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Search Publications by: Marvin Hamstad (Assoc)

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Displaying 1 - 21 of 21

On Lamb Modes as a Function of Acoustic Emission Source Rise Time

January 1, 2010
Author(s)
Marvin A. Hamstad
A study was carried out to examine Lamb-wave modal content as a function of the acoustic emission (AE) source rise time. The study used a validated finite element code to model the source operation and subsequent wave propagation up to a distance of 480 mm

Acoustic Emission Source Location in a Thick Steel Plate Using Lamb Modes

January 1, 2007
Author(s)
Marvin A. Hamstad
Using a validated finite-element modeling code, buried out-of-plane (two dimensional code (2D)) and in-plane (three dimensional code (3D)) acoustic emission (AE) dipole point sources were operated at different depths below the top surface of a 25.4 mm (1

Small Diameter Waveguide for Wideband Acoustic Emission

January 1, 2006
Author(s)
Marvin A. Hamstad
The signals obtained from two wideband conical sensors were compared in the time, frequency and the time/frequency domains. The signals were generated by pencil lead-breaks on the surface (out-of-plane) or close to the midplane of the edge (in-plane) of a

Practical Aspects of Acoustic Emission Source Location by a Wavelet Transform

January 1, 2003
Author(s)
Marvin A. Hamstad, K S. Downs, Agnes O'Gallagher
An algoithmic approach to improve the accuracy of AE source location was demonstrated by using a large database of wideband-acoustic-emission-(AE)-modeled signals and wavelet transform (WT) results. The AE-signal database was created by a three-dimentional

Finite Element and Plate Theory Methods for Modeling Acoustic Emission Waveforms

October 1, 2002
Author(s)
W H. Prosser, Marvin A. Hamstad, John M. Gary, Agnes O'Gallagher
A comparison was made between two approaches to predict acoustic emission waveforms in thin plates. A normal mode solution method for Mindlin plate theory was used to predict the flexural plate mode response to a point source, step-function load, applied

Detectability of Slow Crack Growth in Bridge Seels by Acoustic Emission

December 1, 1998
Author(s)
Marvin A. Hamstad, Joseph D. McColskey
The detectabillity of slow crack growth of cracks in bridge steels has been studied by use of acoustic emission testing technology. Fatigue crack-growth rates of nominally 1x10 -4 mm/cycle (4x10 -6 in./cycle) and 1x10 -3 mm/cycle (4x10-5 in/cycle) were

Development of Practical Wideband High-Fidelity Acoustic Emission Sensors

June 1, 1995
Author(s)
Marvin A. Hamstad
The development of a series of wideband acoustic emission (AE) sensor/preamplifier systems is described. Key design factors are discussed along with the actual design and characterization of the sensors. These new sensors with integral amplification are