Open AccessDEVELOPMENT OF DIRECT IMPACT METHOD FOR DETERMINING DIAGRAMS OF DEFORMATION OF ELASTOPLASTIC MATERIALS AT LARGE DEFORMATIONS
Author(s) -
Artem V. Basalin,
A. Yu. Konstantinov,
Leopold Kruszka
Publication year - 2020
Publication title -
problemy pročnosti i plastičnosti
Language(s) - English
Resource type - Journals
ISSN - 1814-9146
DOI - 10.32326/1814-9146-2020-82-2-135-146
Subject(s) - deformation (meteorology) , bar (unit) , range (aeronautics) , compression (physics) , computer science , viscoplasticity , sample (material) , structural engineering , work (physics) , mechanical engineering , materials science , mechanics , finite element method , engineering , constitutive equation , physics , composite material , thermodynamics , meteorology
The description and results of the analysis of the experimental method that implements the so-called direct impact scheme built on the basis of the measuring bar technique are presented. This method is used to determine the deformation diagrams of viscoplastic structural materials under conditions of high-speed compression at higher strain rates than in the traditional Kolsky method. Particular attention is paid to a variant of the method in which a striker of the same diameter as the measuring bar is used. In this case, it becomes possible to use equipment of the standard test scheme according to the Kolsky method (in particular, loading devices). Thus, a system of basic testing of materials in a wide range of strain rates is built on a single hardware platform. A numerical analysis of this method is performed. A comparison is made of the characteristics of the sample deformation calculated directly in the numerical simulation and determined indirectly from the information from the measuring bar available in the full-scale test. It is shown that the deformation of the sample is determined precisely only on the time interval corresponding to the double run of the elastic wave along the impactor. A modification of the algorithm for processing the information obtained in this experiment is proposed, taking into account the interference of elastic waves in the impactor and allowing expanding the strain range for which this experiment provides reliable information about the material deformation curve. The work of the technique is demonstrated by the example of testing a sample of M1 copper. For this material, using the direct impact method, a deformation curve is constructed at a strain rate of the order of 104 s-1. It is shown that the traditional experimental data processing scheme gives unphysical overestimated values of the sample deformation.