FRC板力学性能分析和材性结构设计

本文采用预测FRC板的复合材料模型,从表面层到夹芯层进行力学性能分析,并根据工程使用的关键力学性能—抗弯强度进行材性结构设计。     

Variable amplitude fatigue of high-strength cast iron alloys for automotive applications

In the automotive sector, the cumulative damage calculation method generally applied is the Palmgren–Miner-Hypothesis with its modification according to Haibach (steeper slope of the SN-line after the knee-point) as a means of also including the damage by stress amplitudes below the knee-point. This approach results in the total damage sum of the spectrum D_spec. However, the resulting question is the value of the allowable damage sum D_al for the evaluation of D_spec ⩽ D_al. The only design code that considers the assessment of cast iron components under spectrum loading is the FKM-Guideline of the Cooperative Research Association for Mechanical Engineering (FKM, Frankfurt/Germany) for designing machine components. Here, the theoretical Palmgren–Miner-damage sum D_th = 1.0 is still suggested as the allowable damage sum D_al despite the fact that this damage sum renders unsafe calculated fatigue lives in about 90% of all published results.The results obtained with component-like notched specimens of modern high-strength cast iron alloys (R_m = 650–800 MPa) such as EN-GJS-500-7, SiboDur 700-10 and MADI (Machinable Austempered Ductile Iron), which were investigated under a standard Gaussian spectrum for chassis applications and also for a fuller injection pump spectrum, suggest the allowable damage sum D_al = 0.3 for fatigue life estimations of components manufactured with these materials can be proposed; i.e. the allowable fatigue life is about one third compared to calculations with the theoretical damage sum D_th = 1.0 that is still used.     

地下盐穴储气库盐岩热损伤机理

基于变质量热力学原理，建立盐穴储气库注采过程中的工程热力学分析数学模型，给出了单个注气和采气过程中温度和压力随时间变化的解析解，作为数值模拟的边界条件。根据金坛储气库的基本数据和盐岩实验研究参数，利用COMSOL Multiphysics有限元软件建立单腔盐穴注采过程的温度-应力耦合模型，模拟恒定注采速率下盐腔围岩的拉伸损伤、剪切损伤和膨胀损伤分布情况，研究夹层和热应力对围岩损伤的影响。基于热应力理论，结合模拟结果分析盐穴储气库注、采气过程中围岩的热损伤机理。模拟结果表明：在热应力存在的情况下，夹层的存在促进了围岩损伤的产生，无夹层时围岩无损伤发生，有夹层时围岩存在损伤；注气过程和采气过程的损伤发生位置存在差别：注气过程损伤多发生在夹层附近的盐岩中，采气过程损伤多发生在夹层中；膨胀损伤的范围最广，且损伤范围覆盖了前2种损伤，因此实际生产过程中推荐使用膨胀损伤判据，损伤评价结果更为保守。     

供热站主厂房工艺布置和结构分析

由于工艺布置和建筑造型的需要,供热站主厂房设计变得相当复杂与繁琐,文中通过工程实例对其进行分析,表明工艺之间相互配合、在充分利用平面和竖向空间基础上、能够达到工艺顺畅和结构抗震性能良好的统一。     

Identification and Avoidance of Systematic Measurement Errors in Lamb Wave Observation With One‐Dimensional Scanning Laser Vibrometry

Abstract: Scanning laser vibrometry is a widely used tool to observe Lamb wave fields for structural health monitoring (SHM) purposes. Lamb waves propagate over long distances in thin‐walled structures and interact with structural inhomogeneities, for example, damages, in spite of wavelengths several times of the damage size. In SHM of sheets and glass‐ or carbon‐fibre‐reinforced plastic plates, this effect is used for determining the position as well as the size of structural faults. With the often employed one‐dimensional vibrometry, a geometrically induced, systematic error occurs when measuring oblique‐angled motion. This error can be, in the specific case of Lamb waves, of a non‐negligible quantity. The nature of this geometrical measurement error in general and concerning Lamb waves in special is discussed analytically for both amplitude and phase data. It is shown that this matter should be taken into account in some applications.     

