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This paper aims to design an active shock absorber scheme for use in conjunction with a passive shock absorber to suppress the horizontal vibration of elevator cars in a smaller range and shorter time. The developed active shock absorber will also improve the safety and comfort of passengers driving in ultra-high-speed elevators.

A six-degree of freedom dynamic model is established according to the position and condition of the car. Then the active shock absorber and disturbance compensation-based adaptive control scheme are designed and simulated in MATLAB/Simulink. The results are analysed and compared with the traditional shock absorber.

The results show that, compared with traditional spring-based passive damping systems, the designed active shock absorber can reduce vibration displacement by 60%, peak acceleration by 50% and oscillation time by 2/3 and is more robust to different spring stiffness, damping coefficient and load.

The developed active shock absorber and its control algorithm can significantly reduce vibration amplitude and converged time. It can also adjust the damping strength according to the actual load of the elevator car, which is more suitable for high-speed elevators.

Vibration measurement is needed in many industrial production processes, such as equipment monitoring, fault diagnosis, and noise analysis and eliminating and so on. The purpose of this paper is to propose a simple vibration testing system which includes the laser, the string, position sensitive detector (PSD) and the corresponding signal processing circuit.

PSD is an optical semiconductor sensor that can fast locate the luminous spot position precisely, which means that it can output different electric current according to the luminous spot at different position of its surface. Moreover, the experiment on PSD sensor using different vibration source and frequency had been carried out. Finally, the vibration waveform of the luminous spot on PSD photosurface was obtained.

According to the experimental results, each kind of vibration parameter with different vibration source, such as vibration frequency and amplitude can be calculated.

The experimental results agreed with the actual parameter, which showed PSD not only had its own good qualities in the position measurement, but also had the unique superiority in the vibration measurement.

This study aims to obtain the dynamic behaviours of cracked rod-fastening rotor bearing system (RFBS), and experimental investigation was carried out to examine the dynamic characteristics of this kind of assembled rotor bearing system with a transverse crack passing through the critical speed.

An experimental test rig of cracked RFBS was established for examining the vibration behaviours between intact and cracked system. The crack on the surface of a fastening rod was simulated by wire-electrode cutting processing method. The comprehensive analysis method of vibration was used to obtain the dynamic characteristics such as vibration amplitude, acceleration and whirling orbits before and after the critical speed as well as the instantaneous response in the process of speed up.

Some experimental vibration datum is obtained for cracked RFBS. The appearance of a crack will introduce the initial bending and make the vibration amplitude, acceleration and instant response in the process of speed up increase greatly as well as the change of whirling orbits.

The actual vibration characteristics for this complex assembled rotor system with a transverse crack are given passing through the critical speed. It can provide some useful help for monitoring the vibration behaviours of this kind of assembled rotor system as well as the detection of the crack fault.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0260/

The purpose of this paper is to present the frictional behaviour of composite materials under external horizontal vibration. Variation of friction coefficient is investigated experimentally when mild steel pin slides on composite materials such as glass fiber reinforced plastic (GFRP) and cloth reinforced ebonite (commercially known as gear fiber).

A pin‐on‐disc apparatus having the facility of vibrating the test samples in a horizontal direction is designed and fabricated. Horizontal vibration is created along (longitudinal direction), and perpendicular (transverse direction) to, the sliding direction. The experimental set‐up has the facility to vary the amplitudes and frequencies of vibration while velocity of vibration is kept constant.

The relative frictional behaviour of these materials and their dimensional analysis are yet to be investigated. Therefore an attempt is made to investigate the relative frictional property of the GFRP and cloth reinforced ebonite (commercially known as gear fiber) and the results of these composite materials are analyzed by dimensional analysis under horizontal vibration.

It is expected that the applications of these results will contribute to the improvement of different concerned mechanical systems.

It can also be noted that there are no clear correlations between friction‐ and other vibration‐related operating parameters. Considering the above conclusion and lack of correlation, the paper meant to find out a suitable correlation and a way of observing the response of friction force by applying known frequency and amplitude of vibration in a particular direction. It is expected that the application of these results will contribute to the improvement of different concerned mechanical systems.

THE present series of articles is intended to cover in a general manner the whole subject of vibration in aircraft. The study of aircraft vibration is a specialized branch of engineering science, calling for considerable practical skill and experience in the design and use of measuring equipment, as well as the ability to carry out the mathematical analyses which render test results intelligible and lead to the successful solution of vibration problems. The leading features of all mechanical vibration problems are, however, of such a nature as to be readily understood, and the aim of this series is to describe these leading features so as to facilitate the appreciation of the broad principles governing the avoidance of unpleasant or dangerous vibrations.

