用有限元结合动态光弹性分析确定动态应力强度因子

本文运用有限元方法结合动态光弹性分析,对动态应力强度因子的计算进行了分析研究.作者在钱伟长教授[1]的基础上,将动态裂尖的奇异性分析解引入有限元计算;并以动态光弹性分析所得的裂纹扩展长度与时间的关系曲线作为定解补充条件,据此建立了有效模拟裂纹扩展的数值模型.通过具体算例证明,本文的方法取得了与实验结果相吻合的效果.     

泡沫硅橡胶老化后的压缩性能

硅橡胶在贮存和使用过程中，常受到不同应力应变的作用，在其使用和贮存期间会产生一系列物理老化和松弛，导致其内部结构发生变化，从而引起各种性能尤其是力学性能的下降，当性能下降到一定程度时，吉卜赛材料允许使用极限，它就失去了使用价值，因此有必要对硅橡胶的库存和老化进行研究。     

Pyroelectricity and Spontaneous Polarization in [111] Oriented 0.955 Pb（Zn1/3Nb2/3）O3-0.045PbTiO3 Single Crystals

We report that the measurements of the pyroelectric current of the pre-poled [111]-oriented 0.955 Pb（Zn1/3Nb2/3） O3-0.045 PbTiO3 （PZN-4.5%PT） single crystals can shed some light on the phase transition and spontaneous polarization characters of this material in a similar way to measures of remanent polarization and dielectric properties. The pyroelectric current is measured and the corresponding spontaneous polarization is calculated as a function of temperature with various poling fields added during cooling the sample from 200℃ to room temperature. Critical electric field of 0.061 k V/cm is found to be essential to induce the intermediate ferroelectric orthorhombic phase between the ferroelectric rhombohedral and tetragonal phases. Below the critical field, the polarization increases almost linearly with the increase of poling field. At the critical field, the polarization at 30OC increases abruptly from 14μC/cm^2 for a poling field of O.06kV/cm to 29.5μC/cm^2 for a poling field of 0.061 kV/cm, and afterwards, increases slowly and saturates to 31 μC/cm^2 for poling fields beyond 0.55 kV/cm.     

一种漂移室定位子性能反常现象的研究

研究了一种漂移室定位子性能的反常现象,它关系到定位子的使用寿命．着重测量了暗电流和随机噪声与时间、高压及温度的关系.     

用相位调制方法测量光盘盘基应力双折射的精度分析

偏振相位调制方法是测量微小双折射的一种高精度检测方法。本文系统全面地分析了以ＰＭＣＳＡ结构形式测量光盘盘基应力双折射的相位调制方法中，由各种误差源造成的对测试结果的影响。     

Effects of Substrate Temperature on Helium Content and Microstructure of Nanocrystalline Titanium Films

Helium-charged nanocrystalline titanium films have been deposited by HeAr magnetron co-sputtering. The effects of substrate temperature on the helium content and microstructure of the nanocrystalline titanium films have been studied. The results indicate that helium atoms with a high concentration are evenly incorporated in the deposited titanium films. When the substrate temperature increases from 60℃ to 350℃ while the other deposition＇parameters are fixed, the helium content decreases gradually from 38.6 at.% to 9.2at.%, which proves that nanocrystalline Ti films have a great helium storage capacity. The 20 angle of the Bragg peak of （002） crystal planes of the He-charged Ti film shifts to a lower angle and that of （100） crystal plane is unchanged as compared with that of the pure Ti film, which indicates that the lattice parameter c increases and a keeps at the primitive value. The grain refining and helium damage result in the diffraction peak broadening.     

Growth of NaBi（WO4）2 Dendrite and Mechanism

The solid-liquid interface motion of NaBi（WO4）2 （NBWO） melt crystal growth is observed in an in situ system, in which the whole processes of interface transition from fiat interface and cellular to dendrite are visualized. The spacing of the dendrite under smaller temperature gradient turns out to be larger than that under larger temperature gradient, which is found to be sensitive to the temperature distribution. The mechanism of dendrite growth of NBWO is studied based on the model of the growth units of anion coordination polyhedra. The { 001} face has two apex links, so it shows higher stability and has high growth rate and forms the arm of dendrite, whereas the {010} face has only one apex link, and thus shows relative slower growth rate and firstly forms the branches.     

热处理条件对双粉工艺中Bi—2212粉末的相组成影响

实验研究了Bi-2212粉末在空气，8％O2和纯O2种处理的相组成特征，指出通过改变热处理温度和气氛可控制前驱粉中对2223成相影响较大的(Bi，Pb)-2212相，Ca2PbO4相，2201相和14：24AEC等相。     

神光Ⅱ上柱形黑腔辐射驱动冲击波

利用神光Ⅱ的八路三倍频激光装置，驱动柱形黑腔产生的x 射线作辐射源驱动台阶铝样品产生冲击波，获得了清晰的冲击波图像，通过冲击波过台阶样 品的时间差获得冲击波速度和压力分别为31.2km/s和17.5×10⁵MPa.采用软x射线能谱 仪通过激光注入孔测量的辐射温度与采用冲击波法测量辐射温度的结果一致. 关键词： 冲击波 辐射驱动 辐射温度