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

Abstract

An analytical micromechanical model for kink-band formation in an unidirectional fibre-reinforced composite is developed. This is supported by the conclusions of experimental and numerical programmes (presented in Part I of this paper) and is based on the equilibrium of an imperfect fibre laterally supported by an elasto-plastic matrix. The model predicts the longitudinal compressive strength of the composite (in closed form), the deflection and main stress fields in fibres and matrix at different stages of kink-band formation, the kink-band width, and the orientation of the fibres at the onset of fibre failure.

A micromechanical model for kink-band formation: Part I — Experimental study and numerical modelling

“…The outputs from the experimental and numerical programmes, namely the sequence of events and the key features, are applied to the development of an analytical micromechanical model for kink-band formation, presented in Part II of this paper [3].…”

“…This paper presents experimental and numerical investigations that were conducted to improve the knowledge on the sequence of events and the key features leading to fibre kinking. The outcome of these studies is used in Part II of this paper [3] to develop an analytical model for kink-band formation.…”

“…The final goal is to provide useful information on the physics and micromechanics of the process, so a phenomenological analytical model can be developed in Part II of this paper [3]. This paper is organised as follows: sections 2 and 3 present respectively the experimental and numerical procedures carried out; based on the results obtained, the sequence of events leading to kink-band formation is proposed in section 4, and key features for kinking are identified in section 5; section 6 summarizes the main conclusions.…”

An experimental study of failure initiation and propagation in 2D woven composites under compression

“…At the microscale, kink band formation in woven and UD composites is expected to occur in a similar fashion: opening of microcracks/plasticity of the matrix ultimately leading to kinking [14,18]. However, while in UD composites the initiation of kink band formation is essentially related to local misalignment/defects, in woven composites it is additionally affected by the local response of the reinforcement and therefore by the weave architecture.…”

The Interaction of Failure Modes in the Compression Response and Failure of Laminated Composites

“…2 While early studies determined that the compressive strength of a single, isolated lamina can be determined by a knowledge of the lamina shear nonlinearity in the stress-strain response, in tandem with a knowledge of initial fiber misalignment, 3 , 4 it was later determined through a combination of experiments and numerical modeling that the kink band formation is an evolutionary process, which is governed by local stress state (including stress multi-axiality), details of the material constitutive model and the fiber misalignment angles as explained in papers by Sun and Jun, 5 Kyriakides et al, 6 Lee and Waas, 7 Vogler et al, 8 Yerramalli and Waas, 9 Yerramalli and Waas, 10 Basu et al, 11 Pimenta et al, 12 , 13 Feld et al 14 As loading proceeds, regions of fiber misalignment in the lamina undergo deformation due to combined compression and shear loading. This region is surrounded by other material whose deformation characteristics, in general, are different.…”