المؤلفون: Muchemi Gathua, Eng John Kihiu, Kenneth Njoroge, James Kuria Kimotho

مصطلحات موضوعية: Failure Analysis in Mechanical Components, Mechanical Engineering, FOS Mechanical engineering, Engineering, Physical Sciences, Materials Engineering in Industrial Applications, Mechanics of Materials, Machine Fault Diagnosis and Prognostics, Control and Systems Engineering, Fault Diagnosis, Vibration Analysis, Rotating Machinery, Turbocharger, Fault geology, Modal, Residual, Rotor electric, Vibration, Helicopter rotor, Computer science, Finite element method, Control theory sociology, Identification biology, Fault detection and isolation, Structural engineering, Algorithm, Actuator, Geology, FOS Earth and related environmental sciences, Artificial intelligence

الوصف: Inappropriate fault detection of turbocharger's operating parameters has generated unnecessary economic loss due to unplanned down-time.This results to a combination of late and inaccurate diagnosis of the turbocharger faults by the employed maintenance systems.This study, used a Model-based fault diagnosis approach to identify imbalance fault in a turbocharger rotor system.In this approach, the generalized theoretical equation of motion for both healthy and faulty system models of a complete turbocharger rotor, were developed using the Finite element method.A test rig for the turbocharger rotor with sensors to monitor its dynamic behavior under the influence of the aforementioned faulty condition was also developed.Following Modal Expansion, curve fitting technique was used to minimize the error between a set of equivalent experimental and numerical results.From the results, the theoretical Frequency response functions developed from Finite Element Method fault models had good agreement with the Time and ... : أدى الكشف غير المناسب عن الأعطال في معلمات تشغيل الشاحن التوربيني إلى خسائر اقتصادية غير ضرورية بسبب التعطل غير المخطط له. وينتج عن هذا مزيج من التشخيص المتأخر وغير الدقيق لأعطال الشاحن التوربيني من قبل أنظمة الصيانة المستخدمة. استخدمت هذه الدراسة نهج تشخيص الأعطال القائم على النموذج لتحديد خلل عدم التوازن في نظام دوار الشاحن التوربيني. في هذا النهج، المعادلة النظرية المعممة للحركة لكل من نماذج النظام الصحي والخطأ لدوار الشاحن التوربيني الكامل، تم تطويرها باستخدام طريقة العناصر المحدودة. جهاز اختبار لدوار الشاحن التوربيني مع مستشعرات لمراقبة سلوكه الديناميكي تحت تأثير الحالة الخاطئة المذكورة أعلاه. بعد التوسع المشروط، تم استخدام تقنية تركيب المنحنى لتقليل الخطأ بين مجموعة من النتائج التجريبية والعددية المكافئة. من النتائج، كان لوظائف استجابة التردد النظرية التي تم تطويرها من نماذج أخطاء طريقة العناصر المحدودة اتفاق جيد مع الاستجابات المستندة إلى الوقت والتردد المقاسة من البيانات التجريبية لحالة خطأ عدم التوازن المستحث، وبالتالي، التحقق من صحة نماذج الخطأ النظرية التي تم تطويرها في هذه الدراسة. باستخدام تقنية ...

العلاقة: https://dx.doi.org/10.60692/v1fkw-5gx08Test

الإتاحة: https://doi.org/10.60692/3gh2g-s3a2510.60692/v1fkw-5gx08Test

المؤلفون: Xiao Huang, Lunhai Zhi, Zhixaing Hu, Jun Li

المصدر: Advances in Structural Engineering. 24:755-770

مصطلحات موضوعية: business.industry, Computer science, 020101 civil engineering, 02 engineering and technology, Building and Construction, Structural engineering, Covariance, Blind signal separation, 0201 civil engineering, Identification (information), Operational Modal Analysis, 020303 mechanical engineering & transports, Modal, 0203 mechanical engineering, Modal matrix, Orthogonal decomposition, Structural health monitoring, business, Algorithm, Civil and Structural Engineering

