VIBRATION ANALYSIS Research Papers - Academia.edu (original) (raw)

The reliable condition monitoring of machines and the early detection of faults play an important role in condition-based maintenance. Information on the condition of machines is needed in different forms but finally it has to be in as... more

The reliable condition monitoring of machines and the early detection of faults play an important role in condition-based maintenance. Information on the condition of machines is needed in different forms but finally it has to be in as simple form as possible so that it can be utilised in the decision-making by the maintenance and management personnel. In the field of machine condition monitoring, there is a wide range of signal processing methods, which are used in feature extraction and fault diagnosis. Differentiation and integration are very common and important operations in vibration signal processing. The order of derivative is typically an integer number but it can also be any fractional number. Especially in the challenging fault and process cases, signals whose order of derivative is a real or complex number could be clearly more sensitive in fault detection than the commonly used signals: displacement, velocity and acceleration. In this paper, the application of complex o...

The paper is aimed at studying the motion conditions of the vibratory compacting machine equipped with the crank excitation mechanism characterized by the changeable geometrical parameters. Unlike numerous scientific publications devoted... more

The paper is aimed at studying the motion conditions of the vibratory compacting machine equipped with the crank excitation mechanism characterized by the changeable geometrical parameters. Unlike numerous scientific publications devoted to similar subject, the novelty of the present research consists in the improved design of the vibro-impact plate compactor and the developed mathematical model describing the motion conditions of the compactor's oscillatory system. It is proposed to use the crank mechanism to excite the oscillations of the impact body acting upon the frame of the compacting plate at a certain angle to the surface being compacted. The main idea of this improvement is to provide the self-propelling locomotion conditions of the compactor and to reduce the pushing force that must be applied by the operator. The research results obtained by means of the numerical modeling in Mathematica software describe the dynamic behavior of the compactor's oscillatory system under different geometrical parameters of the crank excitation mechanism (crank eccentricity, impact gap, etc.). The material of the paper can be of significant practical interest for the designers and engineers dealing with the development of new vibratory compactors and the improvement of compacting technologies.

A differential quadrature element method (DQEM) based on first order shear deformation theory is developed for free vibration analysis of non-uniform beams on elastic foundations. By decomposing the system into a series of sub-domains or... more

A differential quadrature element method (DQEM) based on first order shear deformation theory is developed for free vibration analysis of non-uniform beams on elastic foundations. By decomposing the system into a series of sub-domains or elements, any discontinuity in loading, geometry, material properties, and even elastic foundations can be considered conveniently. Using this method, the vibration analysis of general beam-like structures is to be studied. The governing equations of each element, natural compatibility conditions at the interface of two adjacent elements and the external boundary conditions are developed in a systematic manner, using Hamilton's principle. The present DQEM is to be implemented to Timoshenko beams resting on partially supported elastic foundations with various types of boundary conditions under the action of axial loading. The general versality, accuracy, and efficiency of the presented DQEM are demonstrated having solved different examples and compared to the exact or other numerical procedure solutions.

In the analysis and design of framed structures, the traditional methods are based on the simplified assumption that the joints are completely either pinned or rigid. However, the experimental investigations show that the frame... more

In the analysis and design of framed structures, the traditional methods are based on the simplified assumption that the joints are completely either pinned or rigid. However, the experimental investigations show that the frame connections present an intermediate behaviour between these two extreme cases. The present work is concerned with the dynamic elastic analysis of semi-rigid plane frames subjected to

Operating Deflection Shapes (ODS) has emerged as one of the powerful techniques in vibration analysis to understand and to evaluate the absolute dynamic behaviour of a machine, component or an entire structure. Traditionally,... more

Operating Deflection Shapes (ODS) has emerged as one of the powerful techniques in vibration analysis to understand and to evaluate the absolute dynamic behaviour of a machine, component or an entire structure. Traditionally, accelerometers have been used to get the ODS of a structure. However, recent development shows that certain situation may not allow direct contact with the structure under investigation. Therefore, Scanning Laser Doppler Vibrometer (SLDV) has become popular in the investigation. In this paper, a new ODS Frequency Response Function (ODS FRF) for investigations using SLDV is formulated. The ODS FRF is used to construct the ODS of the structure. A new form of scale factor for the ODS FRF is also introduced to normalize the effects from variable excitation force. The importance of this scale factor is demonstrated on a beam and plate under the excitation of varying forces. It is found that the suggested ODS FRF and the scale factor give the desired result in comparison with theory.

