This paper introduces damping amplifier friction vibration absorbers(DAFVAs),compound damping amplifier friction vibration absorbers(CDAFVAs),nested damping amplifier friction vibration absorbers(NDAFVAs),and levered ...This paper introduces damping amplifier friction vibration absorbers(DAFVAs),compound damping amplifier friction vibration absorbers(CDAFVAs),nested damping amplifier friction vibration absorbers(NDAFVAs),and levered damping amplifier friction vibration absorbers(LDAFVAs)for controlling the structural vibrations and addressing the limitations of conventional tuned mass dampers(TMDs)and frictiontuned mass dampers(FTMDs).The closed-form analytical solution for the optimized design parameters is obtained using the H_(2)and H_(∞)optimization approaches.The efficiency of the recently established closed-form equations for the optimal design parameters is confirmed by the analytical examination.The closed form formulas for the dynamic responses of the main structure and the vibration absorbers are derived using the transfer matrix formulations.The foundation is provided by the harmonic and random-white noise excitations.Moreover,the effectiveness of the innovative dampers has been validated through numerical analysis.The optimal DAFVAs,CDAFVAs,NDAFVAs,and LDAFVAs exhibit at least 30%lower vibration reduction capacity compared with the optimal TMD.To demonstrate the effectiveness of the damping amplification mechanism,the novel absorbers are compared with a conventional FTMD.The results show that the optimized novel absorbers achieve at least 91%greater vibration reduction than the FTMD.These results show how the suggested designs might strengthen the structure's resilience to dynamic loads.展开更多
Friction stir processing(FSP)can be used to improve surface composites.In this study,a modified method of FSP called friction stir vibration processing(FSVP)was applied to develop a surface composite on AZ91 magnesium...Friction stir processing(FSP)can be used to improve surface composites.In this study,a modified method of FSP called friction stir vibration processing(FSVP)was applied to develop a surface composite on AZ91 magnesium alloy.In this technique,the workpiece is vibrated normal to the processing direction.The results illustrated that compared with the FSP method,the FSVP caused a better homogeneous distribution of SiC particles in the microstructure.The results also showed that matrix grains of friction stir vibration processed(FSV-processed)samples((26.43±2.00)μm)were finer than those of friction stir processed(FS-processed)specimens((39.43±2.00)μm).The results indicated that the ultimate tensile strength(UTS)of FSV-processed specimens(361.82 MPa)was higher than that of FS-processed specimens(324.97 MPa).The higher plastic strain in the material during FSVP,due to workpiece vibration,resulted in higher dynamic recrystallization,and consequently,finer grains were developed.The elongation and formability index of the FSV-processed specimen(16.88%and 6107.52 MPa·%,respectively)were higher than those of the FS-processed sample(15.24%and 4952.54 MPa·%,respectively).Moreover,the effects of FSVP were also found to intensify as the vibration frequency increased.展开更多
Friction stir processing (FSP) is a solid-state modification method to process the surface of metals. In this process, due to rotation and traverse motions of a non-consumable tool, metal surface microstructure is ref...Friction stir processing (FSP) is a solid-state modification method to process the surface of metals. In this process, due to rotation and traverse motions of a non-consumable tool, metal surface microstructure is refined and its mechanical characteristics are improved. Different methods have been applied to improving the efficiency of FSP. In this research, a new method entitled friction stir vibration processing (FSVP) was presented to enhance the efficiency of FSP. In this method, metal workpiece was vibrated normal to processing line during FSP. Microstructure and mechanical properties including hardness, ultimate tensile strength (UTS) and elongation of Al5052 alloy specimens processed using FSP and FSVP methods were analyzed and compared. The results showed that grain size decreased by about 33% as vibration was applied. It was also observed that ultimate tensile strength as well as hardness increased by about 7% as FSVP was applied. This was related to the enhanced straining of metal surface material as vibration was applied. The increase in straining results in the increase of dislocation density. It leads to more development of high angle grain boundaries due to dynamic recrystallization. The results also showed that UTS and elongation of FSV processed specimens increased as vibration frequency increased.展开更多
The objective of this work was to study the vibration transmissibility characteristics of the undamped and damped smart spring systems. The frequency response characteristics of them were analyzed by using the equival...The objective of this work was to study the vibration transmissibility characteristics of the undamped and damped smart spring systems. The frequency response characteristics of them were analyzed by using the equivalent linearization technique, and the possible types of the system motion were distinguished by using the starting and ending frequencies. The influences of system parameters on the vibration transmissibility characteristics were discussed. The following conclusions may be drawn from the analysis results. The undamped smart spring system may simultaneously have one starting frequency and one ending frequency or only have one starting frequency, and the damped system may simultaneously have two starting frequencies and one ending frequency. There is an optimal control parameter to make the peak value of the vibration transmissibility curve of the system be minimum. When the mass ratio is far away from the stiffness ratio, the vibration transmissibility is small. The effect of the damping ratio on the system vibration transmissibility is significant while the control parameter is less than its optimal value. But the influence of the relative damping ratio on the vibration transmissibility is small.展开更多
