全胶材料铅酸蓄电池的工业需求及设计

围绕电动自行车全胶材料铅酸蓄电池的工业需求及设计研发,从电池内部结构设计、生极板预处理工艺、胶体配方等多个方面进行了深入地研究,得到了大量可靠的实验结果.实验结果表明:全胶材料铅酸蓄电池可以满足电动自行车的工业需求,能够很好地解决电动自行车电池目前存在的问题,有效提高其使用性能.     

高频电磁涡流检测系统及实验研究

针对碳纤维复合材料电磁涡流检测的特点,自主设计研制了一套高频电磁涡流检测系统,其最高检测频率可以达到10 MHz以上。该系统下位机以高速ARM微控制器STM32F407VGT6芯片为控制核心,上位机以虚拟仪器软件LabVIEW设计用户界面。系统集成了信号发生模块、功率放大模块、可调增益放大模块、锁相放大模块、USB模块以及数据采集模块,集成度高、体积小、使用简单方便。利用制作的高频电磁涡流检测系统对碳纤维复合材料的常见损伤形式进行了检测,包括冲击以及分层等,证明了系统的可行性以及实用性。     

The origin of interfacial delamination in Au/ceramic cofired LTCC structure

The interfacial delamination of electrode/ceramic multilayer structure will seriously damage the reliability of low temperature co-fired ceramic (LTCC) module in practical applications. In this work, three kinds of glasses employed in Au electrode are designed and prepared to study the abnormal expansion and delamination process in the Au/ceramic LTCC multilayer structure. The interfacial delamination in the co-fired structure is found to be attributed to the abnormal expansion of glass in respect to Au electrode at high temperature, which is originated from the enlarged closed pores during the co-firing process. This conclusion is further confirmed by co-firing the sample in a low-pressure condition. The mechanism and elimination of interfacial delamination here provides a feasible solution for the design of novel glasses in Au electrode for LTCC applications.     

Static strength and fatigue life of optimized hybrid single lap aluminum–CFRP structural joints

Hybrid bolted/bonded joints are used to assemble structural components, commonly made by carbon fiber reinforced plastics (CFRP), with aluminum frames. Hence, they have become common solutions in a number of modern structural applications in the industrial fields, as well as civil constructions. Unfortunately, due to the lack of understanding of the relationships between the multiple parameters of influence that characterize their mechanical performance, only limited improvement have been achieved so far over classical bonding approaches, in terms of static and fatigue strength. As a result, further studies are needed in order to better exploit the potential of hybrid bolted/bonded joints and identify optimum joint configurations. This paper describes an optimization procedure of the joints, achieved through a systematic experimental analysis of hybrid single lap aluminum–CFRP structural joints. This, analyzing the effect of overlap length, stiffness imbalance, adhesive curing as well as of size, positioning and preload of the bolt, results in a significant rise of the strength, especially in presence of high cycles fatigue loading. Also, micrographic analysis and related numerical simulations have allowed to gain a better insight into the damage mechanisms occurring during the in-service tensile loading, corroborating the highest mechanical performance of the angle-ply lay-up proposed for the CFRP adherent.     

A fracture analysis of cathodic delamination at polyurea/steel interfaces

A fracture mechanics approach to accelerated life testing of cathodic delamination between steel and polyurea is presented. This required the hyperelastic behavior of the polyurea to be described by the Marlow model based on uniaxial tension and plane strain compression tests. Time-dependence was also considered but could be neglected if proper test protocols were followed in cathodic delamination tests using a strip blister specimen. The variation of J-integral with specimen geometry and loading parameter was obtained, which allowed the resistance to cathodic delamination to be expressed in terms the J-integral and the crack speeds obtained from the tests at several temperatures. The approach established that both temperature and stress can be used to accelerate the cathodic delamination, thereby providing a quantitative and rational basis for conducting accelerated testing. In addition, the discriminating nature of the approach for design purposes was exemplified by quantitatively establishing differences in the delamination resistance of three surface treatments.     

基于动力有限元分析和神经网络技术的含分层复合材料层合板的损伤诊断

本文基于作者提出的含层间分层损伤层合板的动力有限元分析模型和方法,计算了分层长度和位置对含层间分层损伤层合板结构的固有频率的影响,然后应用MATLAB的神经网络工具箱建立了人工神经网络,通过典型结构的仿真结果比较,证明了采用有限元动力分析和BP网络技术相结合的方法是一种可用于复合材料层合板的分层损伤诊断的有效方法.     

Influence of Matrix Ductility and Fibre Architecture on the Repeated Impact Response of Glass-Fibre-Reinforced Laminated Composites

This paper describes the results of falling weight impact tests on glass-fibre-reinforced laminates. The test program consisted of (i) falling weight impact tests for the determination of the penetration energy and the influence of laminate construction on damage development and (ii) repeated falling weight impact tests for the determination of the impact fatigue lifetime and damage development under repeated impact conditions at sub-penetration energy levels. The objective of this work is to compare the impact behaviour of cross-ply laminates based on a brittle unsaturated polyester resin and a more ductile vinyl ester resin system and two types of glass reinforcement, i.e. woven- and multiaxial non-crimp fabric. The penetration energy of the various composite laminates appeared to be mainly influenced by the type of reinforcement, whereas damage development during (repeated) impact is strongly influenced by both fibre architecture and resin. No significant effect of the different material parameters investigated on the number of impacts to penetration (impact fatigue lifetime) is observed. Especially when the repeated impact energy is normalised with respect to the penetration energy, all laminates showed similar behaviour.     

浅议半孤岛工作面掘进期的矿压监测与分析

济二煤矿43下04(北)工作面为一典型的半孤岛工作面,通过对该工作面特点的分析,制定了以顶板离层监测为主,支护质量监测与围岩表面位移监测为辅的监测方案,确定了离层变化较大的地段,提出了加强支护的措施,为今后工作面回采提供了必需的参考资料,对类似工作面的矿压观测积累了经验.     

Stress analysis of plastic IC package containing various interface delaminations using the boundary element method

The purpose of this paper is to carry out stress calculation of the integrated circuit (IC) plastic package under the remote loading or the pressure acting on the delamination surfaces by the boundary element method (BEM). Based on symmetrical property of the problem geometry and the loading, the corresponding fundamental solution can be obtained to further reduce the number of the boundary elements used in the discretization of the problems. Near the interface delamination tips, singular boundary elements are used to accurately obtain the stress intensity factors. For the pre-assumed delamination spaces, the corresponding stress distributions in each domain can be obtained so that the effect of the interface delamination on the stresses can be observed. In order to assure the rightness of the developed code, some special problems in which the analytical solutions are available are studied. The results show that the developed code can produce numerical results with high accuracy.     

Delamination dynamics in through-thickness reinforced laminates with application to DCB specimen

Bridged crack models using beam theory formulations have proved to be effective in modeling quasi-static delamination crack growth under large scale bridging conditions in through-thickness reinforced structures. In this paper, beam theory is used to study dynamic mode I crack propagation in through-thickness reinforced laminar structures. In particular, steady state dynamic crack growth for a Double Cantilever Beam (DCB) loaded with a flying wedge is examined. The steady state crack propagation characteristics are mapped out in terms of controllable loading and material parameters including the crack velocity and the properties of the through-thickness reinforcement. For small crack velocities, the through-thickness reinforcement considerably enhances the delamination resistance of the structure. At higher velocities, the kinetic energy term dominates the overall energetics and the relative effect of the reinforcement on the delamination resistance is insignificant. The model suggests a simple fracture test for estimating the properties of the through-thickness reinforcement under dynamic loading conditions.