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21.
爆炸荷载下矩形板的塑性动力响应 总被引:8,自引:1,他引:8
本文采用Jones-Sawczuk控制方程,导出了脉冲荷载下矩形板最大残余挠度的简单理论计算公式,并应用该公式和动态屈服条件,计算了固支方板在爆炸荷载下的最大残余挠度值,与试验结果比较,取得了令人满意的结果。 相似文献
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以微磁学理论为基础,利用OOMMF软件采用三维动力学模型模拟研究了Sm-Co/α-Fe/Sm-Co交换耦合三层膜体系的磁滞回线,并对其磁性能分别与软、硬磁层厚度的关系进行了系统的分析.研究结果表明:只有当软磁层厚度小于其临界尺寸(5 nm)时,磁滞同线近似为矩形,此时三层膜完全耦合;硬磁层的厚度对体系的磁性能也有着密切的关系,而且硬磁层的厚度对体系软磁相的临界尺寸也有着一定的影响,只有在合适的软、硬磁含量比例的情况下才能得到具有最佳磁性能的三层膜. 相似文献
24.
To predict correctly the rut depths in asphalt pavements, a new nonlinear viscoelastic-elastoplastic constitutive model of
permanent deformation in asphalt pavements is presented. The model combines a generalized Maxwell model with an elastoplastic
one. Then from the creep theory, the linear and nonlinear constitutive equations of the generalized Maxwell model are obtained.
From the nonlinear finite element method for the rutting of the asphalt pavement, the rut depths of 4 asphalt-aggregate mixtures
are obtained. And the results are compared with the ones from the finite element method by SHRP and the experiments by SWK/UN.
The results in this paper are better than the ones by SHRP, and agree with the ones of the experiment by SWK/UN. This shows
that the nonlinear viscoelastic-elastoplastic constitutive model, which is presented in this paper for the rutting of the
asphalt pavement, is effective. The properties, such as nonlinear elasticity, plasticity, viscoelasticity and nonlinear viscoelasticity,
which affect the rutting of an asphalt pavement, can be shown in the model. And the characteristics of the permanent deformation
of the asphalt pavement can be presented entirely in the model. 相似文献
25.
根据实验数据,构造了接近实际纳米晶永磁Pr2Fe14B的样品,用微磁学有限元法进行了模拟计算.计算结果表明,晶界处各向异性的下降会导致矫顽力减小、剩磁值增大,而晶界处交换作用常数的减小则会使剩磁值减小、矫顽力增大.通过对实验样品的模拟研究发现,晶界处各向异性和交换作用常数的共同减小能够同时拟合出真实的矫顽力和剩磁值.模拟计算与实验在退磁曲线形状上的差距则说明模拟还存在不足.
关键词:
纳米晶永磁
磁滞回线
矫顽力
剩磁 相似文献
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Yoichi Sakai Ryo Omatsuzawa Iwao Sakazaki Sayaka Suzuki Hayato Hashino Takanobu Saito Takahiko Iriyama 《Hyperfine Interactions》2005,166(1-4):483-487
Samarium–iron intermetallic compounds were prepared by a melt spinning method with low and high wheel speeds, which resulted in a Th2Zn17-type and a TbCu7-type structure, respectively. Structure comparison between these types was investigated for Sm–Fe intermetallic compounds and their nitrides by 57Fe-Mössbauer spectroscopy. 相似文献
28.
Alex Samorodnitsky 《Journal of Combinatorial Theory, Series A》2008,115(2):279-292
A recent conjecture of Caputo, Carlen, Lieb, and Loss, and, independently, of the author, states that the maximum of the permanent of a matrix whose rows are unit vectors in lp is attained either for the identity matrix I or for a constant multiple of the all-1 matrix J.The conjecture is known to be true for p=1 (I) and for p?2 (J).We prove the conjecture for a subinterval of (1,2), and show the conjectured upper bound to be true within a subexponential factor (in the dimension) for all 1<p<2. In fact, for p bounded away from 1, the conjectured upper bound is true within a constant factor. 相似文献
29.
Bismuthine was on-line trapped on tungsten coil and subsequently electrothermally vaporized for the determination by atomic fluorescence spectrometry (AFS). Several noble metals, including Pd, Rh, Pt, and Ir, were explored as permanent chemical modifier for tungsten coil on-line trapping. Investigation showed that Ir gave the best performance, in which bismuthine was on-line trapped on Ir-coated tungsten coil at 560 °C, and then released at 1550 °C for subsequent transfer to AFS by a mixture of Ar and H2. Under optimum instrumental conditions, the trapping efficiency was found to be 73 ± 3%. With 120 s (12 mL sample volume) trapping time, a limit of detection (LOD) of 4 ng L− 1 was obtained, compared to conventional hydride generation AFS (0.09 μg L− 1); the LOD can be lowered down to 1 ng L− 1 by increasing the trapping time to 480 s. The LOD was found to be better or at least comparable to literature levels involving on-line trapping and some other sophisticated instrumental methods such as ICP-MS and GF-AAS. A comprehensive interference study involving conventional hydride-forming elements and some transition metals was carried out, and the result showed that the gas phase interference from other hydride-forming elements was largely reduced, thanks to the use of on-line tungsten coil trapping. Finally, the proposed method was applied to the determination of bismuth in several biological and environmental standard reference materials, and a t-test shows that the analytical results by the proposed method have no significant difference from the certified values at the confidence level of 95%. 相似文献
30.