A methodology of constructing dynamic deformation diagrams based on the method of direct impact on a vertical gas-gun stand has been developed and theoretically verified. A methodology of determining dynamic yield strength as a function of strain rate in every experiment in the implemented strain rate range has been realized and tested. The methodology has been verified by a step-by-step reconstruction of a given static deformation diagram and a strain-rate/ultimate dynamic yielding relation when substituting the physical experiment by computer modeling of an axisymmetric problem, accounting for the wave processes in the striker-specimen-measuring rod system. The main inaccuracies in determining (reconstructing) viscoplastic characteristics of materials are shown to be determined by the degree of accuracy of experimental measurements. Based on the method of characteristics, an algorithm has been developed for calculating the displacements of the impacted end of the rod based on the results of the measurements of strains by two gauges in the vicinity of the impacted and supported ends of the rod for a multiply passing strain wave. This makes it possible to analyze the deformation process up to the moment the striker stops and to compare the computational and experimental results based on the residual size of the tested specimen.
|
