等离子体源离子渗氮1Cr18n19Ti奥氏体不锈钢磨损特性的试验研究

用等离子体源离子渗氮，即低能（１－３ｋｅＶ）、超大剂量（１０＾１９－１０＾２０ｉｏｎｓ／ｃｍ＾２量级）Ｎ＾＋注入－同步扩散改性技术，在２８０℃和３８０℃下处理１ｃＲ９Ｔｉ奥氏全不锈钢，获得了最大深度分别为１．６μｍ和１０．６μｍ，固溶Ｎ的最高原子浓度均约为２５％的Ｎ过饱和面心立方相（γＮ）改性层。销－盘磨损试验表明：在２ｍ／ｓ和较宽负荷范围（等效正应力０．２－２．８ＭＰａ）条件下，高硬主（ＨＫ０．     

A complete expression of the asymptotic solution of differential equation with three-turning points

Ｗｅｈａｖｅｄｉｓｃｕｓｓｅｄｃｏｎｃｅｐｔｏｆｅｑｕａｔｉｏｎｗｉｔｈｎ＿ｔｕｒｎｉｎｇｐｏｉｎｔｓｉｎｍｙｐａｐｅｒ［１］,ｉ．ｅ．,ａｓｅｃｏｎｄｏｒｄｅｒｌｉｎｅａｒｏｒｄｉｎａｒｙｄｉｆｆｅｒｅｎｔｉａｌｅｑｕａｔｉｏｎｄ２ｙｄｘ２＋［λ２ｑ１（ｘ）＋λｑ２（ｘ,λ）］ｙ＝０,ｗｈｅｒｅｑ１（ｘ）＝（ｘ－μ１）（ｘ－μ２）…（ｘ－μｎ）ｆ（ｘ）,ｆ（ｘ）≠０,ａｎｄλｉｓａｌａｒｇｅｐａｒａｍｅｔｅｒ．Ａｌｔｈｒｏｕｇｈｔｈｅｆｉｒｓｔｔｅｒｍｏｆｔｈｅａｓｙｍｐｔｏｔｉｃｅｘｐａｎ…     

输沙量（率）水平分布的非均一性

实验表明：输沙率沿风洞实验段横截面的水平分布具有明显的非均一性。其正负距平变幅可达平均值的４５－６０％。输沙率与有效起沙风成正比关系，其实验式为ｑ＝８．９５×１０（－１）（ＶＬ－Ｖｔ）（１．９）（ｇ／ｃｍ·ｍｉｎ），Ｖｔ＝５．０ｍ／ｓ。与Ｂａｇｎｏｌｄ，ＲＡ理论公式ｑ＝８．７０×１０（－２）（Ｖ－Ｖｔ）３相比（Ｖｔ＝４．０ｍ／ｓ），前者计算结果更接近室内外实测值。     

等离子体源离子渗氮 1Cr18Ni9Ti 奥氏体不锈钢磨损特性的试验研究

用等离子体源离子渗氮，即低能（１～３ｋｅＶ）、超大剂量（１０１９～１０２０ｉｏｎｓ／ｃｍ２量级）Ｎ＋注入－同步扩散改性技术，在２８０℃和３８０℃下处理１Ｃｒ１８Ｎｉ９Ｔｉ奥氏体不锈钢，获得了最大深度分别为１．６μｍ和１０．６μｍ，固溶Ｎ的最高原子浓度均约为２５％的Ｎ过饱和面心立方相（γＮ）改性层．销－盘磨损试验表明：在２ｍ／ｓ和较宽负荷范围（等效正应力０．２～２．８ＭＰａ）条件下，高硬度（ＨＫ０．１Ｎ２２００）的γＮ相改性层具有较高的承载能力和较长的耐磨寿命．高度过饱和Ｎ在母相奥氏体中的固溶强化作用，是使等离子体源离子渗氮奥氏体不锈钢耐磨性提高的主要原因．     

A solving method for a system of partial differential equations with an application to the bending problem of a thick plate

Ｓｏｍｅｅｎｇｉｎｅｅｒｉｎｇｐｒｏｂｌｅｍｓｃａｎｂｅｅｘｐｒｅｓｓｅｄｂｙｓｕｃｈａｓｙｓｔｅｍｏｆｌｉｎｅａｒｎｏｎ＿ｈｏｍｏｇｅｎｅｏｕｓｄｉｆｆｅｒｅｎｔｉａｌｅｑｕａｔｉｏｎｓａｓＬ１［ｕ１（ｑ）］＝Ｆ１（ｑ）,Ｌ２［ｕ２（ｑ）］＝Ｆ２（ｑ）＋ｆ２［ｕ１（ｑ）］,…Ｌｎ［ｕｎ（ｑ）］＝Ｆｎ（ｑ）＋ｆｎ［ｕ１（ｑ）,ｕ２（ｑ）,…,ｕｎ－１（ｑ）］,（１）ａｎｄｔｈｅｉｒｉｎｉｔｉａｌａｎｄｂｏｕｎｄａｒｙｃｏｎｄｉｔｉｏｎｓ,ｗｈｅｒｅｑｉｓｔｈｅｓｅｔｏｆａｌｌａｒｇｕｍｅｎｔｓｗ…     

