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Strong Coupling of Thermo-Chemical and Thermo-Mechanical States in Applied Materials

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Materials Chemistry".

Deadline for manuscript submissions: closed (15 February 2021) | Viewed by 22989

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Prof. Ingo Steinbach

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Interdisciplonary Centre for Advanced Materials Simulation, Ruhr-University Bochm, Bochum, Germany
Interests: phase-fild modelling and simulation; kinetics and thermodynamics of materials; multi-scale problems; pattern formation
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Dear Colleagues,

Many applied materials, like metals and solid-state polymers, consist of multiple phases. Their properties depend crucially on the internal phase structure, i.e., the fraction and local distribution of the phases and their composition and molecular configuration. Chemical aspects influence the mechanical properties as well as mechanical load couples which, in turn, influence the chemistry. This strong interrelation is expressed in the thermodynamic functional of the material which is composed of a thermochemical or thermosolutal part, on the one hand, and a temperature-dependent mechanical part on the other. The mutual interaction between chemistry and mechanics in applied materials is the central goal of manuscripts in this Special Issue. Examples of such materials are high-strength steels, where the supersaturated crystal lattice locks plastic relaxation, and Ni–base superalloys, in which a two-phase structure is stabilized by mechanical interaction. Immiscible polymer blends show enhanced stiffness and toughness due to phase separation between the components. In filled elastomers and fiber-reinforced polymers, the mechanical properties depend on the chemical state of an interfacial layer which changes under external mechanical load. All these materials cannot be understood if neglecting the interplay between phase structure and mechanics.

Articles are welcomed on aspects of chemomechanical coupling at all scales with a focus on metallic systems and polymers, and these studies may involve numerical simulations in connection with experiments.

Prof. Dr. Ingo Steinbach
Guest Editor

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Keywords

thermodynamically consistent material models
phase field models
micromechanical models
metals
polymers
strongly coupled multiphysics

Published Papers (10 papers)

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Research

11 pages, 595 KiB

Open AccessArticle

Benchmark for the Coupled Magneto-Mechanical Boundary Value Problem in Magneto-Active Elastomers

by Philipp Metsch, Raphael Schiedung, Ingo Steinbach and Markus Kästner

Materials 2021, 14(9), 2380; https://doi.org/10.3390/ma14092380 - 03 May 2021

Cited by 2 | Viewed by 1634

Abstract

Within this contribution, a novel benchmark problem for the coupled magneto-mechanical boundary value problem in magneto-active elastomers is presented. Being derived from an experimental analysis of magnetically induced interactions in these materials, the problem under investigation allows us to validate different modeling strategies by means of a simple setup with only a few influencing factors. Here, results of a sharp-interface Lagrangian finite element framework and a diffuse-interface Eulerian approach based on the application of a spectral solver on a fixed grid are compared for the simplified two-dimensional as well as the general three-dimensional case. After influences of different boundary conditions and the sample size are analyzed, the results of both strategies are examined: for the material models under consideration, a good agreement of them is found, while all discrepancies can be ascribed to well-known effects described in the literature. Thus, the benchmark problem can be seen as a basis for future comparisons with both other modeling strategies and more elaborate material models. Full article

(This article belongs to the Special Issue Strong Coupling of Thermo-Chemical and Thermo-Mechanical States in Applied Materials)

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24 pages, 1683 KiB

Open AccessFeature PaperArticle

Parameter Identification and Validation of Shape-Memory Polymers within the Framework of Finite Strain Viscoelasticity

by Ehsan Ghobadi, Alexey Shutov and Holger Steeb

Materials 2021, 14(8), 2049; https://doi.org/10.3390/ma14082049 - 19 Apr 2021

Cited by 9 | Viewed by 2241

Abstract

Shape-Memory Polymers (SMPs) can be stretched to large deformations and recover induced strains when exposed to an appropriate stimulus, such as heat. This emerging class of functional polymers has attracted much interest and found applications in medicine and engineering. Nevertheless, prior to any application, their physical and mechanical properties must be thoroughly studied and understood in order to make predictions or to design structures thereof. In this contribution, the viscoelastic behavior of a polyether-based polyurethane (Estane) and its rate- and temperature-dependent behavior have been studied experimentally and by the mean of simulations. The model-inherent material parameters are identified with the assumption of the thermo-rheological complexity. Here, the numerical results of uni-axial stress relaxations were compared with the associated experiments in conjucation with the Levenberg-Marquard optimization method to determine the parameters of the Prony equation. The ability of the model to simulate the thermo-mechanical properties of Estane was evaluated by data-rich experimental observations on tension and torsion in various temperature ranges. Heterogeneous tests are included into the experimental program to cover a broader spectrum of loading scenarios. Full article

