Academic literature on the topic 'Curvature damage index'
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Journal articles on the topic "Curvature damage index"
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Shang, Xin, Yue Xu, and Geng Feng Ren. "Research on Curvature Mode Characteristics of Damaged Simply Supported Beam." Applied Mechanics and Materials 455 (November 2013): 261–66. http://dx.doi.org/10.4028/www.scientific.net/amm.455.261.
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This paper approaches the rules of curvature mode and curvature mode difference about a simply supported beam. On the basis of the theory of curvature mode, through numerical simulation analysis of simply supported beam on four conditions, the result of simply supported beam with curvature mode and curvature mode difference were obtained. The results show that for the damaged beam information with numerical simulation, the curvature mode and curvature mode difference index calculated by difference method at the unit length unevenly is with strong noise, which can even submerge the beam damage information, and for different damage index of the beam, damage information from curvature mode difference curve is stronger and effected by unit length weaker than those from curvature mode curve, and damage information from curvature mode curve and curvature mode difference curve decrease with the increasing mode order.
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Xu, Y. F., and J. S. Kim. "Baseline-Free Structural Damage Identification for Beam-Like Structures Using Curvature Waveforms of Propagating Flexural Waves." Sensors 21, no. 7 (April 2, 2021): 2453. http://dx.doi.org/10.3390/s21072453.
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Curvatures in mode shapes and operating deflection shapes have been extensively studied for vibration-based structural damage identification in recent decades. Curvatures of mode shapes and operating deflection shapes have proved capable of localizing and manifesting local effects of damage on mode shapes and operating deflection shapes in forms of local anomalies. The damage can be inversely identified in the neighborhoods of the anomalies that exist in the curvatures. Meanwhile, propagating flexural waves have also been extensively studied for structural damage identification and proved to be effective, thanks to their high damage-sensitivity and long range of propagation. In this work, a baseline-free structural damage identification method is developed for beam-like structures using curvature waveforms of propagating flexural waves. A multi-resolution local-regression temporal-spatial curvature damage index (TSCDI) is defined in a pointwise manner. A two-dimensional auxiliary TSCDI and a one-dimensional auxiliary damage index are developed to further assist the identification. Two major advantages of the proposed method are: (1) curvature waveforms of propagating flexural waves have relatively high signal-to-noise ratios due to the use of a multi-resolution central finite difference scheme, so that the local effects of the damage can be manifested, and (2) the proposed method does not require quantitative knowledge of a pristine structure associated with a structure to be examined, such as its material properties, waveforms of propagating flexural waves and boundary conditions. Numerical and experimental investigations of the proposed method are conducted on damaged beam-like structures, and the effectiveness of the proposed method is verified by the results of the investigations.
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Jing, Hang, Ling Ling Jia, and Yi Zhao. "Structural Damage Detection Using Curvature Mode Difference Curve." Advanced Materials Research 250-253 (May 2011): 1248–51. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.1248.
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Damage detection in civil engineering structures using the dynamic system parameters has become an important area of research. The sensitivity of damage indicator is of great value to structural damage identification. The curvature mode is an excellent parameter in damage detection of structures, while in case that certain curvature mode curve can’t show existence of damage. In this paper, numerical studies are conducted to demonstrate the deficiency of curvature mode to damage detection. Then a new damage indicator called “curvature mode changing rate” (CMCR) is introduced which is processed by numerical differentiation of curvature mode curve. The simulation results show that the new index is superior to curvature mode for structural damage identification, and it is still sensitive to the damaged location in the mode node.
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Xiang, Chang-Sheng, Ling-Yun Li, Yu Zhou, and Zi Yuan. "Damage Identification Method of Beam Structure Based on Modal Curvature Utility Information Entropy." Advances in Civil Engineering 2020 (September 19, 2020): 1–20. http://dx.doi.org/10.1155/2020/8892686.
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Generally, the damage of the structure will lead to the discontinuity of the local mode shape, which can be well reflected by the modal curvature of the structure, and the local information entropy of the beam structure will also change with the discontinuity of the mode. In this paper, based on the information entropy theory and combining the advantages of modal curvature index in damage identification of beam structure, the modal curvature utility information entropy index is proposed. The modal curvature curves of nondestructive structures were obtained by fitting the modal curvature curves of damage structures with the gapped smoothing technique to avoid dependence on the baseline data of nondestructive structures. The index comprehensively reflects the damage state of the structure by calculating mutual weight change matrix and the weight-probability coefficient. The performance of the new index was verified by the finite element simulation and model test of simply supported beam, respectively. The results show that the modal curvature utility information entropy index takes advantage of the modal curvature index which is sensitive to damage and can overcome its shortcomings effectively. The index proposed can identify the damage location and damage degree accurately and has certain noise immunity, which provides an effective damage identification indicator for beam structures.
