A unified numerical approach for soft to hard magneto-viscoelastically coupled polymers

Kadapa, Chennakesava; Hossain, Mokarram

doi:10.1016/j.mechmat.2021.104207

Cited by 37 publications

(19 citation statements)

References 107 publications

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“…The polymer chains of soft elastomers or polymeric materials have limiting length, which limits the deformation of the elastomer during extension [ 8 , 21 , 52 ]. Next, we investigated the effect of polymer chain extensibility on the control of dynamic response of hard-magnetic soft actuator.…”

Section: Resultsmentioning

confidence: 99%

“…Thus, the thermodynamics of an ideal hard-magnetic soft material are characterized by the Helmholtz free-energy density function, written as

in which

is the vacuum permeability, and

is the elastic energy density of the hard-magnetic soft material in the deformed state. In the current investigation, for accounting the effect of strain stiffening or polymer chain extensibility in hard-magnetic soft materials, the phenomenological Gent model of hyperelasticity [ 52 , 55 ] is considered to specify the elastic strain energy density function as

where

, G is the shear modulus, and

is a dimensionless material parameter accounting for the extensibility of polymer chains. Substituting the expressions for elastic strain energy density from Equation ( 4 ) and deformation gradient from Equation ( 2 ) into Equation ( 3 ), the free energy density function for the hard-magnetic soft material is written in terms of stretch parameter as [ 43 , 44 ]

…”

Section: Problem Description and Dynamic Modelingmentioning

confidence: 99%

“…Hard-magnetic soft materials show damping effects during their operation due to material viscoelasticity [ 51 , 52 ]. Making an assumption that the damping forces are linear with respect to the velocity of deformation in the

direction, the energy dissipation function

is written as [ 58 , 59 ]

where c is the damping coefficient.…”

Section: Problem Description and Dynamic Modelingmentioning

confidence: 99%

“…Considering visco-elastic effects, Dadgar-Rad and Hossain [ 51 ] reported a theoretical framework for the finite deformation analysis of hard-magnetic soft beam-type actuators subjected to magnetic loading. Kadapa and Hossain [ 52 ] developed a unified finite element model for the analysis of soft and hard magneto-active elastomers considering the time-dependent visco-elastic effects and simulated a magnetically driven four-finger robotic gripper. Dadgar-Rad and Hossain [ 53 ] developed a micropolar continuum theory and a finite element-based numerical model for the analysis of hard-magnetic soft materials.…”

Section: Introductionmentioning

confidence: 99%

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Alleviation of Residual Vibrations in Hard-Magnetic Soft Actuators Using a Command-Shaping Scheme

et al. 2022

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Hard-magnetic soft materials belong to a class of the highly deformable magneto-active elastomer family of smart materials and provide a promising technology for flexible electronics, soft robots, and functional metamaterials. When hard-magnetic soft actuators are driven by a multiple-step input signal (Heaviside magnetic field signal), the residual oscillations exhibited by the actuator about equilibrium positions may limit their performance and accuracy in practical applications. This work aims at developing a command-shaping scheme for alleviating residual vibrations in a magnetically driven planar hard-magnetic soft actuator. The control scheme is based on the balance of magnetic and elastic forces at a critical point in an oscillation cycle. The equation governing the dynamics of the actuator is devised using the Euler–Lagrange equation. The constitutive behaviour of the hard-magnetic soft material is modeled using the Gent model of hyperelasticity, which accounts for the strain-stiffening effects. The dynamic response of the actuator under a step input signal is obtained by numerically solving the devised dynamic governing equation using MATLAB ODE solver. To demonstrate the applicability of the developed command-shaping scheme, a thorough investigation showing the effect of various parameters such as material damping, the sequence of desired equilibrium positions, and polymer chain extensibility on the performance of the proposed scheme is performed. The designed control scheme is found to be effective in controlling the motion of the hard-magnetic soft actuator at any desired equilibrium position. The present study can find its potential application in the design and development of an open-loop controller for hard-magnetic soft actuators.

