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Jacob Aboudi - One of the best experts on this subject based on the ideXlab platform.
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Micromechanical Analysis of hyperelastic composites with localized damage using a new low-memory Broyden-step-based algorithm
Archive of Applied Mechanics, 2020Co-Authors: Nathan Perchikov, Jacob AboudiAbstract:A multiscale (micro-to-macro) Analysis is proposed for the prediction of the finite-strain behavior of composites with hyperelastic constituents and embedded localized damage. The composites are assumed to possess periodic microstructure and be subjected to a remote field. At the microscale, finite-strain Micromechanical Analysis based on the homogenization technique for the (intact) composite is employed for the prediction of the effective deformation. At the macroscale, a procedure, based on the representative cell method and the associated higher-order theory, is developed for the determination of the elastic field in the damaged composite. The periodic composite is discretized into identical cells and then reduced to the problem of a single cell by application of the discrete Fourier transform. The resulting governing equations, interfacial and boundary conditions in the Fourier transform domain are solved by employing the higher-order theory in conjunction with an iterative procedure to treat the effects of damage and material nonlinearity. The initial conditions for the iterative solution are obtained using the weakly nonlinear material limit and a natural fixed-point iteration. A locally convergent low-memory Quasi-Newton solver is then employed. A new algorithm for the implementation of the solver is proposed, which allows storing in the memory directly the vector function history sequence, which may be advantageous for convergence control based on specific components of the objective vector function. The strong-form Fourier transform-based approach employed here, in conjunction with the new solver, enables to extend the application of the method to nonlinear materials and may have computational efficiency comparable or possibly advantageous to that of standard approaches.
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Micromechanical Analysis of Smart Composite Materials
Micromechanics of Composite Materials, 2012Co-Authors: Jacob Aboudi, Steven M. Arnold, Brett A. BednarcykAbstract:This chapter presents micromechanics models that admit constituents that are so-called ‘smart’ materials: piezo-electro-magnetic materials and shape memory alloys (SMAs). Versions of the Generalized Method of Cells (GMC) and High-Fidelity Generalized Method of Cells (HFGMC) that include electro-magneto-thermo-elastic constituents are derived, along with a generalized, thermo-electro-magneto-elasto-plastic version of classical lamination theory. In addition, versions of HFGMC that admit ferroelectric, electrostrictive, and magnetostrictive constituents are presented. The equations of an array of SMA constitutive models are provided for both infinitesimal and finite strain conditions. Finally, application problems are presented for thermo-electro-magneto-elasto-plastic composites and laminates, ferroelectric and electrostrictive composites, several types of SMA-fiber-reinforced composites, and SMA composite plates. This chapter demonstrates the robustness of GMC and HFGMC in that both can be readily extended to predict the effective behavior of smart-inelastic composites and can thus be utilized for rapid design and Analysis of smart composite materials.
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finite strain Micromechanical Analysis of rubber like matrix composites incorporating the mullins damage effect
International Journal of Damage Mechanics, 2009Co-Authors: Jacob AboudiAbstract:A model for hyperelastic rubber-like materials that includes the Mullins damage effect has been incorporated with a finite strain Micromechanical Analysis for composites with periodic microstructures. As a result, it is possible to predict the response of fiber-reinforced rubber-like matrix composites, including the Mullins effect, from the knowledge of the character and properties of the constituents and their volume ratios. This is expressed by the establishment of macroscopic constitutive equations that govern the behavior of the damaged composite undergoing finite deformations. The reliability and accuracy of the Micromechanical prediction are demonstrated by comparisons with the response of four types of porous materials that are subjected to axisymmetric loading for which exact solutions can be established during loading, and with finite-difference solutions which are valid in both loading and unloading. Next, a master damage function that controls the Mullins effect of a monolithic (unreinforced) hyperelastic material is established from experimental data. This hyperelastic material and its associated damage function are employed to characterize a rubber-like matrix reinforced by continuous nylon fibers. The predicted responses of this composite to transverse normal, transverse shear, axial shear and off-axis loadings are shown.
