The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform

Robin Shandas - One of the best experts on this subject based on the ideXlab platform.

  • Finite Deformation thermo mechanical behavior of thermally induced shape memory polymers
    Journal of The Mechanics and Physics of Solids, 2008
    Co-Authors: Jerry H Qi, Christopher Michael Yakacki, Francisco Castro, Thao D Nguyen, Robin Shandas
    Abstract:

    Abstract Shape memory polymers (SMPs) are polymers that can demonstrate programmable shape memory effects. Typically, an SMP is pre-deformed from an initial shape to a deformed shape by applying a mechanical load at the temperature T H > T g . It will maintain this deformed shape after subsequently lowering the temperature to T L T g and removing the externally mechanical load. The shape memory effect is activated by increasing the temperature to T D > T g , where the initial shape is recovered. In this paper, the Finite Deformation thermo-mechanical behaviors of amorphous SMPs are experimentally investigated. Based on the experimental observations and an understanding of the underlying physical mechanism of the shape memory behavior, a three-dimensional (3D) constitutive model is developed to describe the Finite Deformation thermo-mechanical response of SMPs. The model in this paper has been implemented into an ABAQUS user material subroutine (UMAT) for Finite element analysis, and numerical simulations of the thermo-mechanical experiments verify the efficiency of the model. This model will serve as a modeling tool for the design of more complicated SMP-based structures and devices.

  • Finite Deformation thermo-mechanical behavior of thermally induced shape memory polymers
    Journal of the Mechanics and Physics of Solids, 2008
    Co-Authors: H. Jerry Qi, Christopher Michael Yakacki, Francisco Castro, Thao D Nguyen, Robin Shandas
    Abstract:

    Shape memory polymers (SMPs) are polymers that can demonstrate programmable shape memory effects. Typically, an SMP is pre-deformed from an initial shape to a deformed shape by applying a mechanical load at the temperature TH>Tg. It will maintain this deformed shape after subsequently lowering the temperature to TLTg, where the initial shape is recovered. In this paper, the Finite Deformation thermo-mechanical behaviors of amorphous SMPs are experimentally investigated. Based on the experimental observations and an understanding of the underlying physical mechanism of the shape memory behavior, a three-dimensional (3D) constitutive model is developed to describe the Finite Deformation thermo-mechanical response of SMPs. The model in this paper has been implemented into an ABAQUS user material subroutine (UMAT) for Finite element analysis, and numerical simulations of the thermo-mechanical experiments verify the efficiency of the model. This model will serve as a modeling tool for the design of more complicated SMP-based structures and devices. © 2007 Elsevier Ltd. All rights reserved.

Yonggang Huang - One of the best experts on this subject based on the ideXlab platform.

  • A Finite Deformation theory of strain gradient plasticity
    Journal of The Mechanics and Physics of Solids, 2020
    Co-Authors: K. C. Hwang, Hanqing Jiang, Yonggang Huang, N. Hu
    Abstract:

    Abstract Plastic Deformation exhibits strong size dependence at the micron scale, as observed in micro-torsion, bending, and indentation experiments. Classical plasticity theories, which possess no internal material lengths, cannot explain this size dependence. Based on dislocation mechanics, strain gradient plasticity theories have been developed for micron-scale applications. These theories, however, have been limited to inFinitesimal Deformation, even though the micro-scale experiments involve rather large strains and rotations. In this paper, we propose a Finite Deformation theory of strain gradient plasticity. The kinematics relations (including strain gradients), equilibrium equations, and constitutive laws are expressed in the reference configuration. The Finite Deformation strain gradient theory is used to model micro-indentation with results agreeing very well with the experimental data. We show that the Finite Deformation effect is not very significant for modeling micro-indentation experiments.

  • a Finite Deformation model of planar serpentine interconnects for stretchable electronics
    International Journal of Solids and Structures, 2016
    Co-Authors: Yihui Zhang, Fan Zhang, Haoran Fu, Kehchih Hwang, Yonggang Huang
    Abstract:

    Abstract Lithographically defined interconnects with filamentary, serpentine configurations have been widely used in various forms of stretchable electronic devices, owing to the ultra-high stretchability that can be achieved and the relative simple geometry that facilitates the design and fabrication. Theoretical models of serpentine interconnects developed previously for predicting the performance of stretchability were mainly based on the theory of inFinitesimal Deformation. This assumption, however, does not hold for the interconnects that undergo large levels of Deformations before the structural failure. Here, an analytic model of serpentine interconnects is developed starting from the Finite Deformation theory of planar, curved beams. Finite element analyses (FEA) of the serpentine interconnects with a wide range of geometric parameters were performed to validate the developed model. Comparisons of the predicted stretchability to the estimations of linear models provide quantitative insights into the effect of Finite Deformation. Both the theoretical and numerical results indicate that a considerable overestimation (e.g., >50% relatively) of the stretchability can be induced by the linear model for many representative shapes of serpentine interconnects. Furthermore, a simplified analytic solution of the stretchability is obtained by using an approximate model to characterize the nonlinear effect. The developed models can be used to facilitate the designs of serpentine interconnects in future applications.

