変断面棒の縦衝撃強度

抄録

In high-speed impact test of metals with a rotating disk type high-speed tensile testing machine, the stress-time record obtained by the use of a load cell attached to the specimen in series does not always tell how the specimen itself undergoes. This will become serious at high impact velocities, for the irregularity of strain distribution in such a system becomes conspicuous with in-creasing impact velocity. Therefore, to make clear the relation of stress in the specimen to that in the load cell, a round bar made in two sections of different diameters as a model of the system comprising the specimen and the load cell is pictured, and the longitudinal stress wave propagation in it is discussed in detail. Important problems first encountered with this model are the reflection and transmission of stress wave involving plastic wave at the discontinuity. Since these problems for elastic wave have hitherto been dealt with, calculations are made for plastic wave with some interesting results, and the conducted test and how the stress wave propagates are outlined. Furthermore, the case of elastic wave propagation in a bar of continuously varying cross-section is also dealt with by the use of hypergeometric function and Bessel function. This way of solving can be applied to cases of elastic wave propagation in various forms of bar of varying cross-section, for hypergeometric function involves three arbitrary parameters.