Following a small-scale wedge failure at Yukon Zinc＇s Wolverine Mine in Yukon, Canada, a vibration monitoring program was added to the existing rockbolt pull testing regime. The failure in the 1150 drift occurred aft...Following a small-scale wedge failure at Yukon Zinc＇s Wolverine Mine in Yukon, Canada, a vibration monitoring program was added to the existing rockbolt pull testing regime. The failure in the 1150 drift occurred after numerous successive blasts in an adjacent tunnel had loosened friction bolts passing through an unmapped fault. Analysis of blasting vibration revealed that support integrity is not compromised unless there is a geological structure to act as a failure plane. The peak particle velocity（PPV） rarely exceeded 250 mm/s with a frequency larger than 50 Hz. As expected, blasting more competent rock resulted in higher PPVs. In such cases, reducing the round length from 3.5 m to 2.0 m was an effective means of limiting potential rock mass and support damage.展开更多
Under the condition of ultrasonic vibration, the friction properties of several materials were studied experimentally; and the mechedsm of friction force reduction on the resonance was also analyzed. It is found that ...Under the condition of ultrasonic vibration, the friction properties of several materials were studied experimentally; and the mechedsm of friction force reduction on the resonance was also analyzed. It is found that tungsten carbide and 45# steel are an ideal friction couple for ultrasonic motor.展开更多
Tactile perception is essential for humans to recognise objects.This study systematically investigated the tribological behaviour of the finger and physiological response of the brain related to the width recognition ...Tactile perception is essential for humans to recognise objects.This study systematically investigated the tribological behaviour of the finger and physiological response of the brain related to the width recognition of tactile perception using subjective evaluation,friction and electroencephalography methods.The results show that the texture feeling,recognition accuracy of the texture and proportion of deformation friction increased with the texture width.The average width recognition threshold of the fine texture was 45.4μm.The load index,maximum amplitude of the vibration signal,entropy,longest vertical line and P300 amplitude were positively correlated with the texture width.P300 latency was negatively correlated with the texture width.When the texture width exceeded the width recognition thresholds of tactile perception,the main frequency of the vibration signals increased to the optimal perceptual range of the Pacinian corpuscle.The nonlinear features of the vibration signal increased,and the vibration system transitioned from a homogenous state to a disrupted state.Moreover,the activation intensity and area of the brain and the speed of tactile recognition increased.The study demonstrated that the mechanical stimuli of friction and vibration generated in the touching of fine textures having various widths affected the subjective evaluation and brain response.展开更多
The mechanism of adhesive friction between viscoelastic materials is a key question.In this study,the friction process of the adhesive interface between a friction lining and a wire rope is dynamically observed in rea...The mechanism of adhesive friction between viscoelastic materials is a key question.In this study,the friction process of the adhesive interface between a friction lining and a wire rope is dynamically observed in real time to analyze the adhesion hysteresis friction intuitively and quantitatively.The adhesion is determined by the state of motion,while the relative displacement of the wire rope and lining is used to find the magnitude of the adhesive friction.The hysteresis friction is reflected by the internal deformation of the lining.The magnitude of the hysteresis friction is determined by the displacement difference(Ax)in the sliding direction of two marked points at different distances from the contact surface.The results show that the adhesion friction is proportional to the loss modulus and the hysteresis friction is proportional to the ratio of the loss modulus to the square of the storage modulus(E"/(E'^(2))).The frictional vibration first decreases and then increases with the increase in pressure.The K25 lining has the highest adhesion hysteresis friction and minimal frictional vibration.The result provides a simple and intuitive method for research into the friction transmission and vibration of viscoelastic materials.展开更多
In this study,piezoelectric elements were added to a reciprocating friction test bench to harvest friction‐induced vibration energy.Parameters such as vibration acceleration,noise,and voltage signals of the system we...In this study,piezoelectric elements were added to a reciprocating friction test bench to harvest friction‐induced vibration energy.Parameters such as vibration acceleration,noise,and voltage signals of the system were measured and analyzed.The results show that the piezoelectric elements can not only collect vibration energy but also suppress friction‐induced vibration noise(FIVN).Additionally,the wear of the friction interface was examined via optical microscopy(OM),scanning electron microscopy(SEM),and white‐light interferometry(WLI).The results show that the surface wear state improved because of the reduction of FIVN.In order to analyze the experimental results in detail and explain them reasonably,the experimental phenomena were simulated numerically.Moreover,a simplified two‐degree‐of‐freedom numerical model including the original system and the piezoelectric system was established to qualitatively describe the effects,dynamics,and tribological behaviors of the added piezoelectric elements to the original system.展开更多
