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磁致伸缩和磁记忆问题研究 总被引:9,自引:1,他引:9
从铁磁性材料的基本特性和最小自由能原理出发,探讨了应力和外磁场对磁性材料磁化状态的不同影响,讨论了磁致伸缩现象的规律和特点。用磁致伸缩方程组详细研究了磁记忆现象产生的条件和规律,分析了应力和地磁场在磁记忆现象中的不同作用。结论认为应力可改变材料的磁特性,地磁场则可改变材料的压磁性,两者共同作用产生净磁场,磁记忆现象不仅与应力和材料的磁特性有关,而且还与工件在空间的位置和方向有关。 相似文献
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磁致伸缩材料具有在外加磁场存在时可回复变形和在施加应力时会改变磁性能的特性。可是所有铁磁性材料 ,只有在低场下具有大磁致伸缩的材料才适合于象致动器和传感器之类的用途。TbxDyl-x合金表面出现很大的基面磁致伸缩 (约为 0 1% ) ,但因其有序化温度低以致限制了它在低温下的应用。RFe2 (R是稀土元素 )金属间化合物 ,如Terfenol合金 (DyxTbl-x)Fe2 具有很大的磁致伸缩和较高的居里温度 (在室温以上具有大约为 0 1%的磁致伸缩 ) ,目前广为应用的是Terfenol D成分为 (Dy0 7Tb0 3Fe2 )。但… 相似文献
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从铁磁性材料的基本特性出发,探讨了用磁致伸缩方程组描述磁记忆的方法,给出了磁记忆磁场的数学表示式,讨论了磁记忆现象的基本规律和特点,分析了应力和偏磁场对材料磁特性的不同作用,提出了产生磁记忆的三个基本条件,即材料的压磁性、磁滞性和交变应力的反复作用,并对地磁场的作用给出了明确的解释。同时,分析了磁记忆研究存在的问题及其应用时的局限性等。 相似文献
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超磁致伸缩材料是一种先进的能量转换材料,在高新技术和国防军工领域具有重要的应用价值。在概述TbDyFe超磁致伸缩材料的特点及发展现状基础上,重点介绍了〈110〉取向材料的磁场热处理研究。在实验方面,采用区熔定向凝固技术制备了〈110〉取向TbDyFe多晶材料,在略高于居里点温度退火时施加磁场,不改变晶体学择优取向和凝固组织,但能调控初始磁畴分布状态,改变服役时的磁矩运动过程,从而改善材料磁致伸缩和力学性能。在模拟研究方面,建立了基于能量最低原理的磁畴旋转模型,模拟了磁热感生各向异性诱导的初始磁矩再取向过程,得到了形成单轴各向异性的临界值;模拟了感生各向异性强弱对磁致伸缩“Jump”效应的影响规律,探讨了磁场热处理对〈110〉取向晶体磁致伸缩的作用机理。 相似文献
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The configuration of magnetostrictive transducers for both transmitter and receiver was optimized for the generation and reception of ultrasonic longitudinal guided waves in seven-wire steel strands in a pitch catch arrangement. Three axisymmetric permanent magnets significantly improved the capability of magnetostrictive transducers compared to two permanent magnets, and effectively increased the amplitude of the longitudinal guided wave mode, L(0, 1) at 160 kHz. Experimental results show that the maximum amplitude of a received guided wave signal could be obtained by using a receiver with a three-layer coil in parallel and a transmitter with a three-layer coil in series. The amplitudes of the defect-reflected signal increased by as much as 50% or more as compared with those when both transducers used a single layer coil. As a result, magnetostrictive transducers with an optimized configuration, including permanent magnet distribution and multilayer coil connection, could be efficiently used for the inspection of seven-wire steel strands by using ultrasonic guided waves in a pitch catch arrangement. 相似文献
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稳恒磁场在材料科学中的应用越来越受到关注。本文从稳恒磁场作用下生成的磁化力和洛伦兹力两个角度归纳了稳恒磁场对金属材料的固态相变和液态相变的影响。其中磁化力可以影响固态相变过程,形成取向,引起磁对流,进行磁性分离。而洛伦兹力可以抑制熔体的流动和波动,提高溶质离子在基体中的固溶度,另外,利用洛伦兹力还可以在电磁离心铸造中获得均匀的凝固组织。 相似文献
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针对金属板厚度测量问题,研究了电磁超声波在金属板中的传播特性,根据有限元理论,利用ANSYS有限元分析软件对金属板测厚换能器进行了仿真分析。建立了测厚换能器的三维模型,对模型进行了电磁分析和电磁结构耦合分析。分别得出了被测试件内感生出的涡流和受到的洛伦兹力以及被测试件内部受到的位移情况。仿真结果表明,被测试件内质点受到的洛伦兹力方向为向下,且线圈正下方的洛伦兹力最大;通过不同时刻质点位移的变化可以直观地观察出电磁超声波在板中的传播状况;通过对单个质点位移的分析得出了该模型产生的电磁超声波的质点位移最大方向是向下的;该模型产生的超声波是向下的,可用于模拟电磁超声的测厚情况。 相似文献
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稳恒磁场在材料科学中的应用越来越受到关注。本文从稳恒磁场作用下生成的磁化力和洛伦兹力两个角度归纳了稳恒磁场对金属材料的固态相变和液态相变的影响。其中磁化力可以影响固态相变过程,形成取向.引起磁对流,进行磁性分离。而洛伦兹力可以抑制熔体的流动和波动,提高溶质离子在基体中的固溶度,另外,利用洛伦兹力还可以在电磁离心铸造中获得均匀的凝固组织。 相似文献
