The deteriorating national infrastructures demand improved non-destructive evaluation (NDE) methods for detection of defects which reduce the integrity of the structures. Vibration resonance tests offer an efficient NDE method to identify and characterize shallow (near surface) delamination defects in reinforced concrete slabs In this study, we compare the capability to visualize near surface d...

Background: A known complication following autologous chondrocyte implantation (ACI) for the repair of cartilage defects is graft hypertrophy. Although hypertrophic tissue can sometimes be asymptomatic, it may cause pain, catching, or effusion prompting a debridement operation—the most common reoperation. Indications: Second-look arthroscopy required symptomatic delaminated tissue. Technique De...

Lockin thermography is used by RSAF and other aircraft companies. It involves actively applying sinusoidal thermographic waves to the specimen and observing phase and amplitude changes at the specimen surface in order to evaluate structural information below the surface. Experiments were performed to evaluate defect characteristics such as depth, size and shape. The specimen contained very wide...

In this work, we present an approach of deconvolution ill-posed problems of superimposed signals in time. A priori information must be taken into account to solve this problem. The a priori information translates the physical properties of the ultrasonic signals. The defect impulse response is modelled as a Bernoulli-Gaussian sequence. Deconvolution becomes the detection problem of the optimal ...

Acoustic-laser vibrometry, a non-contact method for nondestructive testing, was studied by altering operational and defect parameters to determine their effects on measured signatures and system performance. The method detects delamination and voids in fiber-reinforced polymer reinforced concrete by vibrating the material with an acoustic excitation and measuring the vibration signature with a ...

The ripplocation is a crystallographic defect which unique to layered materials, combining nanoscale delamination with the slip of basal dislocation. Here, we have studied dislocations and ripplocations, in single multiple van der Waals layers, using analytical computational techniques. Expressions for energetic structural scaling factors surface ripplocations are derived, close correspondence ...

Integrity of layered structures, extensively used in modern industry, strongly depends on the quality of their interfaces; poor adhesion or delamination can lead to a failure of the structure. Can nonlinear waves help us to control the quality of layered structures? In this paper, we numerically model the dynamics of a long longitudinal strain solitary wave in a split, symmetric layered bar. Th...

In this paper a new method for the detection of delamination damage in composite beams using scanning Doppler laser vibrometry is presented. The recent advances in scanning laser technology now allow very accurate measurement of displacement fields, which in the case of undamaged structure must satisfy the fundamental equations of continuum mechanics. A violation of these equations at specific ...

In composite structures subjected to compressive loads, impact damage is a major problem as it promotes delamination, which severely reduces the buckling strength. The problem is further complicated by the fact that internal defects cannot be detected by a visual inspection. In order to assess the effect on a component of any damage it is desirable to determine the behaviour of a defect during ...