الوصف: The smooth orthogonal decomposition method (SOD) is an efficient algorithm that can be used to extract modal matrix and frequencies of lightly damped vibrating systems. It uses the covariance matrices of output-only displacement and velocity responses to form a generalized eigenvalues problem (EVP). The mode shape vectors are estimated by the eigenvectors of the EVP. It is stated in this work that the accuracy of the SOD method is mainly affected by the correlation characteristic of modal coordinate responses. For the damped vibration systems, biases will be contained in the results of using the SOD. Therefore, an iterative smooth orthogonal decomposition (ISOD) method is proposed to identify modal parameters of the damped system from the covariance matrices of the displacement, velocity, and acceleration responses. The modal matrix given by the SOD method is updated in each iteration step using a transformation matrix. The transformation matrix can be efficiently computed using a set of analytical formulations. Meanwhile, natural frequencies and damping ratios are obtained by using a simple search method. The performance of the proposed ISOD method is verified by numerical and experimental studies. The results demonstrate that, by considering the correlation of modal responses, the ISOD method can be used to extract accurately the modal information of vibration systems with coupled modes.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::53924320d92b5674cbab7aef0180c27fTest
https://doi.org/10.1177/1369433220968442Test

المؤلفون: Wei Zhou, Xiongjiang Wang, Dongsheng Liu, Zhongren Feng, Baiben Chen

المصدر: Advances in Structural Engineering. 23:3062-3074

مصطلحات موضوعية: business.industry, Accurate estimation, Computer science, Mode (statistics), 020206 networking & telecommunications, 020101 civil engineering, 02 engineering and technology, Building and Construction, Structural engineering, 0201 civil engineering, Identification (information), Modal, 0202 electrical engineering, electronic engineering, information engineering, Decomposition (computer science), business, Algorithm, Civil and Structural Engineering

الوصف: The accurate estimation of natural frequencies and damping ratios is critical for civil structures. In this article, a method based on short-time narrow-banded mode decomposition is proposed to analyze the modal parameters of civil structures. In this approach, short-time narrow-banded mode decomposition is applied to identify time-varying structures with free vibration responses. On the contrary, by analysis of the weighting factors α and β, short-time narrow-banded mode decomposition is improved to estimate the parameter of time-invariant systems. In the case of enhanced short-time narrow-banded mode decomposition, the original short-time narrow-banded mode decomposition approach is modified in two ways. First, the instantaneous frequency term of the objective function is removed, and one weighting factor remains, that is, α in the objective function. Second, a technique is provided to automatically detect the optimum value of α. Two numerical examples, that is, a three-degree-of-freedom time-variant system and a simple model of the Lysefjord bridge are provided. In addition, an experiment with a real-life pedestrian bridge located at Tufts University, United States, is used to demonstrate the applicability of the proposed method. The analysis results indicate that the proposed method can easily identify high-quality natural frequencies and damping ratios.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::8cf0e1f5b912e53c6e1b1a0762288466Test
https://doi.org/10.1177/1369433220928527Test

المؤلفون: S. El-Ouafi Bahlous, Mohamed Neifar, Sami El-Borgi, Hichem Smaoui

مصطلحات موضوعية: Structural Health Monitoring Techniques, Civil and Structural Engineering, Engineering, Physical Sciences, Automated Pavement Inspection and Maintenance, Guided Wave Structural Health Monitoring in Materials, Mechanics of Materials, Vibration-based Damage Identification, Structural Damage Detection, Damage Detection, Modal Identification, Bridge Inspection, Modal, Vibration, Ambient vibration, Bridge graph theory, Structural engineering, Identification biology, Computer science, Algorithm, Modal analysis, Genetic algorithm, Finite element method, Acoustics, Materials science, Physics, Machine learning, Medicine, Botany, Polymer chemistry

