Estimation of non-coaxiality from crinoid-type pressure fringes: comparison between natural and simulated examples

The development of rigid crinoid-type pressure fringes is simulated for variable shape and orientation of the rigid original grains, matrix flow pattern and total strain, using Etchecopar and Malavieilleʹs model, which is based on a principle of geometrical minimization of the gap between a rigid grain and its ductile matrix. A method of determining the non-coaxiality of the matrix flow is constructed assuming two-dimensional flow with constant area and time-independent flow parameters. In this method, the systematic variation in the geometry of the pressure fringes as a function of the shape and orientation of the rigid original grains, is used as a criterion. The application to the natural examples shows consistent variation in the geometry of pressure fringes with the simulation. This indicates the validity of the method as long as the assumptions hold.