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

A new experimental technique for examining dynamic strain ageing in so lid solutions is proposed. It is based on the imposition of an oscilla tory perturbation on a tensile specimen monotonically deforming under strain or stress control. Experimental measurements on an Al-Mg-Si all oy show that the attendant oscillatory response has characteristic fea tures which may be used to detect and characterize dynamic strain apin g. A constitutive model which accounts for dynamic strain ageing is us ed to provide a theoretical basis for the analysis. A closed-form solu tion of the governing equations is obtained under the assumption of sm all 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 resul ts is obtained.