Dwayne McDaniel

Implementation of the Surface Response to Excitation Method for Pipes

The Surface response to excitation (SuRE) method was developed to detect the defects and loading condition changes on plates without using the impedance analyzer. The SuRE method excites the surface with a piezoelectric exciter. Generally, sweep sine wave is continuously applied and surface waves are monitored with (a) piezoelectric element(s) or noncontact sensor(s). The change of the spectral characteristics is quantified by using the sum of the squares of the differences (SSD) to detect the defects. In this study, the SuRE method was implemented for detection of the defects in pipes. The surface of a pipe was excited with a continuous sweep sine wave and the dynamic response of the pipe on selected points were monitored by using a scanning laser vibrometer. The study shows that the SuRE method can be used effectively for detection of damage and estimation of its severity in pipe like structures.

Load Monitoring Using Surface Response to Excitation Method

Surface response to excitation (SuRE) method is a low-cost alternative to the electromechanical impedance method developed for the structural health monitoring (SHM) applications. This method uses one piezoelectric transducer to excite the surface of a structure with a sweep sine wave. One or more piezoelectric sensors or scanning laser vibrometer monitors the dynamic response of the surface to the excitation. The spectrum of the dynamic response is collected at the optimal operating conditions. Any significant change of the spectral characteristics may indicate defects, improper loading or loose fasteners.

Composites Bond Inspection Using Heterodyne Effect and SuRE Methods

With increasing utilization of the composite materials in commercial and military applications, the longevity of composite bonds has become a crucial concern of the aerospace industry. In spite of the previous studies in the literature for characterization of bonding condition in composite materials, implementation of more advanced structural health monitoring (SHM) techniques are still required to ensure flight safety and quick inspections of structures. In this study, two different SHM methods were used to evaluate the strength of composite bonds by using two separate experimental setups. First, the heterodyne effect method was used for assessing the separation in the composite joint. Then, the surface response to excitation (SuRE) method was used for studying various simulated contamination levels. Results of the experimental studies showed that the proposed methods could be efficiently utilized for evaluating bonding strength of composite materials.