Damages Identification in the Cantilever-based on the Parameters of the Natural Oscillations

2016 ◽  
Vol 66 (1) ◽  
pp. 44 ◽  
Author(s):  
A. V. Cherpakov ◽  
A. N. Soloviev ◽  
V. V. Gritsenko ◽  
O. U. Goncharov
Keyword(s):  
Parametric Identification ◽  
Crack Size ◽  
Crack Identification ◽  
Natural Oscillations ◽  
Crack Location ◽  
Diagnostic Signs ◽  
Cantilever Construction ◽  
Two Stages ◽  
Local Extreme

<p>An approach to parametric identification of damages such as cracks in the rod cantilever construction is described. The identification method is based on analysis of shapes of the natural oscillations. The analytic modelling is performed in the Maple software on the base of the Euler-Bernoulli hypothesis. Crack is modelled by an elastic bending element. Transverse oscillations of the rod are considered. We take into account first four eigen modes of the oscillations. Parameters of amplitude, curvature and angle of bends of the waveforms are analysed. It was established that damage location is revealed by ‘kink’ on corresponding curves of the waveforms. The parameters of oscillation shapes are sensitive to the crack parameters in different degree. The novelty of the approach consists in that the identification procedure is divided into two stages: (a) it is determined the crack location, and (b) it is determined the crack size. Based on analytical modelling, an example of determination of dependence of the crack parameters on its size in the cantilever rod is presented. Study of features of the waveforms during identification of the fracture parameters shows that the features found in the form of ‘kinks’ and local extreme a of the angle between the tangent and curvature of waveforms for different modes of bending oscillations, define the crack location in cantilever. They can serve as one of diagnostic signs of crack identification and allow us to determine its location.</p><p><strong>Defence Science Journal, Vol. 66, No. 1, January 2016, pp. 44-50, DOI: http://dx.doi.org/10.14429/dsj.66.8182</strong></p><p> </p>

Identifying Crack Parameters in Slow Rotating Machinery Using Vibration Measurements and Hybrid Neuro-Particle Swarm Technique

2010 ◽  
Author(s):  
Mohamed S. Senousy ◽  
Tamer M. Khattab ◽  
Mohamed Al-Qaradawi ◽  
Mohamed S. Gadala
Keyword(s):  
Feature Extraction ◽  
Low Cycle Fatigue ◽  
Particle Swarm ◽  
Crack Size ◽  
Crack Identification ◽  
Time Signal ◽  
Full Time ◽  
Vibration Signals ◽  
Crack Location ◽  
Fuzzy Genetic

Low-cycle fatigue-initiated cracks may result in failure in slow-rotating equipments. Online monitoring to identify such fault/crack parameters, namely crack size and crack location, would be critical in providing an early warning signal to the operator and would be used in calculating estimate about the remaining safe life of the equipment in operation. In an earlier study, a scaled-down slow-rotating washer drum was constructed to experimentally investigate the vibrations of a cracked rotor and/or drums. Cracks were simulated using the bolt removal method (BRM), and the vibration signals identifying signatures of certain cracks were measured. Thereafter, a 3D finite element model was used to solve the forward analysis of the inverse problem of crack identification. In this paper, the scaled-down experimental setup is introduced to cracks at different locations of the drum/rotor. Vibration signals identifying signatures of such cracks are measured. Since noisy signals, similar patterns of faults, and similar vibration fault signals create particular challenges for feature extraction systems, two techniques for feature extraction are considered and compared in this work. The fast Fourier transform (FFT) of the vibration signals showing variation in amplitude of the harmonics as time progresses are presented for comparison with the full time signal feature extraction. A hybrid particle-swarm artificial Neural Networks (neuro-particle swarm) is used to identify both the crack size and crack location. The hybrid neuro-particle swarm technique is compared with the previously investigated fuzzy genetic algorithms.

Nondestructive Detection of a Crack in a Triangular Cantilever Beam Based on Frequency Measurement

2007 ◽  
Vol 353-358 ◽  
pp. 2285-2288
Author(s):  
Fei Wang ◽  
Xue Zeng Zhao
Keyword(s):  
Cantilever Beam ◽  
Natural Frequencies ◽  
Frequency Measurement ◽  
Crack Size ◽  
Force Sensors ◽  
Rotational Spring ◽  
Cantilever Deflection ◽  
Crack Location ◽  
Small Force ◽  
Point Of Intersection

Triangular cantilevers are usually used as small force sensors in the transverse direction. Analyzing the effect of a crack on transverse vibration of a triangular cantilever will be of value to users and designers of cantilever deflection force sensors. We present a method for prediction of location and size of a crack in a triangular cantilever beam based on measurement of the natural frequencies in this paper. The crack is modeled as a rotational spring. The beam is treated as two triangular beams connected by a rotational spring at the crack location. Formulae for representing the relation between natural frequencies and the crack details are presented. To detect crack details from experiment results, the plots of the crack stiffness versus its location for any three natural modes can be obtained through the relation equation, and the point of intersection of the three curves gives the crack location. The crack size is then calculated using the relation between its stiffness and size. An example to demonstrate the validity and accuracy of the method is presented.