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Ge, Ji Ping. "Damage Quantitative Investigation of Beam Structure Based on Changing Ratio of Modal Curvature." Advanced Materials Research 255-260 (May 2011): 654–58. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.654.
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The changing ratio of modal curvature is proposed for damage recognition, and its ability of damage localization and damage quantitative has been studied in this paper. For testing the effect of damage recognition, two research parameters, the different section rigidity and the scope of damages, are included. And changing rules of the index with structure rigidity, constraints, and structure supporting system have been studied at the same time. The numerical analysis results indicated: The relation of linear increase exists between the changing ratio of modal curvature and the extent of damage, the changing slope of the index is bigger with the increase of damage extent; The boundary condition and the structure supporting system will affect the value of index; In the view of one special structure, case study should be carried to establish the relationship between value of index and the extent of damage.
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Kim, Byeong Hwa. "Online Monitoring of Flexural Damage Index of a Cable-Stayed Bridge." Shock and Vibration 2019 (November 23, 2019): 1–13. http://dx.doi.org/10.1155/2019/7607214.
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This work introduces a recent application of the online nondestructive damage assessment system into a cable-stayed bridge. A set of ambient modal parameters are automatically extracted every 20 minutes using real-time signal data collected from a total of 26 accelerometers attached on the deck plate of the bridge. Then, a set of modal flexibilities are reconstructed by the combination of the extracted modal parameters with the approximated modal mass of the girder. Next, the curvature of the modal flexibility is approximated by a central difference formula. Finally, the set of flexural damage index equations is constructed by comparing the modal curvature of the damaged state to that of the undamaged state. Solving the overdetermined flexural damage index equations, the desired damage index is finally quantified. The resulting index clearly indicates the location and severity of the potential structural damage on the girder. Based on the overall performance of the implemented health monitoring system, the bridge operator’s damage index control criteria are set to ±20% of the undamaged state.
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Xiang, Yi Qiang, Li Si Liu, and Yu Liang He. "Damage Identification of Multi-Box Steel-Concrete Composite Bridges Based on Modal Curvature Difference Method." Applied Mechanics and Materials 226-228 (November 2012): 1689–92. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.1689.
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Based on the data from dynamic analysis of a 40m-span multi-box steel-concrete composite bridge and the difference value of its modal curvature before and after the structural damage, this paper detects the damage locations in steel-concrete composite bridge by modal curvature difference method (MCDM). Here we adopt the updated finite element model in last work as analytical model, taking concrete density and elastic modulus as updating parameters and modal frequency+MAC as reference data. The results indicate that the modal curvature difference method can well locate the damages in steel-concrete composite bridge, especially the damage in concrete. But the change rate of frequency as damage index is insensitive to the bridge damage and the method can’t be applied solely for practical.
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Zhu, Hua Wei, Hong Mou Wang, and Wei Peng. "Study on Box Girder Damage Identification of Cable-Stayed Bridges." Applied Mechanics and Materials 101-102 (September 2011): 1156–60. http://dx.doi.org/10.4028/www.scientific.net/amm.101-102.1156.
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A comparative study of the girder damage identification of Jintang Cable-stayed Bridge in Zhoushan Island-Land Project using the deflection index, the cable tension index, the beam bottom bending stress index, the modal curvature index and the modal flexibility matrix is introduced. By means of finite element method, a series of damage cases associated with the box girder are analyzed. The result shows that, for different damage types, the best effect of the girder damage identification is the modal curvature index, followed by the cable tension index, the beam bottom bending stress index is nearly of the same effect as the modal flexibility matrix index, and the worst is the deflection index.
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Wang, Pengbo, and Qinghe Shi. "Damage Identification in Structures Based on Energy Curvature Difference of Wavelet Packet Transform." Shock and Vibration 2018 (May 28, 2018): 1–13. http://dx.doi.org/10.1155/2018/4830391.
