نتایج جستجو برای: crack detection

تعداد نتایج: 589151  

2006
J. L. Rose C. M. Lee T. R. Hay Y. Cho I. K. Park

The critical subject of transverse crack detection in a rail head is treated in this paper. Conventional bulk wave ultrasonic techniques often fail because of shelling and other surface imperfections that shield the defects that lie below the shelling. A guided wave inspection technique is introduced here that can send ultrasonic energy along the rail under the shelling with a capability of fin...

2012
Joachim SCHLICHTING Mathias ZIEGLER Christiane MAIERHOFER Marc KREUTZBRUCK

We report on recent developments in the detection of surface breaking cracks using flying laser spot thermography. Application of an infrared camera for mapping the thermal radiation after excitation with a diode laser equipped with an optical scanner allows us to examine a surface containing cracks in an entirely non-destructive, contactless and fast way, without even moving the camera. We dev...

2011
Udaya B. Halabe Reynold Franklin

Ultrasonic testing for fatigue crack detection in metallic members are commonly performed using time domain analysis of Rayleigh waves. This approach will be successful only if the fatigue cracks produce strong interaction with the Rayleigh waves. The optimum frequency range of ultrasonic Rayleigh waves for scanning long structural members in the field is from 0.5 to 2.25 MHz because higher fre...

2008
Adam C. Cobb Jennifer E. Michaels Thomas E. Michaels

Ultrasonic interrogation of metal alloys has been demonstrated to be effective for monitoring fatigue-induced damage in a structural health monitoring (SHM) framework. Before such a method can be implemented, the probability of detection (POD) as a function of crack size must be quantified. POD curves are routinely generated for nondestructive evaluation (NDE) methods, typically by performing l...

Journal: :Journal of Vibration and Control 2010

2017
M. D. Gilchrist

This paper considers the detection of symmetric crack-like defects in thin metallic plates using longitudinal ultrasonic waves. Only physically small defect sizes are considered in order that the initial stages of crack growth, for example during fatigue, can be detected. This method has the potential to be significantly faster for non-destructively detecting defects than conventional ultrasoni...

2008
Jeong Ho Lee Jong Min Lee Jin Wook Park

In the bridge inspection, the information of cracks is important to maintain a bridge. Therefore, automatic crack detection is highly desirable for efficiency and objectivity of crack assessment. However, in general, it is very difficult to detect cracks automatically from noisy concrete surfaces. In this paper, we propose a machine vision system for automatic inspection of bridges. The propose...

2007
K. Yamanaka Y. Ohara S. Yamamoto T. Mihara

A new method for detection and sizing of closed crack is described which uses transient waveform of subharmonics with half input frequency in ultrasonic nondestructive evaluation. In analogy to the resonant characteristics of vibration of bubbles in liquids, we formulate an equation for resonant excitation of subharmonics at partially closed cracks. The equation has been partially verified by c...

2012

Much of the recent research at the NDE Centre at UCL has revolved round the study of the scattering of thin skin electromagnetic fields by a fatigue crack. The early work concentrated on the perturbations to the surface electric field (ACPD), while the more recent work involved the scattered magnetic field (ACFM). The Centre has recently become involved in a collaborative project, a part of whi...

2017
Shi Yan Haoyan Ma Peng Li Gangbing Song Jianxin Wu

Structural health monitoring (SHM) systems can improve the safety and reliability of structures, reduce maintenance costs, and extend service life. Research on concrete SHMs using piezoelectric-based smart aggregates have reached great achievements. However, the newly developed techniques have not been widely applied in practical engineering, largely due to the wiring problems associated with l...

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