This paper describes an investigation into mechanical cross talk within 1-3 and 2-2 connectivity piezoelectric composite array configurations, comprising a matrix of active piezoelectric elements embedded within a passive, polymeric, material. One way to take full advantage of the reported sensitivity and bandwidth improvements from single crystal materials is to configure them as a piezoelectr...

This paper describes a sensor network platform for pipeline system monitoring. Pipeline systems are widely used for distribution and transportation of petroleum, natural gas, water, and sewage. Leaks and ruptures due to an aging and fast decaying pipeline system infrastructure cost millions of dollars a year; they also make clear the necessity for continuous, automatic monitoring systems that c...

Acoustic techniques are used to monitor the temperature of silicon wafers in rapid thermal processing environments from room temperature to 1000" C with f 5 " C accuracy. Acoustic transducers are mounted at the bases of the quartz pins that support the silicon wafer during processing. An electrical pulse applied across the transducer generates an extensional mode acoustic wave which is guided b...

Since today’s aging fleet is now intended to far exceed their proposed design life, monitoring the structural integrity of those aircraft has become a priority issue for today’s Air Force. One of the most critical structural problems is corrosion. In fact the KC-135 now costs $1.2 billion a year to repair corrosion. In this paper, we plan to show the use of Lamb waves to detect material loss in...

Structural Health Monitoring (SHM) is a novel philosophy for an autonomous, built-in nondestructive evaluation of structural “health” on demand to reduce life-cycle costs, increase safety and reduce structural weight. This dissertation investigates ultrasonic guided waves, particularly Lamb waves, and their propagation properties as a method to perform Health Monitoring of viscoelastic composit...

Abstract In this paper a measurement procedure is presented to identify both elastic and viscoelastic material parameters of plate-like samples using broadband ultrasonic waves. These Lamb waves are excited via the thermoelastic effect laser radiation detected by piezoelectric transducer. The resulting data transformed yield information about multiple propagating as well their attenuation. resu...

A new transducer beam model is developed for the generation of Rayleigh surface wave and Lamb plate waves by an angle beam transducer, which is one of the configurations commonly used for the generation of these wave types. The beam model is a fully 3-D model that takes into account the fields generated by the transducer acting on the surface of a wedge. The model also accounts for the leaky wa...

The novel ultrasonic NDT technique based on application of long range guided waves is proposed for detection of defects in a storage tank floor. The technique needs access only to the outer edge of the tank floor and do not require emptying and cleaning inside of the tank. The technique has been developed on the basis of the Lamb wave transmission tomography. The propagation of the guided waves...