Abstract
Compression failure by fiber kinking limits the structural applications of fiber composites. Fiber kinking is especially prevalent in laminates with holes and cutouts. The latter behavior is characterized by strain localization in the matrix material and fiber rotations. To study fiber kinking on the level of the individual constituents, a homogenization of fiber composites is presented. It is based on a total Lagrangian formulation, making it independent of fiber rotations. It accounts for the microstructure of the composite, including fiber-matrix interfacial decohesion, and enables all types of material behavior of the constituents. The response of each constituent of the composite is modeled separately and the global response is obtained by an assembly of all contributions. The model is implemented as a user-defined material model (UMAT) in ABAQUS and used for multiscale modeling of notched unidirectional plies subjected to compression. The model performs well in agreement with a finite element model of an explicit discretization of the microstructure and literature results. The simulations predict the formation of a kink band in near 0-degree plies and show that the open-hole compression strength is sensitive to fiber-matrix interfacial decohesion. The present work suggests a convenient and computationally efficient tool for simulating the elastic-plastic behavior of fiber composites on the fiber-matrix level and predicting the compressive strength of laminates.
Highlights
Automobiles are responsible for around 12 % of the total emissions of carbon dioxide, the main greenhouse gas [1]
To study fiber kinking on the level of the individual constituents, as well as being able to predict the compressive strength of laminates, an alternative homogenization-based constitutive model with fiber-matrix interfacial decohesion is presented
These results suggest that the critical stress is sensitive to fiber-matrix interfacial decohesion, which is in agreement with the experimental observations by Dève [9], and should be considered when designing composite structures for load-bearing applications
Summary
Automobiles are responsible for around 12 % of the total emissions of carbon dioxide, the main greenhouse gas [1]. Jensen [11] extends this formulation to include full decohesion between the matrix and the fibers, while Skovsgaard and Jensen [12] describe the transition between the two models In these papers, the discrete equations are formulated in the current configuration, i.e. the new reference configuration, known as an updated Lagrangian formulation, making the consideration of a rotating local coordinate system necessary. To study fiber kinking on the level of the individual constituents, as well as being able to predict the compressive strength of laminates, an alternative homogenization-based constitutive model with fiber-matrix interfacial decohesion is presented. It is inspired by the rule of mixtures and combines concepts from Refs.
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