الوصف: The authors recently developed a damage identification method which combines ambient vibration measurements and a Statistical Modal Filtering approach to predict the location and degree of damage. The method was then validated experimentally via ambient vibration tests conducted on full-scale reinforced concrete laboratory specimens. The main purpose of this paper is to demonstrate the feasibility of the identification method for a real bridge. An important challenge in this case is to overcome the absence of vibration measurements for the structure in its undamaged state which corresponds ideally to the reference state of the structure. The damage identification method is, therefore, modified to adapt it to the present situation where the intact state was not subjected to measurements. An additional refinement of the method consists of using a genetic algorithm to improve the computational efficiency of the damage localization method. This is particularly suited for a real case study where the number of ... : طور المؤلفون مؤخرًا طريقة لتحديد الضرر تجمع بين قياسات الاهتزاز المحيط ونهج تصفية الوسائط الإحصائية للتنبؤ بموقع الضرر ودرجته. ثم تم التحقق من صحة الطريقة تجريبياً من خلال اختبارات الاهتزاز المحيط التي أجريت على عينات مختبرية كاملة من الخرسانة المسلحة. الغرض الرئيسي من هذه الورقة هو توضيح جدوى طريقة تحديد الهوية لجسر حقيقي. يتمثل أحد التحديات المهمة في هذه الحالة في التغلب على غياب قياسات الاهتزاز للهيكل في حالته غير التالفة والتي تتوافق بشكل مثالي مع الحالة المرجعية للهيكل. وبالتالي، يتم تعديل طريقة تحديد الضرر لتكييفها مع الوضع الحالي حيث لم تخضع الحالة السليمة للقياسات. يتكون التحسين الإضافي للطريقة من استخدام خوارزمية وراثية لتحسين الكفاءة الحسابية لطريقة توطين الضرر. هذا مناسب بشكل خاص لدراسة حالة حقيقية حيث يصبح عدد معلمات الضرر كبيرًا. تشير تنبؤات تشخيص الأضرار إلى أن الجسر المشخص قد تضرر في أربعة عناصر من بين ما مجموعه 168 عنصرًا بدرجات ضرر تتراوح من 6 ٪ إلى 18 ٪. ...

العلاقة: https://dx.doi.org/10.60692/2gpys-dd242Test

الإتاحة: https://doi.org/10.60692/ahbdp-43r1810.60692/2gpys-dd242Test

المؤلفون: Longxi Luo, Zhijun Li, Xiuli Xu, Maria Q. Feng, Dongming Feng

المصدر: Mechanical Systems and Signal Processing. 98:352-367

مصطلحات موضوعية: Engineering, Burr distribution, business.industry, Mechanical Engineering, Bayesian probability, Modal testing, Aerospace Engineering, Spectral density, 020101 civil engineering, 02 engineering and technology, Structural engineering, Bayesian inference, 0201 civil engineering, Computer Science Applications, 020303 mechanical engineering & transports, Modal, 0203 mechanical engineering, Control and Systems Engineering, Signal Processing, Structural health monitoring, business, Spectral method, Algorithm, Civil and Structural Engineering

الوصف: Uncertainty of modal parameters estimation appear in structural health monitoring (SHM) practice of civil engineering to quite some significant extent due to environmental influences and modeling errors. Reasonable methodologies are needed for processing the uncertainty. Bayesian inference can provide a promising and feasible identification solution for the purpose of SHM. However, there are relatively few researches on the application of Bayesian spectral method in the modal identification using SHM data sets. To extract modal parameters from large data sets collected by SHM system, the Bayesian spectral density algorithm was applied to address the uncertainty of mode extraction from output-only response of a long-span suspension bridge. The posterior most possible values of modal parameters and their uncertainties were estimated through Bayesian inference. A long-term variation and statistical analysis was performed using the sensor data sets collected from the SHM system of the suspension bridge over a one-year period. The t location-scale distribution was shown to be a better candidate function for frequencies of lower modes. On the other hand, the burr distribution provided the best fitting to the higher modes which are sensitive to the temperature. In addition, wind-induced variation of modal parameters was also investigated. It was observed that both the damping ratios and modal forces increased during the period of typhoon excitations. Meanwhile, the modal damping ratios exhibit significant correlation with the spectral intensities of the corresponding modal forces.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::2cf5511ea0b12d08eca66f8b3e21cf53Test
https://doi.org/10.1016/j.ymssp.2017.05.005Test

