Figure 3. Gradient Alloys for Carbon Fiber Composite Inserts.

– (a) Schematic of how gradient inserts were machined from a radially graded rod, shown in Fig. 2. (b) Enlargement of a carbon fiber/aluminum honeycomb commonly used in spacecraft applications. (c) Examples of identical inserts machined from the gradient alloy, pure Invar and pure A286 steel. (d) Pull-out testing for the low-temperature cycled inserts that have been attached to the panel using epoxy. (e) Before and after images of the insert pull-out tests, showing deformation in the carbon fiber panel. (f) Load vs. displacement curves for the pull-out tests showing that the gradient insert outperformed the monolithic metal ones.