FJZ-1000型超高速转镜分幅相机及其应用

FJZ-1000型超高速转镜分幅相机最高摄影幅频为1107幅/s，画幅总数160幅，尺寸7.5 mm10 mm。光学系统中新加入场镜以使相机的所有画幅均完整成像，使相机摄影频率全面达到标称值的技术指标。配备了新型数字化微机控制台，使相机的操作更加方便，并且实现了两台气动相机的联合拍摄，与脉冲X光机也进行了联动实验。相机达到了设计技术性能指标，实验取得了满意的结果。     

应用增量理论考虑应变硬化效应包辛格效应和温度对机械性质影响的自增强厚壁圆筒分析

本文提出的采用增量理论的分析模型和方法可以定量分析应变硬化、包辛格效应和材料机械性质随温度变化等因素对自增强厚壁圆筒中残余应力和操作应力分布的影响.厚壁圆筒看成由N个同轴薄壁圆筒套在一起组成的构件;采用包括弹性、塑性和温度应变的增量型本构关系和相容条件导出了自增强圆筒的基本方程;设计了计算机程序并给出了分析实例。分析结果表明,应变硬化会减小塑性区并降低残余应力;包辛格效应使反向屈服容易出现;温度升高将使残余应力和热应力松驰.     

Application of a new fast multipole BEM for simulation of 2D elastic solid with large number of inclusions

A fast multipole method (FMM) is applied for BEM to reduce both the operation and memory requirement in dealing with very large scale problems. In this paper, a new version of fast multipole BEM for 2D elastostatics is presented and used for simulation of 2D elastic solid with a large number of randomly distributed inclusions combined with a similar subregion approach. Generalized minimum residual method (GMRES) is used as an iterative solver to solve the equation system formed by BEM iteratively. The numerical results show that the scheme presented is applicable to certain large scale problems. The project supported by the National Nature Science Foundation of China (10172053) and the Ministry of Education     

Phase Behavior of Methane-Pentane Mixture in Bulk and in Porous Media

The adiabatic calorimetry method is used to measure the isochoric heat capacity and the dew-bubble curves for the methane-normal pentane mixtures in bulk for three different mixture compositions of n-pentane. The near-critical behavior of the mixture heat capacity indicates that at low n-pentane concentrations, this system is close to the special point of the critical locus. The effect of porous medium has been investigated for one of the mixtures studied in bulk. It has been shown that in porous medium the essential shift of the dew-bubble curve takes place. In our opinion this shift is caused by the formation of wetting film on the surface of porous medium. The estimation of film thickness resulting from the data obtained yields the value 7–8 nm.     

A network model with free-strand dynamics for polymer melts

 A network model for polymer melts is presented in which disentangled strands relax under flow conditions and may rejoin the network before complete relaxation. For simplicity, we study Gaussian strands that move affinely when incorporated in the network. Network strands are created and lost according to a time constant λ. Free strands have their dynamics given by the Bird-DeAguiar model as a crude representation of reptation and the hindered rotation experienced by polymer strands in melts. The model yields a shear-thinning viscosity with overshoot in the start-up viscosity η⁺ (t). The double-step strain results compare well with available experimental data. Received: 10 July 2000 Accepted: 10 July 2001     

镍基合金－碳化铬复合涂层耐磨特性的研究

用真空熔烧法在４５＃钢表面制取了镍基合金－碳化铬复合涂层，用扫描电子显微镜和Ｘ射线衍射仪分析了这种涂层的微观结构、物相组成和性能，并对这种涂层的耐磨特性进行了试验研究．结果表明：镍基合金－碳化铬复合涂层与底材形成了牢固的冶金结合，同时还含有较高比例的硬质相；碳化铬的加入使涂层的耐磨性显著提高，在给定的试验条件下分别于干摩擦和２０＃机械油润滑时，镍基合金－碳化铬复合涂层的耐磨性比４５＃钢的分别高５倍和１０倍以上     

摩擦过程中真实接触面积的灰色分析

灰色系统理论是近几年以随机过程为研究对象而形成和发展起来的，在农业和自动控制等方面的研究与应用发展较快．为了使这种理论应用于摩擦学研究领域，从光全反射测量和计算机数值计算两方面，考察了粗糙表面接触时真实接触面积的随机特性，指出摩擦过程中的真实接触面积是一种含有随机成分的变化量，研究目标应当侧重于真实接触面积的变化趋势和范围，而不是它的精确解．在此基础上，首次利用灰色系统理论，分别对静态和动态接触条件下真实接触面积的变化规律进行了灰色分析，建立了精度比较高的预测真实接触面积的灰色模型ＣＭ（１，１）．这种模型对动、静接触面积的计算值与实测值具有良好的一致性，可以用于动态跟踪描述摩擦过程中真实接触面积的变化规律     

Brownian Dynamics simulation of reversible polymeric networks

In this paper we describe the construction of a Brownian Dynamics simulation of reversibly cross-linked networks. The simulation differs from existing analytical approaches and computer simulations of networks in the sense that we also take the topology of the network into account. The motion of the junction points between different molecules is not prescribed but is calculated from a force balance. This makes it possible to measure the effect of network reorganisations on the stress relaxation. The response of networks to shear flow is measured and analysed in terms of transient network theory and within the framework of linear viscoelasticity. It is shown that the average motion of the junction is affine but that there is a long time diffusive process around the affine path. It was found that, even in systems with Gaussian chains and fixed association and disociation rates, a shear thickening of the viscosity and primary normal stress coefficient can occur. The reason was found to be that dangling segments are recaptured by the network before they had the opportunity to fully relax to the equilibrium state where the probability of reattachment to the network increases linearly with the length of a segment. Due to this mechanism the fraction of long segments present in the network is increased. This explanation of shear thickening seems to be consistent with experimental findings.     

硼酸钾做润滑油添加剂的抗磨性能之研究

作者利用Shell-Seta四球试验机研究了白油中所含硼酸钾的抗磨特性,以及分散刘中性烷基苯磺酸钙对硼酸钾抗磨性能的影响,并且利用X-射线光电子能谱仪(XPS)和俄歇电子能谱仪(AES)考察了摩擦表面的元素组成及硼元素的价态。结果表明,含硼酸钾的白油能够在摩擦表面形成含硼酸钾的表面膜而具有较好的抗磨性,硼在摩擦表面膜中以硼酸钾的形式存在,分散剂烷基苯磺酸钙会影响硼酸钾沉积腆的形成及其与金属表面的结合强度而降低抗磨性能。     

树枝状界面相开裂对纤维强度的影响

碳纤维增强铝的复合材料在制造过程中，由于发生化学反应而在界面上形成新相。该相并非均匀附着在纤维表面，而是以纤维为主杆形成树枝状。本文利用剪切滞后理论，同时考虑到界面相亦有承受轴向外载的能力，分析了界面相开裂对纤维强度的影响。结果表明界面相与纤维间界面强度以及该界面脱粘后的摩擦应力的增加都能使纤维在给定外载下破坏的概率减小；另外界面相的厚度、沿纤维方向的弹性模量、剪切模量的增加却使上述概率增加。