Abstract. The aim of the topological sensitivity analysis is to determine an asymptotic expansion of a shape functional with respect to the variation of the topology of the domain. In this paper, we consider a state equation of the form div (A∇u) + ku = 0 in dimensions 2 and 3. For that problem, the topological asymptotic expansion is obtained for a large class of cost functions and two kinds o...

The effective noise reduction schemes in ultrasonic inspection have shown significant role for detection of flaws in materials. This paper presents the comparative result of noise reducing schemes based on Hilbert-Huang transform and Wavelet transform. The basic principle of HHT scheme includes two parts which are empirical mode decomposition (EMD) algorithm and a sum of intrinsic mode function...

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...

Surface mount technology has spurred a rapid decrease in the size of electronic packages, where solder bump inspection of surface mount packages is crucial in the electronics manufacturing industry. In this study we demonstrate the feasibility of using a 230 MHz ultrasonic transducer for nondestructive flip chip testing. The reflected time domain signal was captured when the transducer scanning...

High-density polyethylene (HDPE) piping has been used in place of steel alloys in the petrochemical, power, and mining industries due to its exceptional resistance to corrosion and erosion. Recently, HDPE has also been used for nuclear safety-related cooling water applications. The application of nuclear quality assurance requirements creates reasonable assurance that the production fusion join...

Probing material degradation and properties change to anticipate stages of damage can be achieved using advanced in-situ and hybrid non-contact remote ultrasonic sensing including laser generation and air-coupled detection arrangements. The sensing technology is based on application of guided waves such as plate (Lamb waves) or surface waves (Rayleigh waves) for direct material interrogation th...

We review recent work on the application of fluctuation analyses of time series for pattern classification in nondestructive materials inspection. These analyses are based on the evaluation of time-series fluctuations across time intervals of increasing size, and were originally introduced in the study of fractals. A number of examples indicate that this approach yields relevant features allowi...

This letter discusses the role electrical anisotropy plays in the structural integrity assessment of polycrystalline titanium alloys from the standpoint of fatigue crack detection and the related issue of microstructural noise. In eddy current inspection of noncubic crystallographic classes of polycrystalline metals the electric anisotropy of individual grains produces an inherent microstructur...

Cyclic-tension fatigue of aluminum alloy, Al-4Cu-1Mg, was determined by an analysis of diffracted SH and SV waves, passing through the surface and reflecting the bottom of the specimen, respectively. The internal friction of SV waves begins to increase from fatigue damage ratio(=N/Nf) of 0.5. This suggests increase of movable dislocation. From the analysis of SH waves, the logarithmic damping r...