Nonlinear Magnetic Coupling Research Articles

Design and Study of Vibration Energy Acquisition Equipment Based on Nonlinear Magnetic Coupling Action

Design and Study of Vibration Energy Acquisition Equipment Based on Nonlinear Magnetic Coupling Action

FPGA-Based Implicit–Explicit Real-Time Simulation Solver for Railway Wireless Power Transfer With Nonlinear Magnetic Coupling Components

FPGA-Based Implicit–Explicit Real-Time Simulation Solver for Railway Wireless Power Transfer With Nonlinear Magnetic Coupling Components

Analysis of output characteristics of positive feedback piezoelectric energy harvester based on nonlinear magnetic coupling.

In light of the limitations of the current piezoelectric energy harvesters and the demand for self-power supply in wireless sensor nodes, a novel positive feedback piezoelectric energy harvester based on nonlinear magnetic coupling is proposed. The operational characteristics of this energy harvester are investigated from three perspectives: theory, simulation, and experiment. First, a nonlinear electromechanical coupling mathematical model that describes the dynamic response of the energy harvester system is established by combining the Hamilton variational principle with the piezoelectric theory. This provides a theoretical foundation for subsequent research. Second, finite element method simulations are employed to optimize the structural parameters of the energy harvester and study the impact of nonlinear magnetic force on its output performance. Finally, an experimental prototype is fabricated and an experimental test system is constructed to validate the designed positive feedback piezoelectric energy harvester. The results demonstrate that changes in the longitudinal beam angle have minimal effect on energy capture efficiency. By appropriately increasing the bending surface length, reducing initial magnetic moment, and augmenting mass block weight, wider working frequency bands and higher power generation capacity can be achieved when vibrating in low-energy orbits. The experimental findings align closely with theoretical design values and contribute to advancing broadband multi-directional piezoelectric energy harvesting technology in order to provide high-performance vibration-based power solutions for wireless applications.

Fractional dynamical behavior of a new nonlinear smooth and discontinuous (SD) oscillator for vibration energy harvesting with nonlinear magnetic coupling

Fractional dynamical behavior of a new nonlinear smooth and discontinuous (SD) oscillator for vibration energy harvesting with nonlinear magnetic coupling

Experimental Study on Magnetic Coupling Piezoelectric-Electromagnetic Composite Galloping Energy Harvester.

In order to solve the demand for low-power microcomputers and micro-electro-mechanical system components for continuous energy supply, a magnetic coupling piezoelectric-electromagnetic composite galloping energy harvester (MPEGEH) is proposed. It is composed of a piezoelectric energy harvester (PEH) and an electromagnetic energy harvester (EEH) coupled by magnetic force. The bistable nonlinear magnetic coupling structure improves the output power of the MPEGEH. The advantages and output performance of the MPEGEH are analyzed. The prototype of the energy harvester is made, and the nonlinear output characteristics under different load resistances are analyzed. Through the experiment on the key parameters of the composite energy harvester, it is found that the higher the coupling degree of the two parts of the MPEGEH, the stronger the nonlinear characteristics and the better the output characteristics. The results show that the onset wind velocity and output power of the MPEGEH are better than the classic galloping piezoelectric energy harvester (CGPEH). At the same wind speed, with the increase in the distance d0 between magnets A and B, the output power of both the PEH and the EEH decreases. When d0 is 37 mm, the output power of the EEH is the largest. The distance s0 between magnets B and C has little influence on the output power of the PEH but has a great influence on the EEH. When s0 is 23 mm, the EEH has the best output characteristics. Compared with the CGPEH, the onset wind velocity is reduced by 28%, and the output power is increased by 136% when the wind speed is 11 m/s.

Design and analysis of a double-acting nonlinear wideband piezoelectric energy harvester under plucking and collision

This paper proposes a double-acting nonlinear wideband piezoelectric energy harvester under plucking and collision(W-PEH) for energy during rotation. The device is mainly composed of a base, rectangular piezoelectric patches, circular piezoelectric generating units and permanent magnets. The circular power generation units are constructed by using the nonlinear magnetic coupling mechanism and the contact frequency conversion principle. The nonlinearity caused by the magnetic force makes the circular piezoelectric power generation units work stably and efficiently at low speeds. And the contact-type collision excitation enables the circular piezoelectric patches inside the circular piezoelectric generating units to produce greater deformation and output a higher voltage. The rectangular piezoelectric patches are excited by the plucking, and the vibration amplitude is greater at high speeds, and it also produces a higher output voltage. Two different excitations make W-PEH's working frequency band wider, and the overall output voltage is also higher. The electromechanical coupling dynamics model of the system was constructed from Hamilton's principle and the magnetic dipole theory. The experimental results indicate that W-PEH can work effectively in different frequency bands. Under the load of 10 KΩ, the peak-to-peak power of the 150r/min integrated device is 0.350W, and that of the 450r/min integrated device is 0.107W.

