循环应力加载条件下支撑剂破碎率实验研究

运用微机控制电液伺服万能试验机,对循环应力加载条件下支撑剂破碎率进行实验研究,考察不同支撑剂及不同应力加载次数下支撑剂的破碎率情况。实验结果表明：循环应力加载对支撑剂的破碎率影响很大。随着应力循环加载次数的增加,破碎率上升明显,且破碎率开始上升较快,随着循环次数的增加而上升缓慢。     

加速寿命试验方法及评估

加速寿命试验是为缩短试验时间,在不改变故障模式和故障机理的条件下,用加大应力的方法进行的试验。随着元器件水平的迅速提高,高可靠、长寿命的产品越来越多,在正常应力水平下进行寿命试验来评定产品的可靠性已不能满足实际需要,代价很高,不现实,目前广泛采用了加速寿命试验。本文介绍了加速寿命试验方法及评估,并给出了案例。     

Determination of threshold stress intensities: fatigue of low alloy steel BS4360-50D

An experimental method for obtaining the effective stress intensities necessary for cyclic crack growth prediction is described. Also, it is shown that the critical threshold value, ΔK_{c, th}, can be estimated using simple energetic considerations, leading to an equation:

$\text{Δ}\text{K}{}_{\mathrm{c,th}}\text{=}\text{4π}\text{E}\text{λ}{}_{\mathrm{s}}\text{2?}\text{(θ}{}_{\mathrm{uts}}\text{?}{}_{\mathrm{f}}\text{)}\text{((1+}\text{n}\text{)θ}{}_{\mathrm{yc}}\text{)}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$

The threshold values obtained compare well with the experimentally observed values for a structural steel BS 4360-50D and for other steels.     

聚合物熔体挤出流动中的弹性行为

研究了聚合物熔体挤出过程中出口压力降ΔＰｅｘｉｔ与剪切应力τｗ和挤出胀大比Ｂ三者之间的关系。提出了描述这一关系的方程：ΔＰｅｘｉｔ＝τｗ（Ｂ＾４－１）＾０５／３。初步验证，用该方程计算的ΔＰｅｘｉｔ值与文献提供的毛细管挤出实测值有较好的一致性。     

FBG传感器在水下结构工程中的应用

近年来,光纤光栅传感技术在我国发展很快,已经在桥梁、土建等多个领域中得到了应用,但在水工领域的应用还很少.本文结合白鹤梁工程实例,探索该项技术在这一领域应用的可行性.开展的光纤光栅应变、温度传感器在水下工程领域中较大规模的应用研究结果表明：FBG具有很好的防水性能,测试精度高,长期稳定性好,信号传输距离远,为水下结构的长期监测提供了一种可靠有效的手段.     

偏心受压桩的简便计算方法

建筑地基基础设计规范(GB50007 2002)给出的桩身计算方法对轴心受压桩较为适用,但对于偏心受压桩的计算则非常繁琐.为此,给出偏心受压桩的一种简便计算方法和工程应用实例.     

Obtaining mode mixity for a bimaterial interface crack using the virtual crack closure technique

We review, unify and extend work pertaining to evaluating mode mixity of interfacial fracture utilizing the virtual crack closure technique (VCCT). From the VCCT, components of the strain energy release rate (SERR) are obtained using the forces and displacements near the crack tip corresponding to the opening and sliding contributions. Unfortunately, these components depend on the crack extension size, Δ, used in the VCCT. It follows that a mode mixity based upon these components also will depend on the crack extension size. However, the components of the strain energy release rate can be used for determining the complex stress intensity factors (SIFs) and the associated mode mixity. In this study, we show that several—seemingly different—suggested methods presented in the literature used to obtain mode mixity based on the stress intensity factors are indeed identical. We also present an alternative, simpler quadratic equation to this end. Moreover, a Δ-independent strain energy release based mode mixity can be defined by introducing a “normalizing length parameter.” We show that when the reference length (used for the SIF-based mode mixity) and the normalizing length (used for Δ-independent SERR-based mode mixity) are equal, the two mode mixities are only shifted by a phase angle, depending on the bimaterial parameter ε.     

Analysis of singular stress fields at multi‐material corners under thermal loading

The scaled boundary finite‐element method is extended to the modelling of thermal stresses. The particular solution for the non‐homogeneous term caused by thermal loading is expressed as integrals in the radial direction, which are evaluated analytically for temperature changes varying as power functions of the radial coordinate. When applied to model a multi‐material corner, only the boundary of the problem domain is discretized. The boundary conditions on the straight material interfaces and the side‐faces forming the corner are satisfied analytically without discretization. The stress field is expressed semi‐analytically as a series solution. The stress distribution along the radial direction, including both the real and complex power singularity and the power‐logarithmic singularity, is represented analytically. The stress intensity factors are determined directly from their definitions in stresses. No knowledge on asymptotic expansions is required. Numerical examples are calculated to evaluate the accuracy of the scaled boundary finite‐element method. Copyright © 2005 John Wiley & Sons, Ltd.     

乌江某水电站压力钢管的安全性评价

基于WDL610钢的NDT评价和断裂评定表明,乌江某水电站压力钢管在焊态情况有足够的断裂抗力,是安全的.同时鉴于工程实际情况可以免除消除残余应力处理.     

受钢工况钢包壁应力场的模拟与分析

ANSYS程序是进行热和结构分析的好工具,它在钢包上的应用非常广泛。以钢包二维截面为研究对象,分别讨论受钢工况下耐火材料物性参数和不同的工作层厚度对包壁应力场分布的影响,从而为钢包设计提供一些依据。