带式输送机弯曲变形阻力理论研究

为了减小带式输送机的弯曲阻力,基于黏弹性材料在动载荷下的能耗理 论,对输送带运行时的弯曲变形能耗机理进行了分析,推导出输送带弯曲变形阻力系数的近似理 论公式,并通过试验验证了公式的正确性. 利用公式对各因素对弯曲阻力系数 的影响规律进行了探讨,结果表明可以通过选配合适的输送带橡胶材料获得合适的 输送带黏弹性参数,并结合调整输送带、输送机的结构参数达到降低输送机弯曲阻力的目的.     

花键轴截面抗扭刚度的研究

本文应用电磁涡流比拟方法对花键轴截面的抗扭刚度进行了实验测试,并根据实测的数值结果提出了经验计算公式.还可据此换算得出"抗扭截面模量W_n"值.     

扁铲侧胀试验计算地基承载力

简单介绍扁铲侧胀试验,首次提出用扁铲侧胀试验计算地基承载力的方法。利用上海地区部分重大工程中的扁铲 侧胀试验数据,在与室内土工试验、静力触探试验及十字板剪切试验的试验参数相关分析的基础上,经数理统计后给出了上 海地区用扁铲侧胀试验计算地基承载力的经验公式,并对其计算精度进行了评价。     

任意段变模量桩纵向振动的解析解

建立了均质土中考虑桩端土和桩侧土作用的任意段变模量桩，讨论了在桩顶受纵向激励时的定解问题，并用拉氏变换（Laplace)求得桩顶速度频域响应的解析解，然后利用卷积定理和拉氏逆变换求得桩顶速度时域响应的解析解，并将其运用到桩基质量的动力检测中。对弹性模量突变桩以及模量连续变化桩的振动特性作了进一步的研究，并将理论曲线与实测曲线进行了拟合对比，结果表明，两者吻合较好。     

不同模量理论弹性支承连续梁及框架

弹性支承连续梁及框架结构的内力不仅与各杆件的刚度有关，而且与支承结构的刚度有关．当引入拉压不同模量后，各杆件的抗弯刚度EI不再为常数(与经典力学不同)，而是内力的函数，使结构内力计算成为非线性问题．用分段积分法推导出不同模量弹性支承连续梁及框架的中性轴公式和内力计算表达式并编制非线性内力计算迭代程序．通过实例计算对比分析不同模量与经典力学相同模量两种方法计算结果的差异，最后提出对该类结构计算的合理建议以及利用不同模量对结构进行优化的结论．     

First-principles study of the structural,elastic, and optical properties for Sr0.5Ca0.5TiO3

A detailed theoretical study of the structural, elastic, and optical properties for Sr0.5Ca0.5TiO3 is carried out by first- principles calculations. The band structure exhibits a direct bandgap of 2.08 eV at the F point in the Brillouin zone. The bulk modulus, shear modulus, Young＇s modulus, and Poisson＇s ratio are derived based on the calculated elastic constants. The bulk modulus B = 153 GPa and shear modulus G = 81GPa are in good agreement with available experimental data. Poisson＇s ratio v = 0.275 suggests that Sr0.sCa0.sTiO3 should be classified as being a ductile material. Using the electronic band structure and density of states, we analyze the interband contribution to the optical properties. The real and imaginary parts of the dielectric function, as well as the optical properties such as the optical absorption coefficient, refractive index, extinction coefficient, and energy-loss spectrum are calculated. The static dielectric constant ε1 （0） and the refractive index n（0） are also investigated.     

First-principles study of the electronic structure and optical properties of cubic Perovskite NaMgF_3

The structural, electronic, and optical properties of cubic perovskite NaMgF3 are calculated by plane-wave pseudopo- tential density functional theory. The calculated lattice constant a0, bulk modulus B0, and the derivative of bulk modulus B~ are 3.872/~, 78.2 GPa, and 3.97, respectively. The results are in good agreement with the available experimental and theo- retical values. The electronic structure shows that cubic NaMgF3 is an indirect insulator with a wide forbidden band gap of Eg = 5.90 eV. The contribution of the different bands is analyzed by total and partial density of states curves. Population analysis of NaMgF3 indicates that there is strong ionic bonding in the MgF2 unit, and a mixture of ionic and weak covalent bonding in the NaF unit. Calculations of dielectric function, absorption coefficient, refractive index, electronic energy loss spectroscopy, optical reflectivity, and conductivity are also performed in the energy range 0 to 70 eV.     

拉压模量不同材料的圆孔扩张问题

本文建立了拉、压模量不同材料的圆孔扩展理论，分析了有关参数对圆孔扩张时应力、位移以及塑性区的发展规律的影响。     

YBCO高温超导材料的动态模量

本利用动态激光散斑测振技术测量超小型物体振动特性的实验系统，研究了１２３ＹＢ－ＣＯ温超导体的动态力学性能，运用谱分析仪和时间域分析方法了动态响应信号，识别出了超导体梁的前五阶频率和模态，并根据基频计算了材料的动态模量，为小尺寸脆性功能材料的力学性能测试提供了一种有效的实验方法。