Load Resistance Optimization of a Magnetically Coupled Two-Degree-of-Freedom Bistable Energy Harvester Considering Third-Harmonic Distortion in Forced Oscillation.

In this study, the external load resistance of a magnetically coupled two-degree-of-freedom bistable energy harvester (2-DOF MCBEH) was optimized to maximize the harvested power output, considering the third-harmonic distortion in forced response. First, the nonlinear dynamic analysis was performed to investigate the characteristics of the large-amplitude interwell motions of the 2-DOF MCBEH. From the analysis results, it was found that the third-harmonic distortion occurs in the interwell motion of the 2-DOF MCBEH system due to the nonlinear magnetic coupling between the beams. Thus, in this study, the third-harmonic distortion was considered in the optimization process of the external load resistance of the 2-DOF MCBEH, which is different from the process of conventional impedance matching techniques suitable for linear systems. The optimal load resistances were estimated for harmonic and swept-sine excitations by using the proposed method, and all the results of the power outputs were in excellent agreements with the numerically optimized results. Furthermore, the associated power outputs were compared with the power outputs obtained by using the conventional impedance matching technique. The results of the power outputs are discussed in terms of the improvement in energy harvesting performance.

Nonlinear forced vibration of the magnetic gear system with the internal resonance

Considering the nonlinear magnetic coupling stiffness among components of the magnetic gear with intersecting axes and a straight SP (MGIASS), the nonlinear dynamic model and differential equations of the MGIASS system are established. Then, the expression of the forced response is obtained when the excited frequency is close to the torsional mode frequency of the input rotor. The forced responses analysis of the example system shows that: the response frequencies include the excited frequency and the double frequency. Multiple proximity between the natural frequencies directly affects the stability and resonance amplitude.

Dynamics of a non-smooth type hybrid energy harvester with nonlinear magnetic coupling

In this paper, a system with energy harvester behavior is modeled by non-smooth coupled oscillators subjected to harmonic and random excitations. A modified harmonic balance method is proposed to study the dynamics of the oscillators under harmonic driving. Then, the probabilistic response of the system under bounded and colored noise excitations is tackled through the stochastic averaging method. We show that the proposed modified harmonic balance technique is very effective in parameters regime for which the system output waveform is nearly sinusoidal. In this parameters regime, the harvester performance is improved for optimum nonlinear magnetic coupling coefficients and for weak nonlinearities and damping in the harvester mechanical part. Under random excitations, we find in the weak parameters regime that, the probability density functions (PDFs) for the coupled oscillators amplitudes illustrate a single-peak mode and exhibit phenomenological transitions as the noisy excitations parameters vary. The mean output powers (MOPs) linearly increase with the colored noises intensities, and the piezoelectric MOP especially shows a resonance effect as the bounded noise level increases. Contrariwise, probed with Monte Carlo simulation, we find that the system exhibits the stochastic P-bifurcation for large parameters of coupling and nonlinearity; parameters’ regime for which the harvester under purely harmonic driving demonstrates low performance.

Feasibility of a V-Shaped Magnet Rotor to Convert Vibration into Rotation

Majority of the reported kinetic energy harvesting mechanisms involve translatory transduction mechanisms, which diverges from the long established rotary design for electromagnetic generators. A rotary design can offer a much smaller magnet-coil air gap and clearance guidance that translatory transducers simply cannot physically attain. Therefore, this research investigates the feasibility of implementing a V-shaped magnet rotor for the purpose of coupling base point excitation into rotation, which can eventually be coupled to a generator motor. It was also previously theorised that the nonlinear magnetic coupling can give rise to broadband nonlinear resonant behaviour. The resultant device aims to enhance the overall power conversion efficiency of the captured vibration energy.

Probabilistic response of an electromagnetic transducer with nonlinear magnetic coupling under bounded noise excitation

Abstract The response in terms of probability density function (PDF) of a vibration transducer, whose mechanical and electrical parts are respectively subjected to stochastic force and bounded noise excitation, is revisited in this report, both analytically and numerically. We discuss the phenomenological transitions exhibited by the PDFs as the noisy excitations parameters evolve and analyze the dependence of the mean output power (MOP) on the parameters of noisy excitations. In the weak parameter regime, using the stochastic averaging method, we show that the MOP of the transducer increases with the intensity of the electrical oscillator additive noise; however, it is independent of the mechanical oscillator additive noise intensity. Conversely, in the hard coupling regime, we show, by Monte Carlo simulations, that the PDFs and the MOP are also affected by the mechanical oscillator additive noise parameters. In particular, we find that the system exhibits the stochastic P-bifurcation only for large damping and coupling parameters. The simulations and the approximate analytical treatment are consistent in the weak parameter regime, as expected.

