The Experts below are selected from a list of 12 Experts worldwide ranked by ideXlab platform
Dimitris C Lagoudas - One of the best experts on this subject based on the ideXlab platform.
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a thermodynamical constitutive model for shape memory materials part ii the sma Composite material
International Journal of Plasticity, 1996Co-Authors: James G Boyd, Dimitris C LagoudasAbstract:Abstract The phenomenological SMA equations developed in Part I are used in this second paper to derive the free energy and dissipation of a SMA Composite material. The derivation consists of solving a boundary value problem formulated over a mesoscale representative volume element, followed by an averaging procedure to obtain the macroscopic Composite constitutive equations. Explicit equations are derived for the Transformation tensors that relate the Composite Transformation strain rate to the phase Transformation rate in the fiber and matrix. Some key findings for the two-way SME in a SMA fiber/elastomer matrix Composite are that processing-induced residual stresses alter the Composite austenite start and martensite start temperatures, as well as the amount of Composite strain recovered during a complete cycle of temperature and fiber martensite volume fraction. Relative to the two-way SME response of stiff-matrix Composites, it was found that compliant-matrix Composites: (1) complete the phase Transformation over a narrower temperature range; (2) exhibit greater Transformation strain during the reverse Transformation; and (3) undergo an incomplete strain cycle during a complete cycle of temperature and fiber martensite volume fraction. Due to the interaction of the fiber and matrix during Transformation, macroscopic proportional stressing of the Composite results in non-proportional fiber stressing, which in turn causes a small amount of martensitic reorientation to occur simultaneously with the Transformation.
James G Boyd - One of the best experts on this subject based on the ideXlab platform.
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a thermodynamical constitutive model for shape memory materials part ii the sma Composite material
International Journal of Plasticity, 1996Co-Authors: James G Boyd, Dimitris C LagoudasAbstract:Abstract The phenomenological SMA equations developed in Part I are used in this second paper to derive the free energy and dissipation of a SMA Composite material. The derivation consists of solving a boundary value problem formulated over a mesoscale representative volume element, followed by an averaging procedure to obtain the macroscopic Composite constitutive equations. Explicit equations are derived for the Transformation tensors that relate the Composite Transformation strain rate to the phase Transformation rate in the fiber and matrix. Some key findings for the two-way SME in a SMA fiber/elastomer matrix Composite are that processing-induced residual stresses alter the Composite austenite start and martensite start temperatures, as well as the amount of Composite strain recovered during a complete cycle of temperature and fiber martensite volume fraction. Relative to the two-way SME response of stiff-matrix Composites, it was found that compliant-matrix Composites: (1) complete the phase Transformation over a narrower temperature range; (2) exhibit greater Transformation strain during the reverse Transformation; and (3) undergo an incomplete strain cycle during a complete cycle of temperature and fiber martensite volume fraction. Due to the interaction of the fiber and matrix during Transformation, macroscopic proportional stressing of the Composite results in non-proportional fiber stressing, which in turn causes a small amount of martensitic reorientation to occur simultaneously with the Transformation.
Jorge Goncalves - One of the best experts on this subject based on the ideXlab platform.
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on transitive consistency for linear invertible Transformations between euclidean coordinate systems
arXiv: Optimization and Control, 2015Co-Authors: Johan Thunberg, Florian Bernard, Jorge GoncalvesAbstract:Transitive consistency is an intrinsic property for collections of linear invertible Transformations between Euclidean coordinate frames. In practice, when the Transformations are estimated from data, this property is lacking. This work addresses the problem of synchronizing Transformations that are not transitively consistent. Once the Transformations have been synchronized, they satisfy the transitive consistency condition - a Transformation from frame $A$ to frame $C$ is equal to the Composite Transformation of first transforming A to B and then transforming B to C. The coordinate frames correspond to nodes in a graph and the Transformations correspond to edges in the same graph. Two direct or centralized synchronization methods are presented for different graph topologies; the first one for quasi-strongly connected graphs, and the second one for connected graphs. As an extension of the second method, an iterative Gauss-Newton method is presented, which is later adapted to the case of affine and Euclidean Transformations. Two distributed synchronization methods are also presented for orthogonal matrices, which can be seen as distributed versions of the two direct or centralized methods; they are similar in nature to standard consensus protocols used for distributed averaging. When the Transformations are orthogonal matrices, a bound on the optimality gap can be computed. Simulations show that the gap is almost right, even for noise large in magnitude. This work also contributes on a theoretical level by providing linear algebraic relationships for transitively consistent Transformations. One of the benefits of the proposed methods is their simplicity - basic linear algebraic methods are used, e.g., the Singular Value Decomposition (SVD). For a wide range of parameter settings, the methods are numerically validated.
