Fracture and reliability issues of materials with magnetoelectric coupling

Nowadays, materials with coupling magnetic, electric and mechanical effect have found increasingly applications in engineering structures, particular in the so-called smart materials/intelligent structures. Magnetoelectromechanical coupling effects have been observed in single-phase materials where simultaneous electric and magnetic ordering coexists, and in two-phase composites where the participating phases are piezoelectric and piezomagnetic. The phenomenon of magnetoelectric coupling is generally defined as the interaction between electric, magnetic and mechanical fields with in a body. Due to their high electro-magneto-mechanical coupling effect, magnetoelectric coupling materials are widely used in modern industries such as multilayer actuators, sensors, controlling devices, smart and intelligent structures, and biological devices. In order to address the issues concerning durability and reliability of these advanced devices, their fracture (failure under monotonic electric, magnetic and mechanical loads) behaviors should be investigated and understood thoroughly. A recent review paper by Fiebig reported many increasing research activities in magnetoelectric coupling [1]. Most materials with magnetoelectric coupling are ceramics. Defects are often unavoidable in these materials because of their brittleness. Due to their high electromechanical coupling effect, piezoelectric materials are widely used in multilayer actuators, sensors, controlling devices, smart and intelligent structures. In order to address the issues concerning durability and reliability of these piezoelectric devices, fracture (failure under monotonic mechanical and electrical loads) behaviors of piezoelectric materials should be investigated and understood thoroughly. These multilayer structures are operated under increasing high electric and mechanical loads. Hence, studies of these advanced materials with defects are essential for reliability design. This chapter introduces the fracture and reliability of magnetoelectric coupling materials. It contains eight sections and provides solutions for a range of crack and electrode problems in magneto-electro-mechanical coupling materials.