Effect of magnetostriction on fracture of a soft ferromagnetic medium with a crack-like flaw
Effect of magnetostriction on fracture of a soft ferromagnetic medium with a crack-like flaw
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DOI：
10.1046/j.1460-2695.2003.00707.x
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发表时间：
2003-11
影响因子：
3.7
通讯作者：
Y. Wan;D. Fang;A. Soh;K. Hwang
中科院分区：
文献类型：
--
作者：
Y. Wan;D. Fang;A. Soh;K. Hwang
基于复势理论，确定了无限大软铁磁介质中椭圆夹杂附近的磁感应强度。利用各向同性材料的磁致伸缩本构关系，得到了椭圆形裂纹附近的应力场。此外，在一个细长的椭圆形裂纹的尖端的应力场的情况下，其中只有一个外部磁场垂直于椭圆的长轴施加在无穷远。结果表明，尖端附近的应力场由软磁材料的磁致伸缩和磁导率决定。感应磁致伸缩模量是确定两种机制中哪一种机制的关键参数，即，磁致伸缩和磁力引起的变形，在确定裂纹状缺陷尖端附近的应力场中占主导地位。关于磁场对具有裂纹状缺陷的软铁磁体的表观韧性的影响，软铁磁材料可大致分为两类：一类具有大的感应磁致伸缩模量，另一类具有小的模量。提出了一种近似的材料分类标准。为了便于工程设计，本文给出了这两类软磁材料的应力强度因子表达式。结果表明，应力强度因子不仅与缺陷的几何形状有关，还与缺陷内部介质的渗透率有关。
The magnetic-induction field in the vicinity of an elliptical inclusion embedded in an infinite soft ferromagnetic medium is determined based on complex potential theory. By using a constitutive relation of magnetostriction for isotropic materials, the stress field in the vicinity of an elliptical flaw is obtained. Furthermore, the stress field at the tip of a slender elliptical crack is determined for the case in which only an external magnetic field perpendicular to the major axis of the ellipse is applied at infinity. The results indicate that the stress field in the neighbourhood of the tip is governed by the magnetostriction and permeability of the soft ferromagnetic material. The induction magnetostrictive modulus is a key parameter in determining which of the two mechanisms, i.e., magnetostriction and magnetic-force-induced deformation, is dominant in determining the stress field in the neighbourhood of the tip of a crack-like flaw. With regard to the influence of the magnetic field on the apparent toughness of a soft ferromagnetic body with a crack-like flaw, soft ferromagnetic materials can be roughly divided into two categories: one possesses a large induction magnetostrictive modulus and the other has a small modulus. An approximate criterion for categorizing the materials is presented. For the benefit of engineering design, the expressions of the stress-intensity factor for these two categories of soft ferromagnetic materials are presented. The results show that the stress-intensity factor is affected not only by the flaw geometry, but also by the permeability of the medium inside the flaw.