BOOK REVIEWS a fluid-filled tube in which the tube can be elastic or viscoelastic but the fluid is assumed to be incompressible and inviscid. All articles are very mathematically and analytically oriented. Nevertheless, the articles cover a fairly wide range of wave propagation phenomena in viscoelastic media. In view of the fact that there are not many books available on viscoelasticity and even fewer on wave propagation in viscoelastic media, the appearance of this volume is welcome. It would serve as a useful reference for those who want to venture into this field.

Dispersion of an elastic wave propagating in a 76.2-mm-diameter (3 in.) Split Hopkinson Pressure Bar system was investigated with two consecutive pulses recorded in the transmitter bar. Assuming that the dispersive high frequency oscillatory components riding on the top of the main pulse originate from the first mode vibration, the dispersion was corrected by using the Fast Fourier Transform (FFT) and Fourier series expansion numerical schemes. The good agreement validates the assumption that only the first mode was significant. The dispersion correction technique was employed in a test of a concrete specimen having the same diameter as that of the SHPB. Better agreement of the two specimen-bar interface stresses versus time and fewer oscillations in the stress-strain curve demonstrated advantages of the application of dispersion corrections.

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In addition to delamination, which has been found to be the major failure mode in a fiber-reinforced laminated composite plate subjected to subperforation impact, matrix cracking and fiber breakage have also been observed. Each failure mode, however, does not generate independently. On the contrary, the different modes interact with one another. Therefore, in order to have an overview of the failure mechanism in an impacted com posite plate, it is necessary to find out the mechanism of every failure mode and the in teractions among them. Microscopic observations of the cross sections of impacted com posite materials have revealed the interaction between matrix cracking and delamination. In this study, however, several techniques have been used to present the matrix cracking patterns in impacted glass/epoxy plates with different thickness, geometries, boundary conditions, stacking sequences, and types of loading. The matrix cracking patterns on the surfaces of impacted plates have been enhanced by dye penetrant while those of the in ternal laminae have been investigated by edge replication. Results have shown that the delamination area on the second interface of a three-lamina glass/epoxy plate coincides with both the central matrix cracking zone of the impacted lamina and the middle crack- free zone of the non-impacted lamina. The matrix cracks in the internal lamina are also restricted by the projected delamination area. The association between delamination and matrix cracking has been discussed and also the effect on matrix cracking of the tensile stresses introduced by the flexural wave.

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