数字散斑相关法在聚偏氟乙烯压电薄膜力学性能测试中的应用

利用数字散斑相关方法对PVDF透明压电薄膜进行了单轴拉伸力学性能研究。首先比较了喷漆与不喷漆两种条件下不同厚度薄膜的单轴拉伸曲线,发现当薄膜厚度超过一定值时,样品表面喷漆与否对测试结果无显著影响。然后,利用数字散斑相关方法对PVDF挤出薄膜进行了单轴拉伸下的应力-应变关系研究,得到了PVDF薄膜的应力-应变曲线和反映PVDF薄膜全场应变信息的三维信息图,以及线性阶段的弹性模量和泊松比。实验结果表明:数字散斑相关方法用于PVDF压电薄膜的力学性能研究是一种行之有效的方法。     

TATB钝感炸药本构关系的实验研究

利用分离式霍普金森压杆（ＳＨＰＢ） 完成了对ＴＡＴＢ钝感炸药在２ ～５０ｍ／ｓ 弹速范围内的冲击压缩实验。根据实验结果和回收样品分析确认ＴＡＴＢ属于含预损伤的非线性粘弹性体,并对１０２ ～１０３ｓ－ １ 应变率范围内的应力 应变曲线进行了拟合。     

硬质聚氨酯泡沫塑料动态力学性能的研究

介绍了用分离式Ｈｏｐｋｉｎｓｏｎ压杆对硬质聚氨酯泡沫塑料（ＲＰＵＦ）进行的一种高应变率实验，第一次完整地给出了ＲＰＵＦ在１０￣３ｓ￣（－１）高应变率下的动态应力应变曲线，并对ＲＰＵＦ的动态力学性能及其吸能缓冲机理作了简单的分析。     

SHPB装置应用于测量高温动态力学性能的研究

ＳＨＰＢ（分离式Ｈｏｐｋｉｎｓｏｎ压杆）装置由于具有结构简单、操作方便等优点，为人们普遍采用；但作测量材料的动态高温力学性能方面还存在诸多不便之处。本文研究了附有恒温加热炉的ＳＨＰＢ装置，利用一维应力波传播理论和传热学原理，修正了温度梯度场对波形测量的影响，从而使ＳＨＰＢ装置用于高温动态力学测量更为准确可靠；并实际测量了３０ＣｒＭｎＳｉＡ钢从室温到高温（６００℃）的动态（１．５～４．０×１０３ｓ－１）应力应变曲线。     

二氧化钛薄膜材料的制备及其摩擦学研究

利用溶胶－凝胶法（Ｓｏｌ－ｇｅｌ）制备了单层及双层ＴｉＯ２薄膜材料,分析结果表明所制薄膜主要由非晶ＴｉＯ２纳米颗粒组成,单层及双层ＴｉＯ２与钢球及Ｓｉ３Ｎ４陶瓷球对摩在轻载荷（３Ｎ）下具有良好的减摩与抗磨性能,与钢球对摩时失效循环次数分别为３７６和１８５６,与陶瓷球对摩时失效循环次数分别为２２８０和２３４３,玻璃基片主要发生脆性裂纹及严重的磨粒磨损,ＴｉＯ２薄膜则发生塑性变形及轻微磨粒磨损。     

Effect of dentin tubules to the mechanical properties of dentin. Part II: Experimental study

To verify the theoretical models of varying transversely isotropic stress-strain relations of dentin established in the preceding work (Part I), we perform a set of experiments. Because of the very fine tooth size, it usually seems to be difficult to directly measure the inhomogeneous and anisotropic parameters of dentin. In this paper, by the digital speckle correlation method, tensile experiments are made on the small dentin samples either parallel or perpendicular to the dentin tubules. With the theoretically predicted elastic stress-strain relations, an optimization method is proposed to fit the strain curve adapted to the experimental data. The results show that the theoretical elastic stress-strain relations coincides very well with the experimental observations. The determined Young's modulus and Poisson's ratio of dentin matrix are 29.5 GPa and 0.44, respectively, in the optimization sense. The project supported by the National Natural Science Foundation of China (19525207)     

Distribution of dislocation source length and the size dependent yield strength in freestanding thin films

A method is proposed to estimate the size-dependent yield strength of columnar-grained freestanding thin films. The estimate relies on assuming a distribution of the size of Frank-Read sources, which is then translated into a log-normal distribution of the source strength, depending on film thickness, grain size and theoretical strength of the material, augmented with a single fit parameter. Two-dimensional discrete dislocation plasticity (DDP) simulations are carried out for two sets of Cu films and the fit parameter is determined from independent experiments. Subsequent DDP predictions of the stress-strain curves in comparison with the corresponding experimental data show excellent agreement of initial yield strength and hardening rate for films of varying film thickness and grain size. Having thus demonstrated the power of the proposed strength distribution, it is shown that the mode of this distribution governs the most effective source strength. This is then used to suggest a method to estimate the yield strength of thin films as a function of film thickness and grain size. Simple maps are presented that are in very good agreement with recent experimental results for Cu thin films.     