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Investigation of shape memory alloy honeycombs by means of a Micromechanical Analysis
Modelling and Simulation in Materials Science and Engineering, 2008Co-Authors: Yuval Freed, Jacob Aboudi, Rivka GilatAbstract:Shape memory alloy (SMA) honeycombs are promising new smart materials which may be used for light-weight structures, biomedical implants, actuators and active structures. In this study, the behavior of several SMA honeycomb structures is investigated by means of a continuum-based thermomechanically coupled Micromechanical Analysis. To this end, macroscopic inelastic stress?strain responses of several topologies are investigated, both for pseudoelasticity and for shape memory effect. It was found that the triangular topology exhibits the best performance. In addition, the initial transformation surfaces are presented for all possible combinations of applied in-plane stresses. A special two-phase microstructure that is capable of producing an overall negative coefficient of thermal expansion is suggested and studied. In this configuration, in which one of the phases is a SMA, residual strains are being generated upon recovery. Here, the negative coefficient of thermal expansion appears to be associated with a larger amount of residual strain upon recovery. Furthermore, a two-dimensional SMA re-entrant topology that generates a negative in-plane Poisson's ratio is analyzed, and the effect of the full thermomechanical coupling is examined. Finally, the response of a particular three-dimensional microstructure is studied.
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Thermomechanically coupled Micromechanical Analysis of multiphase composites
Journal of Engineering Mathematics, 2007Co-Authors: Jacob AboudiAbstract:One- and two-way thermomechanically coupled Micromechanical analyses of multiphase composites are presented. In the first type of thermomechanical coupling, a constant temperature that affects the mechanical field only is prescribed at any point of the composite’s constituents. In the two-way thermomechanical coupling, on the other hand, a mutual interaction exists between the mechanical and temperature fields. It is shown that the macroscopic coupled energy equation that is established from a homogenization procedure cannot provide reliable information about the induced temperature that is caused by an applied far-field mechanical loading of the composite. The details of the induced temperature-field variations can be obtained, on the other hand, by the derived two-way thermomechanically coupled Micromechanical Analysis, thus enabling the identification of critical hot spots in the mechanically loaded composite. Results exhibit, in particular, the induced temperature field in metal-matrix and polymer-matrix composites.
Yuval Freed - One of the best experts on this subject based on the ideXlab platform.
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Thermomechanically Coupled Micromechanical Analysis of Shape Memory Alloy Composites Undergoing Transformation Induced Plasticity
Journal of Intelligent Material Systems and Structures, 2008Co-Authors: Yuval FreedAbstract:In this investigation, fully thermomechanically coupled constitutive and energy equations for shape memory alloys (SMAs) that include the effect of transformation induced plasticity are presented. This is followed by a Micromechanical Analysis for the establishment of the fully coupled thermomechanical constitutive equations that model the overall behavior of SMA composites undergoing transformation induced plasticity. The effects of the thermomechanical coupling and permanent inelasticity which arise by the phase transformation were examined. It was found that the response of the monolithic SMA depends upon the thermomechanical coupling. The permanent inelasticity and the resulting induced temperature become significant especially in the case of several repeating cycles. In addition, the induced average temperature caused by the thermomechanical coupling as well as the stress—strain behavior of SMA/epoxy and SMA/aluminum composite materials were determined. A significant thermomechanical coupling, which ...
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Investigation of shape memory alloy honeycombs by means of a Micromechanical Analysis
Modelling and Simulation in Materials Science and Engineering, 2008Co-Authors: Yuval Freed, Jacob Aboudi, Rivka GilatAbstract:Shape memory alloy (SMA) honeycombs are promising new smart materials which may be used for light-weight structures, biomedical implants, actuators and active structures. In this study, the behavior of several SMA honeycomb structures is investigated by means of a continuum-based thermomechanically coupled Micromechanical Analysis. To this end, macroscopic inelastic stress?strain responses of several topologies are investigated, both for pseudoelasticity and for shape memory effect. It was found that the triangular topology exhibits the best performance. In addition, the initial transformation surfaces are presented for all possible combinations of applied in-plane stresses. A special two-phase microstructure that is capable of producing an overall negative coefficient of thermal expansion is suggested and studied. In this configuration, in which one of the phases is a SMA, residual strains are being generated upon recovery. Here, the negative coefficient of thermal expansion appears to be associated with a larger amount of residual strain upon recovery. Furthermore, a two-dimensional SMA re-entrant topology that generates a negative in-plane Poisson's ratio is analyzed, and the effect of the full thermomechanical coupling is examined. Finally, the response of a particular three-dimensional microstructure is studied.
Rivka Gilat - One of the best experts on this subject based on the ideXlab platform.
