Experimental Mechanics

, Volume 8, Issue 7, pp 289–299 | Cite as

Stress waves in pyramids by photoelasticity

Experimental investigation was undertaken for the purpose of gaining a better understanding of how a doubly tapered section conditions stress waves
  • A. Okada
  • D. M. Cunningham
  • W. Goldsmith


The propagation of stress waves in pyramids was studied photoelastically with the application of a laser-photomultiplier tube system and an internal polariscope for recording moving fringes. Dispersion and attenuation of stress waves were considered in a straight bar, a 5-deg pyramid, and a 20-deg pyramid made of Hysol 4290 epoxy plastic. In the straight bar and 5-deg pyramid, longitudinal waves propagate without any dispersion even though the waves attenuate as they progress down the models; in the 20-deg pyramid, however, the dispersion of the stress waves is quite significant. The distributions of the axial and radial stresses and the photoelastic fringe patterns obtained on the 20-deg pyramid show that the stress wave front is spherical with the maximum stress along the central axis of the pyramid. A one-dimensional theory of wave propagation without correction factors in a small-angle infinite cone compares well with the experimental results.


Attenuation Epoxy Fluid Dynamics Longitudinal Wave Pyramid 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



cross-sectional area, in.2


Young's modulus, lb/in.2


applied force, lb


fringe order, dimensionless


strain-gage factor, dimensionless


diameter, in.


stress-optic coefficient, psi/fringe/in.


strain-optic coefficient, (in./in.)/fringe/in.


thickness, in.


mass, lb-sec2/in.


radius, in.


time, μsec


displacement, in.


weight, lb


dilatational wave velocity, in./sec


rod wave velocity, in./sec

pσ,qσ andrσ

principal stresses, lb/in.2

pε,qε andrε

principal strains, in./in.


wavelength, in.


wavelength of the shortest significant Fourier component


stress, lb/in.2


strain, in./in.


mass density, lb-sec2/in.4

λ, μ

Lamé constants, lb/in.2


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Copyright information

© Society for Experimental Mechanics, Inc. 1968

Authors and Affiliations

  • A. Okada
    • 1
  • D. M. Cunningham
    • 2
  • W. Goldsmith
    • 2
  1. 1.Rocketdyne Corp.North American Rockwell Corp.Canoga Park
  2. 2.University of CaliforniaBerkeley

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