BS in Materials Engineering
Materials Engineering Department
Engineering firm Pratt & Miller have developed a new and previously untested carbon fiber/epoxy composite using a spray lay-up process similar to a process commonly used in fiberglass production. This new composite is made by using a pneumatic chop gun that simultaneously cuts the carbon fibers to a specific length and deposits the chopped fibers and resin onto surface of an exposed mold surface. The composite is then rolled down to flatten and better wet the fibers and then the whole mold is vacuum bagged at room temperature to cure. The flexural stiffness and flexural strength of the composite with 1” and ¾” average fiber lengths were found using three-point bend testing. The bend test samples had dimensions of 50.8 mm x 12.7 mm x 1.40 mm as per ASTM 790-03 for thin sheet materials. Because initial tests showed that there was too much scatter in the data due to thickness variations within the samples, they were flattened using a belt sander to within 0.1 mm of their average thickness. The material exhibited an average flexural stiffness of 28 GPa and an average ultimate flexural strength of 400 MPa.