Theoretical Modeling and Exact Solution for Extreme Bending Deformation of Hard-Magnetic Soft Beams

2020 ◽  
Vol 87 (4) ◽  
Author(s):  
Wei Chen ◽  
Lin Wang
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Exact Solutions ◽  
Flexible Electronics ◽  
Soft Materials ◽  
Theoretical Modeling ◽  
Magnetic Field Direction ◽  
Magnetic Actuation ◽  
Governing Equations ◽  
Analysis And Design

Abstract Hard-magnetic soft materials (HMSMs) manufactured by embedding hard-magnetic particles in soft materials belong to a new type of soft active materials. The abilities of fast and complicated transformations of hard-magnetic soft structures provide a promising technology for soft robotics, flexible electronics, and biomedical devices. It is significant to investigate the mechanical behaviors of hard-magnetic soft structures for their better applications. In this work, a hard-magnetic soft beam under an external magnetic field is theoretically modeled and the exact solutions for its mechanical responses are presented. First, the governing equations and boundary conditions are derived based on the principle of minimum potential energy. To solve the derived governing equations analytically, a new polynomial fitting model for hyperelastic materials is proposed for the hard-magnetic soft beam. Then, the exact solutions of a cantilevered hard-magnetic soft beam actuated by a uniform magnetic field in any direction are obtained. The newly derived exact solutions are further verified by comparing current results with those from recent simulations and experiments. For large bending angles up to 90 deg and extreme bending angle up to 180 deg, quite consistent agreement among exact solutions, numerical simulations, and experimental observations can be achieved. Finally, using our theoretical model, the deformation of the hard-magnetic soft beam actuated by magnetic fields in an arbitrary direction with non-zero magnetic declination is explored. When the magnetic actuation is increased from a small level gradually, the hard-magnetic soft beam deflects and it would undergo small, large, and extreme bending deformations in sequence. It is very interesting that, when the magnetic actuation is sufficiently large, the hard-magnetic soft beam is stretched and its centerline tends to align with the external magnetic field direction, implying that the hard-magnetic soft beam undergoes a uniaxial tension. The theoretical modeling and exact solutions for hard-magnetic soft beams are expected to be useful in the analysis and design of soft materials and structures.

Multi-Material Topology Optimization of Ferromagnetic Soft Robots Using Reconciled Level Set Method

2021 ◽  
Author(s):  
Jiawei Tian ◽  
Xianfeng David Gu ◽  
Shikui Chen
Keyword(s):  
Magnetic Field ◽  
Topology Optimization ◽  
External Magnetic Field ◽  
Level Set Method ◽  
Level Set ◽  
Flexible Electronics ◽  
Time Derivative ◽  
Soft Materials ◽  
Soft Material ◽  
Soft Robots

Abstract Ferromagnetic soft materials can generate flexible mobility and changeable configurations under an external magnetic field. They are used in a wide variety of applications, such as soft robots, compliant actuators, flexible electronics, and bionic medical devices. The magnetic field enables fast and biologically safe remote control of the ferromagnetic soft material. The shape changes of ferromagnetic soft elastomers are driven by the ferromagnetic particles embedded in the matrix of a soft elastomer. The external magnetic field induces a magnetic torque on the magnetized soft material, causing it to deform. To achieve the desired motion, the soft active structure can be designed by tailoring the layouts of the ferromagnetic soft elastomers. This paper aims to optimize multi-material ferromagnetic actuators. Multi-material ferromagnetic flexible actuators are optimized for the desired kinematic performance using the reconciled level set method. This type of magnetically driven actuator can carry out more complex shape transformations by introducing ferromagnetic soft materials with more than one magnetization direction. Whereas many soft active actuators exist in the form of thin shells, the newly proposed extended level set method (X-LSM) is employed to perform conformal topology optimization of ferromagnetic soft actuators on the manifolds. The objective function comprises two sub-objective functions, one for the kinematic requirement and the other for minimal compliance. Shape sensitivity analysis is derived using the material time derivative and the adjoint variable method. Three examples are provided to demonstrate the effectiveness of the proposed framework.

scholarly journals Can disordered radical pair systems provide a basis for a magnetic compass in animals?

2009 ◽  
Vol 7 (suppl_2) ◽  
Author(s):  
Erin Hill ◽  
Thorsten Ritz
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Radical Pair ◽  
Magnetic Compass ◽  
Magnetic Field Direction ◽  
Chemical Signal ◽  
Radical Pairs ◽  
Directional Information ◽  
Minimum Number ◽  
Signal Production

A proposed mechanism for magnetic compasses in animals is that systems of radical pairs transduce magnetic field information to the nervous system. One can show that perfectly ordered arrays of radical pairs are sensitive to the direction of the external magnetic field and can thus operate, in principle, as a magnetic compass. Here, we investigate how disorder, inherent in biological cells, affects the ability of radical pair systems to provide directional information. We consider biologically inspired geometrical arrangements of ensembles of radical pairs with increasing amounts of disorder and calculate the effect of changing the direction of the external magnetic field on the rate of chemical signal production by radical pair systems. Using a previously established signal transduction model, we estimate the minimum number of receptors necessary to allow for detection of the change in chemical signal owing to changes in magnetic field direction. We quantify the required increase in the number of receptors to compensate for the signal attenuation through increased disorder. We find radical-pair-based compass systems to be relatively robust against disorder, suggesting several scenarios as to how a compass structure can be realized in a biological cell.