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Damage identification is of tremendous significance in engineering structures. One key issue in damage identification is to determine an index that is sensitive to the structural damage. Current damage identification indices are generally focused on dynamic characteristics such as the natural frequencies, modal shapes, frequency responses, or their mathematical combinations. In this study, based on the wavelet packet transform, we propose a novel index, the energy curvature difference (ECD) index, to identify the damage in structures. The ECD index is the summation of component energy curvature differences after a signal is decomposed using WPT. Moreover, two numerical examples are used to demonstrate the feasibility and validity of the proposed ECD index for damage identification. Stiffness reduction is employed to simulate the structural damage. The damage can be identified by the ECD index curve plot. The results of the examples indicate that the proposed ECD index is sensitive to low damage levels because even 5% stiffness reduction can be apparently identified. The proposed ECD index can be employed to effectively identify structural damage.
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Nayyar, Ayisha, Ummul Baneen, Syed Abbas Zilqurnain Naqvi, and Muhammad Ahsan. "Detection and localization of multiple small damages in beam." Advances in Mechanical Engineering 13, no. 1 (January 2021): 168781402098732. http://dx.doi.org/10.1177/1687814020987329.
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Localizing small damages often requires sensors be mounted in the proximity of damage to obtain high Signal-to-Noise Ratio in system frequency response to input excitation. The proximity requirement limits the applicability of existing schemes for low-severity damage detection as an estimate of damage location may not be known a priori. In this work it is shown that spatial locality is not a fundamental impediment; multiple small damages can still be detected with high accuracy provided that the frequency range beyond the first five natural frequencies is utilized in the Frequency response functions (FRF) curvature method. The proposed method presented in this paper applies sensitivity analysis to systematically unearth frequency ranges capable of elevating damage index peak at correct damage locations. It is a baseline-free method that employs a smoothing polynomial to emulate reference curvatures for the undamaged structure. Numerical simulation of steel-beam shows that small multiple damages of severity as low as 5% can be reliably detected by including frequency range covering 5–10th natural frequencies. The efficacy of the scheme is also experimentally validated for the same beam. It is also found that a simple noise filtration scheme such as a Gaussian moving average filter can adequately remove false peaks from the damage index profile.
Dissertations / Theses on the topic "Curvature damage index"
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Deshmukh, Prutha. "Damage Detection Of a Cantilever Beam Using Digital Image Correlation." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1623169831665585.
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Juliani, Tiago Marrara. "Detecção de danos em pontes em escala reduzida pela identificação modal estocástica." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-18122014-091614/.
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As pontes de concreto armado são obras de arte de extrema importância para a infraestrutura de transportes do Brasil. Portanto sua inspeção e manutenção são atividades estratégicas. A inspeção visual, ensaios destrutivos e não destrutivos fornecem informações sobre a sua integridade estrutural e auxiliam na tomada de decisões relativas à necessidade de reparos e reforços. Entre os ensaios não destrutivos, avalia-se neste trabalho a aplicação da identificação modal estocástica na detecção de danos em pontes. A técnica baseia-se na medição das vibrações ambientais da estrutura, aquelas que ocorrem durante seu uso, identificação de suas propriedades modais, comparação com as propriedades modais da estrutura íntegra e consequente detecção de danos. Diferentemente da análise dinâmica experimental clássica, na identificação modal estocástica as ações dinâmicas não são medidas e nem controladas durante o ensaio. Por este motivo foram adotadas técnicas de identificação modal baseadas apenas nas vibrações medidas em alguns pontos da estrutura, funções de densidade espectral de potência e transmissibilidades de vibrações entre os pontos. Desta forma as frequências naturais e modos de vibração experimentais puderam ser precisamente identificados em modelos íntegros e danificados de pontes em escala reduzida. Em cada modelo, uma danificação foi imposta em uma de suas longarinas no meio do vão ou no segundo quarto de vão. Após a realização dos ensaios dinâmicos nas condições íntegra e danificada, duas técnicas de identificação de danos foram utilizadas: Diferença de Curvatura Modal (DCM) e Índice de Dano (ID). Ambas as técnicas tiveram sucesso na detecção de danos nos modelos de pontes avaliados.Reinforced concrete bridges are extremely important elements of Brazilian transportation infrastructure. Consequently their inspection and maintenance are strategic activities. Visual inspection, destructive or nondestructive tests offer relevant information on their structural integrity and support the decision on the need of retrofitting or strengthening. Among existing types of nondestructive tests, this work focuses on the application of stochastic modal identification in damage detection of bridges. This technique is based on the measurement of environmental vibrations that occur during normal operation of the structure, modal identification, comparison of modal properties between damaged and undamaged bridge and finally damage detection. Opposed to classical dynamic experimental analysis, in stochastic modal identification the loads are not measured or known during the test. For this reason modal identification was only based in vibrations measured in selected points of the structure, power spectral density functions and vibration transmissibilities between these points. With this method natural frequencies and experimental modal shapes could be precisely identified in damaged and undamaged small scale models of bridges. The damage was induced in the middle of the span or in the second quarter of the span in one of the girders. After dynamic testing in undamaged and damaged conditions two damage identification techniques were used: Modal Curvature Difference (MCD) and Damage Index (ID). Both techniques detected successfully the damages imposed to the bridge models.
