Millard Oakley STEM Center

A theoretical model has been developed to represent the interaction of a bar in longitudinal vibration with its surrounding viscous fluid. This model was generated to better predict the length of timber piles used in bridge foundation. Experiments were performed with sand and with several water–glycerin mixtures surrounding an aluminum bar, showing a significant effect of the bounding material on the vibration characteristics of the bar. The viscous fluid was observed to lower the measured frequencies, indicating system mass loading, while ...

In this paper we present the structure and first year results of a program aimed at enhancing the image of the metalcasting industry within multiple engineering and technology disciplines as an industry where high technology opportunities exist. The latter is especially effective in encouraging highly qualified engineering and technology students to choose to do research in the metalcasting industry. A dissemination plan is designed to further increase visibility of high tech research opportunities in the metalcasting industry.

Abstract A common occurrence of cavitation damage is the waterside pitting of a wet sleeve liner in a diesel engine. The automotive industry utilizes an ultrasonic test of 20 kHz according to ASTM standards to quantify the effectiveness of engine coolant additives to prevent damage. However, recent tests indicate a mismatch between the ultrasonic test results and actual engine test runs. The focus of this study is to generate numerical models of bubble dynamics using already published literature. In most of the published papers ...

Abstract The use of acoustic based measurements for machinery health monitoring of rolling element bearings is explored. Acoustic data was taken with several types of microphones placed very close to the bearings, to minimize the effect of background noise. Accelerometer measurements were also made on the system. A frequency spectrum analysis of acoustic and vibration data was done. The experimentation was performed on a Machine Diagnostics Trainer unit. The shaft is driven by a motor and supported by two bearings that can be ...

Abstract The Green's function for potential theory is developed for an axisymmetric void of arbitrary shape located between two parallel walls. Numerical results are given to demonstrate the accuracy in the Green's function formulation by comparison with numerical solutions obtained using a commercial finite element code. The present formulation is attractive since numerical implementation only involves unknowns on the surface of the void.

Flaws were detected in thin composite beams by using an autocorrelation method on frequency response functions (FRFs) obtained from transverse vibration data of a specimen. Signature plots that are representative of the damage state of the specimen were obtained by plotting autocorrelated magnitudes of the FRF against the length of the specimen. Flaws were detected by identifying extra peaks in the signature plot obtained from the damaged specimen when compared to that obtained from an undamaged specimen. From the ...

Abstract The autocorrelation of a structural FRF (frequency response function) can be used to extract structural parameters, such as length from a transversely vibrating beam. Further work has shown that the technique can also detect flaws in the structure. The frequency spacing between resonant peaks is extracted from the autocorrelation process and relates to the length of the object. Indicators of flaws in the structure were observed in the autocorrelation values plotted against a length axis. The first test structure was a free-free ...

Abstract Damage of diesel engine piston sleeve liners due to cavitation of the coolant fluid can be severe. Coolant fluid additives are used to inhibit cavitation damage, and are evaluated by industry suppliers using ASTM G32-98 Standard Test Method for Cavitation Erosion Using Vibratory Apparatus. The ASTM G32-98 test procedure uses an ultrasonic horn at 20 kHz to vibrate a test button in the coolant. The test button mass loss and surface appearance are studied to sort the performance of new coolant additives. Mismatch ...

The measurement of wooden piles for length determination in existing bridges presents a challenge to bridge inspection crews. The need to assess the pile length arises from nonexistent records for many bridges known to be scour susceptible. Where the foundation of a bridge may be compromised by possible SCOUT to a certain depth, it is mandatory for inspectors and engineers to know the full pile length in order to assess the bridge capacity based on the unscoured portion of the embedded pile.

ABSTRACT. A ruggedized field measurement system for determining wood pile lengths of existing bridges is presented. The development of the measuring system was the goal of a two year funded research project sponsored by the Tennessee Department of Transportation. The measurement technique is based on longitudinal vibration theory. Determination of the wave speed in the wood and the resonant frequencies of a pile will yield the length estimation.

Abstract The Green's functions for the line force and dislocation that satisfy the traction free boundary condition on the surfaces of arbitrary multiple straight cracks in the isotropic solids are obtained. We develop the hybrid Green's functions combining the analytical and numerical Green's function methods. The Green's function is split into the singular and the image terms. The crack opening displacement, represented as the continuous distribution of dislocation dipoles over each crack, serves as the source of the image term.