Low velocity impact of composites manufactured using out-of-autoclave process

Autoclaves have been commonly used to manufacture high performance composites for aerospace applications. However, high capital and tooling costs make these composites very expensive. Vacuum-bag-only cure out-of-autoclave (OOA) composite manufacturing process is potentially a lower-cost alternative to autoclave manufacturing. The OOA process does not require the positive pressure of an autoclave but still produces high quality composite parts. In the present study, high performance carbon/epoxy (MTM45-1/CF2412 carbon fabric) composite laminates have been manufactured using the OOA process. The low velocity impact response of the manufactured panels has been evaluated. Series of experiments based on Design of Experiments and Analysis of Variance (ANOVA) were designed and conducted to study the effect of varying the size of the test panel, lay-up configuration and thickness on the impact behavior of composites. Energy absorbed, peak force, contact duration, and maximum displacement were evaluated. Composites manufactured using OOA process had less than 0.25% void content. Impact energy versus time, contact force versus time, and contact force versus displacement plots were presented. Results showed that the amount of energy absorbed by the composites is significantly influenced by size, lay-up, thickness and the two-way interactions among the parameters. The peak force, contact duration and maximum displacement are mainly influenced by size, thickness and the interactions between size and thickness.