The Experts below are selected from a list of 1434822 Experts worldwide ranked by ideXlab platform
L. Karunamoorthy - One of the best experts on this subject based on the ideXlab platform.
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Microstructure based finite element analysis of failure prediction in particle reinforced metal matrix composite
Journal of Materials Processing Technology, 2008Co-Authors: Balasivanandha S Prabu, L. KarunamoorthyAbstract:Abstract This paper reports Microstructure-based finite element analysis of particle-reinforced metal–matrix composite (PRMMC) to evaluate the stress–strain and failure behavior. The optimization of properties was carried out from analysis of Microstructure of MMC since the properties depend on particles arrangement in Microstructure. The Microstructure with random particle arrangement and particle clusters were analysed. In order to model the Microstructure for finite element analysis (FEA), the Microstructures were converted into equivalent CAD file format. The FEA meshes were generated on the CAD model in ANSYS 7. The failures such as particle fracture, interface decohesion and matrix yielding were predicted for particle clustered and non-clustered Microstructures. The effects of particles arrangement on the failure mechanisms were analysed.
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Microstructure-based finite element analysis of failure prediction in particle-reinforced metal–matrix composite
Journal of Materials Processing Technology, 2008Co-Authors: S. Balasivanandha Prabu, L. KarunamoorthyAbstract:Abstract This paper reports Microstructure-based finite element analysis of particle-reinforced metal–matrix composite (PRMMC) to evaluate the stress–strain and failure behavior. The optimization of properties was carried out from analysis of Microstructure of MMC since the properties depend on particles arrangement in Microstructure. The Microstructure with random particle arrangement and particle clusters were analysed. In order to model the Microstructure for finite element analysis (FEA), the Microstructures were converted into equivalent CAD file format. The FEA meshes were generated on the CAD model in ANSYS 7. The failures such as particle fracture, interface decohesion and matrix yielding were predicted for particle clustered and non-clustered Microstructures. The effects of particles arrangement on the failure mechanisms were analysed.
Xixi Dong - One of the best experts on this subject based on the ideXlab platform.
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Evidence of disruption of Si-rich Microstructure in engineering-lightweight Al–12.2at.%Si alloy melt above liquidus temperature
Scientific Reports, 2020Co-Authors: Xixi Dong, Sajjad Amirkhanlou, Pjotr Popel, Ulf Dahlborg, M. Calvo-dahlborgAbstract:The exploration of Microstructures in high temperature alloy melts is important for manufacturing of metallic components but extremely challenging. Here, we report experimental evidence of the disruption of Si-rich Microstructure in engineering-lightweight Al-12.2at.%Si alloy melt at 1100 °C, via melt-spinning (MS) of Al 1−x Si x (x = 0.03,0.07,0.122,0.2) alloy melts from different initial melt temperatures, 800 °C and 1100 °C, under the super-high cooling rate of ~ 10 6 °C/s, in cooperation with the small angle neutron scattering (SANS) measurement. Si particles in 1100 °C MS alloys are abnormally smaller and increased in number at Al-12.2at.%Si, compared with 800 °C MS alloys, which demonstrates the disruption of Si-rich Microstructure in Al-12.2at.%Si alloy melt at 1100 °C. SANS experiment verifies that large quantities of small (0-10 nm) Si-rich Microstructures and small quantities of large (10-240 nm) Si-rich Microstructures exist in Al-12.2at.%Si alloy melt, and the large Si-rich Microstructures disrupt into small Si-rich Microstructures with increasing of melt temperature from 800 to 1100 °C. Microstructure analysis of the MS alloys indicates that the large Si-rich Microstructures in Al-12.2at.%Si alloy melt are probably aggregates comprising multiple small Si-rich Microstructures. This work also provides a pathway for the exploration of Microstructures in other high temperature alloy melts. The structural materials especially metallic alloys are basic support of modern society 1,2. Most of the metallic alloy components are manufactured from the initial melt state via the metallurgy and casting route, and the Microstructure in alloy melts will affect the subsequent solidification and mechanical properties of metallic components 3-7. However, the exploration of Microstructure in alloy melts is always extraordinary challenging, due to the high temperature of alloy melts that usually ranges from several hundreds to ~ 3500 °C. The Al-Si based alloys are important lightweight engineering alloys in automotive, aerospace and other industries, which constitute ~ 90 % of all aluminium shape castings 8-14. As a special system, Al-Si alloy comprises two elements with a large melting point discrepancy at 754 °C (Al: 660 °C, Si: 1414 °C), which provides theoretical possibility for the existence of Si-rich Microstructure in the molten state 15. In addition, the measurement of irreversible changes in physical properties such as density during heating and cooling cycles supported the Microstructure evolution in Al-Si alloy melts with changing of melt temperature 16 , however, we can hardly get information of the detail Microstructure evolution in the Al-Si alloy melts from the measurement of physical properties. open
