COMPOSITE STRUCTURE UNIDIRECTIONALLY STABLE WITH RESPECT TO THERMAL AND MOISTURE EXPANSION.

摘要

A structure which has a low coefficient of thermal and moisture expansion along one dimension (an axis) is formed of an arrangement of fibers surrounded by and bonded to an engineering thermoplastic resin. The fibers are arranged so that essentially all of the fibers are disposed parallel to the axis. The fibers have a negative coefficient of expansion, the resin has a positive coefficient of expansion, and the volume ratio is balanced so that the composite structure has a near zero coefficient of expansion. Perferably the structure is formed by pultrusion of overlapped tapes of aligned carbon fibers preimpregnated with polyphenylene sulfide. A scale having this structure has slots for indicating position on the scale. The slots extend through the scale and are transverse to the axis.