A constitutive relationship for metals compensated for adiabatic and friction effects

An investigation has been performed to determine the flow stress characteristics of two armour plate steels, pure iron and copper over the temperature range -100 degrees C to 20 degrees C and strain rate 10(-3) s(-1) to 5000 s(-2). The main experimental factors affecting the interpretation of Hopkinson bar test results have been examined. These include specimen-platen interfacial friction, adiabatic softening, inertia, wave dispersion and multiple wave reflection within the specimen. Significant corrections have been minimised through both experimental design and analytical techniques allowing the determination of fundamental stress-strain behaviour. The Armstrong-Zerilli model has been applied to corrected data and comparisons drawn between the different metals.