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evidence of disruption of si rich Microstructure in engineering lightweight al 12 2at si alloy melt above liquidus temperature
Scientific Reports, 2020Co-Authors: Xixi Dong, Sajjad Amirkhanlou, Pjotr Popel, Ulf Dahlborg, M CalvodahlborgAbstract:The exploration of Microstructures in high temperature alloy melts is important for manufacturing of metallic components but extremely challenging. Here, we report experimental evidence of the disruption of Si-rich Microstructure in engineering-lightweight Al-12.2at.%Si alloy melt at 1100 °C, via melt-spinning (MS) of Al1-xSix (x = 0.03,0.07,0.122,0.2) alloy melts from different initial melt temperatures, 800 °C and 1100 °C, under the super-high cooling rate of ~ 106 °C/s, in cooperation with the small angle neutron scattering (SANS) measurement. Si particles in 1100 °C MS alloys are abnormally smaller and increased in number at Al-12.2at.%Si, compared with 800 °C MS alloys, which demonstrates the disruption of Si-rich Microstructure in Al-12.2at.%Si alloy melt at 1100 °C. SANS experiment verifies that large quantities of small (0-10 nm) Si-rich Microstructures and small quantities of large (10-240 nm) Si-rich Microstructures exist in Al-12.2at.%Si alloy melt, and the large Si-rich Microstructures disrupt into small Si-rich Microstructures with increasing of melt temperature from 800 to 1100 °C. Microstructure analysis of the MS alloys indicates that the large Si-rich Microstructures in Al-12.2at.%Si alloy melt are probably aggregates comprising multiple small Si-rich Microstructures. This work also provides a pathway for the exploration of Microstructures in other high temperature alloy melts.
Michael De Volder - One of the best experts on this subject based on the ideXlab platform.
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predictive synthesis of freeform carbon nanotube microarchitectures by strain engineered chemical vapor deposition
Small, 2016Co-Authors: Sei Jin Park, Michael De Volder, Hangbo Zhao, Sanha Kim, John A HartAbstract:High-throughput fabrication of Microstructured surfaces with multi-directional, re-entrant, or otherwise curved features is becoming increasingly important for applications such as phase change heat transfer, adhesive gripping, and control of electromagnetic waves. Toward this goal, curved Microstructures of aligned carbon nanotubes (CNTs) can be fabricated by engineered variation of the CNT growth rate within each Microstructure, for example by patterning of the CNT growth catalyst partially upon a layer which retards the CNT growth rate. This study develops a finite-element simulation framework for predictive synthesis of complex CNT microarchitectures by this strain-engineered growth process. The simulation is informed by parametric measurements of the CNT growth kinetics, and the anisotropic mechanical properties of the CNTs, and predicts the shape of CNT Microstructures with impressive fidelity. Moreover, the simulation calculates the internal stress distribution that results from extreme deformation of the CNT structures during growth, and shows that delamination of the interface between the differentially growing segments occurs at a critical shear stress. Guided by these insights, experiments are performed to study the time- and geometry-depended stress development, and it is demonstrated that corrugating the interface between the segments of each Microstructure mitigates the interface failure. This study presents a methodology for 3D Microstructure design based on "pixels" that prescribe directionality to the resulting Microstructure, and show that this framework enables the predictive synthesis of more complex architectures including twisted and truss-like forms.
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Strain-engineered manufacturing of freeform carbon nanotube Microstructures
Nature Communications, 2014Co-Authors: Michael De Volder, Sameh Tawfick, S. Park, A J HartAbstract:The skins of many plants and animals have intricate microscale surface features that give rise to properties such as directed water repellency and adhesion, camouflage, and resistance to fouling. However, engineered mimicry of these designs has been restrained by the limited capabilities of top–down fabrication processes. Here we demonstrate a new technique for scalable manufacturing of freeform Microstructures via strain-engineered growth of aligned carbon nanotubes (CNTs). Offset patterning of the CNT growth catalyst is used to locally modulate the CNT growth rate. This causes the CNTs to collectively bend during growth, with exceptional uniformity over large areas. The final shape of the curved CNT Microstructures can be designed via finite element modeling, and compound catalyst shapes produce Microstructures with multidirectional curvature and unusual self-organized patterns. Conformal coating of the CNTs enables tuning of the mechanical properties independently from the Microstructure geometry, representing a versatile principle for design and manufacturing of complex Microstructured surfaces.Reproducing complex surface geometries for high-performance composite materials is very desirable, although current synthesis methods are limited. Here, the authors present a technique to produce large-area freeform Microstructures via strain-engineered growth of patterned vertically aligned carbon nanotubes.
A J Hart - One of the best experts on this subject based on the ideXlab platform.
