主离合器摩擦片磨损分析与复合刷镀修复工艺

分析了主离合器摩擦片的磨损具有沿径向非均匀分布的特点，指出摩擦片在使用过程中，局部高温和材料软化是产生磨损的重要原因。用复合刷镀工艺修复摩擦片，具有表面镀层高温耐磨性好、工艺简单、成本低的特点。     

风沙对钢结构涂层的冲蚀磨损性能研究

采用气流挟沙喷射法,在不同的冲蚀速度、角度、浓度和时间等风沙冲蚀参数下,对钢结构涂层进行了风沙冲蚀的模拟试验,对试验材料质量损失、抗冲蚀磨损性能和微观失效表面进行了分析.结果表明:钢结构涂层的耐磨性较差;冲蚀率随冲蚀速度呈指数增长,在冲蚀角度为45°时存在低速和高速2个冲蚀阶段;涂层的质量损失在冲角为45°时最大,90°时最小,表现出从脆性材料向塑性材料过渡的特征;低冲角时,材料破坏方式以微切削作用为主,决定材料耐冲蚀性能的主要因素是其硬度;在高冲角时,材料破坏方式以挤压凿削作用为主,决定材料耐冲击性能的主要因素是其柔韧性;涂层质量损失随下沙率的增大在300g/min时出现峰值;涂层累积质量损失随时间大致呈线性增长,冲蚀过程存在明显的潜伏期、加速期和稳定期.     

铝合金化学镀Ni-Cu-P沉积速度的研究

研究了硫酸铜、次亚磷酸钠、络合剂及工艺参数对铝合金镀层沉积速率的影响,并对镀层的结合强度以及耐蚀性等方面进行了考察。确定了合适的工艺条件。根据该工艺制备的Ni-Cu-P镀层具有良好的表面质量、较高的结合强度,提高了铝合金的耐蚀性。     

A semi-analytical method for the elastic-plastic large deflection analysis of welded steel or aluminum plating under combined in-plane and lateral pressure loads

The aim of the present paper is to develop a semi-analytical method which can quickly and accurately compute the elastic–plastic large deflection response of welded steel or aluminum plating under a combination of biaxial compression/tension, biaxial in-plane bending, edge shear and lateral pressure loads, until the ultimate limit state is reached. The post-weld initial imperfections (i.e. initial deflection and residual stresses) are included in the method as parameters of influence. It is assumed that the plating is simply supported at all (four) edges which are kept straight. A unique feature of the developed method is that geometric nonlinearity associated with large deflection response of plating under combined loads is treated by analytically solving the nonlinear governing differential equations of the elastic large deflection plate theory, while material nonlinearity due to plasticity is dealt with implicitly by a numerical procedure. This approach reduces the magnitude of numerical computations, resulting in a saving of modeling effort and computing time. As another contribution, this paper investigates and discusses the ultimate strength characteristics of plating, by varying the plate properties and load combinations, based on elastic–plastic large deflection analysis using the developed method.     

基于微结构参数的饱和软土工程性质的研究

利用液氮冷冻制样、扫描电镜和计算机图像处理技术,采用多元逐步线性回归的方法,对广东科学中心46组饱和软土试样的颗粒分布分维值、孔隙分布分维值、孔隙度、孔隙总面积、孔隙总个数、平均孔隙周长、孔隙平均直径及孔洞的复杂度等微结构参数与压缩系数、压缩模量、内聚力和内摩擦角等宏观工程性质参数的关联性进行了分析,初步探讨了饱和软土微结构参数对工程性质的影响,为饱和软土微观结构力学理论的进一步发展提供了思路和方法。     

Evaluation of the durability of titanium dioxide photocatalyst coating for concrete pavement

