MECHANICAL PROPERTIES OF OUT-OF-AUTOCLAVE NON-CRIMP FABRIC EPOXY COMPOSITES FOR MANUFACTURING PLANT ELEVATIONS

Mechanical properties of a commercial out-of-autoclave non-crimp fabric epoxy prepreg (AR2527 NCF) composite were investigated in detail for the manufacturing plant elevations. To simulate the effects of elevation, the vacuum pump used for pulling vacuum from the laminate during debulking and curing was adjusted to provide two different vacuum pressures: 1) 96 kPa corresponding to 450 m elevation in Wichita KS, and 2) 84 kPa corresponding to 1550 in elevation in Denver CO. One laminate for each vacuum pressure was cured in an oven using manufacturer's recommended cure cycle and subsequently, the laminates were machined into appropriate mechanical test coupons tested at room temperature. It was observed that the average short beam shear, combined loading compression, and flexural strength of the prepreg dropped 5%, 9%, and 12% as a result of 1100 m increase in the elevation. It was also observed that the two laminates had similar porosity (similar to 4%). The decrease in mechanical properties of the prepreg was attributed to the increase in resin content of the laminate.