Use Of Vibration Analysis Research Articles

Technological Advances on Fault Diagnosis in Wind Turbines: A Patent Analysis

Given the urgency of mitigating the effects of global warming and the depletion of fossil energy sources, renewable sources of energy, such as wind power, are the focus of the future. However, due to the rapid growth of this technology, concerns about the security and reliability of wind turbines are increasing, especially because of associated hazards and financial costs. Hence, health monitoring and fault identification for wind turbine blades have become an important focus of research. Thus, the objective of this study was to generate data on the current scenario of the techniques used to identify failures and defects in wind turbines and their components. Through the results found, companies can find ways to make decisions and identify potential new technologies. In this way, a technology prospection was conducted that focused on patents to investigate the use of vibration analysis, thermography, and machine learning. A total of 635 patent documents were found, and the evolution in the number of patents over the years has demonstrated the current interest in developing new technologies in this research area. China, the world’s leading country in the area of wind energy, was the country with the highest number of filings, followed by the United States. In the patent documents analyzed, it was possible to identify that those innovative technologies for predicting and detecting failures are a topic of interest for the world’s largest economies. Additionally, it was clear from the results that the application of artificial intelligence to traditional techniques is a current trend and will continue in the future. Technological prospection studies can foster the development of new methods and devices, providing economic and environmental gains for the wind energy industry.

Development of a Reliable Vibration Based Health Indicator for Monitoring the Lubricating Condition of the Toggle Clamping System of a Plastic Injection Molding Machine

Plastic injection molding has become one of the most widely used polymer processing methods due to its ability to viably produce large volumes of complex parts in a short time frame. Most of the plastic injection molding machines currently used in industry possess a toggle clamping mechanism that undergoes a repeated clamping and unclamping cycle during operation. This toggle must therefore be properly lubricated to avoid catastrophic failure and eventual machine downtime. To overcome this limitation, the industry currently relies on the experience of a skilled operator, paired with a fixed empirical value, to determine the timing for re-lubrication. This method often leads to the machine operator either wasting lubricant by over-lubricating the toggle, or damaging the toggle by failing to re-lubricate when needed. Herein, we explore the use of vibration analysis to perform real-time condition monitoring of the lubrication condition of the toggle clamping system. In this study, our novel structural response analysis out performed both traditional time domain and frequency domain analyses in isolating the vibrational signatures indicative of lubricant degradation. Additionally, this study confirms that the vibration generated during the unclamping period of the toggle, proved to contain more valuable information relevant to the instantaneous lubricant quality than provided by its corresponding clamping period.

Metrological Advantages of Applying Vibration Analysis to Pipelines: A Review

Flow rate is a necessary variable in industrial processes and, therefore, there is a wide variety of instruments designed to measure it. However, the most accepted measuring devices have the problem of being invasive or intrusive. The scientific and technological challenge is to achieve measurement by exploiting all the phenomenological possibilities using a non-intrusive, easy-to-install, portable and low-cost mechanism. This paper presents a literature review on the use of vibration analysis in flow rate metrological systems in order to identify research opportunities for the indirect measurement of this magnitude. A promising line of work was found based on soft flow rate sensors that use the analysis of pipeline vibrations integrated into computational intelligence routines, which allows inference of the flow rate value. The findings promote to continue with new technical and scientific challenges.

Application of operational method to develop dynamic stiffness matrix for vibration analysis of thin beams

Laplace transform operator only accepts initial values at zero in evaluating derivative functions. This limits its use in vibration analysis of beams as a tool for merely finding analytical solutions and coefficients. By extending Laplace transform’s capacity to take non-zero initial conditions, a novel operational method for developing dynamic beam elements is proposed. The method avoids integration and differentiation, which are traditionally used in developing dynamic vibration elements. The ease of application of this operational method is demonstrated by developing dynamic stiffness elements of Euler-Bernoulli beams under various boundary conditions. The proposed technique also allows for easy handling of coupled differential equations, such as the ones applied to bending-torsion vibration of beams, as well as discontinuous functions which appear in elastic support modelling. MATLAB® software has been used as graphing tool and for the mathematical calculations in this research.

Investigation of the Effect of Material on Undamped Free Vibration of Cantilever Beams with Uniform Single Surface Crack

Crack detection in structures is a critical area of research where the developments have been made out since decades. Various techniques are available for early identification and quantification of cracks to predict and prevent the unexpected sudden failure of structure and ensure uninterrupted service. Use of vibration analysis for detecting crack is one of the widely used techniques which offer lots of advantages over other like it is easier and less costly method and can be used for inaccessible components. The present work attempts to use modal analysis through FEA to investigate the effect of crack on natural frequency of vibration in beams of different materials, for three different crack location. From the result, it has been inferred that among Structural Steel (SS), Aluminium alloy (Al) and Gray Cast Iron (CI), the natural frequency is highest for Al beam and lowest for CI beam. Introduction of crack reduces the natural frequency of vibration, however, the effect of crack location on frequency is not uniform for different modes. Also, the trend is similar in beams of all the materials.