The use of titanium dioxide (TiO₂) ultrafine particles as coating for concrete pavement have received considerable attention in recent years as these particles can trap and decompose organic and inorganic air pollutants by a photocatalytic process. In spite of these promising benefits, the durability and resistance to wear of TiO₂ surface coating has not been evaluated. The objective of this study was to determine the abrasion and wear resistance properties of TiO₂ coatings and its effect on the coating’s environmental performance. To achieve this objective, an experimental program was conducted to measure and compare the environmental performance of titanium dioxide coating before and after laboratory-simulated abrasion and wearing. The environmental efficiency of the coating to remove nitrogen oxides (NO_x) from the atmosphere was measured using a newly developed laboratory setup. Microscopic analysis was conducted using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) to determine the distribution of TiO₂ particles on the surface before and after wearing. The measured rut depth using the Loaded-Wheel Tester (LWT) was minimal indicating that the use of the coating did not appear to affect the wear resistance of the surface. Wearing of the specimens with 5% TiO₂ resulted in a small decrease in the coating NO removal efficiency. In contrast, the wearing of the samples with 3% TiO₂ slightly improved the NO removal efficiency. Results presented in this paper support that the use of TiO₂ coating as a photocatalytic compound would provide acceptable durability and wear resistance.     

A viscoplastic degradation model for rocks

In this paper a viscoplastic constitutive model for rocks is proposed in which both yield stress and viscosity undergo variation during the deformation process. The model is initially formulated for a uniaxial stress state; its extension to a general stress state has been also presented. Our model is capable to sufficiently well predict both the pre-peak hardening and post-peak softening response of rock material in compression providing good simulation of material response in both stable and post-critical stages of deformation. Such behaviour can be obtained for both low and high strain rates. In our examples, model parameters are determined from uniaxial compression tests performed on sandstone at different strain rates.     

金属复合屋面板用硬质聚氨酯泡沫的力学性能

针对金属复合屋面板用硬质聚氨酯泡沫材料分别进行了发泡方向和涂层方向的拉伸、压缩力学性能试验,对各向基本力学参数进行了测定.结果表明：硬质聚氨酯泡沫材料在发泡方向和涂层方向的拉伸和压缩力学性能不相同,不能简单看作为各向同性材料.在拉伸情况下,硬质聚氨酯泡沫材料呈脆性破坏,但压缩时存在明显屈服平台且无明显破坏特征.硬质聚氨酯泡沫材料发泡方向与涂层方向的力学参数差异明显,其发泡方向的拉、压弹性模量仅约为涂层方向的1/2,拉伸极限强度及压缩屈服强度也都明显低于涂层方向.根据试验数据,建议了适用于硬质聚氨酯泡沫的横观各向同性本构模型并对主要参数进行了拟合.     

循环流化床锅炉管子的防磨喷涂

对循环流化床锅炉燃烧室卫燃带上部锅炉管火焰喷涂涂层和超声速电弧喷涂复合涂层的施工工艺、涂层质量和使用效果进行了比较，超声速电弧喷涂复合涂层可解决循环流化床锅炉磨损问题：     

氟碳漆在荆山湖进洪闸工程的应用

氟碳漆作为一种新型涂料,可用作外墙装饰。文章通过氟碳漆技术在荆山湖进洪闸工程中的实际应用,阐述氟碳漆施工方法、工艺特点和质量要求,以供今后类似工程参考。     

天然气总能系统制冷性能及成本分析

探讨了天然气总能系统(IES)制冷方式和利用尾气余热为吸收制冷提供热量的方法。对电机驱动压缩制冷，天然气直燃吸收制冷，燃气发动机驱动压缩制冷，燃气轮机发电和吸收制冷系统的一次能源利用率和装置成本进行了比较分析。     

Stub column tests for racking design: Experimental testing,FE analysis and EC3

The Laboratory of Elasticity and Strength of Materials, in the School of Engineering of Barcelona (UPC), has gained a wide experience in pallet-rack testing in recent years. We have gathered a comprehensive set of experimental results from upright cross-sections subject to compression. Twenty different pallet-rack steel profiles have been tested. This information is valuable and allows us to evaluate different methods alternative to testing as a design option. In this paper, two alternative methods are considered: the analytical, by applying the European Standard EN 1993-1-3:2006/AC:2009; a traditional method, which involves the effective width determination for each part of the section subject to compression; and the numerical, by applying finite element analysis, including non-linear material and geometrical behaviour. The results of both methods are compared to the experimental ones. This research reveals that even though the European Standard EN 15512:2009 does only accept the experimental method for perforated sections, theses other two methods can give good accuracy, and be good tools in the stage of design and optimization.     

