Fatigue and stress crack detection in metallic structures is of utmost importance to the in-service inspections of metallic components. Beside the crack detection, the prediction of the crack size leads to a better estimation of the useful life of the metal in service. Currently, there are several prominent nondestructive testing (NDT) techniques for detecting and sizing surface cracks in metal...

A method for the detection of cracks in old paper photographs is presented. Cracks in photographic prints usually result from a folding of the paper support of the photograph; they often extend across the entire image, along a preferred orientation. A first clue we exploit for crack detection is the fact that old prints have a characteristic sepia hue, due to aging and to the type of processing...

This paper proposes a method to reduce noise and extract crack indications from detection signals of a 48-channel ECT system based on its signal phase characteristics. Because this 48-channel ECT system performs two kinds of scanning patterns: U-scan and T-scan, and obtains two sets of signal distributions for one scanning area simultaneously, the proposed method uses a two-stage process that i...

Visual inspection by a human operator has been mostly used up till now to detect cracks in sewer pipes. In this paper, we address the problem of automated detection of such cracks. We propose a model which detects crack fractures that may occur in weak areas of a network of pipes. The model also predicts the level of dangerousness of the detected cracks among five crack levels. We evaluate our ...

In this paper we propose a Genetic-Based Inverse Voting Hough Transform (GBIVHT) method to detect buried crack defects in engineering structures. The method is applied to B-scan images obtained according to the ultrasonic Time Of Flight Diffraction technique. In these image representations of the ultrasound data, crack defects are characterized by multiple arcs of diffraction that can be approx...

Vibrothermography is a relatively new nondestructive evaluation technique for finding cracks through frictional heat generated from crack surface vibrations under external excitations. The vibrothermography inspection method provides a sequence of infrared images as output. We use a matched filter technique to increase the signal-to-noise ratio of the sequence-of-images data. An automatic crack...

Recently, demand for object recognition is rising with the increase of digital images. In this paper, a performance comparison of some object recognition techniques has been made. In a dataset, images usually contain wide background areas other than the object area which is focused in the recognition. This unnecessary areas should be ignored to increase the efficiency and accuracy of object det...

Mode I, quasi-static, steady state crack growth is analyzed for rate dependent materials under plane strain conditions in small scale yielding. The solid is characterized by an elastic-viscoplastic constitutive law and the plane ahead of the crack tip is embedded with a rate dependent fracture process zone. The macroscopic work of fracture of the material is computed as a function of the crack ...

In this paper an exact formulation of the plane elasticity problem for a hollow cylinder or a disk containing a radial crack is given. The crack may be an external edge crack, an internal edge crack, or an embedded crack. It is assumed that on the crack surfaces the shear traction is zero and the normal traction is an arbitrary function of r. For various crack geometries and radius ratios, the ...