板状Fe-基大块非晶合金的制备及其断裂韧性测定

采用电弧熔炼母合金、普通铜模吸铸工艺 ,制备出尺寸规格为 2 0mm× 10mm× 1mm的板状Fe -Co -Zr -Mo -W -B系Fe -基大块非晶合金。经DTA检测 ,所制备的Fe -基非晶合金具有明显的玻璃转变温度和较宽的过冷液相区 (Tg=884K ,ΔTx≥ 6 0K)。采用压痕试验法测定了该板状Fe -基大块非晶合金的断裂韧性 ,其铸态断裂韧性在 1.6MPa·m1/ 2 量级。     

水在渠道防渗工程冻害中的作用及防治冻害对策

我国东北、华北、西北等寒冷地区的渠道防渗工程，因多为薄板式结构，裸露面很大，同时经常与水接触，甚至在冬季负温下仍要输水运用，故其冻胀破坏更为严重，影响了工程效益的充分发挥。本文在简述水在渠道防渗工程冻害中的作用后，从渠道防渗工程的设计、施工和管理运用方面，提出了保证防渗层工程质量、降低基上水分、防止外水渗（流）入渠基、降低地下水位和管理运用等防治冻害较为具体的对策。     

Adhesion strength of leadframe/EMC interfaces

Cu-based leadframe sheets were oxidized in alkaline solutions to produce brown and/or black oxide on the surfaces, and molded with epoxy molding compound (EMC). The adhesion strength of leadframe/EMC interface was measured using sandwiched double-cantilever beam (SDCB) specimens and pull-out specimens. Results showed that the adhesion strength of leadframe/EMC interface was inherently very poor but could be increased drastically with the nucleation of acicular CuO precipitates. The presence of smooth-faceted Cu₂O on the surface of the leadframe gave close to zero fracture toughness (G_C) and suitable pull strength (PS). A direct correlation between G_C and PS showed that PS can be a measure of G_C only in a limited range.     

火控系统中惯性技术的应用

对武器中火控系统应用惯性技术的原因、特点进行了简要的介绍,并对火控系统中的基准设备的配置方案进行了简单的介绍。     

AGM隔膜对VRLA电池性能的影响

介绍了超细玻璃纤维隔膜（AGM）的基本性能以及不同厂家AGM隔膜在相同的极板和装配压力等情况下对所装配电池初期容量、电解液分层情况、密封反应效率、电池循环寿命等的影响。     

基于初始载波频移的孤子互作用抑制方法

介绍了一种基于孤子初始载波频移抑制孤子相互作用的方法.通过分析,发现孤子串最外层的两个孤子受相互作用影响最大,提出将孤子串中最外层的两个孤子进行初始的频率移动,较好地抑制了孤子相互作用.分析了频移量对传输距离的影响,结果表明对于具体的系统,存在最佳频移量.     

Using a strain based failure assessment diagram for creep–brittle materials

Recently, there has been considerable interest in studying creep crack growth in creep–brittle materials. For example, the methodologies for assessing creep ductile materials, using fracture mechanics parameters like C^* and C_t, have been extended to include creep–brittle materials [1]. This paper begins by examining these recent developments and outlines the difficulties in adopting these developments. An alternative approach is then proposed. This new approach leads from recent work proposed by the authors [2], where a strain based failure assessment diagram (SB-FAD) is used. Experimental results from a series of tests on a simulated heat affected zone of a low alloy steel are explored. The application of the methodology for assessing the initiation and growth of a defect in a creep–brittle material is also demonstrated.     

Acoustic Harmonic Generation Due to Thermal Embrittlement of Inconel 718

This paper describes an attempt to characterize the deterioration of a structural material's mechanical properties by nonlinear acoustics. In this particular case, the damage was caused by “thermal embrittlement” during which the material, here the nickel-based alloy Inconel 718, loses a significant fraction of its fracture toughness. Harmonic generation was the experimental method used to characterize the microstructural changes in the material as a function of exposure time at elevated temperatures. Tests were performed on two heats of Inconel 718 with slightly different chemistries, with one heat showing particular sensitivity of the fracture toughness to the elevated temperature exposure with corresponding higher changes in the nonlinearity parameter. As a mechanical measure of the fracture toughness deterioration, a small specimen punch test was used in which the ductility of a thin slice of material is determined. A clear difference between the two heats was noted in the metallographic examination, which is reflected in the harmonic generation as well as the punch test data. An explanation for the changes of the harmonic generation during the embrittlement process is speculative at the present time.     

压榨毛毯与造纸机的高效运行

分析压榨毛毯对造纸机运行效率的影响。在生产上,要保证纸机高效运行,应选择合适的压榨毛毯、快捷更换新毛毯、缩短毛毯初期适应期并加强毛毯的维护。     

Analysis of warp-knitted fabric structure. Part II: theoretical study on initial modulus of warp-knitted fabrics (tricot,locknit, and satin)

In the first part of this series, a 3D straight line model was presented for the geometry of two-guide-bar warp-knitted fabrics. In this part, first, the variation of unit cell geometry under uniaxial tension in the range of elastic deformation is investigated. In the present study, the energy method and Castiglianos's theorem were used to derive the fabric's initial modulus. Energy terms which are considered in this study are extension, bending, and compression energies. Also, the friction phenomenon is taken into account by using frictional energy term. For this purpose, the loop of each bar is divided into eight elements. Free-body diagrams of elements are drawn to show the relative magnitude and direction of all forces acting upon an object in a given situation. After obtaining the force details, strain energy of each element is calculated. Finally, the initial modulus of warp-knitted fabrics is obtained. To verify the model, samples of tricot fabrics were produced and tested. Results showed that the generated model can predict precisely the initial modulus of aforementioned warp-knitted structures.