有辅助能源的太阳能吸收式制冷循环模式

为了扩大太阳能吸收式制冷系统的适用范围,必须对不连续、不稳定的太阳辐射进行能量补偿。从功量补偿角度出发,提出基于太阳能吸收式制冷与蒸气压缩制冷的联合制冷系统。从工作原理上分析了联合制冷系统的联合制冷循环模式的可行性,它可根据太阳辐射的强弱在蒸气压缩制冷与吸收式制冷之间切换和组合,使太阳能吸收式制冷系统的适用性大大增强。     

复合地层中盾构滚刀磨损实用预测方法及应用

盾构机在复合地层掘进过程中常因刀具磨损量过大而产生掘进工效降低和刀具失效等问题。依托深圳地铁13号线白应区间复合地层段滚刀磨损数据,根据Rabinowicz磨粒磨损计算模型提出了一种滚刀磨损量实用预测方法。该方法结合滑移率计算公式和刀盘扭矩、刀盘推力得到滚刀滑动距离,通过科罗拉多矿业学院模型(CSM模型)、岩石强度参数和滚刀贯入深度确定接触面法向荷载,根据滚刀设计参数确定其材料强度。通过确定影响滚刀磨损量的三个主要因素(滑动距离、接触面法向荷载和材料强度),推导出了考虑盾构滚刀磨损体积计算公式,并采用深圳地铁13号线白应区间复合地层段滚刀实测磨损量与磨损量预测值进行对比验证。结果表明:实测磨损量与预测较为吻合,验证了所提出的滚刀磨损量预测方法的合理性,研究成果可为复合地层中盾构滚刀磨损量预测和换刀时机的确定提供理论依据。     

JS聚合物-水泥基复合防水涂料施工质量的控制策略

随着城市建设脚步的快进,大型的地下人防工程也成为现在公共建筑的主旋律,为更好的保证工程的使用,地下防水的质量尤关重要,结合地下工程施工环境略有潮湿的特殊情况,JS聚合物-水泥基复合防水涂料应需而生,该材料由有机高分子液料和无机粉料复合而成的双组分系列防水涂料,是一类既具有有机材料弹性高,又有无机材料耐久性好等优点的新型防水材料,涂膜后可形成高强坚韧的防水涂膜,其可在潮湿或干燥的多种材质的基面上直接施工,但在实际施工中常出现涂层表面不均匀刷花、涂层表面裂纹等问题,严重影响涂膜的耐水性、耐候性、耐久性。为此对涂料施工的关键工序进行研究,找出原因,采取控制策略,圆满地解决了问题。     

Resonance analysis of opposed piston linear compressor for refrigerator application

The opposed piston linear compressor is considered to be the future of silent, reliable and efficient compression technologies. For long valves, less linear compressors have been widely used in cryocoolers for space applications. Recently research has established its high-performance characteristics which are useful in household refrigeration application. Unlike reciprocating compressors which are driven by rotary motors and need a crank connecting rod mechanism to convert rotary into linear motion, a linear compressor is driven by a linear motor which reduces the number of moving parts. This feature makes the compressor more reliable, more efficient and has a silent operation. The piston (suspended on spring stiffness) in the linear compressor is a free piston, i.e. motion of the piston is not constrained hence the performance of the linear compressor is highly dependent on system resonance. Free piston motion offers the unique advantage of ease of modulation, i.e. the stroke of the compressor and hence the delivery mass flow rate coming out of the compressor can be easily controlled by changing the supply voltage. Resonance in the linear compressor is a function of moving mass, spring stiffness and operating or electrical frequency. Achieving resonance in the linear compressor results in maximising the cooling performance of the refrigerator and minimising the input power requirement and hence an increase in the COP of the refrigeration system. The present paper discusses the results from resonance testing of the opposed piston linear compressor for household refrigerator using the fast Fourier transformation analysis. There are different parameters that are considered to optimise the natural frequency of the opposed piston linear compressor, consisting of frequency, moving mass, and spring stiffness. The piston performs compression and suction in a similar manner as in the conventional reciprocating compressor. An opposed piston linear compressor exhibits high energy efficiency due to its simple construction and less moving parts, its mechanical losses are much less than the reciprocating compressor.     

