摘The vibrational motions are usually neglected when calculating(e,2e) triple differential cross sections(TDCSs) of molecules. Here, multi-center distorted-wave method(MCDW) has been modified by including molecular vibrations. This vibrational MCDW method is employed to calculate the TDCSs of 1b3gorbital of ethylene at low(100 eV) and medium(250 eV) incident electron energies in coplanar asymmetric kinematic condition. The results show that molecular vibrations significantly influence the angular distributions of the TDCSs, especially in the binary region along momentum transfer near the Bethe ridge.
文摘以双层隔振系统为研究对象,建立双层隔振系统的三维有限元模型。在给定的刚度范围内,单独改变设备隔振器刚度值或者底座隔振器刚度值时发现,任意一层隔振器刚度的变化对各级隔振均产生一定的影响。从底座隔振器与设备隔振器刚度比的角度出发,对两层隔振器的刚度进行适配,研究结果表明:在刚度适配时,可能出现振动传递过程中振动放大的情况;当刚度比相同时,在刚度值较小的工况下传递到底座上的振动加速度级比刚度值较大的工况小,同时其整体隔振效果也更好;在所计算的工况中,最优刚度适配工况下的整体隔振效果比最差刚度适配工况提高9.8 dB,传递到底座的振动加速度级降低12.3 d B,辐射声功率级总值降低12.8 dB。