The objective of this work is the fault diagnosis in diesel engines to assist the predictive maintenance, through the analysis of the variation of the pressure curves inside the cylinders and the torsional vibration response of the... more

The objective of this work is the fault diagnosis in diesel engines to assist the predictive maintenance, through the analysis of the variation of the pressure curves inside the cylinders and the torsional vibration response of the crankshaft. Hence a fault simulation model based on a zero-dimensional thermodynamic model was developed. The adopted feature vectors were chosen from the thermodynamic model and obtained from processing signals as pressure and temperature inside the cylinder, as well as, torsional vibration of the engines flywheel. These vectors are used as input of the machine learning technique in order to discriminate among several machine conditions, such as normal, pressure reduction in the intake manifold, compression ratio and amount of fuel injected reduction into the cylinders. The machine learning techniques for classification adopted in this work were the multilayer perceptron (MLP) and random forest (RF).

The rotor critical speeds are the speeds accompanied by a great dynamic load, and maximum vibration. The critical speeds of rotation coincide with the natural frequencies of transverse vibration of the non-rotating shaft disc system.... more

The rotor critical speeds are the speeds accompanied by a great dynamic load, and maximum vibration. The critical speeds of rotation coincide with the natural frequencies of transverse vibration of the non-rotating shaft disc system. These speeds should be determined carefully. In this paper, the critical speeds of a shaft-discs system are calculated using several methods. Firstly, Raleigh's method, and transfer matrix method are used to calculate the first and the second critical speeds using MATLAB software. Secondly, the critical speeds are calculated by finite element method using ANSYS package. Finally, an experimental investigation is done to determine the values of critical speeds. The experimental results are presented in comparison with the calculated values.

In these days condition monitoring plays a main role in many of the industries. Lubricantsare essential and expensive components of machine systems needing sampling, analysis and monitoring. Monitoring can be either performance testing or... more

In these days condition monitoring plays a main role in many of the industries. Lubricantsare essential and expensive components of machine systems needing sampling, analysis and monitoring. Monitoring can be either performance testing or oil condition monitoring or vibration analysis. Hear wear debris analysis and vibration analysis plays a curtail role in the maintenance of the cooling tower. Components of the gear box fail without proper maintenance. For the reduce of the heavy expenses analysis is done. Key component of the cooling tower fan is the gearbox. Maintenance of gearboxes is difficult and expensive, given the location and therefore condition monitoring techniques have been applied to detect common failure mechanisms. Future condition monitoring may be possible using low cost on-line techniques. With these oil analysis and vibration techniques, monitoring has been done and gear box failures has been detected.

In this paper, description of vibration analysis method used for condition monitoring of 500MW steam turbine (Kraftwork Union, Germany) has been discussed. The importance and critical role of this technique in predictive maintenance used... more

In this paper, description of vibration analysis method used for condition
monitoring of 500MW steam turbine (Kraftwork Union, Germany) has been discussed.
The importance and critical role of this technique in predictive maintenance used in
thermal power plant is evaluated based on possible type of failures that can be
detected at early stage before any unexpected, unscheduled breakdown during
operation of steam turbine.
Efforts are being made for most of the steam turbines in power generation thermal
plants to run or operate them at Ideal condition by regular technical consultations
resulting in continuous generation of power and reasonable increase in operational
life span of these turbines. This paper deals with one such effort. In this paper real
time condition monitoring of 500MW turbine, which was carried out by them at
NTPC-Ramagundum power plant, using vibration analysis, has been discussed
without disturbing its operational working condition and the causes for increase in the
vibrations and its practical diagnosis by spectrum analysis, Interpretations and
recommended steps to be taken to minimize the vibrations.