(This article belongs to the Special Issue Strong Coupling of Thermo-Chemical and Thermo-Mechanical States in Applied Materials)

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19 pages, 2491 KiB

Open AccessArticle

A Combined Experimental and First-Principles Based Assessment of Finite-Temperature Thermodynamic Properties of Intermetallic Al₃Sc

by Ankit Gupta, Bengü Tas, Dominique Korbmacher, Biswanath Dutta, Yulia Neitzel, Blazej Grabowski, Tilmann Hickel, Vladimir Esin, Sergiy V. Divinski, Gerhard Wilde and Jörg Neugebauer

Materials 2021, 14(8), 1837; https://doi.org/10.3390/ma14081837 - 07 Apr 2021

Cited by 5 | Viewed by 2034

Abstract

We present a first-principles assessment of the finite-temperature thermodynamic properties of the intermetallic Al

_{3}

We present a first-principles assessment of the finite-temperature thermodynamic properties of the intermetallic Al

_{3}

Sc phase including the complete spectrum of excitations and compare the theoretical findings with our dilatometric and calorimetric measurements. While significant electronic contributions to the heat capacity and thermal expansion are observed near the melting temperature, anharmonic contributions, and electron–phonon coupling effects are found to be relatively small. On the one hand, these accurate methods are used to demonstrate shortcomings of empirical predictions of phase stabilities such as the Neumann–Kopp rule. On the other hand, their combination with elasticity theory was found to provide an upper limit for the size of Al

_{3}

Sc nanoprecipitates needed to maintain coherency with the host matrix. The chemo-mechanical coupling being responsible for the coherency loss of strengthening precipitates is revealed by a combination of state-of-the-art simulations and dedicated experiments. These findings can be exploited to fine-tune the microstructure of Al-Sc-based alloys to approach optimum mechanical properties. Full article

(This article belongs to the Special Issue Strong Coupling of Thermo-Chemical and Thermo-Mechanical States in Applied Materials)

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16 pages, 1676 KiB

Open AccessArticle

Phase-Field Modeling of Chemoelastic Binodal/Spinodal Relations and Solute Segregation to Defects in Binary Alloys

by Jaber Rezaei Mianroodi, Pratheek Shanthraj, Bob Svendsen and Dierk Raabe

Materials 2021, 14(7), 1787; https://doi.org/10.3390/ma14071787 - 05 Apr 2021

Cited by 10 | Viewed by 2548

Abstract

Microscopic phase-field chemomechanics (MPFCM) is employed in the current work to model solute segregation, dislocation-solute interaction, spinodal decomposition, and precipitate formation, at straight dislocations and configurations of these in a model binary solid alloy. In particular, (i) a single static edge dipole, (ii) arrays of static dipoles forming low-angle tilt (edge) and twist (screw) grain boundaries, as well as at (iii) a moving (gliding) edge dipole, are considered. In the first part of the work, MPFCM is formulated for such an alloy. Central here is the MPFCM model for the alloy free energy, which includes chemical, dislocation, and lattice (elastic), contributions. The solute concentration-dependence of the latter due to solute lattice misfit results in a strong elastic influence on the binodal (i.e., coexistence) and spinodal behavior of the alloy. In addition, MPFCM-based modeling of energy storage couples the thermodynamic forces driving (Cottrell and Suzuki) solute segregation, precipitate formation and dislocation glide. As implied by the simulation results for edge dislocation dipoles and their configurations, there is a competition between (i) Cottrell segregation to dislocations resulting in a uniform solute distribution along the line, and (ii) destabilization of this distribution due to low-dimensional spinodal decomposition when the segregated solute content at the line exceeds the spinodal value locally, i.e., at and along the dislocation line. Due to the completely different stress field of the screw dislocation configuration in the twist boundary, the segregated solute distribution is immediately unstable and decomposes into precipitates from the start. Full article

(This article belongs to the Special Issue Strong Coupling of Thermo-Chemical and Thermo-Mechanical States in Applied Materials)

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21 pages, 7839 KiB

Open AccessArticle

Quantitative Shape-Classification of Misfitting Precipitates during Cubic to Tetragonal Transformations: Phase-Field Simulations and Experiments

by Yueh-Yu Lin, Felix Schleifer, Markus Holzinger, Na Ta, Birgit Skrotzki, Reza Darvishi Kamachali, Uwe Glatzel and Michael Fleck