岭南大学近代教会建筑结构艺术

文章通过分析近代岭南大学核心校区最具代表性的一批教会建筑的建设背景，以及对结构材料及细部构造与建筑空间、立面形态的关系的深入研究，揭示蕴含于岭南大学近代教会建筑中精彩纷呈的结构艺术。指出中西合璧的结构艺术是近代优秀教会建筑文化遗产的重要组成部分。     

Innovative Work Behaviour: The Impact of Comprehensive HR System Perceptions and the Role of Work–Life Conflict

Human resource (HR) systems have the potential to both foster innovative work behaviour (IWB) and reduce work–life conflict (WLC)—enabling employees to engage in IWB. We investigate the proposed relationships between comprehensive HR systems, WLC and IWB using variance-based structural equation modelling. We found that HR systems that are perceived as comprehensive significantly enhance IWB and decrease feelings of WLC. Contrary to our expectation, we found a significant yet positive effect of WLC on IWB. Employees may respond to WLC constructively by being innovative, improving their environment and making the work–life interface manageable. By promoting IWB, HR systems might also help employees to deal with residual—and, perhaps, unavoidable—levels of WLC.     

The influence of low- and high-linear energy transfers on some physical properties of poly(methyl-methacrylate) samples

Clear poly(methyl-methacrylate)—PMMA—dosimeter is widely used in food irradiations. Positron annihilation lifetime spectroscopy (PALS) is one of the unique tools used for studying free-volumes and open-volume type defects in solid media. The Vicker's microhardness measurements offer a simple and nondestructive tool for investigating the mechanical behavior of polymer materials. PALS as well as microhardness measurements were carried out for PMMA samples, irradiated with low- and high-linear energy transfers (LET). The low-LET irradiations were provided at lethal doses of gamma radiations for vegetative bacteria. Such irradiations showed a chain scission in the PMMA samples. High-LET irradiations showed behavior different from the low-LET ones. The observed behavior depends on the alpha particle fluence. The microhardness testing was carried out for virgin and irradiated PMMA samples at high-LET. A negative correlation was found between PALS measurements and microhardness results. The optical characteristics and structural studies for the virgin and irradiated PMMA samples were in agreement with the PALS and microhardness measurements. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

复采工作面火灾事故案例分析与综合防治

以小煤矿严重破坏区复采综放工作面3起火灾事故为案例,分析火灾原因,提出了复采工作面穿越小煤矿破坏区特殊支护、消火道防灭火等防治小煤矿自然发火技术,结合工作面破坏区灌浆超前防治、局部均压、注氮等防灭火措施,有效地消除了火灾事故,确保工作面顺利回采。     

Long‐Term Structural Evolution of an Intercalated Layered Semiconductor

Intercalated molecules can dramatically modify the electronic band structure of layered semiconductors, significantly altering the optical properties of the material. In the layered monochalcogenide Gallium Telluride (GaTe), exposure to air induces a nearly 1 eV reduction of its band gap due to the interlayer diffusion and chemisorption of oxygen. The effect of oxygen chemisorption at the Te‐terminated surfaces on the structure of GaTe, however, is much less known. To better understand the structure–property relationship of intercalated GaTe, a systematic, long‐term, X‐ray diffraction study has been performed on GaTe exfoliated crystals exposed to ambient conditions. It is observed that the structural changes are not limited to a previously observed short‐term increase in lattice expansion. Over the course of months and even years after exfoliation, the oxygen adsorbates continue to modify the structure of GaTe, inducing significant disorder and grain reorientation. It is estimated that approximately one out of every two grains is slightly displaced by the intercalating oxygen, demonstrating a significant increase in grain mosaicity, while still maintaining the original {?2 0 1} out‐of‐plane texture. Correlating these structural transformations to observed changes in electrical and optical properties will enable capitalization of the use of adsorbates to engineer novel properties in these layered materials.