薄膜涂层材料界面纯剪破坏标准试验法的开发

界面强度是薄膜涂层材料的最重要的性能指标之一，目前尚缺乏有效的测量方法。测量界面强度的主要困难在于寻求一种便于试验的试件形状和加载方式，使得界面上能够产生不同的应力状态，即在不同的剥离应力和剪应力比的状态下发生破坏。本文采用有限元数值分析（ABAQUS），研究了几种具有简单几何形状的试件的界面应力，并基于大量的数值试验，设计了剪应力为破坏支配因素的试件形状和加载方式，并且给出了便于应用的最大界面剪应力的经验估算公式。该经验公式可以适用于各种材料组合和薄膜涂层的厚度。研究结果表明，通过对薄膜涂层材料试件的基体引入缺口以产生应力集中，进行普通的四点弯曲试验，可以进行剪应力占支配地位的界面破坏试验。利用本文提出的试件形状和相应的最大界面剪应力经验公式，可以通过破坏试验简单地得到界面的剪切强度。     

Residual Stress Analysis of Orthotropic Materials by the Through-hole Drilling Method

The present study deals with the development and the application of the through-hole drilling method for the residual stress analysis in orthotropic materials. Through a systematic theoretical study of the stress field present on orthotropic plates with a circular hole, the relationships between the relaxed strains measured by a rectangular strain gauge rosette and the Cartesian components of the unknown residual stresses are obtained. The theoretical formulas of each influence coefficient allow the user an easy application of the method to the analysis of uniform-residual stresses on a generic homogeneous orthotropic material. Furthermore, to extend the method to the analysis of the residual stresses on orthotropic laminates, caused by initial in-plane loadings, an alternative formulation is implemented. The accuracy of the proposed method has been assessed through 3D numerical simulations and experimental tests carried out on unidirectional, cross-ply and angle-ply laminates.     

Net shape manufacturing and the performance of polymer composites under dynamic loads

An experimental investigation was conducted to determine the influence of postmold trimming and resultant edge quality on the performance of fiber-reinforced plastics (FRP) under dynamic loads. Graphite/epoxy and graphite/bismaleimide laminates were machined using three state-of-the-art industrial techniques and subjected to three-point bend impact to failure. The load load-line displacement records were used to obtain the load, bend deflection and energy absorbed to fracture. High-speed photography was also employed to identify the initiation and progression of failure and record the time dependent fracture process. From a comparison of edge quality and subsequent material performance for both polymeric composites, it was found that the impact response of FRPs is highly process dependent. In general, the load and energy absorbed to fracture decreases with increasing surface roughness. Reductions in the load and energy to the onset of fracture with degrading surface quality were as high as 20 percent. The dynamic response was also found to be dependent on the constituents, stacking sequence and impact velocity.     

Strain Measurements of Silicon Dioxide Microspecimens by Digital Imaging Processing

Silicon dioxide thin film is a common component in electronic devices and in MEMS, but its mechanical properties have rarely been studied. Techniques have been adapted and developed to conduct tensile tests on 1.0 μm thick silicon dioxide specimens that are 100, 150, and 200 μm wide and either 1 or 2 mm long. One end of the specimen remains fastened to the substrate, and the other is glued to a silicon carbide fiber attached to a 30 g load cell mounted on a piezoelectric translation stage. Strain is measured by digital imaging of two gold lines applied to the gage section of the transparent specimen. Twenty-five tests yield a Young’s modulus of 60.1 ± 3.4 GPa and a fracture strength of 364 ± 57 MPa.     

金属基纳米复合材料等效弹性模量的均匀化方法数值模拟

均匀化理论利用位移场双尺度渐近展开建立有限元列式，本文将其与有限元通用程序相结合，应用于金属基复合材料的弹性本构数值模拟。通过对不同尺度增强相金属基复合材料等效模量的数值模拟，考察了均匀化方法的适用情况。数值计算结果表明，对常规尺度增强相金属基复合材料，均匀化方法可以较准确地预测其等效弹性模量；对纳米增强相金属基复合材料，该方法仍可给出较好的预测，但存在某种程度的系统偏差。通过对纳米尺度增强机理的分析讨论，认为纳米增强相与基体材料问的界面效应可能有别于连续介质假设，指出可以考虑采用离散原子-连续介质耦合模型改进数值模拟结果。     

数字图像相关方法在闭孔泡沫铝压缩试验中的应用

为了了解相对密度与胞孔结构对闭孔泡沫铝力学性能的影响,本文采用放大成像及数字图像相关技术对两种不同密度的泡沫纯铝试样进行了实验研究.利用数字图像相关方法对泡沫纯铝变形前后的图像进行相关计算,获得了弹性范围内静态压缩情况下闭孔泡沫铝材料表面的全场变形及局部孔结构的变形,同时根据试验结果计算了试件的名义弹性模量.实验结果表明泡沫铝整体孔结构的变形与泡沫金属材料相对密度有关,而单个孔结构的变形主要与孔壁面光滑程度和皱褶有关.实验结果还表明图像相关方法能够有效地应用于闭孔泡沫金属的力学性测量和评估的研究.     

