| Abstract: | Stress-strain relationships for metals at high strain rates have long been studied, but no really reliable and generally accepted theory has emerged. It is sometimes assumed that the dynamic stress-strain diagram is largely insensitive to the rate over a certain range. Another approach is to insert derivatives of the stress and strata with respect to time. One difficulty in establishing the actual reIationships is that experiment provides only indirect evidence (direct tests are usually impossible). Any real dynamic experiment tends to produce complicated effects, which can be interpreted only if the basic equations are taken as known. The best that experiment can then do is to confirm or reject some prior assumptions.Many experimental studies deal with mechanical characteristics such as breaking strength and yield point as functions of strain rate; however, strain rate characterizes a range of conditions rather than defines a parameter. We therefore have to use simple models that allow formulation and solution of definite mechanical problems in relation to the dynamics of elastic-plastic media. |