Book chapters on the topic "Curvature damage index"
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Akinci, Halil, Mustafa Zeybek, and Sedat Dogan. "Evaluation of Landslide Susceptibility of Şavşat District of Artvin Province (Turkey) Using Machine Learning Techniques." In Landslides [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.99864.
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The aim of this study is to produce landslide susceptibility maps of Şavşat district of Artvin Province using machine learning (ML) models and to compare the predictive performances of the models used. Tree-based ensemble learning models, including random forest (RF), gradient boosting machines (GBM), and extreme gradient boosting (XGBoost), were used in the study. A landslide inventory map consisting of 85 landslide polygons was used in the study. The inventory map comprises 32,777 landslide pixels at 30 m resolution. Randomly selected 70% of the landslide pixels were used for training the models and the remaining 30% were used for the validation of the models. In susceptibility analysis, altitude, aspect, curvature, distance to drainage network, distance to faults, distance to roads, land cover, lithology, slope, slope length, and topographic wetness index parameters were used. The validation of the models was conducted using success and prediction rate curves. The validation results showed that the success rates for the GBM, RF, and XGBoost models were 91.6%, 98.4%, and 98.6%, respectively, whereas the prediction rate were 91.4%, 97.9%, and 98.1%, respectively. Therefore, it was concluded that landslide susceptibility map produced with XGBoost model can help decision makers in reducing landslide-associated damages in the study area.
Conference papers on the topic "Curvature damage index"
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Chen, Da-Ming, Y. F. Xu, and W. D. Zhu. "A Round Robin Study: Detection of Damage in a Composite Plate With a Real-Time Moving Sensor Measurement Technique." In ASME 2018 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/detc2018-86160.
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A worldwide round robin study is sponsored by the Society of Experimental Mechanics to detect damage in a composite plate with a scanning laser Doppler vibrometer (SLDV). The aim of this round robin study is to explore the potential of a SLDV for detection of damage in composite plates. In this work, a curvature-based damage detection method with use of a continuously SLDV (CSLDV) is proposed. A CSLDV can be regarded as a real-time moving sensor, since the laser spot from the CSLDV continuously moves on a structure surface and measures velocity response. An operating deflection shape (ODS) of the damaged composite plate can be obtained from velocity response by the demodulation method. The ODS of the associated undamaged composite plate is obtained by using polynomials to fit the ODS of the damaged plate. A curvature damage index (CDI) using differences between curvatures of ODSs (CODSs) associated with the ODSs from the demodulation method and the polynomial fit is proposed to detect damage. With the proposed curvature-based damage detection method, locations of two possible damage are detected in areas with consistently high CDI values at two excitation frequencies, which are in good agreement with prescribed damage locations.
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Chen, Da-Ming, Y. F. Xu, and W. D. Zhu. "Damage Identification Using a Continuously Scanning Laser Doppler Vibrometer System." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-67293.