Probabilistic modeling of graded timber material properties

The probabilistic modeling of timber material characteristics is considered with special emphasis to the modeling of the effect of different quality control and selection procedures used as means for quality grading in the production line. It is shown how statistical models may be established on the basis of the same type of information which is normally collected as a part of the quality control procedures and furthermore, how the efficiency of different control procedures may be quantified and compared. The tail behavior of the probability distributions of timber material characteristics plays an important role in the overall probabilistic modeling. Therefore a scheme for estimating the parameters of probability distribution parameters focusing on the tail behavior has been established using a censored Maximum Likelihood estimation technique. The proposed probabilistic models have been formulated such that they may readily be applied in structural reliability analysis and their format appears to be appropriate for codification purposes of quality control and selection for grading procedures.     

Testing and numerical simulation of a medium strength rock material under unconfined compression loading

This study aims to numerically and experimentally investigate the response of a medium strength rock material under unconfined compression loading up to failure. The unconfined compressive strength (UCS) is one of the most important parameters in characterising rock material behaviour. Hence the UCS is crucial in understanding the failure mechanism of fractured rocks. An effective approach to determine the UCS and to investigate the behaviours of rock materials under unconfined compression is essential in the majority of research fields of rock mechanics. The experimental configuration for the unconfined compression test, suggested by the protocols of the ASTM standard, has some limitations which affect the accuracy in determination of the real UCS. Among several alternative configurations proposed, the Mogi's configuration seems to be the most appropriate one. Therefore, the ASTM and Mogi's configurations were used to perform the tests on a medium strength rock material, i.e. Pietra Serena sandstone. The results using two configurations were discussed in terms of the differences. The tests were also replicated in LS-DYNA using a finite element method (FEM) coupled smooth particle hydrodynamics (SPH) technique. This technique is employed in this study due to its capabilities to cope with large deformation issues related to the rocks. An advanced material model, called the Karagozian and Case Concrete (KCC) model, is implemented in the numerical simulations. The KCC model consists of three independent fixed failure surfaces and it can consider the damage accumulation based on the current state of stress among these failure surfaces. An equation-of-state (EOS) is used in conjunction with KCC material model for decoupling the volumetric and deviatoric responses. The numerical and experimental results were finally compared with the focus on the stress–strain diagram and the failure patterns. The comparison shows that the numerical results are in good agreement with the experimental results.     

岩石类脆性材料冲击性能研究

 基于剪切波跟踪技术(SWT)，对岩盐、水泥砂浆石复合材料进行压剪联合冲击试验，通过冲击剪切性能来揭示脆性材料的损伤状态。 在冲击损伤阶段，脆性材料的冲击压缩性能规律不明显，但剪切方面表现出随损伤程度加深，剪切波波速和剪切强度明显降低的规律。比较有法向应力和无法向应力作用时的剪切强度，当无法向应力作用时，材料损伤后剪切强度随损伤程度的加深逐步降为0，而有法向应力作用时，剪切强度有随损伤程度的加深逐步降低的趋势，但存在一定的波动。这表明，采用剪切波，尤其是卸载剪切波来探测岩石内部动态损伤非常有效。     

高频等离子固相外沉积工艺参数在线测量系统研究

高频等离子固相外沉积工艺工程中沉积温度和沉积量是最为关键的工艺参数,但受到沉积车间温度、强光照和高频信号干扰等不利条件的限制,常规测量方法无法实现精确测量。本文根据工艺特性采用红外测温和影像测量的手段实现工艺过程的在线精确测量,提升了工艺控制精度和石英材料产品品质。