跨座式空中轨道系统杆件制造工艺研究

介绍了跨座式轨道交通的特点及轨道梁、支座、立柱等典型构件,着重阐述了这些典型构件的制作工艺、焊接变形控制及质量控制技术,为后续类似工程的设计和施工提供了参考。     

超高强度马氏体时效钢的研究与应用

介绍马氏体时效钢的种类,分析其强韧化机理,论述了典型的18Ni马氏体时效钢和无钴马氏体时效钢的化学成分和力学特性。系统阐述了循环相变热处理、形变热处理及等径弯曲通道变形(ECAP)这3种目前常用的细晶强化方法,并提出了马氏体时效钢的发展趋势及进一步深入研究强韧性和细晶强化的途径。     

多点输入对大跨空间结构影响初探

在对大跨度结构进行抗震设计时，需要考虑多点地震输入的影响。在地震波的作用下，加速度会对结构产生惯性力。我们研究的重点是多点输入的影响因素及影响大小。     

Effect of thermal stresses on the microstructure of the continuous cooling TiAl alloys

A series of continuous cooling tests were performed on TiAl alloys using a Gleeble3500 machine to investigate the effect of thermal stresses on the microstructure. The results show that macroscopic thermal stresses promote correlated nucleation of γ lamellae. The trend of the dominance of one twin-group γ variants in local regions is weakened, and the γ/γ interfaces tend to be true twin and pseudotwin boundaries rather than 120° rotational faults under macroscopic thermal stresses. Meanwhile, thermal-induced deformation generated under the effect of both microscopic and macroscopic thermal stresses results in numerous low angle grain boundaries (LAGBs) and dislocations. The LAGBs and dislocations distribute heterogeneously among lamellar colonies and phases. No mechanical twins are observed due to the low strain and low strain rate characteristics of the thermal-induced deformation. These findings could shed light on understanding and preventing the cracking of TiAl components during cooling process.     

拉链式路桥变形缝装置施工技术

简要介绍了拉链式路桥变形缝装置工艺原理及特点,详细总结了拉链式路桥变形缝装置各个施工环节的关键技术及操作要点,指出拉链式路桥变形缝装置施工技术简化了施工步骤,降低了使用成本,具有广阔的应用前景。     

30 m超高加筋土挡墙在宁化行洛坑钨矿的应用

论述了超高加筋土挡墙的设计过程与建造及挡墙的变形特征。较大墙高宜采用加筋土挡墙，其对地基的适应性强，占地少，建造周期短。行洛坑钨矿原矿运输铁路跨越深沟谷，与栈桥相比较后，采用了加筋土挡墙方案，设计建造了二级30 m超高加筋土挡墙作为路基，1 a累计最大水平位移16～83 mm，最大沉降24～115 mm，建成5 a来运行正常。     

Displacement bound of beam‐column with time‐dependent boundary constraints

Abstract

A simplified explicit formula for the displacement bounds of the beam‐column subjected to time‐dependent boundary constraints is proposed. The formula is derived by means of removing time dependence from the boundary conditions. The proposed bounds provide a quick estimation of the displacements for problems with complex loading conditions.     

Gaining knowledge on the processability of PLA-based short-fibre compounds – A comprehensive comparison with their PP counterparts

The present study provides a quantitative overview of bio-based compound processing compared to commonly used composites reinforced with short glass fibres (GF). Three reinforcing fibres were compounded with polylactide and polypropylene: abaca, man-made cellulose and conventional E-GF. The flow behaviour of corresponding melts was determined using melt flow rate (MFR) and online flow spiral test. The composite structures were analysed by means of SEM in order to investigate the fibre fracture during processing and the fibre/matrix bonding affinity. The fibre length distribution was correlated with the results from the melt flow experiments, and the structure–property relationships were determined using SEM images. It was confirmed that the fibre texture, interactions between fibres and fibre–matrix bonding are influenced by subsequent processing steps and have a substantial effect on the further composite melt processing.     

节理峰前剪切刚度软化模型及其影响因素分析

节理峰前剪切应力-位移曲线是研究节理剪切行为的重要内容。然而目前对于节理峰前剪切行为大多以线性描述,不能较好的描述非线性的特点。对于非线性的描述也仅仅是唯象描述剪切应力-位移曲线,未能反映影响模型的参数物理意义及影响因素。以峰前节理刚度软化行为为出发点,采用归一化的思想将节理剪切刚度与位移无量纲化,用双曲线函数表示出剪切刚度与位移之间的关系。提出了考虑刚度软化的峰前剪切本构关系,通过与试验结果对比验证了本构关系的合理性。影响该模型最重要的两个因素是初始剪切刚度与峰值剪切位移。以Greenwood和Williamson模型为基础在细观上探讨了初始剪切刚度的影响因素;抓住法向应力与节理粗糙度主要因素,探讨了影响峰值剪切位移的影响因素。对模型参数的研究有助于进一步阐明节理峰前剪切机理。