Journal of Vibroengineering
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Introduction to the Special Issue: Futuristic trends and emergence of technology in biomedical, nonlinear dynamics and control engineering
Get PDFIn the current era of emerging technologies such as deep learning, artificial intelligence, multimedia data analysis, Internet of Things (IoT), the significant role of vibration analysis can be seen in biomedical, nonlinear dynamics, and control engineering. Despite the numerous applications, lots of challenges and issues are still needed to address like nonlinearity, fault diagnosis, vibration spectrum analysis, and biomedical data monitoring and processing. The aim of this Special Issue is to cover and address all the aforesaid challenges and issues and practical solutions for such emerging technologies. We have received 21 manuscripts in total for this Special Issue across the globe and after the rigorous review process, only 10 manuscripts have been accepted for publication. A brief overview of contributions to this Special Issue is as underneath
Casing vibration signal characteristic extractions and applications in rolling bearing
Get PDFA method of combining autocorrelation function with cyclostationary theory and Hilbert envelope analysis is proposed and applied to extract characteristic frequency of rolling bearing. Meanwhile, mean power ratio is calculated and used to identify the fault types of aero-engine rolling bearing based on single-channel casing vibration signal. To verify the effectiveness of proposed method, a comparing analysis is carried out between traditional studies and proposed new method. Furthermore, the influences on the extraction of characteristics and calculation of mean power ratio are taken into account, including the ones of sensor installation position, fault types, type of experiment rigs, failure mode and rotational speed of rolling bearing. The result shows that the proposed method can diagnose running conditions and identify fault types of rolling bearing accurately and effectively just by single-channel casing vibration signal
Research on fault diagnosis of rolling bearings based on conditional variance statistic and cross-correlation spectrum
Get PDFIn this paper, relationships between conditional variance statistic and the center frequency as well as the bandwidth of the filter are researched, and we find that conditional variance statistic is suitable for selecting the center frequency of the filter, but undesirable for selecting the bandwidth. Meanwhile, considering that the traditional iterative way to select the optimal resonance frequency band will be affected by the step size, we choose to fix the bandwidth at five times fault characteristic frequency, then Whale Optimization Algorithm (WOA) is utilized to select the optimal center frequency so as to give consideration to both computing efficiency and accuracy of the selection of center frequency. To further suppress the in-band noise, the filtered signal is analyzed by high order energy operator, and the optimal two energy operators are chosen based on Fault Characteristic Index (FCI) for cross-correlation spectrum analysis. Simulation and experimental results indicate that the proposed algorithm can extract the fault feature of rolling bearings under strong background noise effectively
The shock absorption efficiency of the newly developed neutral equilibrium mechanism in building
Get PDFWhen a structure is hit by an earthquake, the resultant dynamic amplification threatens the safety of the structure. To counteract the seismic force and also reduce structural deformation, a control force, which requires a huge actuator, can be exerted. To avoid the use of excessively large actuators, the power capacity of the actuator needs to be reduced. To overcome these problems, the Neutral Equilibrium Mechanism (NEM) has been developed. The NEM can achieve changes in control with minimal output. The test results of the NEM confirm the following: 1. The total strength of the inner spring is equal to the total strength of the main control spring. 2. The deformation of the main control spring is zero when the angle of the linkage is zero. 3. When the angle of the linkage is +/–90 degrees, the deformation of the inner spring is zero. Considering time delay, the results of analysis show the following: 1. The time delay should be controlled to less than 0.020 seconds, and this mechanism can exert an excellent structural displacement reduction effect. 2. Comparison of the unbalanced force, the maximum output power and the maximum control power of the NEM to those of the direct control method under the same control parameters shows that when the time delay is 0.001 seconds, the unbalanced force of the NEM is only 1/230 and 1/236 of the maximum control force and the maximum output power of direct control respectively. 3. When the time delay is 0.005 seconds, the unbalanced force of the NEM is only 1/150 and also 1/150 of the maximum control and maximum output power of direct control respectively; 4. When the time delay is 0.010 seconds, the unbalanced force of this mechanism is 1/85 and 1/80 of the maximum control force and the maximum output power of direct control. The advantages of the NEM are that the control effect of a building with the NEM under a small unbalanced force and the maximum output power of a small NEM can achieve the same control effect of direct control under the same control parameters
The influence of structural configurations and operating speeds on the sorting arm during high frequency reciprocating operation
Get PDFUnder high-frequency reciprocating operation, the dynamics of the sorting arm are different between operating status and standstill status. First of all, the energy of inertial impact and frequency band depend on the actual motion state, which are closely related to the dynamics of the arm structure. Secondly, during the high-frequency reciprocating operation, the positions of sorting arm change, which causes its configurations changes. At the same time, the acceleration and deceleration in each stage of operation are also inconsistent. These factors make the vibration of the sorting arm structure more complicated. Therefore, the dynamics of the sorting arm mechanism must be analyzed under the actual operating conditions. The paper takes the sorting arm of LED chip sorter as the research object, and it is pointed out that the sorting arm structure has the characteristics of multi-mode high-low frequency during operation. However, the structural configurations and operating parameters of the sorting arm are the main influencing factors of its vibration, which have different characteristics of the high-low frequency response. In this paper, the use of sequential sub-section design to determine the configurations and the corresponding time-series during the operation. Through the analysis of multi-mode frequency response of the sorting arm, the characteristics of high-low frequency range corresponding to the two kind of work excitation are obtained. This paper verifies that the dynamics of the sorting arm are affected by the excitation of structural configurations and the excitation of operating speed during high-speed operation. The laws of high-low frequency response of the sorting arm under different operation parameters and configurations are found out, which provides guidance for the vibration suppression of the sorting arm under operation
