The inspection of large structures using conventional ultrasonic bulk wave techniques is slow because scanning is required if the whole structure is to be tested. Ultrasonic guided waves potentially provide an attractive solution to this problem because they can be excited at one location on the structure and will propagate many metres. However, guided wave testing is complicated by the presenc...

development of ultrasound technique has not been progressing for evaluating the internal quality of fruits as fast as that of processed foods. in this research for quality assessment of pear fruit (shah miveh variety) an ultrasonic measurement system was constructed to transmit and receive the ultrasonic waves. the apparatus included a pulser-receiver, a pair of 75 khz ultrasonic transducers wi...

Ultrasonic guided waves offer the promise of fast and reliable methods for interrogating large, plate-like structures. Distributed arrays of permanently attached, inexpensive piezoelectric transducers have thus been proposed as a cost-effective means to excite and measure ultrasonic guided waves for structural health monitoring (SHM) applications. Guided wave data recorded from a distributed ar...

Rail tracks undergo massive stresses that can affect their structural integrity and produce rail breakage. The last phenomenon represents a serious concern for railway management authorities, since it may cause derailments and, consequently, losses of rolling stock material lives. Therefore, the activities track maintenance inspection are paramount importance. In recent years, use various techn...

Ultrasonic guided wave methods are being widely explored for inspection of large structural areas using a sparse array of surface-mounted transducers. However, structural health monitoring (SHM) with guided waves can be problematic because variable operational conditions can significantly affect the measured ultrasonic signals. Although homogeneous temperature variations have been well-research...

A sparse array guided wave tomography system is investigated for monitoring plate wall thinning status caused by corrosion/erosion. Because of their group velocity dependence on the structure wall thickness of some special modes, ultrasonic guided waves are sensitive to structure wall thinning status. As a low resolution imaging technique, a sparse array system provides many advantages. First, ...

In a low-frequency ultrasonic guided wave dual-probe flaw inspection of a square steel bar with a finite length boundary, the flaw reflected pulse wave cannot be identified using conventional time monitoring when the flaw is located near the reflection terminal; therefore, the conventional ultrasonic echo method is not applicable and results in a non-detection zone. Using analysis and simulatio...

Technical machinery and systems are subject to varying or cyclic service loads and environmental influences, like adverse weather conditions. Such operation conditions can lead to the development of faults during the lifecycle of the structure, e.g., fatigue cracks and severe corrosion damage in offshore oil platforms and oil storage tanks. The corrosion damage often shows as large area thickne...