一种通过条纹方向图提取散斑条纹中心线的方法

在光测力学中,如何从单幅散斑干涉条纹图中消除散斑噪声,高精度自动提取相位信息,是一项较困难的工作。本文提出了一种计算条纹方向的简单算法,以及通过条纹方向图提取散斑条纹中心线的方法。实验表明此方法对高噪声的散斑条纹图非常有效。     

Digital speckle correlation for strain measurement by image analysis

This paper is concerned with small strain measurement utilizing the numerical processing of digital images. The proposed method has its theoretical basis in digital signal analysis and, from a methodological point of view, it can be considered as an extension to digital images of the wellknown white light speckle photography technique. That conventional method is based on the analysis of photographic plates that are exposed twice (before and after the specimen deformation) with the image of a random speckle pattern that has been previously printed on the test piece surface. The digital speckle correlation advantages consist of requiring a very simple specimen preparation and, mainly, of allowing the strain field computation just by numerical elaboration of the acquired images. In this paper, the theoretical basis of the technique and some valuable improvements to the known analogous methodologies are presented. Finally, test results for an application of digital speckle correlation are shown and advantages and disadvantages of the technique are elaborated. In addition, further developments in this area are discussed.     

基于多通道滤波技术的散斑条纹图正则化方法

在光测力学中,条纹图正则化是进一步提取条纹位相信息的重要基础。对于散斑条纹图来说,正则化的过程还需能够有效地抑制散斑噪声。本文提出一种基于多通道滤波技术的散斑条纹图正则化方法。通过使用多个Gabor滤波通道对散斑条纹图进行滤波,并且引入与条纹对比度有关的权重因子把各个滤波通道的滤波结果叠加起来,最终得到滤除了散斑噪声的正则化条纹图。数值模拟和实验结果表明,该方法在将散斑条纹图正则化的同时能够有效地滤除条纹图中的散斑噪声,为进一步提取条纹位相奠定了良好的基础。     

Nondestructive testing using temporal phase evaluation in speckle interferometry

A novel nondestructive testing (NDT) method is reported in which temporal evolution of the speckles in speckle interferometry is used to measure large object deformations. The basic principle of the method is that continuous object movement introduces fluctuations in the phase of the speckle and is recorded as intensity modulation. Acquiring a large number of frames of the object motion, the phase data for the whole object deformation are then retrieved by the Fourier transformation technique. The method is capable of measuring more than 100 μm in-plane and out-of-plane deformation with speckle interferometry and more than 500 μm for speckle shearing interferometry. The authors discuss the NDT results obtained with the three methods and make some relative comparisons of each.     

物体运动、变形及光波长变化时的激光散斑运动规律

被激光照明的漫射面,由漫反射在空间Fresnel区形成的光场,用Fresnel-Kirchhoff积分表示。利用统计的方法,考虑变化前后强度场的相关度,得到关于强度场变化的三个基本方程,从而导出了激光散斑运动的一般公式。考虑了散斑场的变化是由漫射物面运动和变形以及激光光波长变化所引起。     

偏振旋转孔散斑照相法

文提出动态散斑技术中一种新的孔径:偏振旋转孔。在旋转孔径处适当布置偏振片能使衍射晕能量分布均匀,信息存储合理,散斑条纹清晰度提高。偏振转孔法能在一张散斑图上记录下全部动态过程,并连续地再现出来。本文介绍了偏振菱位孔,偏振平移孔,偏振四扇孔,论述了它们的全场分析和逐点分析功能,给出了理论分析和实验证明。     

Laser speckle movement caused by surface deformation and light wavelength change

When a surface is illuminated by laser, the field of diffusing reflective light can be described by Fresnel-Kirchhoff integration in the region of Fresnel. If the correlation, before and after the change of intensity field, is analysed by statistical method, three governing equations for variations of intensity field and speckle movement formulas can be obtained. In these equations, the surface motion, deformation and wavelength change are all considered to cause the speckle movement. The project supported by National Natural Science Foundation of China     

韧性金属裂纹尖端损伤区内应变场测量——数字散斑相关法应用

本文用数字散斑相关方法测量了五种不同幂硬化指数韧性金属材料(铝和铜),双边裂纹尖端细观区域内应变场.对所得结果用韧性损伤模型进行了分析.在此法中以金属自然表面结构为散斑场,不同加载状态的散斑场进行比较,得到相对变形与应变.图象之间相关性 C 是变形参数或是位移及其导数的泛函.使其相关性 C 取最大值的试凑变形即为其真实变形场.这一方法在细观测量中应用得到满意的结果.