  • an atomistic based Finite Deformation shell theory for single wall carbon nanotubes
    Journal of The Mechanics and Physics of Solids, 2008
    Co-Authors: Jian Wu, Kehchih Hwang, Yonggang Huang
    Abstract:

    A Finite-Deformation shell theory is developed for single-wall carbon nanotubes (CNTs) based on the interatomic potential. The modified Born rule for Bravais multi-lattice is used to link the continuum strain energy density to the interatomic potential. The theory incorporates the effect of bending moment and curvature for a curved surface, and accurately accounts for the nonlinear, multi-body atomistic interactions as well as the CNT chirality. It avoids the amibiguous definition of nanotube thickness, and provides the constitutive relations among stress, moment, strain and curvature in terms of the interatomic potential.

  • Finite Deformation analysis of mechanism based strain gradient plasticity torsion and crack tip field
    International Journal of Plasticity, 2003
    Co-Authors: K. C. Hwang, Hanqing Jiang, Yonggang Huang
    Abstract:

    Abstract A Finite Deformation theory of mechanism-based strain gradient (MSG) plasticity is developed in this paper based on the Taylor dislocation model. The theory ensures the proper decomposition of Deformation in order to exclude the volumetric Deformation from the strain gradient tensor since the latter represents the density of geometrically necessary dislocations. The solution for a thin cylinder under large torsion is obtained. The numerical method is used to investigate the Finite Deformation crack tip field in MSG plasticity. It is established that the stress level around a crack tip in MSG plasticity is significantly higher than its counterpart (i.e. HRR field) in classical plasticity.

Francisco Castro - One of the best experts on this subject based on the ideXlab platform.

  • Finite Deformation thermo mechanical behavior of thermally induced shape memory polymers
    Journal of The Mechanics and Physics of Solids, 2008
    Co-Authors: Jerry H Qi, Christopher Michael Yakacki, Francisco Castro, Thao D Nguyen, Robin Shandas
    Abstract:

    Abstract Shape memory polymers (SMPs) are polymers that can demonstrate programmable shape memory effects. Typically, an SMP is pre-deformed from an initial shape to a deformed shape by applying a mechanical load at the temperature T H > T g . It will maintain this deformed shape after subsequently lowering the temperature to T L T g and removing the externally mechanical load. The shape memory effect is activated by increasing the temperature to T D > T g , where the initial shape is recovered. In this paper, the Finite Deformation thermo-mechanical behaviors of amorphous SMPs are experimentally investigated. Based on the experimental observations and an understanding of the underlying physical mechanism of the shape memory behavior, a three-dimensional (3D) constitutive model is developed to describe the Finite Deformation thermo-mechanical response of SMPs. The model in this paper has been implemented into an ABAQUS user material subroutine (UMAT) for Finite element analysis, and numerical simulations of the thermo-mechanical experiments verify the efficiency of the model. This model will serve as a modeling tool for the design of more complicated SMP-based structures and devices.

  • Finite Deformation thermo-mechanical behavior of thermally induced shape memory polymers
    Journal of the Mechanics and Physics of Solids, 2008
    Co-Authors: H. Jerry Qi, Christopher Michael Yakacki, Francisco Castro, Thao D Nguyen, Robin Shandas
    Abstract:

    Shape memory polymers (SMPs) are polymers that can demonstrate programmable shape memory effects. Typically, an SMP is pre-deformed from an initial shape to a deformed shape by applying a mechanical load at the temperature TH>Tg. It will maintain this deformed shape after subsequently lowering the temperature to TLTg, where the initial shape is recovered. In this paper, the Finite Deformation thermo-mechanical behaviors of amorphous SMPs are experimentally investigated. Based on the experimental observations and an understanding of the underlying physical mechanism of the shape memory behavior, a three-dimensional (3D) constitutive model is developed to describe the Finite Deformation thermo-mechanical response of SMPs. The model in this paper has been implemented into an ABAQUS user material subroutine (UMAT) for Finite element analysis, and numerical simulations of the thermo-mechanical experiments verify the efficiency of the model. This model will serve as a modeling tool for the design of more complicated SMP-based structures and devices. © 2007 Elsevier Ltd. All rights reserved.

Thao D Nguyen - One of the best experts on this subject based on the ideXlab platform.

