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磁性材料已经在新技术中起着重要的作用,研究这些磁性材料的力学规律对于磁性材料的应用和发展至关重要.软磁材料在工作状态时,一般受到机械应力场和电磁场双重耦合场的作用,其本构关系本质上是非线性的.这给理论模拟带来了很大困难.目前无论是从实验方面或者是理论模型方面,对软磁材料的力磁耦合本构关系的研究都很不成熟.本文用实验方法,研究了高纯度镍和锰锌复合铁氧体这两种传统软磁材料的力磁耦合本构关系.研制了力磁耦合加载设备,测量设备和监控设备.采用铁氧体粉末烧结方法,烧制了实验所需的圆柱状实验试件.实验结果表明,外加应力对镍和锰锌铁氧体材料的磁致应变具有重要影响,较大预加应力对镍的磁化强度产生较明显的影响.而外应力对锰锌铁氧体材料的磁化曲线影响很小. 相似文献
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由清华大学、东南大学、天津大学、国防科技大学共同发起和中国科协主办的第75次青年科学家论坛(现代科技发展对实验力学带来的挑战和机遇)于2003年8月4日至5日在北京中国科学会堂召开.来自全国各科研院所、大专院校力学、材料、物理、化学、生物等学科的25名青年科学家参加了此次活动.中国科协李慧政处长为本次活动的致欢迎词,中国科协书记处书记冯长根教授、中国科协常委、中国力学学会副理事长杨卫教授、科协学术部主任马阳教授、中科院力学所白以龙院士、清华大学温诗铸院士、戴福隆教授、以及国家自然科学基金委数理学部力学处孟庆国处长出 相似文献
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The strain and size effects on the ferroelectric properties of BaTiO3 films are studied using the molecular dynamics method based on a shell model. It is found that from microscopic view, these two effects share the same physical nature, i.e., the resulting crystal cell distortions lead to the separation of negative and positive charge eentres. The strain and size effects are therefore coupled, and the critical thicknesses of films would depend on the in-plane strains, which provides a possible interpretation on the discrepancies among the experimental measurements of the critical thicknesses. A polarization map is given to clearly reflect the relations among the size, strain and polarization of the nano films. 相似文献
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The existence of shear horizontal surface waves in a magneto-electro-elastic (MEE) half-space with hexagonal (6mm) symmetry is investigated. The surface of the MEE half-space is mechanically free, but subjected to four types of electromagnetic boundary conditions. These boundary conditions are electrically open/magnetically closed, electrically open/magnetically open, electrically closed/magnetically open and electrically closed/magnetically dosed. It is shown that except for the electrically open/magnetically closed condition, the three other sets of electromagnetic boundary conditions allow the propagation of shear horizontal surface waves. 相似文献
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High-temperature oxidation is an important property to evaluate thermal protection materials. However, since oxidation is
a complex process involving microstructure evolution, its quantitative analysis has always been a challenge. In this work,
a phase field method (PFM) based on the thermodynamics theory is developed to simulate the oxidation behavior and oxidation
induced growth stress. It involves microstructure evolution and solves the problem of quantitatively computational analysis
for the oxidation behavior and growth stress. Employing this method, the diffusion process, oxidation performance, and stress
evolution are predicted for Fe-Cr-Al-Y alloys. The numerical results agree well with the experimental data. The linear relationship
between the maximum growth stress and the environment oxygen concentration is found. PFM provides a powerful tool to investigate
high-temperature oxidation in complex environments. 相似文献