Johan Thunberg - One of the best experts on this subject based on the ideXlab platform.
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on transitive consistency for linear invertible Transformations between euclidean coordinate systems
arXiv: Optimization and Control, 2015Co-Authors: Johan Thunberg, Florian Bernard, Jorge GoncalvesAbstract:Transitive consistency is an intrinsic property for collections of linear invertible Transformations between Euclidean coordinate frames. In practice, when the Transformations are estimated from data, this property is lacking. This work addresses the problem of synchronizing Transformations that are not transitively consistent. Once the Transformations have been synchronized, they satisfy the transitive consistency condition - a Transformation from frame $A$ to frame $C$ is equal to the Composite Transformation of first transforming A to B and then transforming B to C. The coordinate frames correspond to nodes in a graph and the Transformations correspond to edges in the same graph. Two direct or centralized synchronization methods are presented for different graph topologies; the first one for quasi-strongly connected graphs, and the second one for connected graphs. As an extension of the second method, an iterative Gauss-Newton method is presented, which is later adapted to the case of affine and Euclidean Transformations. Two distributed synchronization methods are also presented for orthogonal matrices, which can be seen as distributed versions of the two direct or centralized methods; they are similar in nature to standard consensus protocols used for distributed averaging. When the Transformations are orthogonal matrices, a bound on the optimality gap can be computed. Simulations show that the gap is almost right, even for noise large in magnitude. This work also contributes on a theoretical level by providing linear algebraic relationships for transitively consistent Transformations. One of the benefits of the proposed methods is their simplicity - basic linear algebraic methods are used, e.g., the Singular Value Decomposition (SVD). For a wide range of parameter settings, the methods are numerically validated.
Florian Bernard - One of the best experts on this subject based on the ideXlab platform.
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on transitive consistency for linear invertible Transformations between euclidean coordinate systems
arXiv: Optimization and Control, 2015Co-Authors: Johan Thunberg, Florian Bernard, Jorge GoncalvesAbstract:Transitive consistency is an intrinsic property for collections of linear invertible Transformations between Euclidean coordinate frames. In practice, when the Transformations are estimated from data, this property is lacking. This work addresses the problem of synchronizing Transformations that are not transitively consistent. Once the Transformations have been synchronized, they satisfy the transitive consistency condition - a Transformation from frame $A$ to frame $C$ is equal to the Composite Transformation of first transforming A to B and then transforming B to C. The coordinate frames correspond to nodes in a graph and the Transformations correspond to edges in the same graph. Two direct or centralized synchronization methods are presented for different graph topologies; the first one for quasi-strongly connected graphs, and the second one for connected graphs. As an extension of the second method, an iterative Gauss-Newton method is presented, which is later adapted to the case of affine and Euclidean Transformations. Two distributed synchronization methods are also presented for orthogonal matrices, which can be seen as distributed versions of the two direct or centralized methods; they are similar in nature to standard consensus protocols used for distributed averaging. When the Transformations are orthogonal matrices, a bound on the optimality gap can be computed. Simulations show that the gap is almost right, even for noise large in magnitude. This work also contributes on a theoretical level by providing linear algebraic relationships for transitively consistent Transformations. One of the benefits of the proposed methods is their simplicity - basic linear algebraic methods are used, e.g., the Singular Value Decomposition (SVD). For a wide range of parameter settings, the methods are numerically validated.