多铁性复合材料非理想界面的模拟及其影响

为研究多铁性复合材料中界面特性对磁电耦合的影响,建立一种采用界面内聚力单元的多铁性复合材料有限元分析模型.基于压电和压磁材料本构关系的模拟特性,采用压电有限单元模拟各单相材料;将内聚力模型用于表征界面上相间相互作用力和位移间断之间的关系,可描述非理想界面的刚度和强度,并通过相应的内聚力单元来实现.各种非理想界面状况可通过调节内聚力模型参数来表征,而理想界面可通过对界面刚度加强来模拟.具有理想界面的层状多铁性复合材料的算例分析结果与文献一致.采用本文的有限元模型分析了非理想界面的刚度对磁电耦合的影响,计算了相应的磁电耦合系数.结果表明,界面刚度对复合材料的磁电系数有重要影响,当界面刚度足够大时,界面特性接近于理想界面,磁电系数趋于恒定.本文方法和结果对理论和实际中界面处理、磁电耦合性能的预测具有参考意义.

Modeling and influences of imperfect interfaces in multiferroic composites

In order to study the influences of interfaces on magnetoelectric(ME) coupling,a finite element model for multiferroics composites was suggested by employing cohesive zone elements for the interfaces.Piezoelectric elements were utilized for both piezoelectric and piezomagnetic phases based on the analogy between piezoelectric and piezomagnetic constitutive relations.And cohesive zone models(CZM) were employed to represent the relation between tractions and displacement discontinuities on imperfect interfaces,which characterized the stiffness and toughness of interfaces and were implemented by cohesive zone elements.Imperfect interfaces can be modeled by adopting CZM parameters,and perfect interfaces are also possible to be approximately modeled by CZM with enhanced interfacial stiffness.Example results of laminated multiferroics composites with ideal interfaces show good agreement with those in literature.The influences of imperfect interfaces on ME coupling were analyzed by the present finite element model,the corresponding ME coefficients were calculated.The simulation results indicate that the interface stiffness plays a significant role on ME coefficient of the composites.When the interfaces are stiff enough,they tend to be perfect and the ME coefficient tends to a constant.The present method and results are of reference significance to process of interfacial bonding and prediction of ME properties.