Materials 2021, 14(6), 1373; https://doi.org/10.3390/ma14061373 - 12 Mar 2021

Cited by 4 | Viewed by 1925

Abstract

The effectiveness of the mechanism of precipitation strengthening in metallic alloys depends on the shapes of the precipitates. Two different material systems are considered: tetragonal γ′′ precipitates in Ni-based alloys and tetragonal θ′ precipitates in Al-Cu-alloys. The shape formation and evolution of the tetragonally misfitting precipitates was investigated by means of experiments and phase-field simulations. We employed the method of invariant moments for the consistent shape quantification of precipitates obtained from the simulation as well as those obtained from the experiment. Two well-defined shape-quantities are proposed: (i) a generalized measure for the particles aspect ratio and (ii) the normalized λ₂, as a measure for shape deviations from an ideal ellipse of the given aspect ratio. Considering the size dependence of the aspect ratio of γ′′ precipitates, we find good agreement between the simulation results and the experiment. Further, the precipitates’ in-plane shape is defined as the central 2D cut through the 3D particle in a plane normal to the tetragonal c-axes of the precipitate. The experimentally observed in-plane shapes of γ′′-precipitates can be quantitatively reproduced by the phase-field model. Full article

(This article belongs to the Special Issue Strong Coupling of Thermo-Chemical and Thermo-Mechanical States in Applied Materials)

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18 pages, 42230 KiB

Open AccessFeature PaperArticle

Simulation of the θ′ Precipitation Process with Interfacial Anisotropy Effects in Al-Cu Alloys

by Na Ta, Muhammad Umer Bilal, Ines Häusler, Alaukik Saxena, Yueh-Yu Lin, Felix Schleifer, Michael Fleck, Uwe Glatzel, Birgit Skrotzki and Reza Darvishi Kamachali

Materials 2021, 14(5), 1280; https://doi.org/10.3390/ma14051280 - 08 Mar 2021

Cited by 4 | Viewed by 2415

Abstract

The effects of anisotropic interfacial properties and heterogeneous elasticity on the growth and ripening of plate-like θ′-phase (Al₂Cu) in Al-1.69 at.% Cu alloy are studied. Multi-phase-field simulations are conducted and discussed in comparison with aging experiments. The precipitate/matrix interface is considered to be anisotropic in terms of its energy and mobility. We find that the additional incorporation of an anisotropic interfacial mobility in conjunction with the elastic anisotropy result in substantially larger aspect ratios of the precipitates closer to the experimental observations. The anisotropy of the interfacial energy shows comparably small effect on the precipitate’s aspect ratio but changes the interface’s shape at the rim. The effect of the chemo-mechanical coupling, i.e., the composition dependence of the elastic constants, is studied as well. We show that the inverse ripening phenomenon, recently evidenced for δ’ precipitates in Al-Li alloys (Park et al. Sci. Rep. 2019, 9, 3981), does not establish for the θ′ precipitates. This is because of the anisotropic stress fields built around the θ′ precipitates, stemming from the precipitate’s shape and the interaction among different variants of the θ′ precipitate, that disturb the chemo-mechanical effects. These results show that the chemo-mechanical effects on the precipitation ripening strongly depend on the degree of sphericity and elastic isotropy of the precipitate and matrix phases. Full article

(This article belongs to the Special Issue Strong Coupling of Thermo-Chemical and Thermo-Mechanical States in Applied Materials)

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27 pages, 29549 KiB

Open AccessArticle

Modeling Bainitic Transformations during Press Hardening

by Mingxuan Lin, Carina Zimmermann, Kai Wang, Martin Hunkel, Ulrich Prahl and Robert Spatschek

Materials 2021, 14(3), 654; https://doi.org/10.3390/ma14030654 - 31 Jan 2021

Cited by 1 | Viewed by 2364

Abstract

We revisit recent findings on experimental and modeling investigations of bainitic transformations under the influence of external stresses and pre-strain during the press hardening process. Experimentally, the transformation kinetics in 22MnB5 under various tensile stresses are studied both on the macroscopic and microstructural level. In the bainitic microstructure, the variant selection effect is analyzed with an optimized prior-austenite grain reconstruction technique. The resulting observations are expressed phenomenologically using a autocatalytic transformation model, which serves for further scale bridging descriptions of the underlying thermo-chemo-mechanical coupling processes during the bainitic transformation. Using analyses of orientation relationships, thermodynamically consistent and nondiagonal phase field models are developed, which are supported by ab initio generated mechanical parameters. Applications are related to the microstructure evolution on the sheaf, subunit, precipitate and grain boundary level. Full article