Machine condition monitoring enables reliable and economical way of action for maintenance operations in modern industrial plants. Increasing number of measurement points and more demanding problems require automatic fault detection.... more

Machine condition monitoring enables reliable and economical way of action for maintenance operations in modern industrial plants. Increasing number of measurement points and more demanding problems require automatic fault detection. Advanced signal processing methods exposed failures earlier and then it's possible to plan more operating time and less shutdowns. Intelligent methods have been increasingly used in model based fault diagnosis and intelligent analysers. Intelligent methods provide various techniques for combining a large number of features. A test rig was used to simulate different fault types and changes in operating conditions. Linguistic equation (LE) models were developed for the normal operation and nine fault cases including rotor unbalance, bent shaft, misalignment and bearing faults. Classification is based on the degrees of membership developed for each case from the fuzziness of the LE models. The classification results of the experimental cases are very good and logical. As even very small faults are detected by a slight increase of membership, the results are very promising for early detection of faults. Together with the compact implementation and the operability of the normal model, this makes the extension to real world problems feasible.

Maintenance operations have significant influence on the economy and performance of mining companies. Unpredicted repairs cause interruptions and breakdowns in production. This means economic losses but, in some cases, also increasing... more

Maintenance operations have significant influence on the economy and performance of mining companies. Unpredicted repairs cause interruptions and breakdowns in production. This means economic losses but, in some cases, also increasing environmental emissions in off-gases and wastewater. Condition based maintenance (CBM) can significantly reduce maintenance costs. Sensors and measurement devices offer a lot of data and assist workers to identify upcoming maintenance needs in advance. Typical measurement variables are for example vibration, temperature, different speeds and pressures. DEVICO project aims to develop a framework for solutions and combine condition monitoring and process data to integrate CBM to control and timing of the maintenance actions. On-line and periodic CM measurements can be combined with process measurements by using signal processing and feature extraction. Case study is conducted in Pyhäsalmi mine with Sandvik load haul dump (LHD) machinery. The condition monitoring system is installed on LHD front axle. The choice for the installation position was made based on the feedback and maintenance data gathered from mining companies. This information indicates that the axles are among the most critical parts in LHD machines.

This book bridges the gap between theory and practice, showing how a detailed definition of the shear-wave velocity (Vs) profile can be efficiently obtained using limited field equipment and following simple acquisition procedures. It... more

This book bridges the gap between theory and practice, showing how a detailed definition of the shear-wave velocity (Vs) profile can be efficiently obtained using limited field equipment and following simple acquisition procedures. It demonstrates how surface waves (used to define the Vs profile) and vibration data (used to describe the dynamic behaviour of a building) can be recorded using the same equipment, and also highlights common problems, ambiguities and pitfalls that can occur when adopting popular methodologies, which are often based on a series of simplistic assumptions. Today, most national and international building codes take into account a series of parameters aimed at defining the local seismic hazard. Sites are characterised based on the local Vs profile, and the dynamic behaviour of existing buildings is defined through the analysis of their eigenmodes. The book includes a series of case studies to help readers gain a deeper understanding of seismic and vibration data and the meaning (pros and cons) of a series of techniques often referred to as MASW, ESAC, SPAC, ReMi, HVSR, MAAM and HS. It also provides access to some of the datasets so that readers can gain a deeper and more concrete understanding of both the theoretical and practical aspects.