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Strain-engineered manufacturing of freeform carbon nanotube Microstructures
Nature Communications, 2014Co-Authors: Michael De Volder, Sameh Tawfick, S. Park, A J HartAbstract:The skins of many plants and animals have intricate microscale surface features that give rise to properties such as directed water repellency and adhesion, camouflage, and resistance to fouling. However, engineered mimicry of these designs has been restrained by the limited capabilities of top–down fabrication processes. Here we demonstrate a new technique for scalable manufacturing of freeform Microstructures via strain-engineered growth of aligned carbon nanotubes (CNTs). Offset patterning of the CNT growth catalyst is used to locally modulate the CNT growth rate. This causes the CNTs to collectively bend during growth, with exceptional uniformity over large areas. The final shape of the curved CNT Microstructures can be designed via finite element modeling, and compound catalyst shapes produce Microstructures with multidirectional curvature and unusual self-organized patterns. Conformal coating of the CNTs enables tuning of the mechanical properties independently from the Microstructure geometry, representing a versatile principle for design and manufacturing of complex Microstructured surfaces.Reproducing complex surface geometries for high-performance composite materials is very desirable, although current synthesis methods are limited. Here, the authors present a technique to produce large-area freeform Microstructures via strain-engineered growth of patterned vertically aligned carbon nanotubes.
Xiaodong Huang - One of the best experts on this subject based on the ideXlab platform.
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Concurrent optimization of macrostructures and material Microstructures and orientations for maximizing natural frequency
Engineering Structures, 2020Co-Authors: Xiaolei Yan, Haiyan Hua, Weidong Huang, Xiaodong HuangAbstract:Abstract In this paper, an efficient concurrent optimization method of macrostructures, and material Microstructures and orientations is proposed for maximizing natural frequency. It is assumed that the macrostructure is composed of uniform material with the same Microstructure but with various orientation. The bi-directional evolutionary structural optimization (BESO) method is applied to optimize the macrostructure and its material Microstructure under a given weight constraint. Meanwhile, the optimality condition with respect to local material orientation is derived and embedded in the two-scale design of macrostructures and material Microstructures. Numerical examples are presented to demonstrate the capability and effectiveness of the proposed optimization algorithm. The results show that the current design of macrostructures, material Microstructures, and local material orientation greatly improves structural dynamic performance.
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topology optimization of viscoelastic materials for maximizing damping and natural frequency of macrostructures
World Congress of Structural and Multidisciplinary Optimisation, 2017Co-Authors: Xiaodong HuangAbstract:The topology optimization algorithm of viscoelastic material Microstructure based on bi-directional evolutionary structural optimization (BESO) method is proposed for macroscopic damping characteristics of the structures. The optimization aims to obtain the optimal topologies of the material Microstructures within given volume fraction so that the resulting structure has optimal damping characteristics. The design concept of this scheme is essentially a two-scale design which considers the effective properties of material Microstructures and macroscopic performance. Viscoelastic material is used for the damping of the macrostructure and the frequency constraint is also applied so that the resulting macrostructure has the best damping performance with prescribed natural frequencies. The Microstructures of the material are represented by periodic unit cells (PUCs) and the effective properties of the material Microstructures are homogenized and integrated into the finite element analysis of the macroscopic structures. The sensitivity analysis is conducted for iteratively updating the topologies of material Microstructures. Numerical examples are presented to demonstrate the effectiveness of the proposed optimization algorithm.
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Comparing optimal material Microstructures with optimal periodic structures
Computational Materials Science, 2013Co-Authors: Xiaodong Huang, Xiaoying Yang, Jian Hua RongAbstract:The optimal design of periodic structures under the macro scale and that of periodic materials under the micro scale are treated differently by the current topology optimization techniques. Nevertheless, a material point in theory could be considered as a unit cell in a periodic structure if the number of unit cells approaches to infinity. In this work, we investigate the equivalence between optimal solutions of periodic structures obtained from the macro scale approach on the structure level and those of material Microstructures obtained from the micro scale approach using the homogenization techniques. The minimization of the mean compliance of the macrostructure with a volume constraint is taken as the optimization problem for both structural and material designs. On the macro scale, we solve the optimization problem by gradually increasing the number of unit cells until the solution converges, in terms of both the topology and the objective function. On the micro scale, the optimal Microstructure of the material is obtained for the macrostructure under prescribed loading and support conditions. The Microstructure of the material compares very well with the corresponding optimal topology from the periodic macrostructural design. This work reveals the equivalence of the solutions from the macro and micro approaches, and proves that an optimal finite periodic solution remains valid through cell refinement to infinite periodicity.
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Topology optimization of Microstructures of cellular materials and composites for macrostructures
Computational Materials Science, 2013Co-Authors: Xiaodong Huang, Shiwei Zhou, Yi Min XieAbstract:This paper introduces a topology optimization algorithm for the optimal design of cellular materials and composites with periodic Microstructures so that the resulting macrostructure has the maximum stiffness (or minimum mean compliance). The effective properties of the heterogeneous material are obtained through the homogenization theory, and these properties are integrated into the analysis of the macrostructure. The sensitivity analysis for the material unit cell is established for such a two-scale optimization problem. Then, a bi-directional evolutionary structural optimization (BESO) approach is developed to achieve a clear and optimized topology for the material Microstructure. Several numerical examples are presented to validate the proposed optimization algorithm and a variety of anisotropic Microstructures of cellular materials and composites are obtained. The various effects on the topological design of the material Microstructure are discussed.