A vari-stiffness nonlinear isolator with magnetic effects: Theoretical modeling and experimental verification

Nonlinear isolators can decrease dynamic stiffness and thus enhance vibration isolation performance. This paper presents a novel passive vari-stiffness nonlinear isolator with the magnetic repulsive force and magnetic attractive force effects. The isolator consists of a passive mass-spring-damper element and a nonlinear magnetic coupling element. The nonlinear magnetic coupling element contains three moving ring permanent magnets and three fixed ring magnets. The fixed magnets assembled separately at the three adjustable devices that are uniformly distributed along the circumference. The expression of the nonlinear magnetic force is obtained according to the Amperian current model, and the corresponding equivalent nonlinear magnetic stiffness is derived and approximated. The governing equation of the proposed isolator is established and the transmissibility is analyzed with the harmonic balance method. The experiment was set up to verify both the theoretical model and simulations. Both the numerical and experimental results point out that the repulsive force serves as a softening spring to enhance the isolation performance at the higher frequency, while the attractive force serves as a hardening spring to improve the isolation performance at a relative lower frequency bandwidth.

Nonlinear coupling mechanical model for large stroke magnetic-based multistable mechanisms

Abstract In the previous model for small deformation multistable mechanisms, the axial displacement induced by structural vertical deflection is very small and has not been considered. However, for large deformation magnetic based multistable mechanisms, such axial displacement can directly result in the great deviation in predicting the nonlinear magnetic coupling mechanics. To enlarge the multistability design space, an accurate mathematical model was established for analyzing the nonlinear magnetic–mechanical coupling mechanics. To demonstrate the multistability analyzing procedure, a rotation constrained tristable mechanism was introduced which is also called mechanical memory element that can remember three different mechanical states including structural configurations, stable positions, and threshold triggering forces. By theoretically analyzing the influence of the large deformation induced position variation of multiple magnets on the magnetic field distribution and strength, the nonlinear force-displacement characteristic was obtained numerically, which was in good agreement with experimental results, thus validating the feasibility and practicability of the proposed nonlinear coupling mechanical model. Additionally, the multistable features such as stable positions, threshold forces and motion modes can be adjusted in a wide range for switching applications by just adjusting the magnets' arrangement.

Heteroclinic motion and energy transfer in coupled oscillator with nonlinear magnetic coupling

In this paper, we consider two coupled oscillators exhibiting both transient chaos and energy transfer from mechanical to electrical oscillators. Melnikov method is applied to these oscillators with linear damping and strongly nonlinear coupling terms in order to study the possibility of existence of chaos and transversal heteroclinic orbits and their control in a dynamical system. The energy transfer is studied using a qualitative measure of the system which can be obtained by computing the energy dissipated in it. At last, the numerical simulation is carried out for this system.

Separation and detection of rare cells in a microfluidic disk via negative selection

Cyto-analysis of rare cells often requires separation and detection with each procedure posing substantial challenges. This paper presents a disk-based microfluidic platform for both procedures via an immunomagnetic negative selection process. The microfluidic platform's unique features include a multistage magnetic gradient to trap labeled cells in double trapping areas, drainage of fluid to substantially shorten detection time, and a bin-like regions to capture target cells to facilitate a seamless enumeration process. Proof-of-concept was conducted using MCF7 as target rare cells (stained with anti-cytokeratin-FITC antibodies) spiked into Jurkat Clone E6-1 non-target cells (labeled with anti-CD45-PE and anti-PE BD magnetic beads). Then, mononuclear cells (MNC) from healthy blood donors were mixed with MCF7s, modeling rare cells, and tested in the disk. Results show a non-linear magnetic coupling effect of the multistage magnet substantially increased the trapping efficacy over that of a single magnet, contributing to the depletion rate of Jurkats, which reaches 99.96%. Detection time is extensively shortened by depletion of 95% of non-cell-containing fluid in the collection area. The average yield of detected MCF7 cells is near-constant 60 ± 10% over a wide range of rarity from 10(-3) to 10(-6) and this yield also holds for the MCF7/MNC complex mixture. Comparison with autoMACS and BD IMagnet separators revealed the average yield from the disk (60%) is superior to that of autoMACS (37.3%) and BD IMagnet (48.3%). The advantages of near-constant yield, roughly 30 min of operation, an acceptable level of cell loss, and potentially low cost system should aid in cyto-analysis of rare cells.