(This article belongs to the Special Issue Strong Coupling of Thermo-Chemical and Thermo-Mechanical States in Applied Materials)

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21 pages, 6745 KiB

Open AccessEditor’s ChoiceArticle

A Mechanical Analysis of Chemically Stimulated Linear Shape Memory Polymer Actuation

by Hakan Dumlu, Axel Marquardt, Elias M. Zirdehi, Fathollah Varnik, Yucen Shen, Klaus Neuking and Gunther Eggeler

Materials 2021, 14(3), 481; https://doi.org/10.3390/ma14030481 - 20 Jan 2021

Cited by 9 | Viewed by 2217

Abstract

In the present work, we study the role of programming strain (50% and 100%), end loads (0, 0.5, 1.0, and 1.5 MPa), and chemical environments (acetone, ethanol, and water) on the exploitable stroke of linear shape memory polymer (SMP) actuators made from ESTANE ETE 75DT3 (SMP-E). Dynamic mechanical thermal analysis (DMTA) shows how the uptake of solvents results in a decrease in the glass temperature of the molecular switch component of SMP-E. A novel in situ technique allows studying chemically triggered shape recovery as a function of time. It is found that the velocity of actuation decreases in the order acetone > ethanol > water, while the exploitable strokes show the inverse tendency and increases in the order water > ethanol > acetone. The results are interpreted on the basis of the underlying chemical (how solvents affect thermophysical properties) and micromechanical processes (the phenomenological spring dashpot model of Lethersich type rationalizes the behavior). The study provides initial data which can be used for micromechanical modeling of chemically triggered actuation of SMPs. The results are discussed in the light of underlying chemical and mechanical elementary processes, and areas in need of further work are highlighted. Full article

(This article belongs to the Special Issue Strong Coupling of Thermo-Chemical and Thermo-Mechanical States in Applied Materials)

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27 pages, 1300 KiB

Open AccessArticle

Magneto-Mechanical Coupling in Magneto-Active Elastomers

by Philipp Metsch, Dirk Romeis, Karl A. Kalina, Alexander Raßloff, Marina Saphiannikova and Markus Kästner

Materials 2021, 14(2), 434; https://doi.org/10.3390/ma14020434 - 17 Jan 2021

Cited by 16 | Viewed by 2316

Abstract

In the present work, the magneto-mechanical coupling in magneto-active elastomers is investigated from two different modeling perspectives: a micro-continuum and a particle–interaction approach. Since both strategies differ significantly in their basic assumptions and the resolution of the problem under investigation, they are introduced in a concise manner and their capabilities are illustrated by means of representative examples. To motivate the application of these strategies within a hybrid multiscale framework for magneto-active elastomers, their interchangeability is then examined in a systematic comparison of the model predictions with regard to the magneto-deformation of chain-like helical structures in an elastomer surrounding. The presented results show a remarkable agreement of both modeling approaches and help to provide an improved understanding of the interactions in magneto-active elastomers with chain-like microstructures. Full article

(This article belongs to the Special Issue Strong Coupling of Thermo-Chemical and Thermo-Mechanical States in Applied Materials)

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15 pages, 11464 KiB

Open AccessEditor’s ChoiceArticle

On the Size Effect of Additives in Amorphous Shape Memory Polymers

by Elias M. Zirdehi, Hakan Dumlu, Gunther Eggeler and Fathollah Varnik

Materials 2021, 14(2), 327; https://doi.org/10.3390/ma14020327 - 10 Jan 2021

Cited by 4 | Viewed by 1978

Abstract

Small additive molecules often enhance structural relaxation in polymers. We explore this effect in a thermoplastic shape memory polymer via molecular dynamics simulations. The additive-to-monomer size ratio is shown to play a key role here. While the effect of additive-concentration on the rate of shape recovery is found to be monotonic in the investigated range, a non-monotonic dependence on the size-ratio emerges at temperatures close to the glass transition. This work thus identifies the additives’ size to be a qualitatively novel parameter for controlling the recovery process in polymer-based shape memory materials. Full article

(This article belongs to the Special Issue Strong Coupling of Thermo-Chemical and Thermo-Mechanical States in Applied Materials)

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