ABSTRACT

Characteristics of PMCs influencing the design and choice of test methods include the following.

1. The properties are anisotropic to varying degrees (i.e., mechanical, thermal, and electrical properties vary with direction in the material). The highest anisotropy is illustrated by the properties of a fully aligned 60% (by volume) carbon fiber/epoxy laminate, where the properties parallel with the fiber direction can be thirty times greater than in the perpendicular direction, whereas in a molded short-fiber system the ratio of properties in perpendicular directions may only be a factor of two. The fibers themselves may have even higher anisotropy (e.g., carbon and aramid fibers).