Review and propositions for the sliding/impact wear behavior in a contact interface

A thermal-solid-liquid complex operational environment induces structural interface developing a typical coupling sliding/impact wear behavior. It results in contact damage until systems fail, which may cause significant economic losses and catastrophic consequences. The key point of solving this problem is to reveal the coupling damage mechanism of the sliding/impact behavior in typical systems and life characterization under a complicate evolving environment. This has been a hot topic in the area of mechanical reliability. The main work in this paper can be concluded as follows. Firstly, the main industries in which the “sliding/impact behavior” takes place have been introduced. Then, existing studies on the wear mechanism and degree analysis are presented, which includes surface morphology analysis, wear debris analysis, and wear degree measurement. Meanwhile, existing problems in theoretical modeling and experiments in current research are summarized, so as to point out a bright direction for future research on wear prediction. They include interface contact modeling, mathematic coupling mechanism modeling, wear equation establishment, and wear life characterization, which can provide some new ideas for improving the existing studies on the sliding/impact wear behavior.     

现代激励理论在规范地方政府行为中的作用研究

分析现代激励理论在研究地方政府行为中的作用，并运用现代激励理论提出了规范地方政府经济行为的若干建议。     

CVD-Si3N4陶瓷及其复合材料氧化行为研究进展

概述了CVD—Si3N4陶瓷及其复合材料在干燥氧气下的氧化行为。Si3N4陶瓷在高温下氧化时，除生成SiO2保护膜外，还生成一薄层比SiO2膜更优异的氧气扩散阻挡层(Si—O—N化合物层)，该层具有优异的抗氧化性能。介绍了两种氧化机制模型，同时分析了温度、杂质等对CVD—Si3N4陶瓷氧化行为的影响。     

细长体分离起始点的实验研究

本文实验研究了细长体模型在中等迎角下的初始分离问题。观察了不同头部形状的细长体在不同迎角下的分离流态。考察并分析了分离起始点的性质。观察到开式分离的存在,实验结果分析认为开式分离可以起始于正常点。此外,在钝头和尖头模型上都出现了螺旋点形式的头部涡。它们或是闭式分离的起始点,或是奇点型开式分离的起始点。     

单向玻璃纤维增强环氧树脂低温冲击拉伸性能的试验研究

 在经改进后配有低温装置的杆-杆型冲击拉伸装置上,对单向玻璃纤维增强环氧树脂在室温、-50℃、-100℃和-150℃的冲击性能进行了研究。结果表明该材料有温度相关性,所研制的装置性能良好,便于应用。     

GH4169高温合金惯性摩擦焊接头动态再结晶过程

当温度、应变、应变速率达到一定条件时 ,GH4 16 9镍基高温合金在惯性摩擦焊接过程中易发生动态再结晶。本文研究结果表明 ,由于GH4 16 9合金惯性摩擦焊接时间很短 ,动态再结晶进行得相当充分 ,而动态回复不足 ,在动态再结晶的过程中还可以看到有些结晶过程还处于形核阶段 ,这是惯性摩擦焊接头产生细晶乃至超细晶的根本原因     

Effect of curing condition on bonding quality of scarf-repaired composite laminates

Both single-face vacuum bag curing (SVC) and double-face vacuum bag curing (DVC) can be used in scarf repair of composite structures. But different curing conditions caused by the sealing state may affect the bonding quality of scarf-repaired structures. In this paper, the effect of curing condition on bonding quality of scarf-repaired laminates was experimentally investigated in terms of surface profiles, moisture absorption curves and section profiles. In order to further explore the moisture absorption mechanism, finite element model of the repaired laminates using DVC was established with moisture diffusion of both the adhesive and composite laminates considered. This model was verified by experimental results. Based on the model of DVC case, the model of SVC case was built by changing moisture absorption parameters of the adhesive. Results show that SVC reduces the bonding quality, mainly reflecting in more adhesive inner voids and patch-to-parent dislocation. And SVC increases moisture absorption rate and moisture equilibrium content of the adhesive, and its effect on the former is far greater than that on the latter.     

Micro-mechanical model for predicting the elasto-plastic behavior of composites based on secant formulation method

To predict the Elasto-Plastic Behaviors (EPBs) of aligned inclusions reinforced composites, this paper develops an interpolative Mori-Tanaka/Double-Inclusion (MT-DI) homogenization model with the secant formulation, and gives the numerical implementation algorithms of the developed MT-DI model with the secant formulation. The Finite Element (FE) homogenization method is implemented to provide the “exact” EPBs of the composites and thus validate the MT-DI model with the secant formulation. The MT-DI model with the 2nd-order secant formulation is validated to provide the more accurate predictions, while the MT-DI model with the 1st-order secant formulation always gives the stiffer predictions. The results show that using the macro-stress and macro-strain as the inputs, the MT-DI model with the secant formulation gives the identical predictions. The predictions of the MT-DI model with the secant formulation vary between those of the MT and DI models with the secant formulation. Meanwhile, the MT-DI model with the secant formulation does not predict the accurate EPBs for the phases of the composites.     

背包旅游者与旅游目的地的互动行为研究

随着社会经济的发展,互联网时代的到来,背包旅游市场进一步扩大,背包旅游者与旅游目的地之间的联系进一步加强。通过分析背包旅游旅游者与旅游目的地之间的互动行为,分析旅游者行为特点,并指出其中出现的问题,提出针对性的建议,旨在为背包旅游的发展提供参考。     

二维三轴编织复合材料压缩失效行为的细观有限元模拟

为研究典型二维三轴编织复合材料（2DTBC）的压缩破坏机理,建立了细观有限元模拟方法体系。提出了反映编织复合材料真实几何特性的单胞模型建模策略,根据Murakami-Ohno损伤理论建立了各向异性损伤模型来模拟纤维束中的损伤起始和扩展行为,通过引入波动系数描述了纤维束的起伏状态,并采用内聚力单元来模拟界面分层。在此基础上,分析得到了二维三轴编织复合材料在压缩载荷下的破坏过程,研究了压缩载荷下纤维束和界面层的损伤演化,探讨了纤维束波动对压缩性能的影响规律。通过与相关试验结果对比,该模型能够准确预测二维三轴编织复合材料在面内压缩载荷下的力学响应和主要失效行为,以及自由边效应。细观失效过程分析结果表明,二维三轴编织复合材料轴向压缩的破坏是由轴向纤维束的纤维压缩失效主导的;横向压缩破坏则是由偏轴纤维束的纤维压缩失效引起的。