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M. B. Rubin - One of the best experts on this subject based on the ideXlab platform.

  • Time-dependent behavior of passive skeletal muscle
    Continuum Mechanics and Thermodynamics, 2015
    Co-Authors: Touhid Ahamed, M. B. Rubin, Barry A. Trimmer, Luis Dorfmann
    Abstract:

    An isotropic three-dimensional nonlinear viscoelastic model is developed to simulate the time-dependent behavior of passive skeletal muscle. The development of the model is stimulated by experimental data that characterize the response during simple uniaxial stress cyclic loading and unloading. Of particular interest is the rate-dependent response, the recovery of muscle properties from the preconditioned to the unconditioned state and stress relaxation at constant stretch during loading and unloading. The model considers the material to be a composite of a nonlinear hyperelastic Component in parallel with a nonlinear Dissipative Component. The strain energy and the corresponding stress measures are separated additively into hyperelastic and Dissipative parts. In contrast to standard nonlinear inelastic models, here the Dissipative Component is modeled using an evolution equation that combines rate-independent and rate-dependent responses smoothly with no finite elastic range. Large deformation evolution equations for the distortional deformations in the elastic and in the Dissipative Component are presented. A robust, strongly objective numerical integration algorithm is used to model rate-dependent and rate-independent inelastic responses. The constitutive formulation is specialized to simulate the experimental data. The nonlinear viscoelastic model accurately represents the time-dependent passive response of skeletal muscle.

  • Modeling rate-independent hysteresis in large deformations of preconditioned soft tissues
    International Journal of Solids and Structures, 2014
    Co-Authors: M.m. Safadi, M. B. Rubin
    Abstract:

    A phenomenological model is proposed for characterizing rate-independent hysteresis exhibited by preconditioned soft tissues. The preconditioned tissue is modeled as an isotropic composite of a hyperelastic Component and a Dissipative (inelastic) Component. Specifically, the constitutive equations are hyperelastic in the sense that the stress is determined by derivatives of a strain energy function. Inelasticity of the Dissipative Component is controlled by a yield function with different functional forms for the hardening variable during deformation loading and unloading. The constitutive equations proposed in this paper are simple. In particular, they depend on only seven material constants: three controlling the response of the elastic Component and the remainder controlling the response of the Dissipative Component. More importantly, the material constants can be determined to match rather general loading and unloading behavior. It is observed that the hysteretic response of the model compares well with experimental data for passive uniaxial loading/unloading of Manduca muscle. Moreover, the present model treats partial loading and reloading of preconditioned tissue as elastic–plastic response, which is different from the treatment of pseudo-elastic models used in the literature.

  • A three-dimensional nonlinear model for Dissipative response of soft tissue
    International Journal of Solids and Structures, 2002
    Co-Authors: M. B. Rubin, S.r. Bodner
    Abstract:

    A set of three-dimensional constitutive equations is proposed for modeling the nonlinear Dissipative response of soft tissue. These constitutive equations are phenomenological in nature and they model a number of physical features that have been observed in soft tissue. The equations model the tissue as a composite of a purely elastic Component and a Dissipative Component, both of which experience the same total dilatation and distortion. The stress response of the purely elastic Component depends on dilatation, distortion and the stretch of material fibers, whereas the stress response of the Dissipative Component depends on distortional deformation only. The equations are hyperelastic in the sense that the stress is obtained by derivatives of a strain energy function, and they are properly invariant under superposed rigid body motions. In contrast with standard viscoelastic models of tissues, the proposed constitutive model includes the total deformation rate in evolution equations that can reproduce the observed physical feature that the hysteresis loops of most biological soft tissues are nearly independent of strain rate (Biomechanics, Mechanical Properties of Living Tissues, second ed. (1993)). Material constants are determined which produce good agreement with uniaxial stress experiments on superficial musculoaponeurotic system and facial skin.

S.r. Bodner - One of the best experts on this subject based on the ideXlab platform.

  • A three-dimensional nonlinear model for Dissipative response of soft tissue
    International Journal of Solids and Structures, 2002
    Co-Authors: M. B. Rubin, S.r. Bodner
    Abstract:

    A set of three-dimensional constitutive equations is proposed for modeling the nonlinear Dissipative response of soft tissue. These constitutive equations are phenomenological in nature and they model a number of physical features that have been observed in soft tissue. The equations model the tissue as a composite of a purely elastic Component and a Dissipative Component, both of which experience the same total dilatation and distortion. The stress response of the purely elastic Component depends on dilatation, distortion and the stretch of material fibers, whereas the stress response of the Dissipative Component depends on distortional deformation only. The equations are hyperelastic in the sense that the stress is obtained by derivatives of a strain energy function, and they are properly invariant under superposed rigid body motions. In contrast with standard viscoelastic models of tissues, the proposed constitutive model includes the total deformation rate in evolution equations that can reproduce the observed physical feature that the hysteresis loops of most biological soft tissues are nearly independent of strain rate (Biomechanics, Mechanical Properties of Living Tissues, second ed. (1993)). Material constants are determined which produce good agreement with uniaxial stress experiments on superficial musculoaponeurotic system and facial skin.

