scholarly journals A Speed-Variant Balancing Method for Flexible Rotary Machines Based on Acoustic Responses

2021 ◽  
Vol 13 (13) ◽  
pp. 7237
Author(s):  
Andrew Peplow ◽  
Javad Isavand ◽  
Afshar Kasaei ◽  
Babak Afzali ◽  
Delphine Bard-Hagberg
Keyword(s):  
Condition Monitoring ◽  
Vibration Response ◽  
Constant Speed ◽  
Vibration Measurements ◽  
Critical Speeds ◽  
Rotary Machine ◽  
Rotary Machines ◽  
Vibration Responses ◽  
Experimental Laboratory ◽  
Run Up

As rotary machines have become more complicated, balancing processes have been classified as a vital step in condition monitoring to ensure that machines operate reliably, smoothly and safely. All rotating objects will deflect during rotation and all objects possess certain natural frequencies in the absence of rotation. However, an unbalanced object can cause significant unwanted deflection created by resonant vibration at a frequency (cycles/second) close to certain rotational speeds (rotations/second), known as critical speeds. This is especially important for flexible machines which normally work at rotations above their critical speeds. Imbalance is a common problem in flexible rotating machinery that can lead to extreme vibration and noise levels. This is one of the major reasons for studying various balancing methods applied to the vibration response of rotating machines. Recently, the relation between acoustic and vibration response during a rotary machine balancing process based on the original Four-Run method has been presented for constant speed machines. This method cannot be applied to machines in start-up or shut-off. Hence, by considering the acoustic and vibration responses of a machine between its critical speeds, this research presents a new innovative speed-variant balancing method based on the original Four-Run method, named as (PPCS) Peak to Peak for Critical Speeds. The proposed method consists of two major types of application: the first is in the run-up of the machine and the second is in shut down. Experimental laboratory results show that this method can be implemented for speed-variant and flexible rotary machines during run-up or shut-down transient processes based on acoustic and vibration measurements. Further, the results show the same trend in acoustic and vibration responses during balancing process which was shown for constant speed rotary machines. With a 40% improvement in response compared to around 55% obtained by traditional vibration measurements, the results found show an appreciable benefit in an alternative acoustic methodology that may have not been considered previously for run-up and shut-down issues. In addition, since only the magnitude of response is required and this is a non-contact technique an acoustic-only methodology, it can be employed with some confidence as an innovative and readily available method for condition monitoring.

scholarly journals A Speed-Variant Balancing Method for Flexible Rotary Machines Based on Acoustic Responses

2021 ◽  
Author(s):  
Andrew Peplow ◽  
Javad Isavand ◽  
Afshar Kasaei ◽  
Babak Afzali ◽  
Delphine Bard-Hagberg
Keyword(s):  
Condition Monitoring ◽  
Vibration Response ◽  
Contactless Method ◽  
Critical Speeds ◽  
Rotary Machine ◽  
Start Up ◽  
Rotary Machines ◽  
Vibration Responses ◽  
Experimental Laboratory ◽  
Run Up

As rotary machines have become more complicated, balancing processes have been classified as a vital step in condition monitoring to ensure machines operate both reliably and safely. This is especially important for flexible machines which normally work at rotations speeds above critical limits. Imbalance is a common problem in flexible rotating machinery that can lead to extreme vibration and noise levels. This is one of the major reasons for studying various balancing methods applied to the vibration response of rotating machines. Recently, the relation between acoustic and vibration response during a rotary machine balancing process based on the Four-Run method has been presented for constant speed machines. This method cannot be applied to machines in start-up or shut-off. Hence, by considering the acoustic and vibration responses of a machine between its critical speeds, this research presents a new innovative speed-variant balancing method based on the original Four-Run method, named as "Peak to Peak for Critical Speeds (PPCS)". The proposed method consists of two major types of application: the first is in the Run-up of the machine and the second is in Shut-down. Experimental laboratory results show that the PPCS method can be implemented for speed-variant and flexible rotary machines during run-up or shut-down transient processes based on acoustic and vibration measurements. As a phase-less and a contactless method, the PPCS can be employed as an innovative and readily available method for condition monitoring in the future.

Analysis of vibration response and machining quality of hybrid robot based UD-CFRP trimming

2021 ◽  
pp. 095440542098609
Author(s):  
Yan Zhang ◽  
Hao Li ◽  
Xuda Qin ◽  
Jie liu ◽  
Zhuojie Hou
Keyword(s):  
High Performance ◽  
Vibration Response ◽  
Industrial Robots ◽  
Force Characteristic ◽  
Surface Waviness ◽  
Machined Surface ◽  
Machining Quality ◽  
3D Surface Roughness ◽  
Machined Surface Quality ◽  
Vibration Responses

To fulfill the demands of higher precision, better quality, and more flexibility, the usage of high-performance industrial robots is rapidly increased in aerospace industry. Considering the anisotropic and inhomogeneous characteristics of composite materials, this study focuses mainly on dynamic response investigation of a newly designed hybrid robot (named as TriMule) in CFRP trimming process and its influence on the machined quality. First, combined with the cutting force characteristic, the vibration responses of tool center point (TCP) under the dynamic excitation were obtained. The influences of robotic TCP vibration on machined surface quality with different fiber orientations, including surface waviness, cavity, 3D surface roughness, and depth of affected zone, are first studied by comparing hybrid robot and machine tool. From experiment results, it can be concluded the proposed TCP vibration response model has sufficient prediction accuracy. Meanwhile, it is found that larger robotic vibration response is accompanied by higher surface waviness, bigger surface cavity, and greater affected zone. Results also showed that the fiber orientation and milling style are two essential factors that affect robot vibration and machining quality during CFRP trimming.

