Computational homogenization permits to capture the influence of the microstructure on the cyclic mechanical behavior of polycrystalline metals. In this work we investigate methods to compute Laguerre tessellations as computational cells of polycrystalline microstructures, propose a new method to assign crystallographic orientations to the Laguerre cells and use Bayesian optimization to find suitable parameters for the underlying micromechanical model from macroscopic experiments.

Materials of industrial interest often show a complex microstructure which directly influences their macroscopic material behavior. For simulations on the component scale, multi-scale methods may exploit this microstructural information. This work is devoted to a multi-scale approach for brittle materials. Based on a homogenization result for free discontinuity problems, we present FFT-based methods to compute the effective crack energy of heterogeneous materials with complex microstructures.

Written by the leading experts in computational materials science, this handy reference concisely reviews the most important aspects of plasticity modeling: constitutive laws, phase transformations, texture methods, continuum approaches and damage mechanisms. As a result, it provides the knowledge needed to avoid failures in critical systems udner mechanical load. With its various application examples to micro- and macrostructure mechanics, this is an invaluable resource for mechanical engineers as well as for researchers wanting to improve on this method and extend its outreach.

Cyclic Plasticity of Metals: Modeling Fundamentals and Applications provides an exhaustive overview of the fundamentals and applications of various cyclic plasticity models including forming and spring back, notch analysis, fatigue life prediction, and more. Covering metals with an array of different structures, such as hexagonal close packed (HCP), face centered cubic (FCC), and body centered cubic (BCC), the book starts with an introduction to experimental macroscopic and microscopic observations of cyclic plasticity and then segues into a discussion of the fundamentals of the different cyclic plasticity models, covering topics such as kinematics, stress and strain tensors, elasticity, plastic flow rule, and an array of other concepts. A review of the available models follows, and the book concludes with chapters covering finite element implementation and industrial applications of the various models. Reviews constitutive cyclic plasticity models for various metals and alloys with different cell structures (cubic, hexagonal, and more), allowing for more accurate evaluation of a component's performance under loading Provides real-world industrial context by demonstrating applications of cyclic plasticity models in the analysis of engineering components Overview of latest models allows researchers to extend available models or develop new ones for analysis of an array of metals under more complex loading conditions

This dissertation explores the plasticity polycrystalline metals, with particular attention paid to aluminum and its alloys. Specifically aluminum Al-Mg sheet alloys, which are currently replacing steel parts for panel and some structural componentry in the automotive industry. At the forefront of this transition, is the problem of poor room-temperature formability of the aluminum sheet when compared to its steel counterparts. A promising solution to this has been the use of warm-forming to increase formability, preventing redesign of automotive parts from steel to aluminum (Li and Ghosh, 2003). In this thesis, a new constitutive framework and methodology is developed to accurately model elevated temperature behaviour of polycrystalline aluminum. This study describes a picture of the physics behind slip dominated deformation in polycrystalline metals, and the mechanical characterization techniques used to determine modeling parameters for crystal plasticity. A review on modeling techniques and published work on the versatility of crystal plasticity theory and application is also presented. An initial model is then developed for a fully temperature dependent crystal plasticity framework. The model employs a generic hardening law to study the effect of temperature on material hardening, and conclusions are made on the lack of microstructural correlation between the model and physical behaviour of the material. The same framework is then implemented in the well known Marciniak-Kuzynski (1967) based limit strain formulation as an application study with Chang and Asaro (1981) type hardening. Temperature dependency is studied and formability is predicted for different aluminum alloys. The study reveals that, again, phenomenological-based hardening is only satisfactory for predicting elevated-temperature behaviour, and results are very sensitive to model input parameters. In the second half of this dissertation, a physical model is carefully developed from fundamental dislocation theories. The model is formulated on the basis of accumulation of dislocations as the dominating strengthening mechanism in polycrystals, introduces recovery as a thermally activated process leading to temperature dependent softening. The model is used to study temperature dependency of slip deformation in pure aluminum, and the correlation between physical processes and model parameters. The model is able to capture and predict deformation response, as well as suggest explanation to the influence of temperature on microstructural behaviour. Finally, the model is applied to study the temperature dependency of microstructural parameters in 5xxx series Al-Mg sheet alloys. Experimental data is used to characterized material parameters at warm forming temperatures, and the model is used to predict stress-strain response. The model is then used to discuss the effect of temperature on two different alloys and suggests explanation on the microstructural causes leading to variation hardening behaviour between the two alloys over the temperature range studied. The work then concludes the improvement of model predictability, and the utility of such a model in microstructural design.

MEMS and Nanotechnology, Volume 6: Proceedings of the 2012 Annual Conference on Experimental and Applied Mechanics represents one of seven volumes of technical papers presented at the Society for Experimental Mechanics SEM 12th International Congress & Exposition on Experimental and Applied Mechanics, held at Costa Mesa, California, June 11-14, 2012. The full set of proceedings also includes volumes on Dynamic Behavior of Materials, Challenges in Mechanics of Time-Dependent Materials and Processes in Conventional and Multifunctional Materials, Imaging Methods for Novel Materials and Challenging Applications, Experimental and Applied Mechanics, Mechanics of Biological Systems and Materials and, Composite Materials and Joining Technologies for Composites.

New contributions to the cyclic plasticity of engineering materials Written by leading experts in the field, this book provides an authoritative and comprehensive introduction to cyclic plasticity of metals, polymers, composites and shape memory alloys. Each chapter is devoted to fundamentals of cyclic plasticity or to one of the major classes of materials, thereby providing a wide coverage of the field. The book deals with experimental observations on metals, composites, polymers and shape memory alloys, and the corresponding cyclic plasticity models for metals, polymers, particle reinforced metal matrix composites and shape memory alloys. Also, the thermo-mechanical coupled cyclic plasticity models are discussed for metals and shape memory alloys. Key features: Provides a comprehensive introduction to cyclic plasticity Presents Macroscopic and microscopic observations on the ratchetting of different materials Establishes cyclic plasticity constitutive models for different materials. Analysis of cyclic plasticity in engineering structures. This book is an important reference for students, practicing engineers and researchers who study cyclic plasticity in the areas of mechanical, civil, nuclear, and aerospace engineering as well as materials science.