A double transform method is used to solve the problem of determining the elastic strain in a semi-infinite cylindrical bar with a stress free lateral surface, subject to the end conditions that the stress applied normally to the end is uniform and has a step function time dependence and that the radial displacement at the end is always zero. The exact solution appears as a sum of Fourier integrals whose integrands have the form of Pochhammer-Chree waves. These integrals cannot be evaluated in general by simple means, but asymptotic solutions have been obtained which are valid for large distances of travel. The theoretical predictions are compared with the results of experiment in a companion report.
Measurements are presented which show that the elastic strain produced in a cylindrical bar by stepfunction end-loading corresponds closely to predictions of the theory presented in Part I. In particular, even at large distances from the end of the bar, there is an observable strain moving faster than the bar velocity determined by Young's modulus. The theoretical shape for the head of the pulse conforms to experiment, and the head is followed by oscillations having the correct periods and amplitudes. Second-mode oscillations appear at the times predicted and with the expected periods and amplitudes.
Equipment is d escribed for elongating yarns by longitudinal impact at velociti es ranging from 10 to 100 mcters p er seco nd . Th e ra te of straining at impact varies from about 100,000 to 500,000 precen t p er minute .A procedure is di scussed for obtaining load-elongat ion curves for loading and for unloadin g of t he specimen and for loading to rupture in a time interval of only a few mi ll iseconds. The res ul ts of a typicalloftding and un loading test are prese nted.
Equipment is described for elongating yarns by longitudinal impact at velocities ranging from 10 to 100 m/sec. The rate of straining at impact varies from about 100,000 to 500,000% per min.A procedure is discussed for obtaining load-elongation curves for loading and for unloading of the specimen and for loading to rupture in a time interval of only a few milliseconds. The results of a typical loading and unloading test are presented. '
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