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Experimental investigation of transient flexural waves in beams with discontinuities of cross section

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Abstract

There has been little experimental work on flexural wave propagation in general and on flexural wave propagation in beams with discontinuities of cross section in particular. Experimental data are obtained for various test beams subjected to eccentric longitudinal impact. The bending strain versus time results are presented for several positions along a uniform beam and finite beams (of circular cross section) with discontinuities of cross section. Bending strain histories are recorded at several positions before and after the discontinuity. The effect of reflections on the propagated flexural wave is illustrated. The dispersion of the traveling flexural wave caused several alternating peaks within the duration of the original positive input pulse. The importance of investigating discontinuities of cross section in structures subjected to impact loading is clearly manifested.

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Abbreviations

c 1 :

dilatational wave velocity in a beam

c 2 :

shear wave velocity in a beam

d :

diameter of cylindrical bars

D 1 :

diameter of discontinuous cylindrical beam in region 1

D 2 :

diameter of discontinuous cylindrical beam in region 2

DR :

diameter ratio (D 2/D1)

k 2 :

shear correction factor

E :

modulus of elasticity

F :

impact force

G :

modulus of rigidity [E/2(1+ν)]

p :

pressure

t :

time

\(\dot u\) :

particle velocity

ν:

velocity of impact

x :

coordinate along the beam

ν:

Poisson's ratio

ϱ:

density of beam material

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Authors and Affiliations

  1. Department of Mechanical and CAE, North Staffordshire Polytechnic, Beaconside, ST18 0AD, Stafford, England

    M. M. Al-Mousawi (Senior Lecturer)

  2. Department of Mechanical Engineering, The City University, Northampton Square, London, England

    H. R. Harrison (Senior Lectures)

Authors
  1. M. M. Al-Mousawi
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  2. H. R. Harrison
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Al-Mousawi, M.M., Harrison, H.R. Experimental investigation of transient flexural waves in beams with discontinuities of cross section. Experimental Mechanics 27, 404–413 (1987). https://doi.org/10.1007/BF02330315

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  • DOI: https://doi.org/10.1007/BF02330315

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