This paper addresses the determination of the evolution of the dynamic stress intensity factor Ktd(t) for a non-propagating crack subjected to transient loading. A new and rigorous approach is presented in its theoretical and experimental aspects. First, for linear-elastic materials it is shown that crack-tip singularities are related to global mechanical parameters (forces displacements on the boundaries of the structure) through the path-independent H-integral which includes dynamic effects. Ktd(t) is thus determined by solving a time convolution equation. Practical implementation of the method is then illustrated by a simple and original experimental procedure together with its numerical simulation. Experimental and numerical results are finally used to validate the feasibility and efficiency of the proposed method.