Please use this identifier to cite or link to this item: https://hdl.handle.net/11681/11141
Title: Analysis of D'Alembert unfolding technique for Hopkinson bar gage records
Authors: Mississippi State University. Department of Aerospace Engineering.
United States. Defense Nuclear Agency.
Ohrt, Alan Paul.
Keywords: Airblast measurement
Bar gages
D'Alembert unfolding
Reflections
Stress waves
Stress wave transmission
Unfolding
Strain gages
Measurement
Publisher: Structures Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Technical report (U.S. Army Engineer Waterways Experiment Station) ; SL-92-12.
Description: Technical Report
Abstract: The bar gage is an instrument frequently used to make measurements of airblast pressures produced by explosive charges. The blast pressure to be measured is applied to the end of a strain-gaged steel bar. Unfortunately, reflections from the ends of the bar will be superposed upon the pressure input, limiting the useful record length. In 1983, a method of numerically removing these reflections was proposed. This method, based upon the D'Alembert solution to the thin rod wave equation, "unfolds" the reflections, thereby creating a record of original pressure input. In this thesis, the uncertainty of the results from the D'Alembert unfolding method are studied. These error sources are considered: wave speed, reflection coefficients, and dispersion. Numerical and analytical techniques are applied to obtain the uncertainty for an arbitrary pressure wave form. Specific wave forms are unfolded and evaluated to draw general conclusions regarding the uncertainties inherent to the unfolding technique.
URI: http://hdl.handle.net/11681/11141
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