Large viscoelastic deformation of hard-magnetic soft beams

Dadgar‐Rad, Farzam; Hossain, Mokarram

doi:10.1016/j.eml.2022.101773

Cited by 26 publications

(14 citation statements)

References 48 publications

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“…However, only the corner nodes contain the w i , 𝜙, and 𝜃 i DOFs. In other words, the DOF parameters defined after Equations ( 38) and (39) are n u = 8 and n w = n 𝜃 = n 𝜙 = 4. Following Korelc and Wriggers, 71 the enhancing deformation gradient F is considered to be of the following form:…”

Section: Numerical Examplesmentioning

confidence: 99%

A micropolar shell model for hard‐magnetic soft materials

Dadgar‐Rad

Hossain

2022

Numerical Meth Engineering

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Hard-magnetic soft materials (HMSMs) are particulate composites that particles with high coercivity are dispersed in a soft matrix. Since applying the magnetic loading induces a body couple in HMSMs, the resulting Cauchy stress is predicted to be asymmetric. 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 hard-magnetic soft structures under magnetic stimuli is developed. The proposed shell formulation allows for using three-dimensional constitutive laws without any need for modification to apply the plane stress assumption in thin structures. A nonlinear finite element formulation is also presented for the numerical solution of the governing equations. To alleviate the locking phenomenon, the enhanced assumed strain method is employed. Several examples are presented that demonstrate the performance and effectiveness of the proposed formulation.

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Section: Numerical Examplesmentioning

confidence: 99%

A micropolar shell model for hard‐magnetic soft materials

Dadgar‐Rad

Hossain

2022

Numerical Meth Engineering

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“…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%

“…Zhang et al [ 50 ] reported a micromechanics-based theoretical model for investigating the effect of interactions between the hard magnetic particles and the soft elastomer on the actuation performance of hard-magnetic soft materials. 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.…”

Section: Introductionmentioning

confidence: 99%

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.

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“…Next, the linearized equations resulting from Eqs. ( 31), (39), and ( 46) may be written as ∆δU e − ∆δW e = −(δU e − δW e ), (49) from which the following system of algebraic equations is extracted:…”

Section: Finite Element Formulationmentioning

confidence: 99%

“…The same formulation has been employed to model the deformation of magnetoactive shells by Yan et al [38]. Dadgar-Rad and Hossain [39] added the viscoelastic effects to the theory of Zhao et al [24] to analyze the time-dependent dissipative response of HMSBs.…”

Section: Introductionmentioning

confidence: 99%

A micropolar shell model for hard-magnetic soft materials

Dadgar‐Rad¹,

Hossain²

2022

Preprint

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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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Large viscoelastic deformation of hard-magnetic soft beams

Cited by 26 publications

References 48 publications

A micropolar shell model for hard‐magnetic soft materials

A micropolar shell model for hard‐magnetic soft materials

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

A micropolar shell model for hard-magnetic soft materials

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