陶瓷垫片在大功率电源产品中的应用

陶瓷垫片是一种高导热性能的导热材料,主要崩于功率器件、散热器之间的传热和电气隔离。文中分析了陶瓷垫片的性能特点,并对它在电源产品应用中的安规,工艺、结构等设计进行了探讨,最后给出了它在电子负载上的应用。     

Constitutive modeling of reinforced concrete and prestressed concrete structures strengthened by fiber-reinforced plastics

A batch of constitutive models for steel reinforcing bar, prestressing tendon, concrete and fiber-reinforced plastic are proposed for the nonlinear finite element analysis of reinforced concrete structures, prestressed concrete structures, reinforced concrete structures strengthened by fiber-reinforced plastics and prestressed concrete structures strengthened by fiber-reinforced plastics. These material models have been tested against series of experimental data and good agreements have been obtained, which justifies the validity and the usefulness of the proposed nonlinear constitutive models.     

Modelling the response of reinforced concrete panels under blast loading

A finite element model is developed for the simulation of the structural response of steel-reinforced concrete panels to blast loading using LS-DYNA. The effect of element size on the dynamic material model of concrete is investigated and strain-rate effects on concrete in tension and compression are accounted for separately in the model. The model is validated by comparing the computed results with experimental data from the literature. In addition, a parametric study is carried out to investigate the effects of charge weight, standoff distance, panel thickness and reinforcement ratio on the blast resistance of reinforced concrete panels.     

Effects of sustained axial load and cooling phase on post-fire behaviour of reinforced concrete stub columns

In this paper is presented an experimental investigation of the effects of preload and cooling phase on the residual strength, stiffness and ductility of reinforced concrete stub columns which were heated and cooled down to room temperature under sustained axial load. Reinforced concrete stub columns were axially loaded and heated to designed temperatures in a specially built electrical furnace. After the specimens cooled down to ambient temperature with the axial loads kept constant, the stub columns were loaded to failure. The sustained preload led to significant residual deformations of reinforced concrete stub columns during the cooling phase. The test results showed that the mechanical behaviour of the fire-damaged reinforced concrete stub columns with preload was remarkably different from those without preload. The sustained axial loads resulted in obviously increased strength and stiffness during the loading phase, but reduced stiffness and deteriorated ductility in the unloading phase. Based on the test results, it is recommended that the effects of sustained axial loads during the fire and cooling phase should be taken into consideration in assessing the fire-damaged reinforced concrete columns.     

Effect of infiltration on the performance of an unsaturated geotextile-reinforced soil wall

A full-scale geotextile-reinforced soil wall was built in order to assess the characteristics of water infiltration and its effect on the structure performance. Nonwoven geotextiles were selected as inclusions in order to provide not only reinforcement, but also internal drainage to the fine-grained soil used as backfill material. The structure was built in a laboratory setting, which facilitated implementation of a thorough instrumentation plan to measure volumetric water content changes of soil, suction, facing displacements and reinforcement strains. An irrigation system was used to simulate controlled rainfall events. The monitoring program allowed the evaluation of the advancement of infiltration and internal geosynthetic drainage. Evaluation of the effect of the hydraulic response on the overall performance of the structure included assessment of the development of capillary breaks at soil-geotextiles interfaces. Capillary breaks resulted in water storage above the geotextile reinforcements and led to retardation of the infiltration front in comparison to the infiltration that would occur without the presence of permeable reinforcements. After breakthrough, water was also found to migrate along the geotextiles, suggesting that the reinforcement layers ultimately provided in-plane drainage capacity. While generation of positive pore water pressures was not evidenced during the tests, the advancing infiltration front was found to affect the performance of the wall. Specifically, infiltration led to increasing reinforcement strains and facing displacements, as well as to the progressive loss of suction. While the accumulation of water due to the temporary capillary break also resulted in an increased backfill unit weight, its effect on deformation of the wall was not possible to be captured but it is intrinsic on the overall behavior observed in this study. Correlations between reinforcement strains/face displacement and the average of suction in the backfill soil, as measured by tensiometers in different locations within the backfill mass, point to the relevance of the suction as a representative indicator of the deformability of the geotextile-reinforced wall subjected to water infiltration. Reinforcement strains and face displacements were found to reduce more significantly with reduction of suction until a certain value of suction from which the rate of decreasing declines.     

大跨度预应力混凝土结构施工质量控制研究

由于预应力混凝土的施工技术是一项专业性强、操作要求严、技术含量高的工作,所以预应力混凝土的质量控制对于结构施工的优劣起到至关重要的作用,进而影响到整个工程质量的好坏。鉴于此,本文从施工前、施工中和完工后三个阶段分析和归纳了预应力混凝土施工质量控制的要点,以期对工程实践起到参考和指导的作用。     

增强聚丙烯管线在环烷酸回收装置的应用

介绍了增强聚丙烯管线在环烷酸回收装置上的应用情况,说明增强聚丙烯管线完全适应酸性水的耐腐蚀要求,提高了装置的安全可靠性。     

加筋HDPE管在农田灌溉和给水工程中的应用

本文介绍了一种新型复合管材———HDPE筋塑管的特点 ,并与其它管材进行了比较 ,给出了目前的应用领域 ,最后具体介绍了农田灌溉工程中应用的施工过程 ;结论是HDPE筋塑管是一种性能良好、应用前景广泛、与其它管材相比有很强的经济性的管材     

Synthesis of punching failure in reinforced concrete

A synthesis of punching failure in reinforced concrete is given here. First, some recent experimental results are presented allowing one to show the difference between flexural and punching failure. Second, the punching failure mechanism is discussed based on results obtained with numerical simulations demonstrating among others the influence of the concrete tensile strength. Then, using these results, an analytical model is derived for punching load prediction. The model allows a unified treatment of slabs with various types of reinforcement. Finally, the prediction's capabilities are discussed using extended databases as well as special experimental results.     

纤维增强复合材料在探测机器人主车体上的应用

天然纤维增强复合材料亚麻纤维具有良好的抗冲压强度和自洁防腐功能,延伸率和密度也较小,选用其替换由45号钢制作的煤矿井下探测机器人的主车体,在保证主车体性能要求的前提下,质量减少190.5 kg,占主车体质量的80.9%。