المؤلفون: Seyed Alireza Moezi, Amin Zare, Ehsan Zakeri

المصدر: Mechanical Systems and Signal Processing. 99:805-831

مصطلحات موضوعية: 0209 industrial biotechnology, Engineering, Frequency response, Cantilever, business.industry, Mechanical Engineering, Modal analysis, Transfer-matrix method (optics), Aerospace Engineering, 02 engineering and technology, Structural engineering, Computer Science Applications, 020303 mechanical engineering & transports, 020901 industrial engineering & automation, Modal, 0203 mechanical engineering, Control and Systems Engineering, Signal Processing, Convergence (routing), Nelder–Mead method, business, Algorithm, Beam (structure), Civil and Structural Engineering

الوصف: In this study, the number, location and depth of cracks created in several Euler-Bernoulli beams, such as a simple beam and a more complex multi-step beam are investigated. The location and depth of the created cracks are determined using the hybrid Cuckoo-Nelder-Mead Optimization Algorithm (COA-NM) with high accuracy. The natural frequencies of the cracked beams are determined by solving frequency response equations, and performing modal test experiments. Results of COA-NM show a higher accuracy and convergence speed compared with other methods such as GA-NM, PSO-NM, GA, PSO, COA and several previous studies. Amount of calculations performed by COA-NM to achieve this accuracy is much less compared to other methods.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::aa25284c1b56a8eae94e860804c093d6Test
https://doi.org/10.1016/j.ymssp.2017.07.013Test

المؤلفون: Song Yan, Bin Li, Binchao Li, Feng Li

المصدر: Aerospace Science and Technology. 69:412-418

مصطلحات موضوعية: Engineering, Basis (linear algebra), business.industry, Liquid-propellant rocket, Modal analysis using FEM, Coordinate system, Modal testing, Aerospace Engineering, 02 engineering and technology, Structural engineering, Test method, 01 natural sciences, Finite element method, 020303 mechanical engineering & transports, Modal, 0203 mechanical engineering, 0103 physical sciences, business, 010301 acoustics, Algorithm

الوصف: In order to update the finite element model, the modal test results must be highly accurate since they are used as the basis. The major problems with traditional modal test method are limited measurement points and poor mode shape precision. In this paper, modal test based on 3-D Scanning Laser Doppler Vibrometry (SLDV) technique was carried out. High spatial resolution and accurate mode shapes were obtained, which is beneficial to subsequent correlation analysis and updating process. High order modal parameters were identified and more information can be added in the objective function. Due to the consistent coordinate system in modal test and finite element model, the measurement points and corresponding finite element nodes were easily matched in order to compare mode shapes. By means of a real liquid rocket engine nozzle, an integrated model updating process is presented from proper initial model, accurate modal test results, test/analysis correlation to automatic model updating. The single steps of detailed updating process are highlighted. The discrepancy between the finite element model predicted and the experiment measured modal parameters are minimized and satisfactory results were obtained.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::f2bd8385cae9974a30c874683c09fe6bTest
https://doi.org/10.1016/j.ast.2017.07.002Test

المؤلفون: Fabio Pioldi, Egidio Rizzi

المصدر: Earthquake Engineering & Structural Dynamics. 47:257-264

مصطلحات موضوعية: 021110 strategic, defence & security studies, Earthquake engineering, Engineering, business.industry, 0211 other engineering and technologies, System identification, 020101 civil engineering, 02 engineering and technology, Structural engineering, Geotechnical Engineering and Engineering Geology, Physics::Geophysics, 0201 civil engineering, Identification (information), Operational Modal Analysis, Modal, Earth and Planetary Sciences (miscellaneous), Structural health monitoring, business, Frequency domain decomposition, Algorithm, Subspace topology

الوصف: Summary Output-only system identification is developed here towards assessing current modal dynamic properties of buildings under seismic excitation. Earthquake-induced structural response signals are adopted as input channels for two different Operational Modal Analysis (OMA) techniques, namely, a refined Frequency Domain Decomposition (rFDD) algorithm and an improved Data-Driven Stochastic Subspace Identification (SSI-DATA) procedure. Despite that short-duration, non-stationary, earthquake-induced structural response signals shall not fulfil traditional OMA assumptions, these implementations are specifically formulated to operate with seismic responses and simultaneous heavy damping (in terms of identification challenge), for a consistent estimation of natural frequencies, mode shapes, and modal damping ratios. A linear ten-storey frame structure under a set of ten selected earthquake base-excitation instances is numerically simulated, by comparing the results from the two identification methods. According to this study, best up-to-date, reinterpreted OMA techniques may effectively be used to characterize the current dynamic behaviour of buildings, thus allowing for potential Structural Health Monitoring approaches in the Earthquake Engineering range.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::e8ec8f62c6fa71be5346f385326bf45aTest
https://doi.org/10.1002/eqe.2947Test

