In earlier work we developed inductive coupling for surface-mounted Lamb wave transducers operating at relatively low frequencies, such as 300 kHz. We now report on similar inductively-coupled transducers at higher (multiple MHz) frequencies. Our investigation was motivated by a particular application, to examine a box girder top flange, using transducers mounted along the flange edge. We emplo...

Self-healing concrete (SHC) has received a tremendous attention due to its advanced ability of automatic crack detection and crack repairing compared to the standard concrete. Two main approaches which considered as to-date self-healing mechanisms are autogenous and autonomous healing. In the past several years, the effort of the research has been focused on experimental works instead of numeri...

This paper deals with the application of the adjoint variable approach to sensitivity analysis of objective functions used for defect detection from knowledge of supplementary boundary data, in connexion with the use of BIE/BEM formulations for the relevant forward problem. The main objective is to establish expressions for crack shape sensitivity, based on the adjoint variable approach, that a...

the cracked brazilian disc (cbd) specimen is widely used in order to determine mode-i/ii and mixed-mode fracture toughness of a rock medium. in this study, the stress intensity factor (sif) on the crack-tip in this specimen is calculated for various geometrical crack conditions using the extended-finite element method (x-fem). this method is based upon the finite element method (fem). in this m...

This paper provides an overview to detect, locate, and characterize fault in structural and mechanical systems using various methods. Since last few decades experimentally measured frequencies has been extensively used to crack detection. The relationships between frequency changes and structural damage are discussed. Various reverse techniques proposed for detecting fault using natural frequen...

Electrical Impedance Tomography (EIT) is an imaging modality which reconstructs the impedance distribution of a closed domain using the measured boundary voltage data when injecting current [1-6]. It has been applied to numerous industrial applications such as: process tomography [7], nondestructive testing [8], imaging biological cells [9], medical imaging equipment [4] etc. Among them, non-de...

Original scientific paper The relationships between the existence of gear teeth cracks as a cause and symptoms emerging as housing vibrations that can be detected with signals measured was investigated numerically and experimentally. Experimental measurements on one-stage gear drives have been carried out involving gears built in with different notch length in tooth root. Signals measured as ac...

This paper describes the use of a novel method of feature extraction for visual sensor processing. An application to crack detection by a sewer maintenance robot equipped with an infra-red camera is described. A spacefrequency distribution ’signature’ is generated via a three step process involving; space-frequency decomposition, density function estimation, and parameter extraction. These step...

This paper describes a new broad-band approach to the detection of acoustic emission in which a capacitance transducer has been used to record the transient elastic waves generated by crack growth processes as surface displacements. A unique specimen geometry, the 'Yobell' has been developed to reduce interference from internal reflections of the ultrasonic pulse, so that the measured surface d...