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81.
不同加载状态下TA2钛合金绝热剪切破坏响应特性 总被引:2,自引:1,他引:1
一般认为绝热剪切现象在宏观上表现为材料动态本构失稳,即热软化大于应变硬化.本文采用帽型受迫剪切试样研究TA2钛合金的动态力学特性和本构失稳过程.首先对剪切区加载应力状态进行理论和数值分析,通过合理设计帽型试样,剪切区变形可近似按剪切状态处理;结合二维数字图像相关法(two-dimensional digital image correlation,DIC-2D)直接测试试样剪切区应变演化,给出帽型受迫剪切实验的等效应力-应变响应曲线.进一步,利用Hopkinson压杆对TA2钛合金开展动态压缩及帽型剪切对比试验研究,比较压缩、剪切试验得到的等效应力-应变曲线,采用"冻结"试样方法分析试样中绝热剪切局域化演化过程,探讨不同加载状态下TA2钛合金的绝热剪切破坏现象及其动态力学响应特性.实验结果表明,在塑性变形初始阶段,动态压缩及剪切加载下的等效应力-应变曲线符合较好,但随塑性损伤发展及绝热剪切带形成,两者出现分离,表明损伤及绝热剪切演化过程与应力状态相关.剪切试样实验得到的本构"软化"特性能够反映绝热剪切带起始、破坏演化过程的力学响应特性,而在动态压缩实验中,即使试样中已出现双锥形的绝热剪切带及局部裂纹分布,其表观等效应力-应变曲线并不出现软化特征,动态压缩实验无法得到关于绝热剪切起始、发展以及破坏的本构软化响应特性. 相似文献
82.
83.
吴桥杂技文化生态的保护与产业发展研究 总被引:1,自引:0,他引:1
吴桥被誉为杂技之乡,其杂技文化生态发展有着深厚的历史底蕴与丰富内涵。发展杂技文化产业是对吴桥杂技文化生态最好的保护。可以通过创建"吴桥杂技文化生态保护区及将吴桥打造成世界杂技文化名城,发展杂技文化产业,保护杂技文化生态。 相似文献
84.
在对湖北省孝感市孝南区的调查中,发现在农家书屋工程实施过程中得到了广大农民的热烈欢迎,但在书屋的认可度、建设管理、出版物配置等方面还需进一步提高和完善。要实现农家书屋的可持续发展,今后在加强农家书屋自身建设的同时,必须加强农村基层组织建设。 相似文献
85.
Dapeng Xu Yipeng Gu Liang Li Hongzhi Shen Hang Yang Qiang Zhou Zhan Shi Hongming Yuan Tian Cui 《Journal of Physics and Chemistry of Solids》2014
A high-quality ZnNb2O6 single-crystal grown by optical floating zone method has been used as a research prototype to analyze the optoelectronic parameters by measuring the absorption coefficient and transmittance spectra along the b-axis from 200 nm to 1000 nm at room temperature. The optical interband transitions of ZnNb2O6 have been determined as a direct transition with a band gap of 3.84 eV. The refractive index, extinction coefficient, and real and imaginary parts of the complex dielectric constants as functions of the wavelength for ZnNb2O6 crystal are obtained from the measured absorption coefficients and transmittance spectra. In the Urbach tail of 3.16–3.60 eV, the validity of the Cauchy–Sellmeier equation has also been evaluated. Using the single effective oscillator model, the oscillator energy Eo is found to be 4.77 eV. The dispersion energy Ed is 26.88 eV and ZnNb2O6 crystal takes an ionic value. 相似文献
86.
提出了一种系统自定位方法.该方法采用控制点坐标进行约束,按照非线性最小二乘的Levenberg-Marquardt算法求解系统自定位参数.以双发射站为例,给出了新的系统自定位参数的解算模型.通过试验证明此方法是可行的,解算模型是正确有效的,其系统自定位精度完全能够满足工程测量的要求. 相似文献
87.
Khedri Z Li Y Cao H Qu J Yu H Muthana MM Chen X 《Organic & biomolecular chemistry》2012,10(30):6112-6120
Sialidases or neuraminidases catalyze the hydrolysis of terminal sialic acid residues from sialyl oligosaccharides and glycoconjugates. Despite successes in developing potent inhibitors specifically against influenza virus neuraminidases, the progress in designing and synthesizing selective inhibitors against bacterial and human sialidases has been slow. Guided by sialidase substrate specificity studies and sialidase crystal structural analysis, a number of 2-deoxy-2,3-dehydro-N-acetylneuraminic acid (DANA or Neu5Ac2en) analogues with modifications at C9 or at both C5 and C9 were synthesized. Inhibition studies of various bacterial sialidases and human cytosolic sialidase NEU2 revealed that Neu5Gc9N(3)2en and Neu5AcN(3)9N(3)2en are selective inhibitors against V. cholerae sialidase and human NEU2, respectively. 相似文献
88.
Hongzhi Luo Guodong Liu Fanbin Meng Jianqiang Li Enke Liu Guangheng Wu 《Journal of magnetism and magnetic materials》2012
The electronic structure and magnetic properties of new Fe-based Heusler alloys Fe2TiZ (Z = Ga, Ge, As, In, Sn and Sb) have been studied by first-principles calculations. In these alloys, the 24-electron Fe2TiGe, Fe2TiSn are nonmagnetic semiconductors and other compounds are all ferrimagnetic metals. Fe2TiAs and Fe2TiSb are predicted to be half-metals with 100% spin polarization. The spin polarization ratio in Fe2TiGa and Fe2TiIn is also quite high. The calculated total moment for Fe2TiAs and Fe2TiSb is 1 μB, which is mainly determined by the Fe partial moment. The half-metallicity of Fe2TiSb is stable under lattice distortion. The spin polarization of Fe2TiSb is found to be 100% for the lattice variation in a range of 5.6–6.1 Å, which is attractive in practical applications. 相似文献
89.
Based on the structure of polarizer–Faraday modulator–analyzer, a method of measuring the optical rotation is proposed by using Fast Fourier Transform to analyze the output signal of optical material. The output signal detected by a photodetector comprises two AC components, which angular frequencies are ω and 2ω, respectively. So, the amplitude ratio of different frequency signals can be obtained by using the Fast Fourier Transform. According to the relationship between the amplitude ratio and optical rotation, the optical rotation of material can be detected. Furthermore, the experiment results show that the correlation coefficient between the measured optical rotation and the sugar solution concentration is found to be 0.99979. 相似文献
90.
Hongzhi Liu Hongjun Yuan Jiezeng Qiao Fanpei Li 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2012,63(5):865-878
We consider strong solutions to the initial boundary value problems for the isentropic compressible Navier–Stokes equations in one dimension: $$\rho\left\{\begin{array}{lll} t+(\rho u)_x=0\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\, {\rm in}\,(0,T)\times(0,1)\\ (\rho u )_t+(\rho u^2)_x+\rho \Phi_x-(\mu( \rho )u_x)_x+P_x=0\quad\quad {\rm in}\,(0,T)\times(0,1) \\\left(\left(\frac{\delta(\Phi_x)^2\,+\,1}{(\Phi_x)^2\,+\,\delta}\right)^{\frac{2-p}{2}}\Phi_x\right)_x=4\pi g(\rho-\frac{1}{|\Omega|}\int\nolimits_\Omega \rho dx\,\,\,\, )\quad\,\, {\rm in}\,(0,T)\times(0,1)\end{array}\right.$$ Here, the Φ is a non-Newtonian potential and strong solutions of the problem and obtains the uniqueness under the compatibility condition. 相似文献