R. Horowitz - One of the best experts on this subject based on the ideXlab platform.

  • On velocity field control of mechanical systems
    Proceedings of 32nd IEEE Conference on Decision and Control, 1993
    Co-Authors: P.y. Li, R. Horowitz
    Abstract:

    In this paper, we propose control schemes that stabilize the system's behavior to the desired velocity field. In particular, we seek schemes that are divided into a Dissipative Component and an active Component with respect to kinetic energy. We considered two cases: one in which both the Dissipative and the active Components are available for manipulation, and the other in which the active Component is given, but not manipulable. It is shown that in the first case, a space varying damping control is sufficient, and in the second case, a dynamic damping control based on a fictitious manipulator is proposed.

  • On Velocity Field Control of Mechanical
    1993
    Co-Authors: R. Horowitz
    Abstract:

    In this paper, we propose control schemes that stabilize the system's behavior to the desired velocity field. In particular, we seek schemes that are divided into a Dissipative Component and an active Component with respect to kinetic energy. We considered two cases: one in which both the Dissipative and the active Components are available for manipulation, and the other in which the active Component is given, but not manipulable. It is shown that in the first case, a space varying damping control is sufficient, and in the second case, a dynamic damping control based on a fictitious manipulator is proposed.

Tongxi Yu - One of the best experts on this subject based on the ideXlab platform.

  • random response of vibro impact systems with inelastic contact
    International Journal of Non-linear Mechanics, 2013
    Co-Authors: Ming Xu, Yungui Wang, Z.l. Huang, Tongxi Yu
    Abstract:

    Abstract The probability density and statistics of random response are investigated for vibro-impact systems with inelastic contact in this paper. The inelastic contact is described through an empirical model incorporating highly non-linear and inelastic mechanical property of the impact interface, and the system response is determined through the stochastic averaging and energy dissipation balance technique. The inelastic contact force is separated into an elastic restoring Component and a Dissipative Component; the former is expressed as the gradient of the potential energy preserved in the system while the latter is approximated by a damping force with energy-dependent damping coefficient through energy dissipation balance technique. The averaged Ito stochastic differential equation with respect to system total energy is then derived through stochastic averaging. The solution of the associated Fokker–Plank–Kolmogorov equation yields stationary probability density of system total energy, joint probability density of system displacement and velocity, as well as statistics of system response. The agreement between analytical results and Monte-Carlo simulations validates effectiveness of the proposed technique.

Kim Joo-von - One of the best experts on this subject based on the ideXlab platform.

  • Asymmetric skyrmion-antiskyrmion production in ultrathin ferromagnetic films
    2020
    Co-Authors: Ritzmann Ulrike, Desplat Louise, Dupé Bertrand, Camley, Robert E., Kim Joo-von
    Abstract:

    Ultrathin ferromagnets with frustrated exchange and the Dzyaloshinskii-Moriya interaction can support topological solitons such as skyrmions and antiskyrmions, which are metastable and can be considered as particle-antiparticle counterparts. When spin-orbit torques are applied, the motion of an isolated antiskyrmion driven beyond its Walker limit can generate skyrmion-antiskyrmion pairs. Here, we use atomistic spin dynamics simulations to shed light on the scattering processes involved in this pair generation. Under certain conditions a proliferation of these particles and antiparticles can appear with a growth rate and production asymmetry that depend on the strength of the chiral interactions and the Dissipative Component of the spin-orbit torques. These features are largely determined by scattering processes between antiskyrmions, which can be elastic, result in bound states, or annihilation.Peer reviewe

  • Asymmetric skyrmion-antiskyrmion production in ultrathin ferromagnetic films
    'American Physical Society (APS)', 2020
    Co-Authors: Ritzmann Ulrike, Desplat Louise, Dupé Bertrand, Camley, Robert E., Kim Joo-von
    Abstract:

    peer reviewedaudience: researcherUltrathin ferromagnets with frustrated exchange and the Dzyaloshinskii-Moriya interaction can support topological solitons such as skyrmions and antiskyrmions, which are metastable and can be considered as particle-antiparticle counterparts. When spin-orbit torques are applied, the motion of an isolated antiskyrmion driven beyond its Walker limit can generate skyrmion-antiskyrmion pairs. Here, we use atomistic spin dynamics simulations to shed light on the scattering processes involved in this pair generation. Under certain conditions a proliferation of these particles and antiparticles can appear with a growth rate and production asymmetry that depend on the strength of the chiral interactions and the Dissipative Component of the spin-orbit torques. These features are largely determined by scattering processes between antiskyrmions, which can be elastic, result in bound states, or annihilation

  • Asymmetric skyrmion-antiskyrmion production in ultrathin ferromagnetic films
    2020
    Co-Authors: Ritzmann Ulrike, Desplat Louise, Dupé Bertrand, Camley, Robert E., Kim Joo-von
    Abstract:

    Ultrathin ferromagnets with frustrated exchange and the Dzyaloshinskii-Moriya interaction can support topological solitons such as skyrmions and antiskyrmions, which are metastable and can be considered as particle-antiparticle counterparts. When spin-orbit torques are applied, the motion of an isolated antiskyrmion driven beyond its Walker limit can generate skyrmion-antiskyrmion pairs. Here, we use atomistic spin dynamics simulations to shed light on the scattering processes involved in this pair generation. Under certain conditions a proliferation of these particles and antiparticles can appear with a growth rate and production asymmetry that depend on the strength of the chiral interactions and the Dissipative Component of the spin-orbit torques. These features are largely determined by scattering processes between antiskyrmions, which can be elastic, result in bound states, or annihilation.Comment: 8 pages, 6 figure