A New Approach to the Forming of Thermoplastic-Matrix Continuous-Fiber Composites — Part 2: Experiments and Model

ABSTRACT: "Die-less forming " is a new concept, intended to manufacture long compo-nents of continuous-fiber thermoplastic-matrix composites. The concepts behind die-less forming have been tested in experiments on a two-roller demonstration machine. The experiments focused on finding the effects of important forming parameters on the shape. Laminates with special lay-up were also made and formed to study the effect of lay-up on shape. Quasi-isotropic laminates showed an unexpected "excess bending. " An elastic/visco-plastic model has been developed to explain and predict this excess bending during die-less forming. The model is rate dependent and captures the shape dependency on strain rate, transverse feed magnitude and the lay-up. The model is based on the application of the principle of virtual displacements. The model predicts the net bend angle well for quasi-isotropic laminates. 1. EXCESS BENDING DUE TO INCREMENTAL FORMING I N THE DIE-LESS forming process, we control the position of the rollers andhence the way the component exits the forming zone. The material does not allow in-plane changes in area. Hence, we consider only developable shapes to be formed out of continuous fiber laminates. Although the shapes before and after the bend is propagated are developable (inextensible) surfaces, the interme-diate shapes are not. Referring to Figure 1, the constraints on the component are as follows: o The left of the component is fixed to an XZ table. This article was invited by the edito