Contact:
Rani Warsi Sullivan
Mississippi State University
Aerospace Engineering
P.O. Box A
MS State, MS 39762
Tel: (662) 325-3274
sullivan@raspet.msstate.edu

In order for advanced composite materials to be more widely used for structural applications, it is necessary to understand the nature of changes in mechanical behavior as composite laminates are scaled to size. In order to reduce production cost, full-scale structures are typically designed using small-scale coupon and/or scale model testing. These results must then be used to predict the behavior of the full-scale part. It is necessary, therefore, to know if composite materials show any size effects.

Certain brittle materials such as glass and ceramics exhibit size effects. While not classically brittle, composites do display brittle failure mechanisms. Hence, particularly at cryogenic temperatures, it is of interest to know whether composites also demonstrate size effects.

MSU has commenced an effort to determine the "Size Effects in Ply- and Sublaminated-level Fiber Composites at Cryogenic Temperatures" in order to better understand the impact of extreme temperatures on composite materials. Three baseline laminates are being studied; one non-structural and two structural laminates. The materials utilized are typical graphite/epoxy. All tests are being conducted at the same cryogenic temperature.

It is anticipated that the results of these experiments will lead to a better understanding of scaling issues at low temperatures.