(Received 27 August 2014; accepted 2 March 2015)
Published Online: 06 May 2015
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Tactile pressure sensors are flexible, thin sheets containing a matrix of sensors, which are used to measure earth pressures in geotechnical applications. Although more successful in static and 1-g shaking table tests, available tactile sensors do not capture the full amplitude content of dynamic signals in centrifuge experiments. This is due to under-sampling and the sensor’s frequency-dependent response. A minimum sampling rate of 3000 samples per second is recommended in centrifuge testing to avoid under-sampling and capture frequencies up to 300 Hz in model scale. A new dynamic calibration methodology is proposed to characterize the sensor’s frequency-dependent response by evaluating how it attenuates pressure at higher frequencies. Sinusoidal loads are applied to the sensor at different frequencies, and the applied pressure is simultaneously recorded by a reference load cell and a tactile sensor. A transfer function is then calculated by dividing the Fourier pressure amplitude of the load cell by that of the tactile sensor at a given frequency. To dynamically calibrate tactile sensors, this transfer function may be used as an amplitude correction function under general loading. Through a series of blind dynamic tests, the proposed frequency-dependent, dynamic calibration methodology is shown to reduce the peak residuals between the tactile and reference sensor recordings from approximately 0.55 to 0.15 at frequencies below 300 Hz.
Ph.D. Candidate, Department of Civil, Environmental, and Architectural Engineering, Univ. of Colorado, Boulder, CO
Assistant Professor, Department of Civil, Environmental, and Architectural Engineering, Univ. of Colorado, Boulder, CO
Hashash, Youssef M. A.
Professor, Department of Civil and Environmental Engineering, Univ. of Illinois at Urbana-Champaign, Champaign, IL
Stock #: GTJ20140184