| Summary: | 碩士 === 國立交通大學 === 土木工程系所 === 102 === The magnetoelectric (ME) effect in multiferroic materials, which refers to the coupling between electric and magnetic fields, has great potential for practical device applications such as sensors, actuations and memories. However, the ME effect in single-phase multiferroic materials is too weak and cannot be observed at room temperature. On the other hand, multiferroic composites provide an alternative option for improvement. Many of the existing works about multiferroic composites assume that the interface between ferromagnetic and ferroelectric constituents are perfect. But in reality, the imperfect interfaces which can affect the ME effect may be present in many circumstance such as sliding, debonding and flaws.
This research studies the effective properties of piezoelectric-piezomagnetic fibrous composites with imperfect interfaces under longitudinal shear with in-plane electromagnetic fields. We employ the decoupling transformation method to reduce the multi-field coupled problem to a set of equivalent single-field problems. Both mechanically stiff and electromagnetic highly conducting interfaces and mechanically soft and electromagnetic weakly conducting interfaces are considered. Numerical results are compared with the known solutions and are shown in good agreement. It is observed that imperfect interfaces have great influence on the ME voltage coefficient and that moduli of composites with imperfect interfaces do not satisfy the compatibility relations. Finally, we use the two-level recursive scheme to show the validity of the three-phase composite assumption in modeling the imperfect effect.
|
|---|
