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Wang Z.,Nanjing University of Aeronautics and Astronautics | Wang Z.,Nan Hang Jin Cheng College | Yuan S.,Nanjing University of Aeronautics and Astronautics | Qiu L.,Nanjing University of Aeronautics and Astronautics | And 2 more authors.
Journal of Vibroengineering | Year: 2014

Multiple-damage-inflicted scattering signals usually overlap with each other due to Lamb wave dispersion and multi-mode characteristics. As a result, it is difficult to accurately distinguish damages that occur relatively close to each other using the conventional ultrasonic phased array method. In order to solve this problem, an improved linear mapping (ILM) dispersion compensation method is proposed and is applied to enhance the ultrasonic phased array monitoring resolution. Through a uniform linear array arrangement, the damage scattering signals are collected in a round-robin pattern of ultrasonic phased array, and then compensated based on the linear relation wavenumber curve from actual measurement. At last, the scan can be obtained by monitoring the energy scattered by the damages using delay-and-sum method. To verify the proposed method, experiments are performed on an aluminum (LY-12) plate. Two results of multiple artificial damages show that the proposed method can effectively compensate the dispersion characteristics of Lamb waves. The direction estimation error and distance estimation error are less than 4° and 2 cm, respectively. © JVE INTERNATIONAL LTD. JOURNAL OF VIBROENGINEERING.


Wang Z.,Nanjing University of Aeronautics and Astronautics | Wang Z.,Nan Hang Jin Cheng College | Yuan S.,Nanjing University of Aeronautics and Astronautics | Qiu L.,Nanjing University of Aeronautics and Astronautics | Liu B.,Nanjing University of Aeronautics and Astronautics
Vibroengineering Procedia | Year: 2014

The disadvantages of linear arrays are such that the range of damage detection is limited up to only 180°, and also that the detection accuracy is very poor at angles close to 0° and 180°. In order to solve this problem, this paper puts forward a new damage detection and localization method by coupling the image enhancement technology with two-dimensional piezoelectric ultrasonic phased arrays arranged in the shape of a cross. The basic detection principle as well as the detailed process of damage localization will be covered in this paper. Along with the implementation of the cross-shaped sensor arrays, a new image enhancement algorithm is proposed with the aim to deal with the problem of phantom image emerging in the opposite side of the original image. The results of the experiments conducted on an aluminum plate show that the above proposed method can not only effectively solve the limitation of the linear sensor array, but also accurately detect multiple damages in full angle mode. © JVE INTERNATIONAL LTD.


Wang Z.,Nanjing University of Aeronautics and Astronautics | Wang Z.,Nan Hang Jin Cheng College | Yuan S.,Nanjing University of Aeronautics and Astronautics | Qiu L.,Nanjing University of Aeronautics and Astronautics | Liu B.,Nanjing University of Aeronautics and Astronautics
Journal of Vibroengineering | Year: 2015

A full-range (360°) damage detection is necessary for structural health monitoring of large plate-like structures. However, the linear arrays are mainly limited by the range of damage detection, which is maximum up to 180°. Moreover the detection accuracy is also very poor at angles close to 0° and 180°. In order to solve this problem, a novel damage detection and localization method is presented in this paper. The proposed method combines the image enhancement technology and the cruciform piezoelectric phased array to improve the performance of the linear array based system. In addition to the implementation of cruciform phased array, a new image enhancement algorithm is proposed with an aim to deal with the problem of phantom image emerging in the opposite side of the original image. The results of the experiments conducted on aluminum plate and epoxy composite laminate plate show that the proposed method can effectively solve the limitations of the linear sensor array, and accurately detect single or multiple damages in full angle mode. © 2015, JVE INTERNATIONAL LTD.


Wang Z.,Nanjing University of Aeronautics and Astronautics | Wang Z.,Nan Hang Jin Cheng College | Yuan S.,Nanjing University of Aeronautics and Astronautics | Qiu L.,Nanjing University of Aeronautics and Astronautics | Zhong Y.,Nanjing University of Aeronautics and Astronautics
Zhendong Ceshi Yu Zhenduan/Journal of Vibration, Measurement and Diagnosis | Year: 2014

The active structural health monitoring based on ultrasonic phased array is a new development direction in the field of aircraft structural health monitoring, which is also one of the difficult points of current research, and ultrasonic phased array structural health monitoring is still in its infancy in China. Based on the existing application of ultrasonic phased array technology of single damage location, multi-damage monitoring is further studied in the aircraft structure. Direction of arrive can be controlled by time delay and the multi-damage location can be identified by scanning structure in all orient. Experiments compared the damage reflection signals of different angles before the delayed with the signals after the delayed and the synthesized signal on the aluminum structure, and the results verified the ultrasonic phased array can effectively improve the multi-damage signal energy by delaying and superposing them, as well as, reduce the energy of the signal where there is no damage, thus increasing the signal to noise ratio, and has a high accuracy for multiple damage identification.

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