An Introduction to the Vibration Analysis for the Precision Honing of Bores

Honing is mostly the last step in the production process for precise elements and thus has to comply with high standards for the resulting quality regarding form, measurement and surface quality. Tolerances are currently even further reduced. Crucial for the ability of the honing process to reach the high quality is the process control. A new approach to a further improvement of the honing process could be the use of vibration analysis during the machining process. Vibration analysis for process control is already successfully used, e.g. for grinding. The paper presents an experimental setup for the measurement of vibrations during the honing process and shows first results of conducted experiments.

Monitoring Natural Pitting Progress on Helical Gear Mesh Using Acoustic Emission and Vibration

Over the last few decades, there has been an awareness of the role of predictive maintenance on large industrial gearboxes. To apply effective condition base maintenance on gears, it is important to diagnose the gear fault at its earliest stage of development. The application of the acoustic emission (AE) technology in relation to gear box diagnosis is well documented [1–4]. Asperity contact has been found to be the major source of AE activity within the gear mesh [5]. Researchers have investigated the influence of other operational factors such as oil film thickness [6], load and speed [7, 8] on the level of AE activity. Tan et al. [9] presented the first and only conclusive research in which the applicability of AE in monitoring the natural progressive pitting was investigated. Tan employed a back-to-back gearbox to study the accelerated surface pitting on spur gears while a comparative study between effectiveness of spectrometric oil analysis, AE and vibration techniques was undertaken. Their research showed that the AE r.m.s from the pinion gear was more sensitive in detecting the pitting progress on the gear surface. Raja et al. [7] performed a comparative study on the effect load and speed on the generation of AE for both helical and spur gears, while Eftekharnejad et al. [10] investigated the capability of AE technology in locating and identifying seeded surface defects on helical gears. To date, apart from the work by Eftekharnejd et al. and Raja et al. [7, 10], there has been no other investigation into application of AE in diagnosis of the helical gears. The use of vibration analysis for gear fault diagnosis and monitoring has been widely investigated and its application in industry is well established [11]. This is mainly reflected in the aviation industry for diagnosis of the helicopter engine, drive trains and rotor systems [12]. The spectral kurtosis (SK) is gaining ground in application to vibration diagnosis. To determine the SK, the signal is first decomposed into the time-frequency domain after which the Kurtosis values are determined for each frequency band [13]. The concept of SK analysis was first developed by Dwyer [14] as a tool which was able to trace non-Gaussian features in different frequency bands using the fourth order moment of the real part of the short-Time Fourier transform (STFT). Dwyer only investigated the application of SK on stationary processes but did not account for non-stationary vibration signatures typical of rotating machines. To date, the most comprehensive calculations of the SK has been developed by Antoni [15] as the fourth order cumulant of the spectral moment (K):

Remote Health Monitoring for Offshore Machines, using Fully Automated Vibration Monitoring and Diagnostics


 
 
 This paper describes the use of vibration analysis with a fully automated diagnostics system to detect common machine faults such as imbalance and misalignment as well as bearing and gearbox faults of offshore machines. Other faults types, e.g. when a large object hits the propeller blades may be detected using the STFT. As the mechanical properties of the structure can change because of changes of temperature and oil quality, these (and other) state data are also stored. The data fusion process is currently under work. Experiments were performed on a home cooling fan system to demonstrate and illustrate the faults detection capability of the vibration and diagnostics system. Vibration data were also acquired from selected equipment on a small boat with different combinations (on/off status) of the engine, generator and hydraulic pump. The trending and alarm features were demonstrated for the different types of data. The vibration and diagnostics system is implemented with threshold limits for the alerts and alarms corresponding to each technique. The model also allows for automatic storing of raw data periodically and after any deviations from normal conditions; i.e., when alerts are on.
 
 

Vibration Analysis Based on AR Trispectrum in Milling Process

This paper presents the use of vibration analysis based on autoregressive (AR) trispectrum in milling process to indicate the relationship between machined surface quality of workpiece and spectrum character under a variety of different cutting parameter settings, such as the depth of cut, the feed rate and the spindle speed. The metal cutting experiments were performed on steel A3 material without using any cutting fluid. The experimental results for slices analysis of trispectra indicated that the spectral peaks were abundant as the milling process went smoothly. The roughness value measured reflects the machined surface quality of workpice. According to the changes for spectral peak and roughness value, a conclusion was made that the proposed trispectrum slices method for choosing cutting parameters and monitoring the machined surface quality in milling process was practicable.

