What happens is the fluid that's sprayed into each fibre of the yarn starts to stiffen up and resist that mechanical strain.

The strain sensitivity characteristic of long-period fibre grating (LPFG) was studied by coupled-mode theory and the strain sensitivity analytic equation of the resonant wavelength was deduced.

The forging processes of the both kinds of billets were simulated by contrast with FEM and the distributions of their velocity, strain and fibre flown line were gotten.