Abstract
An experimental study of the propagation of flexural waves in an elastic beam of circular cross section subjected to an approximate-step-function bending moment is given. The test beam was a low-carbon-steel bar 2 in. diam × 30-ft long and was suspended in a vertical position by a pin located near the upper end. The step moment was applied at the upper pinned end of the bar by an arrangement of two high-pressure, nitrogen-operated cylinders. The strains were measured with strain gages located at eight stations along the bar.
The experimental results are compared with results obtained from a solution of the “Timoshenko” beam by W. Flügge and E. E. Zajac for a semi-infinite pinned-end beam subjected to a suddenly applied bending moment at the pinned end. The experimental results are correlated with the predictions of the theoretical solution.
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Abbreviations
- A :
-
cross-sectional area, in.2
- A s :
-
effective shear area, in.2
- C m =C b :
-
propagation velocity of a discontinuity in bending=\(\sqrt {E/\rho } \), fps
- C v :
-
propagation velocity of a discontinuity in shear=\(\sqrt {GA_S /\rho A} \), fps
- E :
-
Young's modulus, psi
- G :
-
shear modulus, psi
- I :
-
area moment of inertia of cross section, in.4
- M 0 :
-
moment input, ft-lb
- a :
-
radius of bar, in.
- ω:
-
deflection normal to axis of bar, in.
- x :
-
space coordinate
- t :
-
time, sec
- λ:
-
wave length, in.
- ξ:
-
space coordinate, dimensionless
- ρ:
-
mass density at beam, mass per unit volume
- τ:
-
time, dimensionless
- K :
-
physical constant=ρA/EI
Bibliography
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at time that paper was prepared; is now Mechanical Research and Development Engineer, Hallibuton Co., Duncan, Okla.
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Stephenson, J.G., Wilhoit, J.C. An experimental study of bending impact waves in beams. Experimental Mechanics 5, 16–21 (1965). https://doi.org/10.1007/BF02320899
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DOI: https://doi.org/10.1007/BF02320899