Squeeze flow in thermoplastic composites

The simplest approach to modelling the behavior of an idealized (incompressible and inextensible) thermoplastic composite under squeeze flow conditions has been proposed by Rogers [5] using a Newtonian fluid continuum model. Provided the fibers do not bend or rotate during forming, the inextensibility constraint only allows a plane 

For a constant cross-head speed, the platen gap decreases in a nonlinear manner with time and the predicted compression load is highly dependent on the interface condition. In reality, a slip-stick boundary condition applies at the contact surface, unless special care is taken to lubricate the interface to ensure full-slip. 

Using the concept of a shear thinning fluid, Shuler and Advani [8] investigated the use of a Carreau fluid model to fit the squeeze flow data for a clay/nylon and an APC-2 composite material. Their results were calculated numerically assuming a full-stick flow condition and seem to match their experimental data quite well. In particular, they studied the 

Rogers, T.G. (1989) Rheological characterisation of anisotropic materials. Composites, 20(1), 21-27. 

and Gutowski, T.G. (1991) Laps and gaps in thermoplastic composites processing. Composites Manufact., 2, 69-78. 

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