An improved compression molding technology for continuous fiber reinforced composite laminate: Part 1: AS-4/LaRC-TPI 1500 (HFG) prepreg system

Original publisher: Hampton, Va. : National Aeronautics and Space Administration, Langley Research Center ; [Springfield, Va. : National Technical Information Service, distributor, 1991] OCLC Number: (OCoLC)58957608 Excerpt: ... CONSOLIDATION MECHANISM As noted above, a 12 % difference in the degree of volume compaction is observed between panel MW103, which employed internal molding stops, and panel MW104, which did not. Despite the use of an identical molding cycle, i.e., 15 minute hold at 750 ° F and 100 psi, a dramatic difference in the consolidation qualities between these two composite panels was noted from the C-scans shown in Figures 3 and 5. Such a difference is attributable to the observed 12 % difference in the volume compaction experienced by these two panels. The following discussion will address the origins which give rise to the observed variation of the volume compaction. In the case of run MWl03, two molding stops measured. 250 " in total width were used during the initial B-stage at the 650 ° F cure step. Prepreg plies were cut to 3.000 " in the fiber direction and 2.750 " in the lateral direction. The Whole assembly ( prepreg plies and molding stops ) were fitted into the space of a 3.000 " x 3.000 " mold cavity. After the B-stage cure step the stops were removed. A 15 minute hold at 750 ° F and 100 psi was then applied to the composite panel to complete the final consolidation step. At the completion of the molding cycle, the composite panel had spread to fill the mold dimensions of 3.000 " x 3.000 " and was fully consolidated. Obviously, the extra space provided by the removal of the molding stops during the final consolidation step contributes to the higher volume compaction level noted for this panel ( MW103 ). Given the final panel ( MW103 ) thickness of 0.058 " ( see Table 3 ), it is calculated that Effective volume of stops = 3.000 " x 0,250 " x 0.058 " = 0.0833 Volume of panel 3.000 " x 3.000 " x 0.058 " where the effective volume of...