Kinkband formation is a non-linear phenomenon involving interacting effects of non-linear material behavior of the matrix materials and fiber buckling including fiber misalignment in fiber composites under compressive loading. Taking into account the non-linearties of the constituents a constitutive model for unidirectional layered materials was developed and incorporated as a user material in a commercially available finite element code to study the localized effects for a given load level and kinkband inclination angle at kinkband formation. The investigation is focused to gain a better understanding of the influence of the macro-geometry and micro-geometry. In addition studying the mechanics of kinkband formation, focus is also directed in computing the critical compressive stress for steady state kinkband broadening under compression in the fiber direction. The present theory demonstrates the transition of the failure mode by buckling of long, slender beams to material instability by the kinkband mechanism for short plate panels. The results are in accordance with different widely used approaches and indicate that bifurcation stresses are sensitive to the moduli ratio between constituent materials and the volume fractions.
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ASME 2011 Applied Mechanics and Materials Conference