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Investigation of shape memory alloy honeycombs by means of a Micromechanical Analysis
Modelling and Simulation in Materials Science and Engineering, 2008Co-Authors: Yuval Freed, Jacob Aboudi, Rivka GilatAbstract:Shape memory alloy (SMA) honeycombs are promising new smart materials which may be used for light-weight structures, biomedical implants, actuators and active structures. In this study, the behavior of several SMA honeycomb structures is investigated by means of a continuum-based thermomechanically coupled Micromechanical Analysis. To this end, macroscopic inelastic stress?strain responses of several topologies are investigated, both for pseudoelasticity and for shape memory effect. It was found that the triangular topology exhibits the best performance. In addition, the initial transformation surfaces are presented for all possible combinations of applied in-plane stresses. A special two-phase microstructure that is capable of producing an overall negative coefficient of thermal expansion is suggested and studied. In this configuration, in which one of the phases is a SMA, residual strains are being generated upon recovery. Here, the negative coefficient of thermal expansion appears to be associated with a larger amount of residual strain upon recovery. Furthermore, a two-dimensional SMA re-entrant topology that generates a negative in-plane Poisson's ratio is analyzed, and the effect of the full thermomechanical coupling is examined. Finally, the response of a particular three-dimensional microstructure is studied.
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Micromechanical Analysis of lattice blocks
International Journal of Solids and Structures, 2005Co-Authors: Jacob Aboudi, Rivka GilatAbstract:Abstract Multiphase lattice blocks with periodic structure are analyzed by a continuum-based Micromechanical approach. As a result, effective stiffness tensors, global initial yield surfaces, global damage thresholds, effective inelastic stress–strain responses and critical yielding temperatures of lattice blocks are established. Applications are given for various types of elastic and inelastic lattice blocks made of an aluminum alloy. Furthermore, a lattice block with negative effective Poisson’s ratios is considered, and two types of two-phase lattice blocks that are capable to produce negative effective coefficients of thermal expansion are presented.
J. F. Shao - One of the best experts on this subject based on the ideXlab platform.
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Micromechanical Analysis of damage in saturated quasi brittle materials
International Journal of Solids and Structures, 2012Co-Authors: N. Xie, Qi-zhi Zhu, J. F. ShaoAbstract:In this paper, we propose a Micromechanical Analysis of damage and related inelastic deformation in saturated porous quasi brittle materials. The materials are weakened by randomly distributed microcracks and saturated by interstitial fluid with drained and undrained conditions. The emphasis is put on the closed cracks under compression-dominated stresses. The material damage is related to the frictional sliding on crack surface and described by a local scalar variable. The effective properties of the materials are determined using a linear homogenization approach, based on the extension of Eshelby's inclusion solution to penny shaped cracks. The inelastic behavior induced by microcracks is described in the framework of the irreversible thermodynamics. As an original contribution, the potential energy of the saturated materials weakened by closed frictional microcracks is determined and formulated as a sum of an elastic part and a plastic part, the latter entirely induced by frictional sliding of microcracks. The influence of fluid pressure is accounted for in the friction criterion through the concept of local effective stress at microcracks. We show that the Biot's effective stress controls the evolution of total strain while the local Terzaghi's effective stress controls the evolution of plastic strain. Further, the frictional sliding between crack lips generates volumetric dilatancy and reduction in fluid pressure. Applications of the proposed model to typical brittle rocks are presented with comparisons between numerical results and experimental data in both drained and undrained triaxial tests.
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Micromechanical Analysis of coupling between anisotropic damage and friction in quasi brittle materials: Role of the homogenization scheme
International Journal of Solids and Structures, 2008Co-Authors: Q.-z. Zhu, Djimedo Kondo, J. F. ShaoAbstract:This paper deals with Micromechanical Analysis of anisotropic damage and its coupling with friction in quasi brittle materials. The anisotropic model is formulated in the framework of Eshelby-based homogenization methods. The emphasis is put on the study of effects of spatial distribution of microcracks and their interactions. Microcracks closure effects as well as coupling between damage evolution and frictional sliding on closed cracks lips are taken into account. The interaction of sliding and damage evolution is addressed by performing a global thermodynamic Analysis on two macroscopic criteria established in the paper. The role of the homogenization scheme is discussed in detail through various applications.
Marko Rakin - One of the best experts on this subject based on the ideXlab platform.