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A continuously scanning laser Doppler vibrometer (CSLDV) system is capable of rapidly obtaining spatially dense operating deflection shapes (ODSs) by continuously sweeping a laser spot from the system over a structure surface. This paper presents a new damage identification methodology for beams that uses their ODSs under sinusoidal excitation obtained by a CSLDV system, where baseline information of associated undamaged beams is not needed. A curvature damage index (CDI) is proposed to identify damage near a region with high values of the CDI at an excitation frequency. The CDI uses the difference between curvatures of ODSs associated with ODSs that are obtained by two different CSLDV measurement methods, i.e., demodulation and polynomial methods; the former provides rapid and spatially dense ODSs of beams, and the latter provides ODSs that can be considered as those of associated undamaged beams. Phase variables are introduced to the two methods for damage identification purposes. The proposed damage identification methodology was experimentally validated on a beam with damage in the form of machined thickness reduction. The damage and its region were successfully identified in neighborhoods of prominent peaks of CDIs at different excitation frequencies.
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Chen, Da-Ming, Y. F. Xu, and W. D. Zhu. "Non-Model-Based Multiple Damage Identification of Beams Under Spatially Dense Vibration Measurement." In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-72430.
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An effective non-model-based multiple damage identification method for beams by using a continuously scanning laser Doppler vibrometer (CSLDV) system is presented. Velocity response of a beam along a scan line under sinusoidal excitation is measured by the CSLDV system and a spatially dense operating deflection shape (ODS) of the beam along the scan line is obtained by the demodulation method from velocity response. The ODS of an associated undamaged beam is obtained by using a polynomial with a proper order to fit the ODS from the demodulation method. The curvature of an ODS (CODS) is used to identify abnormality induced by multiple damage. A curvature damage index (CDI) using differences between CODSs associated with ODSs that are obtained by the demodulation method and the polynomial fit is proposed to identify multiple damage. An auxiliary CDI obtained by averaging CDIs at different excitation frequencies is defined to further assist identification of multiple damage. Experiments on three beams with three damage on each beam in the form of three small cuts are conducted. Widths and depths of the three damage are varied from 3 mm to 9 mm with an increment of 3 mm and from 5% of thickness reduction to 15% with an increment of 5%, respectively, and their effects on ODSs, CODSs, and CDIs are investigated. Three frequencies close to natural frequencies of the beams and one randomly selected frequency that is not close to any natural frequencies of the beams are used as sinusoidal excitation frequencies. Each damage is successfully identified near regions with consistently high values of CDIs at different excitation frequencies when the damage is not close to a nodal point of an ODS. The three damage on each beam is successfully identified with the auxiliary CDI by obvious peaks at locations of the three damage.
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Lau, Dennis, and S. W. Ricky Lee. "Correlation Between the Strain on the Printed Circuit Board and the Stress in Chips for the Failure Prediction of Passive Components." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-82084.
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Due to the demand for miniaturization of microelectronic devices, the density of packaging has become higher and higher. Also, the sizes of components have become smaller and smaller. In addition to advanced active components such as chip scale packages (CSPs) and flip chips (FCs), mini sized passive components such as chip capacitors and resistors are also important elements for high density packaging. It is quite common to see dozens up to hundreds of passive components on printed circuit boards (PCBs). Both active and passive components contribute to the function (and also malfunction) of electronic systems. However, the reliability issues of passive components are often overlooked because they are relatively small in size and cheap in cost. In view of the fact that “small components could lead to big problems”, the present study is conducted to evaluate the threat to passive components assembled on PCBs under a specific type of mechanical loading. Because of the nature of mass production, microelectronic devices are always manufactured in a batch mode. It is quite often that several PCBs are linked together during the surface mount assembly process. Even if the PCB is a stand-alone unit, extra peripheral frames or tie bars are needed for tooling and fixture. After the board level assembly, a depaneling process is usually required to singulate individual PCBs or to remove the tooling frames for the system level assembly. Some depaneling processes may be automated with precision control. However, it is not unusual for operators in the factory to perform manual depaneling. During this process, the PCB is subjected to mechanical bending and the curvature of the bent PCB may be big enough to damage small passive components. The present study is intended to establish a model for the failure prediction of passive components under depaneling load condition. Computational stress analysis is performed with a 3D finite element model. The emphasis is placed on finding the correlation between the bending strain on the PCB (which is an index of the local curvature of the bent PCB) and the bending stress in the passive components (which is the reason to crack capacitors/resistors). It is observed that such a relationship can be established. With this model, the cracking of passive components may be predicted under the depaneling load condition. The understanding of this potential threat can be turned into a design rule to avoid mounting passive components in the “high risk” area on the PCB. As a result, the objective of “design for reliability” (DFR) can be achieved. The details of the aforementioned model and the results of stress analysis will be presented in this paper.