破碎岩石气体渗透性的试验测定方法

为了测试采矿工程中松散破碎岩体的气体渗透特性,设计了与MTS815.02岩石力学伺服机配套的气体渗透仪和测试系统。依靠MTS伺服机改变压力和位移条件,渗透仪用以稳定破碎岩石并连接气体测试系统,接入气源、组成回路和测试气透特性等由测试系统完成。通过对几组破碎砂岩岩样氮气渗透性能的测试,结合考虑状态方程的渗透率换算公式,得出破碎砂岩气体渗透率随压力和粒径条件的变化规律。该测试方法和测试结果在研究采动破碎岩体瓦斯等气体流动规律方面具有重要意义。     

Ag—Cu／Ti纳米双层膜结合强度测试方法研究

用粘结法（拉伸法，扭转法，断裂力学方法等）和划痕法分别测试了Ag-Cu/Ti纳米双层膜的结合强度，并对其实验结果进行了分析，对比和讨论。结果表明，粘结法由于受胶粘剂粘结强度的限制，只能适用于中低结合强度测试；划痕法适用于软金属薄膜结合强度测试，尤其对高结合强度的薄膜特别有效，而且能测出双层膜及多层膜中膜－膜界面的结合强度和膜基界面的结合强度。     

三轴模拟转台的外框结构有限元优化设计

本文建立了某三轴模拟转台的外框结构分析模型和结构优化设计模型，利用基于性态模型的约束变尺度法对其进行了优化设计，得出了在一阶固有频率和静态变形约束下的最优方案。     

On Anisotropic Elastic Materials for which Young''s Modulus E ( n ) is Independent of n or the Shear Modulus G ( n , m ) is Independent of n and m

It is shown that, among anisotropic elastic materials, only certain orthotropic and hexagonal materials can have Young modulus E(n) independent of the direction n or the shear modulus G(n,m) independent of n and m. Thus the direction surface for E(n) can be a sphere for certain orthotropic and hexagonal materials. The structure of the elastic compliance for these materials is presented, and condition for identifying if the material is orthotropic or hexagonal is given. We also study the case in which n of E(n) and n, m of G(n,m) are restricted to a plane. When E(n) is a constant on a plane so are G(n,m) and Poisson's ratio ν(n,m). The converse, however, does not necessarily hold. A plane on which E(n) is a constant can exist for all anisotropic elastic materials. In particular, existence of such a plane is assured for trigonal, hexagonal and cubic materials. In fact there are four such planes for a cubic material. For these materials, not only E(n) is a constant, two other Young's moduli, the three shear moduli and the six Poisson's ratio on the plane are also constant.     

破碎岩石渗透性的试验测定方法

传统的试验仪器和方法仅能测试岩石破坏前的渗透系数，文中介绍了一种自行设计并已获国家专利的破碎岩石压实渗透仪，依靠其与MTS815.02岩石力学伺服系统连接匹配。利用MTS的两套闭环系统施加轴压和孔压，可测试压力作用下岩石破碎后的渗透系数，对破碎砂岩进行高压下的渗透测试进一步说明该方法的可行性。利用该方法得出的测试结果。对破碎岩体中渗流问题研究及灾害防治具有参考价值。     

SPF规格材弹性模量的频率法测试及其评价

本文首先借助模态试验验证了文中提出的试验装置对试件实现了自由支承, 然后用瞬态激励测试了试件的一阶固有频率,并推算出SPF规格材的弹性模量。根据GB50005-2003《木结构设计规范》,评价了这批SPF规格材的弹性模量达Ⅱc级要求的概率为96.3%。瞬态激励频率法具有快速、简便、重复性好、精度高的优点。该方法对轻型木结构行业的检测工作具有一定的应用价值。     

复合材料冲击损伤及冲击后压缩强度的等效实验方法

简要论述了复合材料低速冲击及冲击后压缩的研究情况,比较了几种不同的冲击后的压缩实验方法,选取一种小尺寸试件方法,对复合材料低速冲击后的压缩行为进行研究,并将结果与有关文献进行了比较,实验结果与文献结果具有一致的变化规律。研究结果显示,对于材料研究,该方法可用来表征复合材料冲击后的压缩特性。使用该方法可以大大节省实验费用及周期。     

