Investigation of the computational efficiency and validity of the surface response to excitation method

• SuRE method is implemented using DSP, spectrum analyzer and laser vibrometer.
• The DSP system was the fastest device capable to obtain the system characteristics.
• Only laser vibrometer method was able to estimate the location of external load.
• The SuRE method was found accurate as long as the surface was excited properly.
• Goertzel algorithm estimated the magnitude most robust against environmental noise.

The Surface Response to Excitation (SuRE) method excites the surface of the structure with a piezoelectric element. The generated vibrations at critical points on the surface are measured with other piezoelectric elements, a laser vibrometer or other sensors. Then the magnitude of the transfer function between the excitation and the sensory signal is monitored. The performance of the SuRE method was evaluated using a low cost Digital Signal Processor (DSP) system, spectrum analyzer, and laser vibrometer. The accuracies of the Teager–Kaiser (TKA), Goertzel, RMS and average of the positive values algorithms were evaluated for magnitude estimation. The SuRE method was employed successfully for detection of compression loads by using the DSP system. Existence of composite coating was inspected using a spectrum analyzer. Finally, the method was used to detect localized loads on an aluminum plate with a laser vibrometer. The study indicated that the SuRE method may be used as a low cost alternative to impedance method. The inconvenience of using separate sensor(s) is the disadvantages of the SuRE method respect to the impedance method. The main advantages are requirement of simpler and cheaper instrumentation for data analysis, defect location estimation capability when multiple sensors are used, faster data acquisition at low noise environments, and allowing non-contact sensors such as laser vibrometers for measurement of surface response.