Finite temperature theory of noncollinear magnetism in amorphous Fe

Noncollinear magnetism in the vicinity of amorphous Fe has been investigated by developing the finite temperature theory of amorphous metallic magnetism which takes into account the transverse spin fluctuations. The theory is based on the functional integral technique to the degenerate-band Hubbard Hamiltonian with Hund’s rule coupling and the distribution function method for local magnetic moments with structural disorder. It is shown that an isotropic spin-glass is realized in amorphous Fe, by taking into account the transverse components of local magnetic moments. The origin of the spin-glass around amorphous Fe is explained by the nonlinear magnetic couplings between Fe local moments and the local environment effects on the amplitude of Fe local moments. When the d electron number N is increased, the isotropic spin-glass changes to a noncollinear ferromagnet at N=7.40 and finally changes to a collinear ferromagnet beyond N=7.47 at 35 K.

Theory of magnetism in amorphous FeZr alloys

Various magnetic properties of amorphous FeZr alloys have been investigated on the basis of the finite-temperature theory of amorphous magnetic alloys. The numerical results explain the overall features of the magnetization versus concentration curve and the magnetic phase diagram showing the spin glass, the ferromagnetism, and the paramagnetism, including the re-entrant spin-glass behavior in the Fe-rich region. It is verified by various analyses that the spin glass is caused by the nonlinear magnetic couplings and the fluctuations of the amplitudes of local moments due to structural disorder, while the ferromagnetism is stabilized by the decrease in the average coordination number of Fe atoms due to atomic size effects. Broad distributions of the local magnetic moments are found in both spin-glass and ferromagnetic states in the Fe-rich region. Their concentrations and temperature dependences are elucidated on the basis of the electronic structure and nonlinear magnetic couplings. Calculated high-field susceptibilities explain the anomaly around the re-entrant spin-glass region. Calculated effective Bohr magneton numbers predict a minimum around 35 at% Fe. The effects of atomic short-range order on the magnetic phase diagram are also investigated. It is found that the ferromagnetism disappears in the whole concentration when the probability of finding an Fe atom at the neighboring site of an Fe atom is larger than 0.8.

Finite-temperature magnetism in amorphous Fe - Y alloys

Various magnetic properties of amorphous Fe - Y alloys at finite temperatures such as the densities of states, local magnetic moments, susceptibilities, and the magnetic phase diagram have been investigated on the basis of the finite-temperature theory of amorphous magnetic alloys. It is found that the calculated magnetization, distribution of local moments, susceptibilities, and magnetic phase diagram in the most random atomic configuration show a spin-glass phase, a re-entrant spin-glass phase, ferromagnetism, and paramagnetism with reducing Fe concentration. These results describe qualitatively the experimental data for the melt-spun Fe - Y alloys. It is verified that the nonlinear magnetic couplings between Fe local moments and the large-amplitude fluctuations of local moments due to structural disorder result in the spin glass in the Fe-rich region. The decrease of the average coordination number of the Fe atom due to the large difference in atomic size between Fe and Y atoms, on the other hand, stabilizes the ferromagnetism at lower Fe concentrations. The difference in magnetic phase diagram between the melt-spun and the sputtered Fe - Y alloys is interpreted in terms of that between the atomic short-range orders.

Spin glass and ferromagnetism in amorphous FeM (MZr, Y) alloys

Abstract The formations of spin glass and ferromagnetism in amorphous FeM (MZr, ) alloys have been clarified on the basis of the finite-temperature theory of amorphous magnetic alloys: the spin glass is caused by the nonlinear magnetic couplings between Fe local moments, while the ferromagnetism is realized by the atomic size effect.

Existence of the spin-glass state in amorphous Fe.

The volume dependence of magnetic properties in amorphous Fe has been calculated on the basis of the finite-temperature theory of amorphous metallic magnetism which self-consistently determines the distribution of local magnetic moments. The calculated magnetic phase diagram on the T-V plane and magnetization-vs-volume curve show the existence of the spin-glass state in a wide range of volume (10.50 A${\mathrm{\r{}}}^{3}$\ensuremath{\lesssim}V\ensuremath{\lesssim}12.5 A${\mathrm{\r{}}}^{3}$) after disappearance of ferromagnetism. The results verify our previous conclusion of the spin-glass state in amorphous Fe, which is expected from the experimental data of Fe-rich amorphous alloys containing early transition metals and rare-earth metals, but disagree with those obtained from the supercell approaches in the ground-state electronic structure calculations. It is shown that the nonlinear magnetic couplings between the nearest-neighbor Fe local moments and the local environment effects on the amplitude of Fe local moments via structural disorder lead to the spin-glass state in the weak magnetic region, while the volume expansion develops the ferromagnetic couplings and therefore the ferromagnetism.