RAMPED OSCILLATORY TESTING - A NEW TECHNIQUE TO EXAMINE DYNAMIC STRAIN-AGING

A new experimental technique for examining dynamic strain ageing in solid solutions is proposed. It is based on the imposition of an oscillatory perturbation on a tensile specimen monotonically deforming under strain or stress control. Experimental measurements on an Al-Mg-Si alloy show that the attendant oscillatory response has characteristic features which may be used to detect and characterize dynamic strain aping. A constitutive model which accounts for dynamic strain ageing is used to provide a theoretical basis for the analysis. A closed-form solution of the governing equations is obtained under the assumption of small oscillatory perturbations. A full numerical solution is given for the Al-Mg-Si alloy which was tested using the technique proposed. Good agreement of the predictions of the model with the experimental results is obtained.