Kink band formation and band broadening in fiber composites under compressive loading

Effects of thickness and fibre misalignment on compression fracture in cross-ply (very) long cylindrical shells under external pressure

“…Figure 11a,b clearly exhibits the broadening of the kink-crack (damage) half bandwidth with the kink-crack growth starting from a fibre misalignment defect located at the inner surface of each lamina. This is in general agreement with the experimental results of Moran et al [38] and Moran & Shih [39]. Figure 1 of Moran & Shih [39] schematically depicts the steady 'state kink band broadening in which edges propagate laterally into unhardened material.…”

“…These complexities and uncertainties relate to very fundamental questions pertaining to (i) linkage between macrostructural instability, such as buckling/postbuckling failure of a structural component, e.g. a ring or cylindrical shell at the geometric scale of at least several centimetres and larger [11,31,32,[35][36][37], and microstructural instability, such as kink band type failure at the fibre-matrix level (at the geometric scale of about 10 µm) investigated by Chaudhuri & Garala [10], Chaudhuri et al [12], Chaudhuri [6], Moran et al [38], Moran & Shih [39], Gutkin et al [40] and others. The nonlinear finite-element analysis (FEA) results [11,31,32,[35][36][37][41][42][43] pertaining to the appearance of a limit point on the equilibrium path that results in localization of the deformation pattern in and lowering of the load-carrying capability of laminated carbon/epoxy composite cylindrical shells and rings, demonstrate their extreme sensitivity to thickness shear, modal/local geometric imperfections as well as material nonlinearity ('yield' stress and strain hardening).…”

A micromechanical model for kink-band formation: Part II—Analytical modelling

“…The P [v(x)] curve obtained with the analytical model (figure 5.a) represents the common behaviour documented for kink-band formation [12].…”

Microbuckle tunnelling in fibre composites

“…1a. Such a model gives useful insight into the relation between the initiation strength and the initial ®bre misalignment angle (Fleck et al, 1995), and can also be used to reveal the post-collapse phenomenon of steady-state axial broadening of a kink band under constant applied stress (Budiansky et al, 1998;Jensen, 1999), as observed by Moran et al (1995) in experiments on IM7/PEEK composites and by Vogler and Kyriakides (1997) on AS4/PEEK composites. To a good approximation, ®bre rotation arrests within the broadening band when the volumetric strain equals zero.…”

“…Plastic microbuckling has been investigated extensively in recent years (for example, Moran et al, 1995;Kyriakides et al, 1995;Kyriakides and Ru, 1997;Hsu et al, 1998;Vogler and Kyriakides, 1997;Schapery, 1995;Jensen and Christoersen, 1997; also, see the reviews of Schultheisz and Waas (1996), Waas and Schultheisz (1996), and ). Analytical solutions have been obtained by Budiansky and Fleck (1993) for the one-dimensional case of an in®nite band of initial ®bre waviness.…”