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Title: Analysis of Hopkinson bar pressure gage
Authors: United States. Defense Nuclear Agency.
Baylot, James T.
Keywords: Airblast pressure
Elastic wave propagation
Finite element analysis
Finite element method
Hopkinson bar
Pressure gages
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-93-1.
Description: Technical Report
Abstract: U.S. Army Engineer Waterways Experiment Station (WES) designed Hopkinson pressure bar gages were fielded on the Dilute Explosive Tile (DET) test along with New Mexico Engineering Research Institute (NMERI) designed bar gages and pressure gages manufactured by PCB Piezotronics, Inc. On the Mineral Find 3 (MF3) explosive test, WES bar gages were fielded along with pressure transducers manufactured by Kulite. The peak pressures recorded by the PCB gages were much higher than those recorded by the WES bar gages on the DET test. The peak stresses were higher for the Kulite gages than for the WES bar gages in the MF3 test. In each of these tests, the stresses recorded later in time for the bar gage were higher than those recorded for the other types of gages. The NMERI gages indicated that the pressure time-history had two significant peaks while the WES gages indicated only one significant peak. One-half of the surviving PCB gages agreed with the WES gages, while one-half agreed with the NMERI gages. Analytical and finite element (FE) calculations were performed to assess the response of the bar gages in these tests. The analytical solutions included only the bar and agreed extremely well with comparable FE calculations. These calculations indicated that the primary reason for the low peak stress readings in the bar gages was the lower frequency response capability of the recording system used to record the bar gage data. The calculations also indicated that the presence of water around the bar did not significantly affect the measured peak stress in the bar, and that the drag of the water past the bar did not cause significant forces to be developed in the bar. It appears that the late time rise in the stresses measured by the bar gages was due to the spacer block and water seal sliding down the bar. The calculations also indicated that the response of the NMERI bar gage should not be significantly different than the response of the WES bar gage. Therefore, it is concluded that the difference in character of the pressure time-histories between the two gage types is due to differences in character of the loading applied to the different gage types.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Technical Report

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