59. Bending behavior and tensile failure of carbon fibers

✍ Scribed by W.S Williams; D Steffens

• Publisher: Elsevier Science
• Year: 1968
• Tongue: English
• Weight: 133 KB
• Volume: 6
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(68)90362-x

✦ Synopsis

The bending behavior of 7 p dia. carbon filaments at room temperature was studied by forming a loop in a vertical plane and measuring the loop diameter corresponding to various loads applied to the free end. The initial slope of the resulting stress-strain curve gave values of Young's modulus equal to those determined by tensile testing. However, above one-half per cent strain, all carbon fibers tested showed nonlinear stress-strain behavior. The effect was largely reversible and similar to that found for stranded stainless steel wire. We suggest that the nonlinear behavior in both materials results from slippage of individual subunits when a critical stress is reached. The observed tensile failure of carbon fibers at one-half per cent strain can then be attributed to the initiation of cracks around stress concentrations caused by local cross-link failures.