Out-of-Plane Buckling of Fiber-Reinforced Thermoplastic Sheets Under Homogeneous Biaxial Conditions

The mechanical behavior of fiber-reinforced composite thermoplastic sheets during forming processes is modelled as a viscous fluid with inextensibility and incompressibility constraints. Techniques of linear stability analysis are used to study the growth or decay of initial imperfections in plane sheets reinforced by two families of fibers subjected to biaxial strains. This theory delimits situations when buckles can be expected to form during forming operations.