Statistical quality control through overall vibration analysis

The present study introduces the concept of statistical quality control in automotive wheel bearings manufacturing processes. Defects on products under analysis can have a direct influence on passengers’ safety and comfort. At present, the use of vibration analysis on machine tools for quality control purposes is not very extensive in manufacturing facilities. Noise and vibration are common quality problems in bearings. These failure modes likely occur under certain operating conditions and do not require high vibration amplitudes but relate to certain vibration frequencies. The vibration frequencies are affected by the type of surface problems (chattering) of ball races that are generated through grinding processes. The purpose of this paper is to identify grinding process variables that affect the quality of bearings by using statistical principles in the field of machine tools. In addition, an evaluation of the quality results of the finished parts under different combinations of process variables is assessed. This paper intends to establish the foundations to predict the quality of the products through the analysis of self-induced vibrations during the contact between the grinding wheel and the parts. To achieve this goal, the overall self-induced vibration readings under different combinations of process variables are analysed using statistical tools. The analysis of data and design of experiments follows a classical approach, considering all potential interactions between variables. The analysis of data is conducted through analysis of variance (ANOVA) for data sets that meet normality and homoscedasticity criteria. This paper utilizes different statistical tools to support the conclusions such as chi squared, Shapiro–Wilks, symmetry, Kurtosis, Cochran, Hartlett, and Hartley and Krushal–Wallis. The analysis presented is the starting point to extend the use of predictive techniques (vibration analysis) for quality control. This paper demonstrates the existence of predictive variables (high-frequency vibration displacements) that are sensible to the processes setup and the quality of the products obtained. Based on the result of this overall vibration analysis, a second paper will analyse self-induced vibration spectrums in order to define limit vibration bands, controllable every cycle or connected to permanent vibration-monitoring systems able to adjust sensible process variables identified by ANOVA, once the vibration readings exceed established quality limits.

Tool condition monitoring in milling using vibration analysis

Monitoring the condition of cutting tools in any machining operation is very important to avoid unexpected machining trouble and improve machining accuracy. This paper presents the use of vibration analysis of the cutting process in milling to indicate the presence and progression of damage incurred by an end mill. The metal cutting experiments were performed on a mild steel workpiece without using any coolant to accelerate damage to cutter, and classical processing schemes in time and frequency domains were applied to the resulting vibrations of cutting process to obtain diagnostic information. Moreover, developing fault features were also illustrated using both scalogram and its mean frequency variation. It has been found that scalogram and its mean frequency are both capable of revealing the features of not only localized, but progressive fault more clearly in the presence of strong noise than conventional time and frequency domain analyses. Furthermore, the global average of the mean frequency variation provides a useful indicator signifying the progression of wear, whereas time domain statistics do not give any consistent trend.

Intra-operative evaluation of cementless hip implant stability: A prototype device based on vibration analysis

Cementless implants are mechanically stabilized during surgery by a press-fitting procedure. Good initial stability is crucial to avoid stem loosening and bone cracking, therefore, the surgeon must achieve optimal press-fitting. A possible approach to solve this problem and assist the surgeon in achieving the optimal compromise, involves the use of vibration analysis. The present study aimed to design and test a prototype device able to evaluate the primary mechanical stability of a cementless prosthesis, based on vibration analysis. In particular, the goal was to discriminate between stable and quasi-stable implants; thus the stem–bone system was assumed to be linear in both cases. For that reason, it was decided to study the frequency responses of the system, instead of the harmonic distortion. The prototype developed consists of a piezoelectric exciter connected to the stem and an accelerometer attached to the femur. Preliminary tests were performed on four composite femurs implanted with a conventional stem. The results showed that the input signal was repeatable and the output could be recorded accurately. The most sensitive parameter to stability was the shift in resonance frequency of the stem–bone system, which was highly correlated with residual micromotion on all four specimens.

Gear tooth stiffness reduction measurement using modal analysis and its use in wear fault severity assessment of spur gears

Due to excessive service load, inappropriate operating conditions or simply end of life fatigue, damage can occur in gears. When a fault, either distributed or localised, is incurred by gears, the stiffness and consequently vibration characteristics of the damaged tooth will change. A possible non-destructive technique for damage detection and severity assessment can be derived from vibration analysis. This paper presents the use of vibration analysis in the detection, quantification, and advancement monitoring of damage incurred by spur gear teeth. The stiffness of a single spur gear tooth is analysed theoretically, and due to the difficulties in measuring the gear tooth stiffness, an experimental procedure based on the modal analysis is developed to assess the severity of the gear tooth damage. A pair of spur gears was tested under accelerated wear conditions, and conventional time and frequency domain techniques are applied to the gear vibrations to indicate the presence and progression of the wear. The developed modal stiffness assessment technique is then used to quantify the resulting wear damage to the spur gear teeth.

