基于Autodyn数值模拟的卡钻处理技术研究

为了解决卡钻实际操作存在的问题，采用了理论分析与数值模拟相结合的方法。通过理论分析，以应力波原理为基础，研究了选择装药的形状以及装药的半径；采用Autodyn软件进行数值模拟。研究得出:选择半径60 mm、高150 cm的炸药，在距离钻头100 cm处安放，可以在钻机薄弱位置形成应力集中，进而使钻头与加重杆有效分离；选择合理安排药包药量和安装位置，产生冲击加载，可以在钻具薄弱部位形成应力集中，实现准确断裂。     

Fabrication and machining of ceramic composites — A review on current scenario

Ceramic matrix composites (CMCs) are the best-suited material for various engineering application due to their superior properties. The different processing methods involved in the fabrication and machining of these CMCs are a center for attraction to researchers and industrial society. This review article primarily focuses on the development of different processing methods and machining methods for ceramic matrix composites since the last few years. Out of these fabrication methods, powder metallurgy emerged as a most promising and cost-effective technique. In addition, electric discharge machining (EDM) has proved to be time saving, cost effective, and capable of machining complex shapes in composites. At the end, challenges in the processing and machining of ceramic matrix composites have been identified from the literature, and further benefits of microwave sintering and electric discharge machining of materials have been addressed in the paper.     

Analysis for vertical velocity of seismic waves

Abstract

Presented here are the results of seismic wave velocities analyzed using the acceleration time‐histories recorded at the downhole strong motion array of the Lotung large scale seismic test site during the May 20, 1986 Hualien earthquake. The spectral ratios between the surface and downhole accelerograms were used to identify the frequencies of maximum amplification of soil layers, and an elastic 1‐D wave propagation model was proposed to estimate the wave velocities of the ground during the earthquake. The results obtained indicate that significant reduction of shear wave velocity as well as soil modulus was induced by earthquake excitation as compared to the values obtained from low strain level soil testings.     

Wells turbine for wave energy conversion: a review

In the past 20 years, the use of wave energy systems has significantly increased, generally depending on the oscillating water column concept. Wells turbine is one of the most efficient oscillating water column technologies. This article provides an updated and a comprehensive account of the state‐of‐the‐art research on Wells turbine. Hence, it draws a roadmap for the contemporary challenges, which may hinder future reliance on such systems in the renewable energy sector. In particular, the article is concerned with the research directions and methodologies, which aim at enhancing the performance and efficiency of Wells turbine. The article also provides a thorough discussion of the use of CFD for performance modeling and design optimization of Wells turbine. It is found that a numerical model using the CFD code can be employed successfully to calculate the performance characteristics of W‐T as well as other experimental and analytical methods. The increase of research papers about CFD, especially in the last 5 years, indicates that there is a trend that considerably depends on the CFD method. Copyright © 2016 John Wiley & Sons, Ltd.     

海管测漏技术在海洋平台的应用

总结管道泄漏监测和定位方法的工作原理及其优缺点。给出适用于海洋平台的测漏方法,同时列出测漏系统的关键技术参数,并重点分析负压波法和音波法方案比选结果及其在海洋平台的应用案例。     

Principle and application of ball SAW devices

A thin beam of waves usually diverges due to diffraction, which is a limitation of any device using such waves. However, a surface acoustic wave (SAW) on a sphere with an appropriate aperture does not diverge but is collimated, realizing ultra‐multiple roundtrips along an equator of the sphere. This effect is caused by the balance between diffraction and focusing on a spherical surface, and it enables realization of high‐performance ball SAW sensors. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 168(1): 41–51, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20817     

纳米吸波材料在人体防护中的现状及发展方向

电磁辐射对人类健康及其生活环境造成极大威胁 ,回顾了人体防护服的发展 ,就纳米吸波材料的吸波机理、与纤维或织物的结合等进行探讨 ,并对其发展前景给出了一些设想     

轴向超声振动辅助铣削TiB2/7050Al复合材料残余应力试验研究

针对TiB2颗粒增强铝基复合材料可加工性差、切削温度高、刀具磨损严重等问题,开展TiB2/7050Al复合材料轴向超声振动辅助铣削残余应力试验,研究各加工参数对超声振动辅助铣削表面及亚表层残余应力的影响规律,并分析力热耦合作用对超声振动辅助铣削残余应力的作用机制。研究表明:TiB2/7050Al复合材料超声振动辅助铣削表面残余应力均为残余压应力,且残余压应力随每齿进给量、切削速度的增加而减小,而随着切削深度及超声频率的增加呈现先增大后减小的趋势;工件亚表层残余应力影响层厚度为90~120μm,且未观测到明显的加工硬化现象。     

Effect of ultrasonic field treatment on degassing of 2024 alloy

The 2024 aluminum alloy was prepared with different ultrasonic processes. Effects of ultrasonic treatment parameters including ultrasonic power, treatment time, treatment temperature, and frequency resonance, as well as C₂Cl₆ degasser on degassing of the 2024 aluminum alloy were investigated. Results indicate that increasing ultrasonic power at the same ultrasonic treatment time can improve the degassing effect. The optimum degassing efficiency can be obtained under the resonant ultrasound condition. With the combination of 1% C₂Cl₆ addition and 150 W ultrasonic treatment for 40 s, the hydrogen content of the alloy is decreased by 52.9%. At the same time, the tensile strength and elongation are increased by 28.3% and 92.3%, respectively, and the yield strength is slightly increased by 6.7%. The degassing mechanism is also discussed.

     

提高50Mn-C材质船用锻件质量的措施

本文主要介绍了50Mn-C材质船用锻件在生产过程中,有效控制了锻件草状波、性能不合格等问题的发生,提高了锻件一次探伤及性能的合格率。