Stamp forming of fabric‐reinforced thermoplastic composites

Abstract A stamp forming technique has been used to process a fabric woven composite made of glass fibers (GF) and polyetherimide (PEI). A hemispherical mold with a built‐in hold‐down arrangement was designed and used at room temperature to stamp parts from preheated flat preconsolidated laminates. Tensile properties of the material were measured under similar heating conditions as in the relevant stamp‐forming process. Stretch in the fiber direction was found to be smaller than the maximum elastic extension of the glass fibers. Reduction of the angle between the crossing fibers was quite large when the satin woven fabric composite was pulled in the 45° direction. The effect of die geometries and original laminate dimensions on the “shear‐buckling” were studied. The results described the correlations between processing parameters and fiber buckling. Finally, the local strain of fiber bundles was investigated in relation to different directions of fiber orientation.