Condition monitoring of slow-speed rolling element bearings using stress waves

Condition monitoring of rolling element bearings through the use of vibration analysis is an established technique for detecting early stages of component degradation. However, this success is not mirrored at rotational speeds below 16r/min. At such speeds the energy generated from bearing defects might not show as an obvious change in signature and thus becomes undetectable using conventional vibration measuring equipment. This paper presents an investigation into the applicability of stress wave analysis for detecting early stages of bearing damage at a rotational speed of 1.12r/min (0.0187 Hz). Furthermore, it reviews work undertaken in monitoring bearings rotating at speeds below 16r/min.

Condition monitoring of low-speed rotating machinery using stress waves Part 1

Condition monitoring through the use of vibration analysis is an established and effective technique for detecting the loss of mechanical integrity of a wide range and classification of rotating machinery. Equipment rotating at low rotational speeds presents an increased difficulty to the diagnostician [1-4, 23], since conventional vibration measuring equipment is not capable of measuring the fundamental frequency of operation. Also, component distress at low operational speeds does not necessarily show an obvious change in vibration signature.

Non-destructive condition monitoring of nuclear power plants by use of vibration analysis : Runkel, J.; Stegemann, D. Proceedings of the 12th World Conference on Non-Destructive Testing, Amsterdam (Netherlands) 23–28 Apr. 1989, Vol. 1, pp. 628–633. Edited by J. Boogaard and G.M. van Dijk, Elsevier, 1989

Non-destructive condition monitoring of nuclear power plants by use of vibration analysis : Runkel, J.; Stegemann, D. Proceedings of the 12th World Conference on Non-Destructive Testing, Amsterdam (Netherlands) 23–28 Apr. 1989, Vol. 1, pp. 628–633. Edited by J. Boogaard and G.M. van Dijk, Elsevier, 1989

NASTRAN: A Preliminary Discussion of User Impacts

INDUSTRY and government agencies have devoted serious and concerted efforts to developing tools to aid in solving a wide variety of large, structural analysis problems. The NASA Structural Analysis Computer Program (NASTRAN) was specifically designed to provide such a capability. NASTRAN is a general purpose digital computer program designed to analyze the behavior of elastic structures under a range of loading conditions, using a finite-element displacement method approach. Analytical capabilities include 1) static response to concentrated and distributed loads, thermal expansion, and enforced deformation; 2) dynamic response to transient loads, steadystate harmonic loads, and random excitation; and 3) determination of real and complex eigenvalues for use in vibration analysis, dynamic stability analysis and elastic stability analysis. The system has the capability of treating problems of virtually unlimited size, because economic considerations will generally limit the problem size long before reaching the limitations of the NASTRAN algorithms. NASTRAN is highly user-oriented, which partially accounts for its widespread acceptance and popularity. The program is systematically organized to do much of the work automatically and minimize the burden on the analyst. NASTRAN includes over 151,000 fortran statements, which translate into more than 1,000,000 machine language statements. It is machine independent, with options available for the IBM 360 and 7090 series, UNIVAC 1108 and CDC 6000 series. The NASTRAN program has an extensive plotting capability. NASTRAN was developed during the period 1965-1970 at NASA's Goddard Space Flight Center at an estimated cost of $3,000,000. Since its release for public use in November, 1970, continued development and management of the program have been transferred to the Langley Research Center. Because it represents the capture of significant secondary returns on the investment of the public research and development dollar, NASA has sponsored a study to survey the extent of the usage of NASTRAN and estimate some of the benefits that have accrued to users. In addition, information has been compiled regarding costs of performing certain applications, as well as new improvements or adaptions which have been developed by users. The following are the major results of that study.

Deflection of beams by the operational method

Laplace transform operator only accepts initial values at zero in evaluating derivative functions. This limits its use in vibration analysis of beams as a tool for merely finding analytical solutions and coefficients. By extending Laplace transform’s capacity to take non-zero initial conditions, a novel operational method for developing dynamic beam elements is proposed. The method avoids integration and differentiation, which are traditionally used in developing dynamic vibration elements. The ease of application of this operational method is demonstrated by developing dynamic stiffness elements of Euler-Bernoulli beams under various boundary conditions. The proposed technique also allows for easy handling of coupled differential equations, such as the ones applied to bending-torsion vibration of beams, as well as discontinuous functions which appear in elastic support modelling. MATLAB® software has been used as graphing tool and for the mathematical calculations in this research.