How ‘mixed’ is dynamic mixed-mode crack propagation? — A dynamic photoelastic study

Dynamic photoelastic fringe recordings associated with rapid curved crack propagation, crack division and the interaction between moving cracks and elastic waves show global dynamic mixed-mode crack-tip fringe patterns. When analysed by means of K-determination procedures an ‘apparent’ dynamic mixed-mode ratio K₂/K₁ may be denned which turns out to be a function of the particular selection of measurement data points. This paper compares experimentally recorded fringe data with numerical results in an attempt to resolve the dynamic photoelastic mixed-mode crack problem.