基金the postdoctoral research grant received from the University of Glasgow for the partial financial support for this research work。
文摘This paper introduces damping amplifier friction vibration absorbers(DAFVAs),compound damping amplifier friction vibration absorbers(CDAFVAs),nested damping amplifier friction vibration absorbers(NDAFVAs),and levered damping amplifier friction vibration absorbers(LDAFVAs)for controlling the structural vibrations and addressing the limitations of conventional tuned mass dampers(TMDs)and frictiontuned mass dampers(FTMDs).The closed-form analytical solution for the optimized design parameters is obtained using the H_(2)and H_(∞)optimization approaches.The efficiency of the recently established closed-form equations for the optimal design parameters is confirmed by the analytical examination.The closed form formulas for the dynamic responses of the main structure and the vibration absorbers are derived using the transfer matrix formulations.The foundation is provided by the harmonic and random-white noise excitations.Moreover,the effectiveness of the innovative dampers has been validated through numerical analysis.The optimal DAFVAs,CDAFVAs,NDAFVAs,and LDAFVAs exhibit at least 30%lower vibration reduction capacity compared with the optimal TMD.To demonstrate the effectiveness of the damping amplification mechanism,the novel absorbers are compared with a conventional FTMD.The results show that the optimized novel absorbers achieve at least 91%greater vibration reduction than the FTMD.These results show how the suggested designs might strengthen the structure's resilience to dynamic loads.
基金the Amirkabir University of Technology(AUT)Sharif University of Technologythe National Elites Foundation of Iran for their support during this research。
文摘Friction stir processing(FSP)can be used to improve surface composites.In this study,a modified method of FSP called friction stir vibration processing(FSVP)was applied to develop a surface composite on AZ91 magnesium alloy.In this technique,the workpiece is vibrated normal to the processing direction.The results illustrated that compared with the FSP method,the FSVP caused a better homogeneous distribution of SiC particles in the microstructure.The results also showed that matrix grains of friction stir vibration processed(FSV-processed)samples((26.43±2.00)μm)were finer than those of friction stir processed(FS-processed)specimens((39.43±2.00)μm).The results indicated that the ultimate tensile strength(UTS)of FSV-processed specimens(361.82 MPa)was higher than that of FS-processed specimens(324.97 MPa).The higher plastic strain in the material during FSVP,due to workpiece vibration,resulted in higher dynamic recrystallization,and consequently,finer grains were developed.The elongation and formability index of the FSV-processed specimen(16.88%and 6107.52 MPa·%,respectively)were higher than those of the FS-processed sample(15.24%and 4952.54 MPa·%,respectively).Moreover,the effects of FSVP were also found to intensify as the vibration frequency increased.
文摘Friction stir processing (FSP) is a solid-state modification method to process the surface of metals. In this process, due to rotation and traverse motions of a non-consumable tool, metal surface microstructure is refined and its mechanical characteristics are improved. Different methods have been applied to improving the efficiency of FSP. In this research, a new method entitled friction stir vibration processing (FSVP) was presented to enhance the efficiency of FSP. In this method, metal workpiece was vibrated normal to processing line during FSP. Microstructure and mechanical properties including hardness, ultimate tensile strength (UTS) and elongation of Al5052 alloy specimens processed using FSP and FSVP methods were analyzed and compared. The results showed that grain size decreased by about 33% as vibration was applied. It was also observed that ultimate tensile strength as well as hardness increased by about 7% as FSVP was applied. This was related to the enhanced straining of metal surface material as vibration was applied. The increase in straining results in the increase of dislocation density. It leads to more development of high angle grain boundaries due to dynamic recrystallization. The results also showed that UTS and elongation of FSV processed specimens increased as vibration frequency increased.
基金Project(51375226)supported by the National Natural Science Foundation of ChinaProject(20113218110017)supported by the Doctoral Program Foundation of Institutions of Higher Education of China+2 种基金Project(PAPD)supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions,ChinaProject(CXZZ11_0199)supported by the Funding of Jiangsu Innovation Program for Graduate Education,ChinaProject(2014)supported by the the Fundamental Research Funds for the Central Universities,China
文摘The objective of this work was to study the vibration transmissibility characteristics of the undamped and damped smart spring systems. The frequency response characteristics of them were analyzed by using the equivalent linearization technique, and the possible types of the system motion were distinguished by using the starting and ending frequencies. The influences of system parameters on the vibration transmissibility characteristics were discussed. The following conclusions may be drawn from the analysis results. The undamped smart spring system may simultaneously have one starting frequency and one ending frequency or only have one starting frequency, and the damped system may simultaneously have two starting frequencies and one ending frequency. There is an optimal control parameter to make the peak value of the vibration transmissibility curve of the system be minimum. When the mass ratio is far away from the stiffness ratio, the vibration transmissibility is small. The effect of the damping ratio on the system vibration transmissibility is significant while the control parameter is less than its optimal value. But the influence of the relative damping ratio on the vibration transmissibility is small.
