Analysis of Material Behaviour at High Strain Rates for Modeling Machining Processes
Today, in the field of numerical FEM simulation of processes, the availability of
reliable material data and models is becoming more and more important. It is recognised that
mechanical properties of materials are influenced by the conditions of loading. In all
industrial forming processes the workpiece material is deformed at different rates of straining
and at different temperatures: in the case of machining processes, the rate of straining in the
shear zone is in the 10 3 -10 5 s -1 range. So a material constitutive model that does not take the
effect of strain rates into account is not reliable. This work aims to present one approach to
the problem of obtaining both data and a proper constitutive model of the material to be
implemented into FEM code for the numerical simulation of machining processes. In this
approach, material behaviour is studied at the wide range of temperatures and strain rates
that are typical of machining processes. High strain rate tests cannot be done with
conventional hydraulic machines, but the Split Hopkinson Pressure Bar offers an effective
tool for studying the rate sensitivity of materials. A special heating device is utilised to raise
the temperature of the specimen in order to analyse material behaviour at typical shearing
zone and chip formation temperatures.
Paolo BARIANI, Guido BERTI, Stefano CORAZZA
Reçu le 25 septembre 2001.
Accepté le 29 octobre 2001.
High strain rate, flow stress, material behavior.