Determination of Critical Crack Size Utilizing a Fracture Mechanics Test in Equipment Under Fatigue

2009 ◽  
Author(s):  
Irene Garcia Garcia ◽  
Radoslav Stefanovic
Keyword(s):  
Heat Treatment ◽  
Fracture Mechanics ◽  
Crack Size ◽  
Operational Experience ◽  
Element Analysis ◽  
Critical Crack ◽  
Circumferential Welds ◽  
Fea Model ◽  
Critical Crack Size

Equipment that is exposed to severe operational pressure and thermal cycling, like coke drums, usually suffer fatigue. As a result, equipment of this sort develop defects such as cracking in the circumferential welds. Operating companies are faced with the challenges of deciding what is the best way to prevent these defects, as well as determining how long they could operate if a defect is discovered. This paper discusses a methodology for fracture mechanics testing of coke drum welds, and calculations of the critical crack size. Representative samples are taken from production materials, and are welded employing production welding procedures. The material of construction is 1.25Cr-0.5Mo low alloy steel conforming to ASME SA-387 Gr 11 Class 2 in the normalized and tempered condition (N&T). Samples from three welding procedures (WPS) are tested: one for production, one for a repair with heat treatment, and one for repair without heat treatment. The position and orientation of test specimen are chosen based on previous surveys and operational experience on similar vessels that exhibited cracks during service. Fracture mechanics toughness testing is performed. Crack finite element analysis (FEA) model is used to determine the path-independed JI-integral driving force. Methodology for the determination of critical crack size is developed.

Determination of the Problems Experienced by Patients Post-Thyroidectomy

2017 ◽  
Vol 28 (5) ◽  
pp. 615-635
Author(s):  
Semra Atasayar ◽  
Sevil Guler Demir
Keyword(s):  
Postoperative Period ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cross Sectional ◽  
Telephone Interviews ◽  
Two Stages ◽  
First Time ◽  
Benign Thyroid

This descriptive, cross-sectional study investigated problems experienced by patients after undergoing a thyroidectomy. The study included 60 first-time, post-thyroidectomy patients diagnosed with benign thyroid disease from a university hospital’s general surgery clinic in Ankara, Turkey. The data were collected in two stages: interviews with patients on the first day following surgery and postoperative follow-up telephone interviews in each of the first 4 weeks following surgery. The follow-ups revealed that patients principally experienced varying degrees of pain and difficulties in connection with work and recreation, communication, body image, and movement, for up to 4 weeks after surgery. These results showed that patients were particularly prone to problems on the first day and during the first week of the postoperative period; therefore, patients should be provided with follow-up telephone interviews to facilitate easier recovery and to help them overcome any problems experienced during the postoperative period.

scholarly journals Dynamic Response of a Cracked Rotor With Some Comments on Crack Detection

1994 ◽  
Author(s):  
G. Meng ◽  
Eric J. Hahn
Keyword(s):  
Dynamic Response ◽  
Crack Detection ◽  
Harmonic Component ◽  
Major Axis ◽  
Vertical Axis ◽  
Crack Size ◽  
Cracked Rotor ◽  
Response Component ◽  
Crack Location ◽  
Backward Whirl

By considering time dependent terms as external excitation forces, the approximate dynamic response of a cracked horizontal rotor is analysed theoretically and numerically. The solution is good for small cracks and small vibrations in the stable operating range. For each steady state harmonic component the forward and backward whirl amplitudes, the shape and orientation of the elliptic orbit and the amplitude and phase of the response signals arc analysed, taking into account the effect of crack size, crack location, rotor speed and unbalance. It is found that the crack causes backward whirl, the amplitude of which increases with the crack. For a cracked rotor, the response orbit for each harmonic component is an ellipse, the shape and orientation of which depends on the crack size. The influence of the crack on the synchronous response of the system can be regarded as an additional unbalance whereupon, depending on the speed and the crack location, the response amplitude differs from that of the uncracked rotor. The nonsynchronous response provides evidence of crack in the sub-critical range, but is too small to be detected in the supercritical range. Possibilities for crack detection over the full speed range include the additional average (the constant) response component, the backward whirl of the response, the ellipticity of the orbit, the angle between the major axis and the vertical axis and the phase angle difference between vertical and horizontal vibration signals.

scholarly journals PENINGKATAN KAPASITAS KEMAMPUAN PERAWAT DALAM MENENTUKAN DIAGNOSA KEPERAWATAN BERDASARKAN TEORI PATIENT CENTERED DI RSUD BANGIL

2020 ◽  
Vol 7 (1) ◽  
pp. 51-55
Author(s):  
Moch bahrudin Bahrudin
Keyword(s):  
Hospital Treatment ◽  
Patient Centered ◽  
Nursing Diagnosis ◽  
Lecture Method ◽  
Training Activities ◽  
Patient Responses ◽  
Conducting Research ◽  
Two Stages ◽  
Nursing Diagnoses

