The feasibility of tuning the band structure of phononic crystals is demonstrated by employing magnetostrictive materials and applying an external magnetic field. Band structures are calculated with a plane wave expansion method that accounts for coupling between the elastic behavior and the magnetic field through the development of elastic, piezomagnetic, and magnetic permeability effective tensors. We show the contactless tunability of the absolute band gaps of a two-dimensional phononic crystal composed of an epoxy matrix and Terfenol-D inclusions. The tunable phononic crystal behaves like a transmission switch for elastic waves when the magnitude of an applied magnetic field crosses a threshold.

Tunable magnetoelastic phononic crystals

Power ultrasound and its applications: A state-of-the-art review.

The deployment of wireless sensor networks (WSNs) for the internet of things (IoT) and remote monitoring devices has made tremendous progress in the last few years. At the same time, energy harvesters are also being developed to satisfy the power requirement of WSNs and other low power consumption electronics, to increase the device operating time and overcome the limitations of conventional electric power supplies, including batteries. Among various resources for energy harvesting, the magnetic noise produced by power transmission infrastructures and associated mechanical vibrations are ubiquitous energy sources that could be converted into electricity by high efficiency energy conversion materials or devices. Electromagnetic energy conversion systems that operate on the principle of Faraday's induction law can provide sufficient power from strong magnetic fields. However, under weak magnetic fields with low frequency such as 50/60 Hz, the power generated from an electromagnetic device is disappointingly small. Alternative energy harvesting technologies with high power density and small device volume/dimensions are obviously necessary for WSNs of IoT. In this review article, the current status and prospects of an emerging magnetic energy harvesting technology, the so-called magneto-mechano-electric (MME) generators, are reviewed. MME generators utilize the magnetoelectric (ME) coupling in composites of piezoelectric and magnetostrictive materials and interaction between the proof magnet mass and magnetic field. Since the piezoelectric phase in the composite also responds to mechanical vibration directly, an ME-based energy harvester can harness energy from both mechanical vibrations and magnetic fields simultaneously. This combination is expected to enhance the total power output and conversion efficiency. The MME generator can be a ubiquitous power source for WSNs, low power electronic devices, and wireless charging systems by harvesting energy from the tiny magnetic fields present as parasitic magnetic noise in an ambient environment.

Magnetic energy harvesting with magnetoelectrics: an emerging technology for self-powered autonomous systems

The current investigation deals with the nonlinear oscillation response of conical microshells made of a composite material with functional graded (FG) in-plane heterogeneity is studied in the presence of the size dependency. To accomplish this purpose, various types of homogenization schemes including Voigt model, Reuss model, Mori-Tanaka model, and Hashin-Shtrikman bounds model are employed. The size-dependent characteristics are taken into consideration on the basis of the modified couple stress theory of elasticity within the framework of the higher-order shear deformation shell theory. The couple stress-based differential equations of motion are constructed via the Hamilton's principle. An efficient numerical solution methodology adopting generalized differential quadrature (GDQ) method together with the pseudo-arc technique is put to use to obtain the modified couple stress-based nonlinear frequency of homogenized FG composite conical microshells. It is demonstrated that by increasing the value of the maximum shell deflection, the couple stress type of size effect plays more important role in the nonlinear vibration response of FG composite conical microshells. Additionally, it is indicated by changing the boundary conditions from simply supported one to clamped one, the influence of couple stress size dependency decreases.

Nonlinear oscillations of composite conical microshells with in-plane heterogeneity based upon a couple stress-based shell model

Algorithmic two-scale transition for magneto-electro-mechanically coupled problems

Tunability of band structures in a two-dimensional magnetostrictive phononic crystal plate with stress and magnetic loadings

Theoretical study on nonlinear magnetoelectric effect and harmonic distortion behavior in laminated composite

A nonlinear magnetoelectric model for magnetoelectric layered composite with coupling stress

A way based on the temperature effect is investigated to adjust the longitudinal wave band gaps of one-dimensional epoxy/Terfenol-D phononic crystals. For both the cases (with and without consideration of demagnetization effect), the dependences of component materials' effective parameters on temperature are obtained by applying a nonlinear mechanical-magneto-thermal coupling constitutive model and fitting the experimental data, respectively. Further, the influence of temperature on the band structure of wave propagation in phononic crystals consisting of epoxy and Terfenol-D is discussed in detail. Meanwhile, the effects of magnetic field, pre-stress, and filling fraction are studied. Numerical results show that temperature has a significant influence on the band structure of wave propagation in phononic crystals: As temperature rises from −40 °C to 40 °C, the widths of the first, second, and fourth band gaps increase, while that of the third band gap decreases. In addition, the demagnetization effect sh...

Yang Shi

Papers

Tunability of band structures in a two-dimensional magnetostrictive phononic crystal plate with stress and magnetic loadings

Theoretical study on nonlinear magnetoelectric effect and harmonic distortion behavior in laminated composite

A nonlinear magnetoelectric model for magnetoelectric layered composite with coupling stress

A mechanical-magneto-thermal model for the tunability of band gaps of epoxy/Terfenol-D phononic crystals

A functionally graded composite cantilever to harvest energy from magnetic field