Teknik perawatan secara prediktif banyak diaplikasikan di dunia industri yang salah satunya adalah untuk rotating equipment. Teknik perawatan ini dapat mendeteksi jenis kerusakan pada suatu mesin tanpa menghentikan operasi mesin tersebut... more

Teknik perawatan secara prediktif banyak diaplikasikan di dunia industri yang salah satunya adalah untuk rotating equipment. Teknik perawatan ini dapat mendeteksi jenis kerusakan pada suatu mesin tanpa menghentikan operasi mesin tersebut dengan cara analisis getaran melalui identifikasi terhadap sinyal getaran yang dihasilkan. Sinyal getaran tersebut diperoleh dengan melakukan pengukuran dengan alat ukur getaran. Setiap kerusakan mempunyai karakteristik getarannya sendiri. Salah satu kerusakan yang umum terjadi pada jenis rotating equipment berupa motor dan pompa adalah misalignment, kerusakan ini terjadi karena ketidaksumbuan poros yang dihubungkan dengan kopling antara motor dan pompa. Dalam Tugas Akhir ini akan dianalisis sinyal getaran yang dibangkitkan oleh misalignment melalui pengambilan data sinyal getaran pada arah aksial dan radial (vertikal dan horizontal) pada motor dan pompa. Dari hasil analisis sinyal getaran, dapat diketahui jenis dan besarnya tingkat getaran yang dibangkitkan dalam interval waktu oleh misalignment melalui perbandingan nilai getaran terhadap trending dan dengan standar yang berlaku memperlihatkan amplitudo tinggi pada motor aksial kondisi getaran zona C sebesar 6,32 mm/s, serta amplitudo tinggi pada pompa horizontal kondisi getaran zona B sebesar 2,72 mm/s, berdasarkan standar ISO 10816-3. Sinyal getaran pada motor dibangkitkan oleh jenis kerusakan kombinasi misalignment paralel dan sudut melalui spektrum 1x dan 2x rpm, serta mengakibatkan looseness bantalan secara keseluruhan melalui spektrum harmonik kelipatan 1x dan 1½x rpm.

This presentation shows how electrical machinery operating on ships is often subjected to excessive vibration due to electrical/mechanical defects in the electromagnetic machinery system (internal faults) and distortions in the ship " s... more

This presentation shows how electrical machinery operating on ships is often subjected to excessive vibration due to electrical/mechanical defects in the electromagnetic machinery system (internal faults) and distortions in the ship " s power line (external faults) which degrades the machinery. The information is based on the author " s many years of experience in the field of rotating machinery vibration diagnostics, including electrical machines operating in a Maritime Electrical System. A short theoretical analysis of electromagnetic excitation forces based on classical electric machinery theory is included to exemplify how the internal and external electrical faults create parasitic radial forces (rotating waves) and tangential forces (pulsating torques) inside the electric machines, which deteriorates equipment health. These faults are illustrated in numerous case histories of electromagnetic problems from different industries, which result in machinery vibration that is significantly above acceptable standards. Among them are: voltage (current) unbalance, voltage waveform distortion, faulty control of Variable Frequency Drives (VFD), motor eccentric air gap, induction motor winding (stator and rotor) damage, DC motor power supply quality, and combinations of mechanical and electrical problems.

This article aims to study the self-supporting truss towers used to support large wind turbines in areas with high altitude. The goal is to evaluate and validate numerically by finite element method the structural analysis when the... more

This article aims to study the self-supporting truss towers used to support large wind turbines in areas with high altitude. The goal is to evaluate and validate numerically by finite element method the structural analysis when the lattice structures of the towers of wind turbines are subjected to static loads and these from common usage. With this, it is expected minimize the cost of transportation and installation of the tower and maximize the generation of electricity, respecting technical standards and restrictions of structural integrity and safety, making vibration analysis and the required static and dynamic loads, thereby preventing failures by fractures or mechanical fatigue. Practical examples of towers will be designed by the system and will be tested in structural simulation programs using the Finite Element Method. This analysis is done on the entire region coupling action of the turbine, with variable sensitivity to vibration levels. The results obtained for freestandi...