On kink-band propagation in fiber composites

Two kinds of kink-band propagation in the compression of aligned-fiber composites are studied analytically: band broadening, discovered experimentally by Moran, Liu and Shih in 1995, in which a uniform kink band grows in the direction of loading at constant stress under increasing deformation; and transverse kink propagation, in which a kink band traverses a specimen quasi-statically under constant overall shortening. The analysis is based on a 1-D, geometrically nonlinear couple-stress theory of composite kinking that takes elastic fiber bending resistance into account together with idealized nonlinear stress-strain relations, but assumes non-breaking fibers. Simple results for the band-broadening and transverse propagation stresses are deduced, and their significance is discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.