SEDL / STP / STP497-EB / STP27768S

The Transverse Strength of Boron Fibers

Kreider, KG
Program manager, Composite Materials, and research scientist, United Aircraft Research Laboratories, East Hartford, Conn.

Prewo, KM
Program manager, Composite Materials, and research scientist, United Aircraft Research Laboratories, East Hartford, Conn.

Pages: 12    Published: Jan 1972

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Abstract

A fiber crushing test which relates to previous testing procedures for brittle materials was developed. The test is used to determine the tensile strengths of fibers, particularly with respect to the propagation of preexisting flaws. The transverse strength of 4-mil (0.010-cm)-diameter boron and Borsic fibers was surprisingly low (30,000 psi) indicating severe anisotropy. This strength anisotropy was related to the residual stress pattern retained from manufacture and preexistent flaws in the fiber. Boron and Borsic fibers 5.6 mil in diameter did not suffer such severe strength anisotropy and demonstrated excellent transverse strength properties in the fiber crushing test. Both observations are confirmed in tests of metal matrix composites.