The Observation of Stress Wave in a Rectangular Bar Using the High-Speed Holographic Interferometry

抄録

In this paper, the stress wave propagating in a steel bar with rectangular cross section is observed by using the holographic interferometry with pulsed laser, and the distribution of the in-plane displacement is obtained. In order to evaluate the displacement produced by the stress wave, the relative fringe order method is convenient, but there are two fundamental problems in this measurement. One is that holographic images recorded by pulsed laser are usually reconstructed by continuous beam with different wavelength and the reconstructed images are more or less distorted. The effect of wavelength of the reconstruction beam on the fringe order is discussed. The second problem is that if the spatial array of the fringe order is not monotonous, usual method can not be used to obtain the relative fringe order. A process is presented for determining the relative fringe order in such a case. From the hologram record of the transient wave in a steel bar, the in-plane displacement distribution along the center line of the surface is obtained. This result is compared with that measured by use of a strain gauge, and the former agrees with the latter very well.