scholarly journals Flux tubes in Nf = 2 + 1 QCD with external magnetic fields

2018 ◽  
Vol 175 ◽  
pp. 12008 ◽  
Author(s):  
Claudio Bonati ◽  
Salvatore Calì ◽  
Massimo D’Elia ◽  
Michele Mesiti ◽  
Francesco Negro ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Tree Level ◽  
Magnetic Field Direction ◽  
Physical Point ◽  
Flux Tubes ◽  
Gauge Action ◽  
Uniform External Magnetic Field ◽  
Static Quark ◽  
The Magnetic Field

We study the behavior of the confining flux tube in Nf = 2 + 1 QCD at the physical point, discretized with the stout smearing improved staggered quark action and the tree level Symazik gauge action. We discuss how it depends on a uniform external magnetic field, showing how it displays anisotropies with respect to the magnetic field direction. Moreover, we compare the observed anisotropy pattern with that of the static quark-antiquark (QQ̅) potential we obtained in [1, 2].

scholarly journals Method of Measuring Deformations of Magnetoactive Elastomers under the Action of Magnetic Fields

2019 ◽  
Vol 7 (4) ◽  
pp. 81-91 ◽  
Author(s):  
D. V. Saveliev ◽  
L. Yu. Fetisov ◽  
D. V. Chashin ◽  
P. A. Shabin ◽  
D. A. Vyunik ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Polymer Matrix ◽  
Deep Understanding ◽  
Soft Materials ◽  
Point Of View ◽  
Magnetic Microparticles ◽  
Deformation Curves ◽  
Uniform External Magnetic Field ◽  
Manufacturing Technologies

Magnetic deformation is a change in the size and shape of a sample under the action of a uniform external magnetic field. The study of this effect in various materials provides deep understanding of the nature of magnetic and mechanical interactions. Moreover, magnetic deformation is of great interest from an engineering point of view for designing new devices. In magnetoactive elastomers containing magnetic microparticles in the polymer matrix, a giant deformation is detected under the action of an external magnetic field. The generally accepted methods for measuring magnetic deformation in magnetoactive soft materials are now practically absent. The article describes the installation for the study of the magnetomechanical characteristics of magnetoactive elastomers and demonstrates its experimental capabilities. The installation allows to measure deformations in the range from 0 to 12.5 mm with a resolution of 1 micron. The deformation curves obtained using these installations are required for developing actuators and sensors based on magnetoactive elastomers, and also for improving their manufacturing technologies.

Characteristics of Ultrasound Propagation in a Magnetic Fluid Under Uniform Magnetic Field

2003 ◽  
Author(s):  
Masaaki Motozawa ◽  
Tatsuo Sawada
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Fluid ◽  
Uniform Magnetic Field ◽  
Colloidal Particles ◽  
Magnetic Field Intensity ◽  
Magnetic Field Direction ◽  
Ultrasound Propagation ◽  
Ultrasonic Propagation ◽  
The Magnetic Field

When an external magnetic field is applied to a magnetic fluid, some of the colloidal particles coagulate and form chain-like clusters. Properties of ultrasonic propagation wave are changed by these chain-like clusters. We carried out measurement of the ultrasonic propagation velocity in a magnetic fluid. Measurement were made by changing the magnetic field intensity from 0 mT to 570 mT, and the angle between the magnetic field direction and direction of the ultrasound propagation from 0° to 180°. The ultrasound frequencies were 1 MHz, 2 MHz and 4 MHz. Some of experimental results for the characteristics of ultrasound propagation in a magnetic fluid under a uniform magnetic field were reported.

The Effect of Low-Intensity Static Magnetic Field on Ni-P-PTFE Electroless Composite Plating Coatings

2016 ◽  
Vol 717 ◽  
pp. 112-117
Author(s):  
Jun Ying Hou ◽  
Hong Jiang Gao ◽  
Xiao Lin Liu ◽  
Yu Jiao ◽  
Li Liu
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Field Strength ◽  
Composite Coating ◽  
Magnetic Field Strength ◽  
Composite Coatings ◽  
Magnetic Field Direction ◽  
Composite Plating ◽  
External Magnetic Field Strength ◽  
New Processing

A new processing concept has been developed to produce Ni-P-PTFE electroless composite coating. This method combines magnetic field and electroless composite plating techniques to prepare high-quality Ni-P-PTFE electroless composite coating. The influence of magnetic on composite plating process and coatings performance by changing some factors such as the plating time, magnetic field strength, magnetic field direction. The results indicate that the external magnetic field improved deposition rate and the PTFE particles content of composite coatings, meanwhile, some performances of composite coating like thickness, corrosion resistance, were effected by external magnetic field strength. Therefore, the method combines magnetic field and electroless completing techniques had a wide application prospect in the aspect of improving the properties of electroless composite coating.

