Single prepreg layer

Single Prepreg Layer. For the sake of illustration, we shall first confine ourselves to the lamination of one prepreg layer for which the two resin layers are of equal initial thickness ( Ao Ai = A). 

All specimens were made from IM7/977-2 prepreg supplied by Cytec. One single panel, 300 mm X 750 mm was laid up by hand on a warm table because the prepreg was not particularly tacky. Hot de-bulks (vacuum only, 60 C) were carried out after every fourth layer. A 10 p.m FIFE film was inserted in the mid-plane of the laminate in order to simulate an artificial crack. A final pressurised de-bulk (120 C, 3 bar pressure, 30 minutes) was carried out in order to reach a laminate thickness close to neat cured thickness, prior to Z-pinning with 0.28 mm diameter pins (T600/BMI), at densities of 0.5%, 2% and 4% in the selected locations. Table 1 summarises the range of specimens made. 

Far and away, the most common process extant is to place layers (called courses) of prepreg carbon tow onto a mold or tool, then cover the form with a single layer of sateen weave carbon cloth to prevent drill breakout, and to bake the resultant element in an oven under pressure while applying a vacuum to the matrix interior to reduce the gas content of the matrix. Gasses are inevitably produced during the matrix curing and must be dissolved or extracted to eradicate voids. 

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