Demagnetizing field in single crystal ferromagnetic shape memory alloys
Demagnetizing field in single crystal ferromagnetic shape memory alloys
复制标题
单晶铁磁形状记忆合金的退磁场
DOI：
10.1088/1361-665x/aaf20e
复制
发表时间：
2019
影响因子：
4.1
通讯作者：
C. Ciocanel
中科院分区：
文献类型：
--
作者：
J. Eberle;H. Feigenbaum;C. Ciocanel
铁磁材料，包括铁磁形状记忆合金（FSMA 或 MSMA），会发生退磁。由于这种退磁，MSMA 文献对于应在何处进行实验测量所施加磁场的问题不一致。此外，许多研究人员在建模 MSMA 时假设退磁因子恒定，但很少有分析来确定该假设的准确性。在这项工作中，我们使用有限元 (FE) 模拟来确定 (1) 应在何处通过实验测量所施加的磁场，以及 (2) 恒定退磁因子的假设捕获 MSMA 所经历的磁场的准确度。为了通过实验确定测量外加磁场的正确位置，使用有限元模拟和恒定退磁因子来计算椭圆体样本的平均外加磁场。然后将该值与在不同位置的有限元模拟中测量的磁场进行比较。模拟表明，放置 MSMA（但不存在 MSMA）的空气体积中的平均磁场是测量所施加磁场的正确方法。在 MSMA 放置位置的中心点测量施加的场（但没有 MSMA 存在）可以提供更容易测量的位置，并且几乎同样准确。进行了额外的 FE 模拟，以测试使用体积平均退磁因子计算棱柱状样品的 MSMA 内部磁场的有效性。将使用有限元分析确定的内部磁场与使用恒定退磁因子计算的内部磁场值进行比较表明，当有限元计算的内部磁场在空间上平均时，这两个值相似，但是，在棱柱样品的体积内存在内部磁场的显着变化。
Ferromagnetic materials, including ferromagnetic shape memory alloys (FSMAs or MSMAs), are subject to demagnetization. Because of this demagnetization, the MSMA literature is inconsistent with regards to where the applied magnetic field should be measured experimentally. In addition, many researchers assume a constant demagnetization factor when modeling MSMAs, but there has been little analysis to determine the accuracy of that assumption. In this work, we use finite element (FE) simulations to determine (1) where the applied magnetic field should be measured experimentally and (2) how accurately the assumption of a constant demagnetization factor captures the magnetic field experienced by MSMAs. To determine the correct location for measuring the applied magnetic field experimentally, FE simulations and a constant demagnetization factor were used to calculate an average applied magnetic field with ellipsoidal specimens. This value was then compared to the magnetic field measured in the FE simulations at various locations. Simulations showed that the average magnetic field in the air volume where the MSMA would be placed, but without the MSMA present, was the correct method for measuring the applied magnetic field. Measuring the applied field at the center point of where the MSMA would be placed, but without the MSMA present, provides an easier to measure location, which is nearly as accurate. Additional FE simulations were conducted to test the validity of using a volume average demagnetization factor in calculating an MSMA’s internal magnetic field for prismatic specimens. Comparing the internal magnetic field determined using FE analysis to calculated values of the internal magnetic field using a constant demagnetization factor showed that these two values were similar when the FE calculated internal field was spatially averaged, however, significant variation of the internal magnetic field was present within the volume of prismatic specimens.