大口径光学元件装夹转运结构设计及分析

为了实现大口径光学元件的安全装夹、转运,通过光学元件开槽与不开槽两种装夹方式的分析,得出开槽夹紧转运方式将带来微裂纹、应力集中、成本高等缺陷,提出了利用摩擦力克服光学零件的重力和惯性力的低应力装夹转运方案。通过对光学元件低应力夹紧结构设计,并利用有限元分析方法,得到不开槽装夹方式下,光学元件的最大主应力为1.11 MPa,最大切应力为0.73 MPa,远低于光学元件破坏的强度极限,且受力均匀,无应力集中现象。     

纵向泵浦Cr∶ Nd∶GSGG激光棒的热透镜效应研究

对纵向泵浦Cr∶Nd∶GSGG激光棒的热透镜效应进行了详细的理论分析。对温度分布的函数表达式 ,进行了讨论 ;分析了热引起的应力 ,得到了激光棒破裂的临界功率公式 ;最后对光学畸变进行了分析与讨论 ,推导了光程差计算公式     

数字电视用中分辨率74cm纯平彩色显像管BC配列不良的分析与对策

通过对74cm中分辨率纯平彩色显像管BC配列局部严重群散不良的调查分析,确定荫罩受力塌陷是主要原因,通过改良设计、工艺优化及其它方面的综合对策,使以上技术难题得到满意的解决,整管不良率由4.78%下降到0.172%。     

微桥法镍膜的弹性模量和残余应力测量

利用MEMS技术制作了不同尺寸的镍(Ni)膜微桥结构样品。采用纳米压痕仪XP系统测量了微桥载荷与位移的关系,并结合微桥力学理论模型得到了两种不同尺寸的Ni膜的弹性模量和残余应力。结果表明,两种不同尺寸的Ni膜的弹性模量结果一致,为190 GPa左右,但是残余应力变化较大。与采用纳米压痕仪直接测得的带有硅(Si)基底的Ni膜弹性模量186.8 7.5 GPa相比较,两者符合较好。     

Stress Distribution in an Infinite Elastic Body with a Locally Curved Fiber in a Geometrically Nonlinear Statement

Within the framework of a piecewise homogeneous body model, with the use of three-dimensional geometrically nonlinear exact equations of elasticity theory, a method for determining the stress—strain state in unidirectional fibrous composites with locally curved fibers is developed for the case where the interaction between the fibers is neglected. All the investigations are carried out for an infinite elastic body containing a single locally curved fiber. Numerical results illustrating the effect of geometrical nonlinearity on the distribution of the self-balanced normal and shear stresses acting on the interface and arising as a result of local curving of the fiber are presented.__________Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 41, No. 4, pp. 433–448, July–August, 2005.     

Numerical analysis of turbulent structure in compound meandering open channel by algebraic Reynolds stress model

The turbulent flow in a compound meandering channel with a rectangular cross section is one of the most complicated turbulent flows, because the flow behaviour is influenced by several kinds of forces, including centrifugal forces, pressure‐driven forces and shear stresses generated by momentum transfer between the main channel and the flood plain. Numerical analysis has been performed for the fully developed turbulent flow in a compound meandering open‐channel flow using an algebraic Reynolds stress model. The boundary‐fitted coordinate system is introduced as a method for coordinate transformation in order to set the boundary conditions along the complicated shape of the meandering open channel. The turbulence model consists of transport equations for turbulent energy and dissipation, in conjunction with an algebraic stress model based on the Reynolds stress transport equations. With reference to the pressure–strain term, we have made use of a modified pressure–strain term. The boundary condition of the fluctuating vertical velocity is set to zero not only for the free surface, but also for computational grid points next to the free surface, because experimental results have shown that the fluctuating vertical velocity approaches zero near the free surface. In order to examine the validity of the present numerical method and the turbulent model, the calculated results are compared with experimental data measured by laser Doppler anemometer. In addition, the compound meandering open channel is clarified somewhat based on the calculated results. As a result of the analysis, the present algebraic Reynolds stress model is shown to be able to reasonably predict the turbulent flow in a compound meandering open channel. Copyright © 2005 John Wiley & Sons, Ltd.     

Raman properties embeddedof GaSb nanoparticlesin SiO2 films

The Raman shifts of nanocrystalline GaSb excited by an Ar^ ion laser at wavelengths 514.5, 496.5, 488.0, 476.5,and 457.9nm are studied by an SPEX-1403 laser Raman spectrometer respectively, and they are explained by phonon confinement, tensile stress, resonant Raman scattering and quantum size effects. The Stokes and anti-Stokes Raman spectra of GaSb nanocrystals strongly support the Raman feature of GaSb nanocrystals. The calculated optical spectra compare well with experimental data on Raman scattering GaSb nanocrystals.     

Closed-form solutions for a rectangular layer with central crack under anti-plane shear stress

We consider the problem of determining the stress distributionin a finite rectangular elastic layer containing a Griffithcrack which is opened by internal shear stress acting alongthe length of the crack. The mode III crack is assumed to belocated in the middle plane of the rectangular layer. The followingtwo problems are considered: (A) the central crack is perpendicularto the two fixed lateral surfaces and parallel to the othertwo stress-free surfaces; (B) all the lateral surfaces of therectangular layer are clamped and the central crack is parallelto the two lateral surfaces. By using Fourier transformations,we reduce the solution of each problem to the solution of dualintegral equations with sine kernels and a weight function whichare solved exactly. Finally, we derive closed-form expressionsfor the stress intensity factor at the tip of the crack andthe numerical values for the stress intensity factor at theedges of the cracks are presented in the form of tables.     

Au(111)上烷烃硫醇SAMs表面应力的理论研究

应用已建立的关于金属表面吸附层中表面应力的统计热力学理论 ,计算了Au(111)上烷烃硫醇SAMs的表面应力及其与烷烃硫醇链长、吸附覆盖度的定量关系 .计算结果与实验相符 ,较好地解释了Berger等人的实验结果 ,特别是解决了在表面应力符号性质上理论与实验的矛盾 .在表面吸附层应力的多种物理起源中 ,通过底物的分子间作用力有着决定性的贡献 ,揭示了分子的吸附能间接地起着重要作用 .这与阴离子化学吸附体系Cl-/Au(111)的有关研究结果相同 .