Field test investigations for condition monitoring of a concrete culvert bridge using vibration responses

2020 ◽  
Vol 27 (10) ◽  
Author(s):  
Solomon T.K. Lin ◽  
Ye Lu ◽  
Mehrisadat Makki Alamdari ◽  
Nguyen L.D. Khoa
Keyword(s):  
Condition Monitoring ◽  
Field Test ◽  
Vibration Responses

scholarly journals Diagnosis of Faulty Wind Turbine Bearings Using Tower Vibration Measurements

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1474 ◽  
Author(s):  
Francesco Castellani ◽  
Luigi Garibaldi ◽  
Alessandro Paolo Daga ◽  
Davide Astolfi ◽  
Francesco Natili
Keyword(s):  
Wind Turbine ◽  
Condition Monitoring ◽  
Wind Turbines ◽  
Statistical Tests ◽  
Novelty Detection ◽  
General Idea ◽  
Data Set ◽  
Vibration Measurements ◽  
Bearing Fault ◽  
Operation Conditions

Condition monitoring of gear-based mechanical systems in non-stationary operation conditions is in general very challenging. This issue is particularly important for wind energy technology because most of the modern wind turbines are geared and gearbox damages account for at least the 20% of their unavailability time. In this work, a new method for the diagnosis of drive-train bearings damages is proposed: the general idea is that vibrations are measured at the tower instead of at the gearbox. This implies that measurements can be performed without impacting the wind turbine operation. The test case considered in this work is a wind farm owned by the Renvico company, featuring six wind turbines with 2 MW of rated power each. A measurement campaign has been conducted in winter 2019 and vibration measurements have been acquired at five wind turbines in the farm. The rationale for this choice is that, when the measurements have been acquired, three wind turbines were healthy, one wind turbine had recently recovered from a planetary bearing fault, and one wind turbine was undergoing a high speed shaft bearing fault. The healthy wind turbines are selected as references and the damaged and recovered are selected as targets: vibration measurements are processed through a multivariate Novelty Detection algorithm in the feature space, with the objective of distinguishing the target wind turbines with respect to the reference ones. The application of this algorithm is justified by univariate statistical tests on the selected time-domain features and by a visual inspection of the data set via Principal Component Analysis. Finally, a novelty index based on the Mahalanobis distance is used to detect the anomalous conditions at the damaged wind turbine. The main result of the study is that the statistical novelty of the damaged wind turbine data set arises clearly, and this supports that the proposed measurement and processing methods are promising for wind turbine condition monitoring.

Damped Vibration Response of an Axially Moving Wire Subject to an Oscillating Boundary Condition and the Application to Slurry Wiresaws

2020 ◽  
pp. 1-37
Author(s):  
Liming Li ◽  
Imin Kao
Keyword(s):  
Boundary Condition ◽  
Analytical Solution ◽  
Traveling Waves ◽  
Solution Space ◽  
Vibration Response ◽  
Temporal Variables ◽  
Rocking Motion ◽  
Vibration Responses ◽  
Oscillating Boundary ◽  
Axially Moving

Abstract This paper presents the analysis of a new class of differential continuum system with a solution of traveling waves containing coupled spatial and temporal variables. Herein, we derive the analytical solution of the damped vibration response of a longitudinally moving wire with damping, subject to an oscillating boundary condition. The vibration response is the outcome of combining four traveling waves, induced by a wave initiating from the oscillating boundary, and traveling between the two boundaries. The four different traveling waves are the independent bases of the vibration responses that span the solution space of vibration of such continuum system. The combination, or the interference, of these traveling waves in the undamped condition produces nodal points in the vibration response, which can be formulated through the analytical solution. The impacts of wire speed, oscillating frequency at the boundary and damping factors on the vibration response are investigated. Furthermore, the vibration induced by the oscillating motion of the boundary has a profound impact on the effectiveness of slicing ingots with rocking motion of oscillating wire guides in wiresaw manufacturing processes.

Simulation of nonlinear vibration responses of cab system subject to suspension damper complete failure for trucks

2020 ◽  
Vol 11 (02) ◽  
pp. 2050017
Author(s):  
Leilei Zhao ◽  
Jian Guo ◽  
Yuewei Yu ◽  
Xiaohan Li ◽  
Changcheng Zhou
Keyword(s):  
Nonlinear Vibration ◽  
Periodic Motion ◽  
Chaotic Motion ◽  
Vibration Response ◽  
Maintenance Cost ◽  
Bench Test ◽  
Friction Forces ◽  
Response Characteristics ◽  
Vibration Responses ◽  
Complete Failure

The strong vibration responses of the cab system can be restrained by the damper force and the friction of the suspensions for trucks. After the failures of dampers, especially in the case of the complete failure, the anti vibration effect of the friction is prominent. However, the nonlinear vibration response characteristics of the cab subject to the damper complete failure have not been revealed. In order to reveal the nonlinear vibration response characteristics, a dynamic model of the cab system was established and its vibration equations were given. The friction forces existing in the suspensions were determined by the bench test. The influences of the friction forces on the cab vibration under different amplitude harmonic inputs were investigated when the dampers completely fail. The cab vertical displacement changes with the excitation amplitude and the vibration represents various motion states, including the periodic motion, the quasi-periodic motion, and the chaotic motion. The simulation results show that when the dampers fail, the proper friction forces help to suppress the quasi-periodic motion and the chaotic motion of the cab and to reduce the amplitude of the periodic motion. The proper friction forces can make the cab movement far away from the chaos area. They also help to avoid the fatigue damage of the cab floor and suspension parts to improve the service life of the suspension parts and to reduce the maintenance cost of the cab suspensions.

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