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ductile fracture of pipe ring notched bend specimens Micromechanical Analysis
Engineering Fracture Mechanics, 2017Co-Authors: W. Musraty, Bojan Medjo, Nenad Gubeljak, Andrej Likeb, Aleksandar Sedmak, Ivana Cvijovicalagic, Marko RakinAbstract:Abstract Integrity of pipes is typically assessed by testing fracture mechanics specimens, such as compact tensile (CT) or single-edge notched bending (SENB). However, for some pipe dimensions it is not easy or possible to fabricate a specimen conforming to the requirements of standard procedures. A new type of specimen is proposed recently, which can be advantageous for relatively small pipe diameters and axial defects - the pipe ring notch bend specimen - PRNB. In this work, criteria for failure by ductile fracture of PRNB specimens are determined experimentally and by application of Micromechanical Analysis. The influence of size of the specimen, as well as size and shape of the stress concentrator, is analysed. The results of this study, along with previous authors’ results, lead to the conclusion that the pipe ring specimens can be applied in integrity assessment of pipes with defects. Also, the benefits of their application include much simpler fabrication and the same material history as the pipe itself.
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Ductile fracture of pipe-ring notched bend specimens – Micromechanical Analysis
Engineering Fracture Mechanics, 2017Co-Authors: W. Musraty, Bojan Medjo, Nenad Gubeljak, Andrej Likeb, Ivana Cvijović-alagić, Aleksandar Sedmak, Marko RakinAbstract:Abstract Integrity of pipes is typically assessed by testing fracture mechanics specimens, such as compact tensile (CT) or single-edge notched bending (SENB). However, for some pipe dimensions it is not easy or possible to fabricate a specimen conforming to the requirements of standard procedures. A new type of specimen is proposed recently, which can be advantageous for relatively small pipe diameters and axial defects - the pipe ring notch bend specimen - PRNB. In this work, criteria for failure by ductile fracture of PRNB specimens are determined experimentally and by application of Micromechanical Analysis. The influence of size of the specimen, as well as size and shape of the stress concentrator, is analysed. The results of this study, along with previous authors’ results, lead to the conclusion that the pipe ring specimens can be applied in integrity assessment of pipes with defects. Also, the benefits of their application include much simpler fabrication and the same material history as the pipe itself.
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Micromechanical Analysis of mechanical heterogeneity effect on the ductile tearing of weldments
Materials & Design, 2012Co-Authors: Bashir Younise, Bojan Medjo, Nenad Gubeljak, Aleksandar Sedmak, Marko Rakin, Meri Burzić, M. ZrilicAbstract:Abstract The objective of this study is determination of the effect of mechanical heterogeneity on ductile crack initiation and propagation in weldments using Micromechanical approach. Welded single-edge notched bend (SENB) specimens were experimentally and numerically analysed. Material properties of welded joint zones were estimated using a combined experimental and numerical procedure; strains on a smooth tensile specimen were determined using ARAMIS stereometric measuring system in order to obtain true stress – true strain curves. High-strength low-alloyed steel was used as base metal, in quenched and tempered condition. J – R curves and crack growth initiation values of fracture mechanics parameter were experimentally and numerically obtained for specimens with a pre-crack in the heat-affected zone (HAZ) and weld metal (WM). The complete Gurson model (CGM) was used in prediction of J – R curves and crack growth initiation. It is shown that the resistance to crack initiation and growth can be predicted using Micromechanical Analysis, and that the results are significantly affected by mechanical heterogeneity of the weldment.
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prediction of ductile fracture initiation using Micromechanical Analysis
Engineering Fracture Mechanics, 2004Co-Authors: Marko Rakin, Z Cvijovic, Vencislav Grabulov, S Putic, Aleksandar SedmakAbstract:Abstract In the paper ductile fracture initiation Analysis of low-alloyed ferritic steel has been made by application of two Micromechanical models: the Rice–Tracey void growth model and the Gurson–Tvergaard–Needleman (GTN) model. The aim of the study was to analyse transferability of Micromechanical parameters determined on specimens without initial crack to pre-cracked specimens. A significant part of the research has been carried out through participation in the round robin project organised by the European Structural Integrity Society (ESIS). Tensile tests have been performed on cylindrical smooth specimens and CT specimens. Critical values of Micromechanical parameters determined on smooth specimen for both applied models, have been used for prediction of the crack growth initiation in CT specimen. Modelling of the first phase of ductile fracture––void nucleation––has been carried out using quantitative metallographic Analysis of non-metallic inclusion content in tested steel. For determination of critical values of model parameters corresponding to ductile fracture initiation a simple procedure has been applied based on a combination of experimental and numerical results. Evaluated J -integral values corresponding to onset of crack growth, J i , are in good agreement with experimental result and both models have proved to be suitable for determination of the ductile fracture initiation in tested steel. The effect of FE size at a crack tip on J i -value has been particularly analysed: it has been established that the calculation with FE size corresponding to the mean free path λ between inclusions in steel gives results that are in accordance with the experimental ones.