المؤلفون: Fabio Pioldi, Egidio Rizzi

المصدر: Earthquake Engineering and Engineering Vibration. 16:627-648

مصطلحات موضوعية: earthquake response identification input, Earthquake engineering, Engineering, 0211 other engineering and technologies, 020101 civil engineering, Context (language use), 02 engineering and technology, Chebyshev filter, FEMA P695 seismic database, 0201 civil engineering, Earthquake simulation, Modal dynamic identification, Settore ICAR/08 - Scienza delle Costruzioni, Civil and Structural Engineering, 021110 strategic, defence & security studies, business.industry, refined Frequency Domain Decomposition (rFDD), Mechanical Engineering, Operational Modal Analysis (OMA), Building and Construction, Structural engineering, Geotechnical Engineering and Engineering Geology, Strong ground motion, Modal, Structural health monitoring, Frequency domain decomposition, business, Algorithm

الوصف: Output-only structural identification is developed by a refined Frequency Domain Decomposition (rFDD) approach, towards assessing current modal properties of heavy-damped buildings (in terms of identification challenge), under strong ground motions. Structural responses from earthquake excitations are taken as input signals for the identification algorithm. A new dedicated computational procedure, based on coupled Chebyshev Type II bandpass filters, is outlined for the effective estimation of natural frequencies, mode shapes and modal damping ratios. The identification technique is also coupled with a Gabor Wavelet Transform, resulting in an effective and self-contained time-frequency analysis framework. Simulated response signals generated by shear-type frames (with variable structural features) are used as a necessary validation condition. In this context use is made of a complete set of seismic records taken from the FEMA P695 database, i.e. all 44 “Far-Field” (22 NS, 22 WE) earthquake signals. The modal estimates are statistically compared to their target values, proving the accuracy of the developed algorithm in providing prompt and accurate estimates of all current strong ground motion modal parameters. At this stage, such analysis tool may be employed for convenient application in the realm of Earthquake Engineering, towards potential Structural Health Monitoring and damage detection purposes.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::13d0051515307513be5e7eee72c772beTest
https://doi.org/10.1007/s11803-017-0394-9Test

المؤلفون: Tao Yin, Qinghui Jiang, Ka-Veng Yuen

المصدر: Engineering Structures. 132:260-277

مصطلحات موضوعية: Engineering, business.industry, Modal analysis using FEM, Computation, Bayesian probability, Frame (networking), 020101 civil engineering, 02 engineering and technology, Structural engineering, Finite element method, 0201 civil engineering, 020303 mechanical engineering & transports, Modal, 0203 mechanical engineering, Normal mode, Reduction (mathematics), business, Algorithm, Civil and Structural Engineering

الوصف: Most of the existing damage detection methods focused on damage along members of the structure without considering possible damage at its connections. Under the Bayesian framework, the finite element (FE) model reduction technique and the system mode concept, this paper presents a practical method for structural bolted-connection damage detection using noisy incomplete modal parameters identified from limited number of sensors. Based on the incomplete modal identification results, the most probable structural model parameters, the most probable system eigenvalues and partial modes shapes together with the associated uncertainties can be identified simultaneously. There are several significant features of the proposed method: (1) it does not require computation of the system mode shapes for the full model due to the FE model reduction technique; (2) matching between measured modes and model predicted modes is avoided in contrast to most existing methods in the literature; and (3) an efficient iterative solution strategy is also proposed to resolve the difficulties arisen from the high-dimensional nonlinear optimization problem for the structural model parameters and the incomplete system modal parameters. Numerical simulations and experimental verifications of a four-storey two-bay bolt-connected steel frame and a two-storey laboratory bolted frame, respectively, are utilized to demonstrate the validity and efficiency of proposed methodology.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::0299b59303c7a36c4d3b81f157e955d4Test
https://doi.org/10.1016/j.engstruct.2016.11.035Test