Experimental Mechanics

, Volume 17, Issue 11, pp 415–419 | Cite as

Measuring small internal pressures along a tube during steady flow

Equiangular strain-gage rosettes aligned as stress-gage pressure transducers measured the small strains and pressures along a thin-walled aluminum tube during extrusion of a viscous silicone oil
  • H. S. FreynikJr.
  • G. R. Dittbenner


A tube that can accurately measure small strains and pressure profiles during flow of non-Newtonian paste explosives has been designed and strain gaged. Equiangular rosette strain gages were installed along the length of a 6-mm-diam, 0.46-m-long thin-walled aluminum tube. The rosettes were oriented in the classical stress-gage configuration to measure circumferential stress and, hence, internal pressure independent of other stresses.

The tube was static calibrated on a floating-piston pressure calibrator. Steady flow calibration was accomplished by extruding a viscous Newtonian silicone oil. Inlet pressure ranged from 0.52 to 2.1 MPa (75 to 300 psi). For the low-pressure 0.52-MPa silicone-oil extrusion, the full-scale strain levels varied from 6 to 53 μm/m. For all eight strain-gage stations, the maximum deviation from a linear pressure profile was equivalent to 0.5 μm/m. A pulsed-current-excitation signal-conditioning and digital data-acquisition system provided the necessary stability and precision to measure these unusually low-strain levels accurately.


Internal Pressure Steady Flow Pressure Profile Inlet Pressure Circumferential Stress 
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Copyright information

© Society for Experimental Mechanics, Inc. 1977

Authors and Affiliations

  • H. S. FreynikJr.
    • 1
  • G. R. Dittbenner
    • 1
  1. 1.Lawrence Livermore LaboratoryUniversity of CaliforniaLivermore

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