show abstract

Section: Resultsmentioning

confidence: 99%

“…Thus, the thermodynamics of an ideal hard-magnetic soft material are characterized by the Helmholtz free-energy density function, written as

in which

is the vacuum permeability, and

where

, G is the shear modulus, and

…”

Section: Problem Description and Dynamic Modelingmentioning

confidence: 99%

direction, the energy dissipation function

is written as [ 58 , 59 ]

where c is the damping coefficient.…”

Section: Problem Description and Dynamic Modelingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Alleviation of Residual Vibrations in Hard-Magnetic Soft Actuators Using a Command-Shaping Scheme

et al. 2022

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show abstract

“…Soft grippers made of magneto-active materials have the potential as actuating components in soft robotics. For instance, Ju et al [77] and Carpenter et al [78] demonstrated additively manufactured magneto-active grippers while Kadapa and Hossain [79] simulated the viscoelastic influences of underlying polymeric materials. In our case, the gripper is composed of 12 equal arms.…”

Section: A Magnetic Grippermentioning

confidence: 99%

A micropolar shell model for hard-magnetic soft materials

Dadgar‐Rad¹,

Hossain²

2022

Preprint

Self Cite

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Hard-magnetic soft materials (HMSMs) are particulate composites that consist of a soft matrix embedded with particles of high remnant magnetic induction. Since the application of an external magnetic flux induces a body couple in HMSMs, the Cauchy stress tensor in these materials is asymmetric, in general. Therefore, the micropolar continuum theory can be employed to capture the deformation of these materials. On the other hand, the geometries and structures made of HMSMs often possess small thickness compared to the overall dimensions of the body.Accordingly, in the present contribution, a 10-parameter micropolar shell formulation to model the finite elastic deformation of thin structures made of HMSMs and subject to magnetic stimuli is developed. The present shell formulation allows for using three-dimensional constitutive laws without any need for modification to apply the plane stress assumption in thin structures. Due to the highly nonlinear nature of the governing equations, a nonlinear finite element formulation for numerical simulations is also developed. To circumvent locking at large distortions, an enhanced assumed strain formulation is adopted. The performance of the developed formulation is examined in several numerical examples. It is shown that the proposed formulation is an effective tool for simulating the deformation of thin bodies made of HMSMs.

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The Modeling of Magnetorheological Elastomers: A State‐of‐the‐Art Review

Saber

2023

Adv Eng Mater

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The magnetorheological elastomers (MREs) are novel multifunctional materials wherein their viscoelastic properties can be varied instantly under an application of applied magnetic field. Due to their field‐dependent stiffness and damping properties, MREs are widely used in the development and design of MRE‐based adaptive vibration isolators and absorbers and also biomedical engineering. Moreover, MREs due to their inherent magnetostriction effect have enormous potential for the development of soft actuators. The dynamic behavior of MREs is affected by various material parameters (e.g., matrix and particle types, particle concentration, additives) as well as mechanical and magnetic loading parameters (e.g., frequency, amplitude, temperature, magnetic flux density). Understanding and predicting the effect of materials and loading parameters on the response behavior of MREs are of paramount importance for the design of MRE‐based adaptive structures and systems. This review paper mainly aims to provide a comprehensive study of material constitutive models to predict the nonlinear magnetomechanical behavior of MREs. Particular emphasis is paid to physics‐based models including continuum‐ and microstructure‐based models. Moreover, phenomenological models describing the dynamic magnetoviscoelastic behavior of MREs as well as the effect of temperature on the magnetomechanical behavior of such materials are properly addressed.

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A unified numerical approach for soft to hard magneto-viscoelastically coupled polymers

Cited by 37 publications

References 107 publications

Alleviation of Residual Vibrations in Hard-Magnetic Soft Actuators Using a Command-Shaping Scheme

Alleviation of Residual Vibrations in Hard-Magnetic Soft Actuators Using a Command-Shaping Scheme

A micropolar shell model for hard-magnetic soft materials

The Modeling of Magnetorheological Elastomers: A State‐of‐the‐Art Review

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