文摘Following a small-scale wedge failure at Yukon Zinc＇s Wolverine Mine in Yukon, Canada, a vibration monitoring program was added to the existing rockbolt pull testing regime. The failure in the 1150 drift occurred after numerous successive blasts in an adjacent tunnel had loosened friction bolts passing through an unmapped fault. Analysis of blasting vibration revealed that support integrity is not compromised unless there is a geological structure to act as a failure plane. The peak particle velocity（PPV） rarely exceeded 250 mm/s with a frequency larger than 50 Hz. As expected, blasting more competent rock resulted in higher PPVs. In such cases, reducing the round length from 3.5 m to 2.0 m was an effective means of limiting potential rock mass and support damage.
文摘Under the condition of ultrasonic vibration, the friction properties of several materials were studied experimentally; and the mechedsm of friction force reduction on the resonance was also analyzed. It is found that tungsten carbide and 45# steel are an ideal friction couple for ultrasonic motor.
基金National Natural Science Foundation of China(52375224)Natural Science Foundation of Jiangsu Province(BK20242086)+2 种基金Graduate Innovation Programme of China University of Mining and Technology(2024WLKX075)Fundamental Research Funds for the Central Universities(2024‐10976)Postgraduate Research and Practice Innovation Programme of Jiangsu Province(KYCX24_2719).
文摘Tactile perception is essential for humans to recognise objects.This study systematically investigated the tribological behaviour of the finger and physiological response of the brain related to the width recognition of tactile perception using subjective evaluation,friction and electroencephalography methods.The results show that the texture feeling,recognition accuracy of the texture and proportion of deformation friction increased with the texture width.The average width recognition threshold of the fine texture was 45.4μm.The load index,maximum amplitude of the vibration signal,entropy,longest vertical line and P300 amplitude were positively correlated with the texture width.P300 latency was negatively correlated with the texture width.When the texture width exceeded the width recognition thresholds of tactile perception,the main frequency of the vibration signals increased to the optimal perceptual range of the Pacinian corpuscle.The nonlinear features of the vibration signal increased,and the vibration system transitioned from a homogenous state to a disrupted state.Moreover,the activation intensity and area of the brain and the speed of tactile recognition increased.The study demonstrated that the mechanical stimuli of friction and vibration generated in the touching of fine textures having various widths affected the subjective evaluation and brain response.
基金supported by the joint Ph.D.program of"double first rate"construction disciplines of China University of Mining and Technology(CUMT).
文摘The mechanism of adhesive friction between viscoelastic materials is a key question.In this study,the friction process of the adhesive interface between a friction lining and a wire rope is dynamically observed in real time to analyze the adhesion hysteresis friction intuitively and quantitatively.The adhesion is determined by the state of motion,while the relative displacement of the wire rope and lining is used to find the magnitude of the adhesive friction.The hysteresis friction is reflected by the internal deformation of the lining.The magnitude of the hysteresis friction is determined by the displacement difference(Ax)in the sliding direction of two marked points at different distances from the contact surface.The results show that the adhesion friction is proportional to the loss modulus and the hysteresis friction is proportional to the ratio of the loss modulus to the square of the storage modulus(E"/(E'^(2))).The frictional vibration first decreases and then increases with the increase in pressure.The K25 lining has the highest adhesion hysteresis friction and minimal frictional vibration.The result provides a simple and intuitive method for research into the friction transmission and vibration of viscoelastic materials.
基金This project was supported by the National Natural Science Foundation of China(Nos.51822508 and 11672052)the Sichuan Province Science and Technology Support Program(No.2020JDTD0012).
文摘In this study,piezoelectric elements were added to a reciprocating friction test bench to harvest friction‐induced vibration energy.Parameters such as vibration acceleration,noise,and voltage signals of the system were measured and analyzed.The results show that the piezoelectric elements can not only collect vibration energy but also suppress friction‐induced vibration noise(FIVN).Additionally,the wear of the friction interface was examined via optical microscopy(OM),scanning electron microscopy(SEM),and white‐light interferometry(WLI).The results show that the surface wear state improved because of the reduction of FIVN.In order to analyze the experimental results in detail and explain them reasonably,the experimental phenomena were simulated numerically.Moreover,a simplified two‐degree‐of‐freedom numerical model including the original system and the piezoelectric system was established to qualitatively describe the effects,dynamics,and tribological behaviors of the added piezoelectric elements to the original system.
