Guided wave testing

About: Guided wave testing is a research topic. Over the lifetime, 4884 publications have been published within this topic receiving 79633 citations.

Quasi-optical coupler

Abstract: A quasi-optical coupling system launches and extracts surface wave communication transmissions from a wire. At millimeter-wave frequencies, where the wavelength is small compared to the macroscopic size of the equipment, the millimeter-wave transmissions can be transported from one place to another and diverted via lenses and reflectors, much like visible light. Transmitters and receivers can be positioned near telephone and power lines and reflectors placed on or near the cables can reflect transmissions onto or off of the cables. The lenses on the transmitters are focused, and the reflectors positioned such that the reflected transmissions are guided waves on the surface of the cables. The reflectors can be polarization sensitive, where one or more of a set of guided wave modes can be reflected off the wire based on the polarization of the guided wave modes and polarization and orientation of the reflector.

Repeater and methods for use therewith

Abstract: Aspects of the subject disclosure may include, for example, a repeater device having a first coupler to extract downstream channel signals from first guided electromagnetic waves bound to a transmission medium of a guided wave communication system. An amplifier amplifies the downstream channel signals to generate amplified downstream channel signals. A channel selection filter selects one or more of the amplified downstream channel signals to wirelessly transmit to the at least one client device via an antenna. A second coupler guides the amplified downstream channel signals to the transmission medium of the guided wave communication system to propagate as second guided electromagnetic waves. Other embodiments are disclosed.

Finite-dimensional piezoelectric transducer modeling for guided wave based structural health monitoring

Abstract: Among the various schemes being considered for structural health monitoring (SHM), guided wave (GW) testing in particular has shown great promise. While GW testing using hand-held transducers for non-destructive evaluation (NDE) is a well established technology, GW testing for SHM using surface-bonded/embedded piezoelectric wafer transducers (piezos) is relatively in its formative years. Little effort has been made towards a precise characterization of GW excitation using piezos and often the various parameters involved are chosen without mathematical foundation. In this work, a formulation for modeling the transient GW field excited using arbitrary shaped surface-bonded piezos in isotropic plates based on the 3D linear elasticity equations is presented. This is then used for the specific cases of rectangular and ring-shaped actuators, which are most commonly used in GW SHM. Equations for the output voltage response of surface-bonded piezo-sensors in GW fields are derived and optimization of the actuator/sensor dimensions is done based on these. Finally, numerical and experimental results establishing the validity of these models are discussed.

Guided-wave transmission device and methods for use therewith

Abstract: Aspects of the subject disclosure may include, for example, a transmission device that includes a transmitter that generates a first electromagnetic wave to convey data, the first electromagnetic wave having at least one carrier frequency and corresponding wavelength. A coupler couples the first electromagnetic wave to a transmission medium having at least one inner portion surrounded by a dielectric material, the dielectric material having an outer surface and a corresponding circumference, wherein the coupling of the first electromagnetic wave to the transmission medium forms a second electromagnetic wave that is guided to propagate along the outer surface of the dielectric material via at least one guided-wave mode that can include an asymmetric mode, wherein the at least one carrier frequency is within a microwave or millimeter-wave frequency band and wherein the at least one corresponding wavelength is less than the circumference of the transmission medium. Other embodiments are disclosed.

Omni-directional guided wave transducer arrays for the rapid inspection of large areas of plate structures

Abstract: Omni-directional guided wave array transducers contain a circular pattern of elements that individually behave as omni-directional point transmitters or receivers. The data set acquired from such an array contains time-domain signals from each permutation of transmitter and receiver. A phased addition algorithm is developed that allows an omni-directional, B-scan image of the surrounding plate to be synthesized from any geometry of array. Numerically simulated data from a single reflector is used to test the performance of the algorithm. The results from an array containing a fully populated circular area of elements (Type I array) are found to be good, but those from an array containing a single ring of elements (Type II array) contain many large side-lobes. An enhancement to the basic phased addition algorithm is presented that uses deconvolution to suppress these side-lobes. The deconvolution algorithm enables a Type II array to equal the performance of a Type I array of the same overall diameter. The effect of diameter on angular resolution is investigated. Experimental data obtained from a guided wave array containing electromagnetic acoustic transducers (EMAT) elements for exciting and detecting the S/sub 0/ Lamb wave mode in a 5-mm thick aluminium plate are processed with both algorithms and the results are discussed.