ABSTRACT One of the nursing processes is determining nursing diagnoses. The determination of nursing diagnoses is based on the theory used, one of which is Carpenito's theory, which is based on patient responses as a guide in determining nursing diagnoses. This theory is not in line with the current situation. So this theory cannot answer the needs of patients because patients who are hospitalized cannot always respond or complain. Based on these problems, the authors provide instructions for determining nursing diagnoses based on the Abdella Faya theory, which is based on body physiological disorders. The service targets are nurses in the Bangil Hospital treatment room. The problem is resolved in two stages of activity, namely preparation and implementation. Preparation is carried out by conducting research in 2017 to see conditions in the field regarding nurses' procedures for determining nursing diagnoses. Implementation is carried out by the lecture method, namely the technique of determining nursing diagnoses and case exercises as a form of nursing diagnosis determination workshop activities. The results of the training activities show the level of success with an indication of the suitability of the material with the needs of nurses in determining nursing diagnoses, a positive response from the participants and the majority (90% of participants have understood the concept and how to determine nursing diagnoses.   Key words: determination, nursing diagnosis, Patient Centered, Bangil  general Hospital

scholarly journals Crack Identification and Localization In Structural Beams Using Numerical and Experimental Modal Analysis- A Review

2020 ◽  
pp. 62-68
Keyword(s):  
Modal Analysis ◽  
Natural Frequency ◽  
Structural Damage ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Crack Identification ◽  
Engineering Structures ◽  
Aircraft Wings ◽  
Crack Location ◽  
Damaged Beams

This article presents a critical review of recent research done on crack identification and localization in structural beams using numerical and experimental modal analysis. Crack identification and localization in beams are very crucial in various engineering applications such as ship propeller shafts, aircraft wings, gantry cranes, and Turbo machinery blades. It is necessary to identify the damage in time; otherwise, there may be serious consequences like a catastrophic failure of the engineering structures. Experimental modal analysis is used to study the vibration characteristics of structures like natural frequency, damping and mode shapes. The modal parameters like natural frequency and mode shapes of undamaged and damaged beams are different. Based on this reason, structural damage can be detected, especially in beams. From the review of various research papers, it is identified that a lot of the research done on beams with open transverse crack. Crack location is identified by tracking variation in natural frequencies of a healthy and cracked beam

Determining the Most Probable Position

1953 ◽  
Vol 6 (1) ◽  
pp. 44-58 ◽  
Author(s):  
J. B. Parker
Keyword(s):  
Previous Article ◽  
Two Stages

There are two stages in the determination of position from current observations. The observations are first resolved into positional form on the chart and plotted so as to give either a fix or a position line. When more than two position lines are available, some of the information is redundant and a problem exists of determining the most likely fix. In the case of air navigation, the number of position lines seldom exceeds three, and the determination of position in this case has been studied in a previous article.

Dynamic Response of a Cracked Rotor With Some Comments on Crack Detection

1997 ◽  
Vol 119 (2) ◽  
pp. 447-455 ◽  
Author(s):  
G. Meng ◽  
E. J. Hahn
Keyword(s):  
Dynamic Response ◽  
Crack Detection ◽  
Harmonic Component ◽  
Major Axis ◽  
Vertical Axis ◽  
Crack Size ◽  
Cracked Rotor ◽  
Response Component ◽  
Crack Location ◽  
Backward Whirl

By considering time-dependent terms as external excitation forces, the approximate dynamic response of a cracked horizontal rotor is analyzed theoretically and numerically. The solution is good for small cracks and small vibrations in the stable operating range. For each steady-state harmonic component, the forward and backward whirl amplitudes, the shape and orientation of the elliptic orbit, and the amplitude and phase of the response signals are analyzed, taking into account the effect of crack size, crack location, rotor speed, and unbalance. It is found that the crack causes backward whirl, the amplitude of which increases with the crack. For a cracked rotor, the response orbit for each harmonic component is an ellipse, the shape and orientation of which depend on the crack size. The influence of the crack on the synchronous response of the system can be regarded as an additional unbalance whereupon, depending on the speed and the crack location, the response amplitude differs from that of the uncracked rotor. The nonsynchronous response provides evidence of crack in the subcritical range, but is too small to be detected in the supercritical range. Possibilities for crack detection over the full-speed range include the additional average (the constant) response component, the backward whirl of the response, the ellipticity of the orbit, the angle between the major axis and the vertical axis, and the phase angle difference between vertical and horizontal vibration signals.

Experimental Determination of Diagnostic Signs of Damage to the Rotor Windings of High-Voltage Power Plant Motors in Startup Mode

2020 ◽  
Vol 56 (5) ◽  
pp. 408-416
Author(s):  
A. N. Nazarychev ◽  
E. M. Novoselov ◽  
D. A. Polkoshnikov ◽  
A. S. Strakhov ◽  
A. A. Skorobogatov ◽  
...  
Keyword(s):  
Power Plant ◽  
Experimental Determination ◽  
High Voltage ◽  
Diagnostic Signs
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