The main purpose of this research is to investigate finite-element analysis (FEA) on flux reversal-free stator switched reluctance motor (FRFSSRM) for industrial applications. The vibration analysis for an electrical machine is essential because of the acoustic noises. The acoustic noises originate by coincidence of natural frequencies of motor with the vibration frequencies.

The identification with the performance for FRFSRM by torque ripple, vibration. The vibration of the machine is because of unbalanced electromagnetic forces. The mutual coupled winding and a common pole between two adjacent exciting poles reduce these unbalanced forces.

The accelerometer is used to monitor the vibration amplitude in transient mode. A comparison study shows that the vibration is less in the E-core SRM than in the conventional flux reversal SRM.

The shorter flux path reduces the torque ripple and vibration content in SRM. This research article mainly focuses on the parameters such as vibration and torque ripple. The vibration of FRFSRM is identified by accelerometer; ANSYS Package predicts the simulation of the vibration measurement. The dynamic behaviors of this E-core SRM model with rated conditions the vibration had predicted.

The purpose of this paper is to examine a new idea of vibration control which minimizes joint‐torques and suppresses vibration of the flexible redundant manipulator.

Using the kinematics redundancy feature of the flexible redundant manipulator, the self‐motion in the joint space can be properly chosen to both suppress vibration and minimize joint‐torques.

The study shows that the flexible redundant manipulator still has the second optimization feature on the premise of vibration suppression. The second optimization feature can be used to minimize joint‐torques on the premise of vibration suppression.

To a flexible redundant manipulator, its joint‐torques and vibration can be reduced simultaneously via its kinematics redundancy feature.

The method and algorithm discussed in the paper can be used to minimize joint‐torques and suppress vibration for the flexible redundant manipulator.

The paper contributes to the study on improving dynamic performance of the flexible redundant manipulator via its kinematics redundancy feature. The second optimization capability of the flexible redundant manipulator is discovered and used to both minimize joint‐torques and suppress vibration.

The purpose of this paper is to investigate experimentally the effect of external vertical vibration on wear property of mild steel.

A pin‐on‐disc apparatus capable of vibrating the test samples in a vertical direction is designed and fabricated. The experimental setup has the ability to vary the amplitudes and frequencies of vibration while velocity of vibration is kept constant. During the experiment, the frequency and amplitude of vibration are varied from 0 to 500 Hz and 0 to 200 μm, respectively.

Results show that the wear rate decreases with the increase of amplitude and frequency of vibration for mild steel. These results are analyzed by dimensional analysis to correlate the wear rate with sliding velocity, normal load, frequency and amplitude of vibration. The experimental results are also compared with those available in literature and simple physical explanations are provided. Considering the lack of correlation between wear rate and other vibration‐related operating parameters, the present research is started to find out suitable correlation and a way of reducing wear rate by applying known frequency and amplitude of vibration at a particular direction.

It is expected that the applications of these results will contribute to the improvement of different concerned mechanical systems.

The paper can be used for design‐related purposes.

This paper presents experiment results that examine the validity of extracting blade vibration signature from the shaft torsional vibration signals. A special test rig was designed and manufactured for this objective. A set of strain gages were bonded to the shaft and to the blades to measure the shaft twisting and blade bending deformations respectively. A controlled frequency exciter excited the blade vibration. The shaft torsional and blade bending vibration signals were simultaneously recorded and presented in the time and frequency domains. The blade bending vibration frequencies appeared dominantly in the shaft torsional vibration signals for all blade vibration frequencies up to 100Hz. For frequencies higher than 100Hz, less sensitivity of the torsional vibration to blade vibration was observed.

This study aims to reconstruct the frictional vibration signal from noise and characterize the running-in process by frictional vibration.

There is a strong correlation between tangential frictional vibration and normal frictional vibration. On this basis, a new frictional vibration reconstruction method combining cross-correlation analysis with ensemble empirical mode decomposition (EEMD) was proposed. Moreover, the concept of information entropy of friction vibration is introduced to characterize the running-in process.

Compared with the wavelet packet method, the tangential friction vibration and the normal friction vibration reconstructed by the method presented in this paper have a stronger correlation. More importantly, during the running-in process, the information entropy of friction vibration gradually decreases until the equilibrium point is reached, which is the same as the changing trend of friction coefficient, indicating that the information entropy of friction vibration can be used to characterize the running-in process.

The study reveals that the application EEMD method is an appropriate approach to reconstruct frictional vibration and the information entropy of friction vibration represents the running-in process. Based on these results, a condition monitoring system can be established to automatically evaluate the running-in state of mechanical parts.

The EEMD method was applied to reconstruct the frictional vibration. Furthermore, the information entropy of friction vibration was used to analysis the running-in process.