A direct estimate of JIc from the load versus load-line displacement record

The purpose of this study is to examine the current standard fracture toughness test procedure to determine if there could be an easier method to get a J_Ic value from the test record. The current method for determining J_Ic involves a detailed computational and construction procedure. The objective in this study is to simplify the analysis for the determination of J_Ic. The results of this study show that the load and displacement record for a fracture toughness test can be used to directly estimate a J_Q value, a provisional value for fracture toughness, J_Ic. The J value taken at the maximum load point can be used along with an adjustment factor to estimate a J_Q value. This J_Q estimate is close to the one obtained from the construction procedure of ASTM Standard E 1820. When a unit‐sized specimen is tested, that is, a specimen with a width of 50 mm and a thickness of 25 mm the maximum load point provides a direct estimate of J_Q. Other sizes require a size adjustment factor, which is simply a square root relationship between the width of the test specimen and a unit width. The proposed new method of estimating J_Q is simple in concept and requires a minimum number of calculations. It appears to produce values of J_Q which are comparable to those obtained from the ASTM E1820 construction procedure and may produce less scatter.     

Effect of strain waveform on creep-fatigue life for Sn–8Zn–3Bi solder

This paper describes the creep‐fatigue life of Sn–8Zn–3Bi under push–pull loading. Creep‐fatigue tests were carried out using Sn–8Zn–3Bi specimens in fast–fast, fast–slow, slow–fast, slow–slow and hold–time strain waveforms. Creep‐fatigue lives in the slow–slow and hold‐time waveforms showed a small reduction from the fast–fast lives but those in the slow–fast and fast–slow waveforms showed a significant reduction from the fast–fast lives. Conventional creep‐fatigue life prediction methods were applied to the experimental data and the applicability of the methods was discussed. Creep‐fatigue characteristics of Sn–8Zn–3Bi were compared with those of Sn–3.5Ag and Sn–37Pb.     

An approach to efficient business intelligent system for financial prediction

A concept of business intelligent system for financial prediction is considered in this paper. It provides data needed for fast, precise and good business decision support to all levels of management. The aim of the project is the development of a new online analytical processing oriented on case-based reasoning (CBR) where a previous experience for every new problem is taken into account. Methodological aspects have been tested in practice as a part of the management information system development project of “Novi Sad Fair”. A case study of an improved application of CBR in prediction of future payments is discussed in the paper. This paper is originally presented at The International Conference on Hybrid Information Technology 2006, at the special session on “Intelligent Information Systems for Financial Engineering”, November 2006 in Cheju Island, Korea.     

泡沫酸化工艺对川中低压裂缝性油藏适应性的认识

针对川中油田经过多年的消耗式开采,各主产油田压力很低,增产改造的难度增大的发展现状,提出应用泡沫酸化工艺技术在川中低压油层增产改造的技术方案,其中分析了泡沫酸的物理特性、其在地层优良的渗流特性(滤失小、酸岩反应速度慢、返排迅速等优点),并进行了泡沫酸液体系的室内配方研究,提出了工艺设施的矿场配套研究内容.得出了泡沫酸化工艺对川中低压裂缝性油藏改造具有很强的适应性,具有推广应用的价值.     

朝阳沟裂缝性低渗透油田井网适应性研究

通过对比分析朝阳沟裂缝性低渗透油藏与裂缝主方向分别成11.5°和22.5°的两种不同井网的开发效果,表明与裂缝成11.5°的井网与裂缝匹配性较差,开发效果相对较差。并从油藏的水驱控制程度、压力传导情况、采收率及经济效益等方面研究评价了朝1.55区井网的适应性,为指导油田的加密调整,在技术和经济两方面综合评价确定了合理的井距和井网密度,并针对朝1-55区的地质特征,提出了井网和注水方式调整办法,在朝55区块实施后,取得了较好的现场试验效果。     

连轧机用人字轮齿轴断裂失效分析

用宏观断口分析、化学检验、力学性能测定、低倍检查、金相组织及夹杂物评定鉴别、受力分析及强度寿命定量估算的方法，对人字轮被动齿轴端断裂失效原因进行分析，并提出改进措施。     

65MnTi盘条拉拔过程中出现断裂的原因分析

分析检验拉拔过程中发生断裂的65MnTi盘条的金相组织和断口形貌，得出结论；65MnTi金条发生断裂的原因是热轧后冷却速度过快，金相组织中出现了低温转变组织──马氏体组织；而理想的组织应为京氏体；并且最佳冷却速度为5℃／s左右。     

Experimental and numerical investigation of fracture in double-edge notched steel plates

Double-edge notched (DENT) steel plates were pulled until complete fracture and several experimental observations were made (using profilometry and scanning electron microscopy). The essential work of fracture (EWF) model was found to be well verified. Numerical simulations—up to the maximum load only—of some experiments were performed using the finite element method (FEM), and incorporating geometric and material non-linearities (large deformation elasto-plasticity). Some experimental measurements were compared with the corresponding numerical computations and excellent agreement was found.     

THE FRACTURE MECHANISM OF 475°C EMBRITTLEMENT IN A DUPLEX STAINLESS STEEL

The mechanism of “475°C embrittlement” of a duplex stainless steel was investigated using finite element modelling of the stress distribution at brittle fracture initiation. Brittle fracture initiated at a critical shear stress, which increased with ferrite hardness. The fracture stress was affected by the duplex microstructure. Fracture was nucleated by deformation twins, which were identified using electron back-scatter diffraction. The ductile-to-brittle fracture transition was sensitive to age-hardening and could be described simply by the effect of age-hardening and test temperature on the yield stress.     

快速二阶BP网络及其在城市用水量预测中的应用

针对BP网络收敛速度慢，易导致局部极小值的缺点，提出一种快速二阶BP网络，并以城市年用水量预测为例，与BP网络对比，结果表明，该方法加快了收敛速度，提出了结果的准确度。