Download or read book Homogenization of the Linear and Non linear Mechanical Behavior of Polycrystals written by Katja Jöchen and published by KIT Scientific Publishing. This book was released on 2014-05-13 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work is dedicated to the numerically efficient simulation of the material response of polycrystalline aggregates. Therefore, crystal plasticity is combined with a new non-linear homogenization scheme, which is based on piecewise constant stress polarizations with respect to a homogeneous reference medium and corresponds to a generalization of the Hashin-Shtrikman scheme. This mean field approach accounts for the one- and two-point statistics of the microstructure.

Download or read book Modeling martensitic phase transformation in dual phase steels based on a sharp interface theory written by Ruck, Johannes and published by KIT Scientific Publishing. This book was released on 2021-05-07 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: artensite forms under rapid cooling of austenitic grains accompanied by a change of the crystal lattice. Large deformations are induced which lead to plastic dislocations. In this work a transformation model based on the sharp interface theory, set in a finite strain context is developed. Crystal plasticity effects, the kinetic of the singular surface as well as a simple model of the inheritance from austenite dislocations into martensite are accounted for.

Download or read book Work hardening of dual phase steel written by Rieger, Florian and published by KIT Scientific Publishing. This book was released on 2016-07-01 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dual-phase steels exhibit good mechanical properties due to a microstructure of strong martensitic inclusions embedded in a ductile ferritic matrix. This work presents a two-scale model for the underlying work-hardening effects; such as the distinctly different hardening rates observed for high-strength dual-phase steels. The model is based on geometrically necessary dislocations and comprises the average microstructural morphology as well as a direct interaction between the constituents.

Download or read book Microstructural Modeling and Computational Homogenization of the Physically Linear and Nonlinear Constitutive Behavior of Micro heterogeneous Materials written by Felix Fritzen and published by KIT Scientific Publishing. This book was released on 2014-08-22 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Engineering materials show a pronounced heterogeneity on a smaller scale that influences the macroscopic constitutive behavior. Algorithms for the periodic discretization of microstructures are presented. These are used within the Nonuniform Transformation Field Analysis (NTFA) which is an order reduction based nonlinear homogenization method with micro-mechanical background. Theoretical and numerical aspects of the method are discussed and its computational efficiency is validated.

Download or read book Micromechanical modeling of short fiber reinforced composites written by Mueller, Viktor and published by KIT Scientific Publishing. This book was released on 2016-06-16 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work is focused on the prediction of elastic behavior of short-fiber reinforced composites by mean-field homogenization methods, which account for experimentally determined and artificially constructed microstructure data in discrete and averaged form. The predictions are compared with experimental measurements and a full-field voxel-based approach. It is investigated, whether the second-order orientation tensor delivers a sufficient microstructure description for such predictions.

Download or read book Nonlinear Homogenization and its Applications to Composites Polycrystals and Smart Materials written by P. Ponte Castaneda and published by Springer Science & Business Media. This book was released on 2006-02-17 with total page 371 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although several books and conference proceedings have already appeared dealing with either the mathematical aspects or applications of homogenization theory, there seems to be no comprehensive volume dealing with both aspects. The present volume is meant to fill this gap, at least partially, and deals with recent developments in nonlinear homogenization emphasizing applications of current interest. It contains thirteen key lectures presented at the NATO Advanced Workshop on Nonlinear Homogenization and Its Applications to Composites, Polycrystals and Smart Materials. The list of thirty one contributed papers is also appended. The key lectures cover both fundamental, mathematical aspects of homogenization, including nonconvex and stochastic problems, as well as several applications in micromechanics, thin films, smart materials, and structural and topology optimization. One lecture deals with a topic important for nanomaterials: the passage from discrete to continuum problems by using nonlinear homogenization methods. Some papers reveal the role of parameterized or Young measures in description of microstructures and in optimal design. Other papers deal with recently developed methods – both analytical and computational – for estimating the effective behavior and field fluctuations in composites and polycrystals with nonlinear constitutive behavior. All in all, the volume offers a cross-section of current activity in nonlinear homogenization including a broad range of physical and engineering applications. The careful reader will be able to identify challenging open problems in this still evolving field. For instance, there is the need to improve bounding techniques for nonconvex problems, as well as for solving geometrically nonlinear optimum shape-design problems, using relaxation and homogenization methods.

Download or read book Finite element simulation of dislocation based plasticity and diffusion in multiphase materials at high temperature written by Albiez, Jürgen and published by KIT Scientific Publishing. This book was released on 2019-05-22 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: A single-crystal plasticity model as well as a gradient crystal plasticity model are used to describe the creep behavior of directionally solidi?ed NiAl based eutectic alloys. To consider the transition from theoretical to bulk strength, a hardening model was introduced to describe the strength of the reinforcing phases. Moreover, to account for microstructural changes due to material ?ux, a coupled diffusional-mechanical simulation model was introduced.

Download or read book Single crystal Gradient Plasticity with an Accumulated Plastic Slip Theory and Applications written by Eric Bayerschen and published by KIT Scientific Publishing. This book was released on 2016 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: In experiments on metallic microwires, size effects occur as a result of the interaction of dislocations with, e.g., grain boundaries. In continuum theories this behavior can be approximated using gradient plasticity. A numerically efficient geometrically linear gradient plasticity theory is developed considering the grain boundaries and implemented with finite elements. Simulations are performed for several metals in comparison to experiments and discrete dislocation dynamics simulations.

