Mixed mode partition theories for one dimensional fracture

The crack in a double cantilever beam is the most fundamental one-dimensional fracture problem. It has caused considerable confusion due to its in-depth subtleness and complex entanglement with different theories and numerical simulations. The present paper presents completely analytical theories based on Euler and Timoshenko beam theories using a brand new approach which reveals the hidden mechanics of the problem. Orthogonal pairs of pure modes are found and used to partition mixed modes. The developed theories are extensively validated against numerical simulations using finite element methods. Moreover, the fracture mode partition space is thoroughly investigated and crack tip running contact is found which results in a region of pure mode II. The theories are finally applied to general one-dimensional fracture in beams and axisymmetric plates.

► Double cantilever beams are modelled with Euler, Timoshenko beam theory.
► Two sets of orthogonal pure modes are found.
► Hidden interactions between pure orthogonal modes are discovered.
► Crack tip running contact and a pure mode II region are found.
► A completely analytical mixed mode partition theory is developed.