| 1. |
- Linder, David, et al.
(author)
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An energy release rate approach to cemented carbide fracture toughness for computational materials design
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Other publication (other academic/artistic)abstract
- Integrated computational materials engineering and computational materials design have the potential to greatly accelerate materials development at reduced cost compared to conventional experimentally-based methods. These methodologies, however, require physically-based property models to be truly predictive. Fracture toughness is a critical material property of cemented carbides for high-performance mining and metal cutting tools. In the present work, a fracture toughness model framework based on the energy release rate formalism is presented and applied to conventional and alternative-binder cemented carbides. The framework is physically-based and designed to be modular, where each sub-model can be independently modified or replaced without disturbing the calculation-flow of the overall framework. In the presented examples, the sub-models are based on e.g. finite element simulations and atomistic calculations as well as limited calibration to experimental data. The model framework is intended for integration with previously developed computational tools and models, such as a composite hardness model and a grain growth model, for computational design of novel and improved cemented carbides with the aim to potentially substitute cobalt as the dominating binder phase in cemented carbides.
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| 2. |
- Linder, David, et al.
(author)
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Modeling confined ductile fracture – a void-growth and coalescence approach
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Other publication (other academic/artistic)abstract
- In a composite material a soft, ductile matrix can be confined by a hard, brittle phase, altering its deformation and fracture behavior. Increasing confinement leads to embrittlement of the matrix and, in turn, also the composite. From a materials design perspective, it is usually desired to avoid brittle fracture without compromising the hardness of the material. Understanding confined ductile fracture is therefore critical for modeling the mechanical response of composite materials with fine microstructure. The present work is focused on confined ductile fracture of a thin ductile film, with elasto-plastic power-law hardening behavior, sandwiched between ideal linear elastic substrates. Fracture of the ductile layer is modeled by growth and coalescence of prescribed voids in 2D. Influences of material properties, initial void volume fraction, geometric constraints and elastic mismatch are investigated. The results show a loss of ductility with decreasing film thickness that is accompanied by a severe decrease in fracture initiation toughness as well as an increased stress at the interface. The influence of materials properties is significant in all cases while the effect of initial void volume fraction is comparatively less critical for highly confined materials than for bulk materials. Increasing confinement also results in increasing normal stress at the phase interface, promoting interface decohesion prior to ductile fracture of the film. The present approach and results are a step towards more detailed prediction of composite fracture toughness and crack-growth resistance.
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