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Experimental and numerical evaluation of electromagnetic acoustic transducer performance on steel materials 总被引:2,自引:0,他引:2
Electromagnetic Acoustic Transducers (EMATs) are an attractive alternative to standard piezoelectric probes in a number of applications thanks to their contactless nature. EMATs do not require any couplant liquid and are able to generate a wide range of wave-modes; however these positive features are partly counterbalanced by a relatively low signal-to-noise ratio and by the dependence of EMAT performance on the material properties of the test object. A wide variety of steel materials is employed in many industrial applications, so it is important to assess the material-dependent behaviour of EMATs when used in the inspection of different types of steel. Experimental data showing the performance of bulk shear wave EMATs on a wide range of steels is presented, showing the typical range of physical properties encountered in practice. A previously validated Finite Element model, including the main transduction mechanisms, the Lorentz force and magnetostriction, is used to evaluate the experimental data. The main conclusion is that the Lorentz force is the dominant transduction effect, regardless of the magnitude and direction of the bias magnetic field. Differently from magnetostriction, the Lorentz force is not significantly sensitive to the typical range of physical properties of steels, as a consequence the same EMAT sensor can be used on different grades of ferritic steel. 相似文献
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Zhen-Yuan JiaHui-Fang Liu Fu-Ji WangChun-Ya Ge 《Journal of Alloys and Compounds》2011,509(5):1760-1767
A novel magnetostrictive force sensor which can measure static force and dynamic force using giant magnetostrictive material rod as the sensitive element was studied. A special structure was proposed which was a stainless steel ring around the Hall sensor to improve the force measuring sensitivity. In view of the hysteresis nonlinearity of the giant magnetostrictive material and actual working process of the sensor, a model was established based on the combination of Jiles-Atherton model and magnetomechanical effect method. The unknown magnetic and magnetostrictive parameters in the model were identified by a hybrid algorithm of genetic algorithm and simulated annealing algorithm. Moreover, the numerical solution method and simulation process of the model were expounded in detail. The results showed that the force measuring sensitivity is about 6.14 times higher than that of the sensor without this special structure. The model can reveal the magnetization process mechanism clearly and describe the relationship between force input and electromagnetic output effectively. 相似文献
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从电磁场的基本原理出发,利用ANSYS有限元软件建立铝硅合金半固态电磁铸造的磁流耦合场模型,通过数值模拟计算磁场对流场和温度场的影响。结果表明,电磁场频率直接决定流场及温度场的分布,高频电磁场感应加热效果明显、洛伦兹力主要表现为电磁压力,有利于电磁铸造约束成型。 相似文献