Mechanics and full-field deformation study of the Ring Hoop Tension Test

We investigate the mechanics of the Ring Hoop Tension Test (RHTT), as a means to assess the properties of anisotropic tubes in the hoop direction. This test involves placing a ring extracted from the tube over two close-fitting D-shaped mandrels that are then parted using a universal testing machine. Since the curvature of the ring does not change during loading, the ring undergoes only stretching. We determine the effects of contact pressure, radial stress, and friction between the tube and mandrels using FEA simulations. The effects of the pre-existing thickness eccentricity and of the specimen-making procedure on the recorded RHTT response are also assessed with a combination of experiments and analysis. We tested tubes from Al-6061-T4 with a diameter/thickness ratio of 20. We found that as the friction increases beyond 0.1–0.15, the state of uniaxial tension is deteriorated, indicating that care must be taken to minimize the tube-mandrel friction. We determined that although these tubes have a relatively large thickness eccentricity (±4% of the nominal thickness), this had no effect on the recorded results. We showed that the tubes should not be turned to remove that eccentricity, as the machining process induces damage that is noticeable in the results. We found that the contact pressure and the contact-induced radial stress cause limited deviations from uniaxial tension, comparable to the case of a tube under axial load and internal pressure which is often used for assessing the material properties in the hoop direction. Central in our analyses is the knowledge of the hoop strain field, which was assessed using 3D Digital Image Correlation. We propose a data reduction procedure for RHTT that accounts for all the above effects. Finally, with all effects accounted for, we establish the anisotropy of the extruded Al-6061-T4 tubes studied.     

捷联陀螺动态误差系数的正交三轴速率试验标定及其试验设计

本文提出了一种在三轴转台上标定捷联陀螺动态误差系数的正交三轴速率试验方法，同时应用最优试验设计理论，进行了试验计划的优化设计。采用该方案只需一次测试就可辨识出陀螺的全部动态误差系数，且辨识结果具有统计优良性     

桩基完整性测试的非线性最小二乘优化方法

针对桩基检测中低应变反射波法存在的应力波被桩土吸收和散射而衰减问题,把包含桩土衰减系数和介质不连续界面反射系数的反射波方程转化为非线性最小二乘优化问题,并采用信赖域法进行求解。由于采用信赖域法并采用了Gauss-Newton方向定义信赖域二维子空间,具有较好的收敛速度。通过模型桩算例表明该方法是确实可行的。     

Using the Sequential Self-calibration Method and Genetic Algorithm Method to Optimally Design Tracer Test to Estimate Conductivity Distribution

A gradient-based inverse method – the sequential self-calibrated method – is combined with a genetic algorithm method to search the optimal design scheme for a tracer test. The sequential self-calibrated method is developed for estimating conductivity distribution in a study domain conditioning on tracer test data. To improve the calculation efficiency, a fast streamline-based approach is used to compute the derivative of concentration with respect to the changes of hydraulic conductivity. Performance of the sequential self-calibrated method has been studied using a synthetic aquifer having a sandwich-like geologic structure where hypothetical tracer tests are conducted. The study results indicate that the locations and number of sampling wells will significantly affect accuracy in the estimates. To maximize estimating accuracy in the sequential self-calibrated method for a fixed number of sampling wells, a genetic algorithm method is applied to search the optimal locations for sampling wells. The results indicate that the optimal sampling well locations depend on the apparent geologic structure and the difference in conductivity values for the various regions. For the sandwich-like structure, when the difference between conductivity values in the two separate regions is large enough, the optimal locations for the sampling wells will be fixed, regardless of conductivity values. The study results also show that based on the optimal sampling-well scheme, estimating accuracy will increase as the number of sampling wells increases, even though the rate of increasing accuracy slows as the number of wells increases.     

落柱式高压粘度装置的研制与压粘试验结果

作者研制了一台可测试润滑油在高压下的粘度和密度的落柱式高压粘度装置。本装置采用了新型高压粘性动密封和新型高压流变平垫静密封,经1200MPa试压、1000MPa压力下48小时保压和使用试验证明均无泄漏。用本装置所获得的压粘数据的重现性好、灵敏度高、可比性强。     

铝合金舟桥甲板结构极限承载能力模型试验与数值分析

铝合金夹心板结构是现代舟桥甲板常用的结构形式,具有重量低、强度高的优点。本文针对五种铝合金夹心板模型(两种型材断面)进行了静态极限承载能力模型试验,并作了相应的非线性有限元数值模拟。数值计算中考虑了材料非线性和几何非线性效应,有限元模型中还考虑了坦克履带的刚化作用和初始焊接变形的影响。研究表明,铝合金夹心板在横向履带载和轮载的作用下,主要表现为受压面板的屈曲和夹心斜撑板的屈曲。本文的试验和计算结果符合较好,表明了二者的有效性。     

基于边界位移的复合材料力学参数无损反演方法

非均质材料参数识别在工程学、医学以及生物力学等众多领域具有重要意义.目前求解材料参数识别这类反问题主要采用优化方法,通常需要已知结构的全场位移信息,使含有位移的目标函数最小化,从而获得材料参数分布.然而在实际工程中,结构内部的位移较难测量且测量精度低.因此,本文拟提出一类仅利用边界位移就能进行非均质材料参数分布反演的方...