Study of anti-swing control of ship cranes based on time delay feedback
Get PDF2 tons 3 meters ship crane as the research object, establish the complete mathematical model of ship crane, and design the time-delay feedback control algorithm to eliminate payload swing on the basis of the built mathematical model. First, a high-precision potentiometer is used to measure the in-plane and out-of-plane oscillation of the payload. Measuring devices for the rotary angle and variation amplitude angle are created, and the anti-swing control hardware system is built by the sensing unit and the High-Speed Data Acquisition hardware system. Secondly, the control software on the VB platform is developed using the time-delay feedback algorithm. Experimentally study the effect of time-delayed feedback controller on payload swing elimination, and use induction method to get the optimal control parameters of the time-delayed feedback control algorithm. At last, the AMEsim-ADAMS co-simulation platform was built to evaluate the payload sway of the ship crane under simulated working conditions. The results show that: the hardware and software systems for anti-swing control built-in the paper can give the real-time and the exact payload swing angles. The method of adding time-delay feedback control signal to the slewing operation signal can achieve better anti-swing effects than the others. At the same time, the delayed feedback control algorithm still has a nice control effect in the case of virtual ship deck motion
Transverse vibration analysis of wire rope in deep mining hoisting system
Get PDFIn this paper, the transverse vibration displacement, velocity and acceleration of the wire rope of deep mining hoisting system is acquired by establishing a mathematical model and solving it by Galerkin discrete method. The results show that: for the deep mining hoisting system with hoisting depth of 1000m and hoisting load of 25 t, when there is an excitation with amplitude of 0.002 m and frequency of 10 Hz at one end, the transverse vibration displacement of the wire rope at 200 m is between -0.015 m and 0.015 m, the transverse vibration velocity is between –0.05 m/s and 0.05 m/s, and the transverse vibration acceleration is between –0.5 m/s2 to 0.5 m/s2. Meanwhile, it can be found that different loads, accelerations and mass of wire rope per unit length have little influence on the transverse vibration displacement of the wire rope, but different external excitation frequency have an impact on the transverse vibration displacement of the wire rope. Then the vibration energy and natural frequencies are analyzed. And the maximum vibration energy and 30 natural frequencies are obtained. Finally, the mathematical model is verified through the experiment and the validity of the mathematical model is proved
Gear compound fault detection method based on improved multiscale permutation entropy and local mean decomposition
Get PDFThe traditional multiscale entropy algorithm shows inconsistency because some points are ignored when the signal is coarsened. To solve this problem, this paper proposes an improved multiscale permutation entropy (IMSPE). Firstly, the fault signal is decomposed into several product functions (PF) by local mean decomposition (LMD). Secondly, IMSPE is proposed to extract fault features of product functions. IMSPE integrates the information of multiple coarse sequences and solves problems of entropy inconsistency. Finally, the proposed method based on LMD and IMSPE is applied into gear fault diagnosis system. The experiment shows the proposed method can distinguish different gear fault types with a higher accuracy than traditional methods
Building vibration monitoring based on digital optical cameras
Get PDFThe complex and process-critical conditions of machineries are needed to be continuously monitored in order for incipient breakdown to detect and ensure its high performance and operating safety. The change in the resonant frequency is focused by the spectrum analysis which is caused by the structural degradation and for health monitoring, useful information is produced. A test signal is required by the spectral analysis for health monitoring of structural condition. A test signal is the easiest way for structural spectral characteristics measurement but during every measurement, a structure vibration is impractical. Several techniques are presented for the condition of a machine depending on the application monitoring. The structure health would be able to be monitored if structural vibrations are utilized for spectral characteristics measurement due to wind and ground motion. The vision-based monitoring with the sources of errors are detailed and presented in this paper. Different parameters are observed for the different signals, unify the scale and can also be used to signals errors as compared with different levels of amplitudes. The PSNR and Structural Similarity are analyzed, the PSNR value is obtained in the range of 40 dB to 50 dB and the SSIM values are nearby to the 1 for all the signals. The MAPE and MAE values obtained by the presented technique are less for all the signal samples. The presented method outperforms the existed technique by 3.21 % to 44.02 % in form of MAPE. The presented method is 3.21 % to 44.02 % better than the previously existed technique in form of MAPE. The percentage improvement of the presented method outperforms by 33.93 % and 42.43 % in terms of MAE
Application of dynamic adaptive technology based on symbolic regression to identify modal parameters of chip sorter
Get PDFCantilever structure, which needs high-frequency rotating motion, is widely used in the field of chip manufacturing. The motion stability of high-frequency rotation motion of cantilever structure directly affects the production efficiency. The traditional dynamic analysis method is no longer applicable to analyze the vibration of cantilever structure under high-frequency rotating motion. It is also urgent to control the high-frequency rotation motion of cantilever mechanism. In this paper, experiments are designed to collect strain signals of chip sorter’s cantilever under high-frequency operation, and modal parameters are extracted from time domain signals by symbolic regression algorithm. The results of modal parameter identification at high-frequency are selected as the samples, and the Gaussian process regression model of machine learning algorithm is used to train the samples. The prediction results can be used as the basis of structural stability research and vibration suppression