Non-destructive testing of the root area of a low-pressure (LP) turbine's blades and disks was performed in a restrictive manner. When the turbine blades and disks were disassembled or not, the root area surface was examined by conventional ultrasonic testing (UT), that is, magnetic particle or liquid penetrant testing. Recent developments have led to the use of phased array ultrasonic testing ...

In ultrasonic non-destructive testing of materials with a coarse-grained structure the scattering from the grains causes backscattering noise, which masks flaw echoes in the measured signal. Several filtering methods have been proposed for improving the signal-to-noise ratio. In this paper we present a comparative study of methods based on the wavelet transform. Experiments with stationary, dis...

Flexible ultrasonic transducers (FUTs) consisting of a 75 μm thick metal membrane, a piezoelectric composite with a thickness larger than 85 μm and a top electrode were developed for structural health monitoring (SHM) and non-destructive testing (NDT) applications. The piezoelectric films were made by a sol-gel spray technique. Its ultrasonic performance in terms of signal strength is at least ...

In this research, the sensitivity distribution properties of a phase-shifted fiber Bragg grating (PS-FBG) to ultrasonic waves were investigated employing the surface attachment method. A careful consideration was taken and examined by experimental results to explain that the distances and angles between the sensor and ultrasonic source influence not only the amplitudes, but also the initial pha...

Integrated (IUTs) and flexible ultrasonic transducers (FUTs) are presented for NDT at high temperatures. These transducers are made of sol-gel sprayed piezoelectric thick (> 40μm) ceramic films. The ceramic materials are lead-zirconate-titanate, bismuth titanate and lithium niobate which are for thickness measurement up to 150°C, 400°C and 800°C, respectively. The IUT can be also deposited onto...

In this work, we report a non-destructive and non-contacting ultrasound system with novel air-coupled transducer to continuously monitor the drying process of prickly pear (nopal) pads in lab environment. Compared conventional imaging spectroscopic methods or electrical-based approaches, ultrasound-based are non-invasive, cost-effective, suitable for large volume evaluation. The time-dependent ...

This paper deals with the study of damage produced during freeze-thaw (F-T) cycles using two non-destructive measurement approaches-the first approach devoted to continuous monitoring using embedded sensors during the cycles, and the second one, performing ultrasonic imaging before and after the cycles. Both methodologies have been tested in two different types of concrete specimens, with and w...