With an increasing use of adhesively bonded joints in the industry, there is a correspondingly growing need for the inspection of adhered joints. It is necessary to detect defects in the adhesively bonded materials such as voids inclusions, chemical miscure of the adhesive, or delaminations of the bonded layers. In order to use an ultrasonic technique to detect these defects, a thorough underst...

Asymptotically exact and nonlocal third order nonlinear evolution equations are derivedfor two counterpropagating surface capillary gravity wave packets in deep water in thepresence of wind flowing over water.From these evolution equations stability analysis ismade for a uniform standing surface capillary gravity wave trains for longitudinal perturbation. Instability condition is obtained and g...

Cost-effective and reliable damage detection is critical for the utilization of composite materials. This paper presents the conclusions of an experimental and analytical survey of candidate methods for in-situ damage detection in composite structures. Experimental results are presented for the application of modal analysis and Lamb wave techniques to quasi-isotropic graphite/epoxy test specime...

the velocity data of seismic waves in a region has an important role in locating occurred events. information such as velocity ratio of vp/vs and velocity curves for pg, pn, sg, and sn phases directly affect the locating results. it is well known that the vp/vs ratio can be used to predict lithology, and that s-waves are sensitive to microcracks aligned by the present day stress field. also, th...

Acoustic emission testing (AET) often utilises waveguides to separate delicate sensors from hot surfaces or to facilitate access to otherwise obstructed materials such as lagged vessels. In the authors’ work, restricted access to mechanical seals on a hot water pump necessitated the use of a short rod to transmit acoustic emission (AE) information from the ceramic seal face. Consequently, an ap...

the present paper studies the possibility of propagation of torsional surface waves in an inhomogeneous anisotropic layer lying between two heterogeneous half-spaces (upper and lower half-space). both the half-spaces are assumed to be under compressive initial stress. the study reveals that under the assumed conditions, a torsional surface wave propagates in the medium. the dispersion relation ...

Lamb waves in plates and in cylindrical pipes have been the subject of extensive study, largely because they propagate great distances with little attenuation, and can therefore be used to detect flaws. In this paper we report finite element simulations and experimental studies of Lamb waves in steel bridge girder geometries. In our studies the Lamb waves are generated by PZT wafer-type transdu...

In the present paper, discrete element method (DEM) is used to study wave propagation phenomenon in granular soils. The effect of factors such as coefficient of friction, frequency, normal stiffness and soil gradation on the wave velocity is studied. Using the wall motion based on the sinusoidal function is the method of loading used in this simulation, through which the pressure wave is transf...

Integrated Vehicle Health Management (IVHM) combines the use of onboard sensors with artificial intelligence algorithms to automatically identify and monitor structural health issues. A fully integrated approach to IVHM systems demands an understanding of the sensor output relative to the structure, along with sophisticated prognostic systems that automatically draw conclusions about structural...

The use of composites in primary and secondary structures of aerospace vehicles is important for increased performance with little weight penalty. Determining the response to thermal damage is necessary for a complete understanding of the total use environment of these materials. The objective of the research presented here is to provide a method of quantifying the amount of thermal damage in c...