4.1 Experimental Results

The rate influence seems to be the central problem of dynamic plasticity. It has been known for many years that during dynamic testing, solids behave in a more or less different way than in static tests. Many theoretical and experimental papers have been devoted to this problem. Let us consider the problem shortly.

We discuss the main conclusion resulting from the experiments that have been performed. Details concerning the experimental techniques will not be given here. We shall see however, that in some experimental papers the wave propagation phenomena were disregarded, although the rate of loading was high. This can be done only if the specimen is very short. The old tests are discussed in detail by Cristescu [1967], Cambell [1970], Cristescu and Suliciu [1982] and Goldsmith [2001], and will not be mentioned here any more. Only a few tests will be revealed. Strain rates ranging between 10 ^?5 sec ^{? 1} and 10 ^{? 3} sec ^?1 are termed static tests. Tests in which the rates of strain range between 10 ^?2 sec ^?2 and 10 ² sec ^{? 1} can be termed intermediate tests (these are the rates of strains usually met in various metal working processes, for instance), while the tests producing rates of strains above 10 ² sec ^{? 1} (and certainly of the order of magnitude of 10 ³ sec ^{? 1} and higher) can be called dynamic in the...