Magneto-hydrodynamic Blasius flow and heat transfer from a flat plate in the presence of suspended carbon nanofluids

2017 ◽  
Vol 232 (1) ◽  
pp. 31-40
Author(s):  
Mahantesh M Nandeppanavar ◽  
Rama Subba Reddy Gorla ◽  
S Shakunthala
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
External Magnetic Field ◽  
Flat Plate ◽  
Linear Partial Differential Equation ◽  
Governing Equations ◽  
Linear Ordinary Differential Equations ◽  
Similarity Transformations ◽  
Flow And Heat Transfer ◽  
Non Linear

In this article, we have discussed the effect of external magnetic field and other governing parameters on the flow and heat transfer in the presence of suspended carbon nanotubes over a flat plate. The governing equations of flow and heat transfer are derived from the Navier–Stokes and Prandtl boundary layer concept. The derived governing equations of flow and energy are non-linear partial differential equation, and these equations are converted into non-linear ordinary differential equations with corresponding boundary conditions using some suitable similarity transformations and are solved numerically using fourth-order Runge–Kutta method with efficient shooting technique. Effects of governing parameters on flow and heat transfer are shown through various graphs and explained with physical interpretation in detail. This study has applications in glass-fiber production and technology. On observing the results of this study, we can conclude that external magnetic field shows opposite behaviors on velocity and temperature and it enhances the rate of heat transfer.

scholarly journals Exstraordinary and planar Hall effects in thin permalloy films

2021 ◽  
pp. 53-60
Author(s):  
Victoryia I. Halauchyk ◽  
Michail G. Lukashevich
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Film Plane ◽  
Field Direction ◽  
Hall Resistance ◽  
Magnetic Field Direction ◽  
Full Width ◽  
Half Maximum ◽  
Hall Effects ◽  
The Magnetic Field

The Hall resistance hysteresis loops in thin (d = 80 –280 nm) magnetically ordered permalloy films (Ni0.8 Fe0.2) were studied at room temperature at different angles between the film plane and the magnetic field direction (φ = 0 –360°) (extraordinary and ordinary Hall effects), at different angles (θ = 0 – 90°) between the magnetic field direction and the flowing current (planar Hall effect at φ = 0°) in a magnetic field up to B = 1.25 T. The thin films were obtained on sitall dielectric substrate by ion beam sputtering. Sharp peaks of the Hall resistance were observed in the extraordinary and planar Hall effects during the magnetisation reversal of the films due to a change of the magnetisation direction with respect to the sampling current direction. In the extraordinary Hall effect the position and full width at half maximum of a peak is determined by the angle between the magnetic field direction and the film plane. It has been shown that as the direction of the external magnetic field approaches the spontaneous magnetisation direction, both the peak magnetic field position Bp and the full width at half maximum of the peak Δ Bp increase. In the angles range of φ = 0 – 90° Bp and Δ  Bp varies in the magnetic field range from Δ  В ≈ 0.2 to 5.0 mT. A non-monotonic dependence of the planar Hall resistance and its peak position on the angle between the flowing current and the magnetic field direction was detected. It is related to the change of the longitudinal and transverse components the resistance of the magnetically ordered solids by an external magnetic field. The values of the ordinary and extraordinary Hall effects coefficients have been determined: RH0 = 6 ⋅ 10–9 m3/C and RH1 = 3.2 ⋅ 10–8 m3/C, respectively.

Anisotropic Thermal Transport in Magnetic Fluids

2009 ◽  
Author(s):  
Xiaopeng Fang ◽  
Yimin Xuan ◽  
Qiang Li
Keyword(s):  
Magnetic Field ◽  
Thermal Conductivity ◽  
External Magnetic Field ◽  
Magnetic Fluid ◽  
Thermal Transport ◽  
Present Method ◽  
Field Direction ◽  
Magnetic Field Direction ◽  
The Magnetic Field ◽  
Anisotropic Feature

The inhomogeneous morphology of magnetic fluid may appear in the presence of an external magnetic field, which shows the structure controllability of magnetic fluid and will lead to anisotropic thermal transport inside the magnetic fluid. Based on the microstructure of magnetic fluid and considering the effect of nanolayer, a model for the thermal conductivity of the magnetic fluid has been developed. The anisotropic thermal transport inside the magnetic fluid is investigated by the present method. The results show that in the presence of an external magnetic field the particles form chainlike clusters along the magnetic field direction, which leads to an increment in the thermal conductivity along the field direction and little change in the thermal conductivity perpendicular to the magnetic field direction. The thermal conductivity of magnetic fluid presents an anisotropic feature. With the increase of the magnetic field strength the chainlike clusters in the magnetic fluid becomes more obvious and the anisotropic feature of heat conduction in the fluids becomes more evident. Comparisons show that the results predicted by the present method are well coincident with the experimental data.

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