OUT-OF-PLANE BUCKLING OF FIBER-REINFORCED THERMOPLASTIC SHEETS UNDER HOMOGENEOUS BIAXIAL CONDITIONS

The mechanical behavior of fiber-reinforced composite thermoplastic sh eets during forming processes is modelled as a viscous fluid with inex tensibility and incompressibility constraints. Techniques of linear st ability analysis are used to study the growth or decay of initial impe rfections in plane sheets reinforced by two families of fibers subject ed to biaxial strains. This theory delimits situations when buckles ca n be expected to form during forming operations.