Download or read book Two Scale Thermomechanical Simulation of Hot Stamping written by Neumann, Rudolf and published by KIT Scientific Publishing. This book was released on 2017-10-27 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hot stamping is a hot drawing process which takes advantage of the polymorphic steel behavior to produce parts with a good strength-to-weight ratio. For the simulation of the hot stamping process, a nonlinear two-scale thermomechanical model is suggested and implemented into the FE tool ABAQUS. Phase transformation and transformation induced plasticity effects are taken into account. The simulation results regarding the final shape and residual stresses are compared to experimental findings.

Download or read book Deep material networks for efficient scale bridging in thermomechanical simulations of solids written by Gajek, Sebastian and published by KIT Scientific Publishing. This book was released on 2023-08-25 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: We investigate deep material networks (DMN). We lay the mathematical foundation of DMNs and present a novel DMN formulation, which is characterized by a reduced number of degrees of freedom. We present a efficient solution technique for nonlinear DMNs to accelerate complex two-scale simulations with minimal computational effort. A new interpolation technique is presented enabling the consideration of fluctuating microstructure characteristics in macroscopic simulations.

Download or read book Thermomechanical Modeling and Experimental Characterization of Sheet Molding Compound Composites written by Lang, Juliane and published by KIT Scientific Publishing. This book was released on 2023-06-28 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of this work is to model and experimentally characterize the anisotropic material behavior of SMC composites on the macroscale with consideration of the microstructure. Temperature-dependent thermoelastic behavior and failure behavior are modeled and the corresponding material properties are determined experimentally. Additionally, experimental biaxial damage investigations are performed. A parameter identification merges modeling and experiments and validates the models.

Download or read book Numerically Efficient Gradient Crystal Plasticity with a Grain Boundary Yield Criterion and Dislocation based Work Hardening written by Wulfinghoff, Stephan and published by KIT Scientific Publishing. This book was released on 2014-12-10 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a contribution to the further development of gradient plasticity. Several open questions are addressed, where the efficient numerical implementation is particularly focused on. Thebook inspects an equivalent plastic strain gradient plasticity theory and a grain boundary yield model. Experiments can successfully be reproduced. The hardening model is based on dislocation densities evolving according to partial differential equations taking into account dislocation transport.

Download or read book Biaxial Characterization and Mean field Based Damage Modeling of Sheet Molding Compound Composites written by Schemmann, Malte and published by KIT Scientific Publishing. This book was released on 2018-11-09 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: The focus of this work lies on the microstructure-based modeling and characterization of a discontinuous fiber-reinforced thermoset in the form of sheet molding compound (SMC). A microstructure-based parameter identification scheme for SMC with an inhomogeneous fiber orientation distribution is introduced. Different cruciform specimen designs, including two concepts to reinforce the specimens' arms are evaluated. Additionally, a micromechanical mean-field damage model for the SMC is introduced.

Download or read book Micromechanical Modeling and Simulation of Forming Processes written by Glavas, Vedran and published by KIT Scientific Publishing. This book was released on 2016-12-21 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: The deep drawing of an aluminum alloy used in the packaging industry for the beverage can manufacturing process is investigated. In this work, the effective constitutive behavior is based on a crystal plasticity model in combination with a non-linear Hashin-Shtrikman type homogenization scheme in which a reference stiffness controls the stress and strain fluctuations. The simulation results are compared to experiments in terms of deep drawing earing profiles, texture evolution, and localization.

Download or read book Thermomechanical Mean Field Modeling and Experimental Characterization of Long Fiber Reinforced Sheet Molding Compound Composites written by Kehrer, Maria Loredana and published by KIT Scientific Publishing. This book was released on 2019-06-13 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: A discontinuous fiber-reinforced thermoset material produced by the Sheet Molding Compound process is investigated. Due to the process-related fiber orientation distribution, a composite with an anisotropic microstructure is created which crucially affects the mechanical properties. The central objectives are the modeling of the thermoelastic behavior of the composite accounting for the underlying microstructure, and the experimental characterization of the pure resin and the composite material.

Download or read book A computational multi scale approach for brittle materials written by Ernesti, Felix and published by KIT Scientific Publishing. This book was released on 2023-04-17 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Dislocation Mechanics of Metal Plasticity and Fracturing written by Ronald W. Armstrong and published by MDPI. This book was released on 2020-11-03 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: The modern understanding of metal plasticity and fracturing began about 100 years ago, with pioneering work; first, on crack-induced fracturing by Griffith and, second, with the invention of dislocation-enhanced crystal plasticity by Taylor, Orowan and Polanyi. The modern counterparts are fracture mechanics, as invented by Irwin, and dislocation mechanics, as initiated in pioneering work by Cottrell. No less important was the breakthrough development of optical characterization of sectioned polycrystalline metal microstructures started by Sorby in the late 19th century and leading eventually to modern optical, x-ray and electron microscopy methods for assessments of crystal fracture surfaces, via fractography, and particularly of x-ray and electron microscopy techniques applied to quantitative characterizations of internal dislocation behaviors. A major current effort is to match computational simulations of metal deformation/fracturing behaviors with experimental measurements made over extended ranges of microstructures and over varying external conditions of stress-state, temperature and loading rate. The relation of such simulations to the development of constitutive equations for a hoped-for predictive description of material deformation/fracturing behaviors is an active topic of research. The present collection of articles provides a broad sampling of research accomplishments on the two subjects.