Papers by Keyword: Damage Identification

Abstract: To identify damaged position of oil derrick, this paper presents a damage identification method for oil derrick using LMD and sample entropy to extract eigenvector and SVM to identify classes. Hammering vibration response signal of damaged derrick is decomposed into several PF components. The sample entropy of PF components is calculated and used as eigenvectors. SVM classifier is constructed based on eigenvectors of different damage location, and this method can identify damage position accurately. This method is verified by comparison with recognition result of LMD and information entropy.

Abstract: To have a comprehensive summary of existing methods for damage identification of transmission tower so as to provide systematic and effective information, from aspeces of data sources and analytical methods, the existing methods of damage identification were summarized to sort out the technical evolution of the various damage identification methods including the static and dynamic damage identification and inversion and pattern recognition methods.Then, the application status, advantages and disadvantages of various methods were analzed, and the improvement ideas and methods were summarized. Finally, establishment of four-in-one multi-system damage identification method was proposed based on construction monitoring, loads tsets, health monitoring and artificial patrol, which is the development trend of the transmission tower structure damage identification.

Abstract: Continuous rigid frame bridge is widely used in bridge construction because of its superior characteristics, with its piers increasing. Shown in previous studies, the key positions of the side pier or lower pier at the top and the bottom of the pier yield firstly and then get into the plastic stage in the action of earthquake. So in this condition, dynamic analysis of the continuous rigid frame bridge impacted by the consolidation damage that may occur at the pier top and the bottom is studied in the paper. In the process, the consolidation damage degree is introduced in order to characterize the damage qualitatively. And then Midas/Civil 2010 is adopted to analyze the structure by modeling. Finally, some conclusions are obtained, including that the consolidation damage has a significant impact on the dynamic features, effect on the structure when the damage respectively happens at the two key sections is extremely close, and almost all value of the dynamic feature changes is located in the condition when the damage degree is less than 10%. The job above all in this paper may provide a valuable reference for the seismic analysis and the technique of damage identification and location in continuous rigid frame bridge.

Abstract: Damage detection in anisotropic composite plates based on Lamb wave technique has been investigated. A network of transducers is used to detect barely visible damage caused by impact. A CFRP composite plate has been impacted and tested to verify the proposed damage detection algorithms. The difference in the propagational properties of Lamb waves in the pristine state and the damage state is used through data fusion and imaging algorithms to detect, locate and characterise the damage. The influence of directionality of the velocity on the validity of the detection algorithm is examined and some results are presented.

Abstract: Plates are commonly used in engineering structures. However crack is the most common form of damages in the plate structures. The crack in the plate will open and close during vibrational cycle, making the cracked structure with nonlinear dynamic characteristics. Based on vibrational power flow theory, the nonlinear dynamic analysis of a plate structure is carried out. The contact elements are used to simulate the nonlinear behavior of the breathing crack. Aiming to study the input power characteristics and the super harmonic resonance of a breathing cracked plate which is under the resonant excitation. By the finite element calculation, the structural input power curve is analyzed, which provides a theoretical basis for the damage identification of cracked structures.

Abstract: This paper first describes the importance of structural damage identification and diagnosis in civil engineering, and introduces domestic and foreign status of damage identification and diagnosis methods, and on the basis of this, it also introduces all kinds of methods for damage identification and diagnosis of civil engineering structures, and finally puts forward the development direction of civil engineering structure damage identification and diagnosis.

Abstract: Structural damage identification is a hot research topic in the field of building structural health monitoring, according to the problem of building structural damage is difficult to accurately identify, conducting the research of the abnormal monitoring data. In the summary and the research on the basis of the current domestic construction structure damage identification theory, this paper proposes a combined with finite element method based on displacement measurement data of structural damage identification methods, verified by the structure model building in PKPM finite element software, the method has higher recognition accuracy and operability and effectiveness.

Abstract: As the foundation work of the damage identification for the blade, the purpose of this paper is to determine which parts of the blade are more sensitive to the damage and how serious damage could affect the dynamic response of the blade structure. Several damage states are simulated using the magnets, and then the distributed fiber Bragg grating sensor system is used to measure the dynamic strain response of the blade under the random excitation. The dynamic strain time domain signal is first analyzed, and then the different damage states are identified. In order to eliminate the adverse affect of the environmental and operational variations, the Hilbert-Huang Transform method is used to extract the damage-induced signal component. Lastly the damage index based on the autoregressive model and Mahalanobis distance method is constructed to detect damage. Some conclusions are obtained from the experimental results.

Abstract: A simple and robust methodology is presented to identify damages in a structure using changes in vibration data. A comparison is made among damage indicators such as natural frequencies, mode shape data, curvature damage factors and flexibility matrices to study their efficacy in damage assessment. Continuous ant colony optimization (ACO_R) technique is used to solve the inverse problem related to damage identification. The outcome of the simulated results demonstrates that the flexibility matrix as a damage indicator provides better damage identification.

Abstract: With the expansion and development of scale of construction on metro engineering, the damage diagnosis and the safety evaluation on underground engineering structure have become vital problems to be solved. This paper raised an idea to distinguish underground engineering structure based on BP neural network: define change rate of curvature of structure, and recognize it as the input scalar of BP neural network, using a reducing unit elastic modulus method to simulate damage location and damage degree, through various set of underground structure extent of damage, recognize the first four order curvature structure change rate as input of BP neural network. The results show that the method using BP neural network can identify the damage degree of underground engineering structure accurately and can solve the damage identification problem of underground engineering structure conveniently and effectively.