  • Finite Deformation thermo mechanical behavior of thermally induced shape memory polymers
    Journal of The Mechanics and Physics of Solids, 2008
    Co-Authors: Jerry H Qi, Christopher Michael Yakacki, Francisco Castro, Thao D Nguyen, Robin Shandas
    Abstract:

    Abstract Shape memory polymers (SMPs) are polymers that can demonstrate programmable shape memory effects. Typically, an SMP is pre-deformed from an initial shape to a deformed shape by applying a mechanical load at the temperature T H > T g . It will maintain this deformed shape after subsequently lowering the temperature to T L T g and removing the externally mechanical load. The shape memory effect is activated by increasing the temperature to T D > T g , where the initial shape is recovered. In this paper, the Finite Deformation thermo-mechanical behaviors of amorphous SMPs are experimentally investigated. Based on the experimental observations and an understanding of the underlying physical mechanism of the shape memory behavior, a three-dimensional (3D) constitutive model is developed to describe the Finite Deformation thermo-mechanical response of SMPs. The model in this paper has been implemented into an ABAQUS user material subroutine (UMAT) for Finite element analysis, and numerical simulations of the thermo-mechanical experiments verify the efficiency of the model. This model will serve as a modeling tool for the design of more complicated SMP-based structures and devices.

  • Finite Deformation thermo-mechanical behavior of thermally induced shape memory polymers
    Journal of the Mechanics and Physics of Solids, 2008
    Co-Authors: H. Jerry Qi, Christopher Michael Yakacki, Francisco Castro, Thao D Nguyen, Robin Shandas
    Abstract:

    Shape memory polymers (SMPs) are polymers that can demonstrate programmable shape memory effects. Typically, an SMP is pre-deformed from an initial shape to a deformed shape by applying a mechanical load at the temperature TH>Tg. It will maintain this deformed shape after subsequently lowering the temperature to TLTg, where the initial shape is recovered. In this paper, the Finite Deformation thermo-mechanical behaviors of amorphous SMPs are experimentally investigated. Based on the experimental observations and an understanding of the underlying physical mechanism of the shape memory behavior, a three-dimensional (3D) constitutive model is developed to describe the Finite Deformation thermo-mechanical response of SMPs. The model in this paper has been implemented into an ABAQUS user material subroutine (UMAT) for Finite element analysis, and numerical simulations of the thermo-mechanical experiments verify the efficiency of the model. This model will serve as a modeling tool for the design of more complicated SMP-based structures and devices. © 2007 Elsevier Ltd. All rights reserved.

Christopher Michael Yakacki - One of the best experts on this subject based on the ideXlab platform.

  • Finite Deformation thermo mechanical behavior of thermally induced shape memory polymers
    Journal of The Mechanics and Physics of Solids, 2008
    Co-Authors: Jerry H Qi, Christopher Michael Yakacki, Francisco Castro, Thao D Nguyen, Robin Shandas
    Abstract:

    Abstract Shape memory polymers (SMPs) are polymers that can demonstrate programmable shape memory effects. Typically, an SMP is pre-deformed from an initial shape to a deformed shape by applying a mechanical load at the temperature T H > T g . It will maintain this deformed shape after subsequently lowering the temperature to T L T g and removing the externally mechanical load. The shape memory effect is activated by increasing the temperature to T D > T g , where the initial shape is recovered. In this paper, the Finite Deformation thermo-mechanical behaviors of amorphous SMPs are experimentally investigated. Based on the experimental observations and an understanding of the underlying physical mechanism of the shape memory behavior, a three-dimensional (3D) constitutive model is developed to describe the Finite Deformation thermo-mechanical response of SMPs. The model in this paper has been implemented into an ABAQUS user material subroutine (UMAT) for Finite element analysis, and numerical simulations of the thermo-mechanical experiments verify the efficiency of the model. This model will serve as a modeling tool for the design of more complicated SMP-based structures and devices.

  • Finite Deformation thermo-mechanical behavior of thermally induced shape memory polymers
    Journal of the Mechanics and Physics of Solids, 2008
    Co-Authors: H. Jerry Qi, Christopher Michael Yakacki, Francisco Castro, Thao D Nguyen, Robin Shandas
    Abstract:

    Shape memory polymers (SMPs) are polymers that can demonstrate programmable shape memory effects. Typically, an SMP is pre-deformed from an initial shape to a deformed shape by applying a mechanical load at the temperature TH>Tg. It will maintain this deformed shape after subsequently lowering the temperature to TLTg, where the initial shape is recovered. In this paper, the Finite Deformation thermo-mechanical behaviors of amorphous SMPs are experimentally investigated. Based on the experimental observations and an understanding of the underlying physical mechanism of the shape memory behavior, a three-dimensional (3D) constitutive model is developed to describe the Finite Deformation thermo-mechanical response of SMPs. The model in this paper has been implemented into an ABAQUS user material subroutine (UMAT) for Finite element analysis, and numerical simulations of the thermo-mechanical experiments verify the efficiency of the model. This model will serve as a modeling tool for the design of more complicated SMP-based structures and devices. © 2007 Elsevier Ltd. All rights reserved.