A MODEL FOR KINKING IN FIBER COMPOSITES .2. KINK BAND FORMATION

In Part II of this series, the critical strain at which a fully formed kink band can exist in a compressed fiber composite is calculated. This calculation is based on a comparison of the energies of the kinked and unkinked configurations, assuming both satisfy all relevant field equations. The critical strain is found to be on the order of 2τs EL, where τs, is the longitudinal shear strength and EL is the composite elastic modulus parallel to the fibers. In Part I, the strain to cause the fibers to break was found to be significantly higher, in general, closer to observed failure strains. This suggests that fiber breakage is the critical step in the process of kinking, not the actual formation of the band. © 1990.