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Study on micro-texture and skid resistance of aggregate during polishing

Zhenyu QIAN, Lingjian MENG

《结构与土木工程前沿(英文)》 2017年 第11卷 第3期   页码 346-352 doi: 10.1007/s11709-017-0409-7

摘要: The skid resistance performance of pavement is closely related to the micro-texture of pavement aggregate, while there is very few research on the relationship between micro-texture and the skid resistance. In this paper, the optical microscope is used to acquire the surface morphology of three types of aggregates including basalt, limestone and red sandstone respectively, where a total of 12 indicators are developed based on the surface texture information. The polishing effect on aggregate is simulated by Wehner/Schulze (W/S) device, during the polishing procedure, the skid resistance are measured by British Pendulum Tester (BPT). Based on the results of independent T-test and the polishing resistance analysis, it shows that the surface texture of basalt is significantly different between limestone and red sandstone. Three indicators including the average roughness ( ), the kurtosis of the surface ( ) and the mean summit curvature ( ) are selected to describe the characteristics of aggregate micro-texture based on the correlation analysis. The contribution of micro-texture to the skid resistance can be described with the secondary polynomial regression model by these indicators.

关键词: skid resistance of pavement     micro-texture     aggregates     polishing test    

静电自组装制备复合磨粒及其对铜的抛光特性研究

黄亦申,许雪峰,姚春燕,胡建德,彭伟

《中国工程科学》 2012年 第14卷 第10期   页码 82-89

摘要:

研究苯代三聚氰胺甲醛(BGF)微球与阳离子型聚电解质聚二烯丙基二甲基氯化铵(PDADMAC)、阴离子型聚电解质聚4-苯乙烯璜酸钠(PSS)之间的吸附特性,利用静电自组装技术改变和控制BGF微球的荷电特性,制备出不同形式的PEi BGF/SiO2复合磨粒,以Zeta电位、透射电子显微镜(TEM)和热重分析(TG)等手段对复合磨粒进行了表征,并利用这些复合磨粒制备了铜片抛光用的复合磨粒抛光液。抛光试验表明,吸附在聚合物微球表面和游离于抛光液中的SiO2磨粒在抛光中均起到材料去除作用。传统单一SiO2磨粒抛光液的铜材料去除率为264 nm/min,PE0 BGF/SiO2混合磨粒抛光液的铜材料去除率为348 nm/min,PE3 BGF/SiO2复合磨粒抛光液的铜材料去除率为476 nm/min。经上述3种抛光液抛光后的铜表面,在5 μm×5 μm范围内,表面粗糙度Ra从0.166 μm分别降至3.7 nm、2.6 nm和1.5 nm,峰谷值Rpv分别小于20 nm、14 nm和10 nm,复合磨粒抛光液对铜片有良好的抛光性能。

关键词: 化学机械抛光     抛光液     复合磨粒     聚电解质     铜片    

Review on mechanism and process of surface polishing using lasers

Arun KRISHNAN, Fengzhou FANG

《机械工程前沿(英文)》 2019年 第14卷 第3期   页码 299-319 doi: 10.1007/s11465-019-0535-0

摘要: Laser polishing is a technology of smoothening the surface of various materials with highly intense laser beams. When these beams impact on the material surface to be polished, the surface starts to be melted due to the high temperature. The melted material is then relocated from the ‘peaks to valleys’ under the multidirectional action of surface tension. By varying the process parameters such as beam intensity, energy density, spot diameter, and feed rate, different rates of surface roughness can be achieved. High precision polishing of surfaces can be done using laser process. Currently, laser polishing has extended its applications from photonics to molds as well as bio-medical sectors. Conventional polishing techniques have many drawbacks such as less capability of polishing freeform surfaces, environmental pollution, long processing time, and health hazards for the operators. Laser polishing on the other hand eliminates all the mentioned drawbacks and comes as a promising technology that can be relied for smoothening of initial topography of the surfaces irrespective of the complexity of the surface. Majority of the researchers performed laser polishing on materials such as steel, titanium, and its alloys because of its low cost and reliability. This article gives a detailed overview of the laser polishing mechanism by explaining various process parameters briefly to get a better understanding about the entire polishing process. The advantages and applications are also explained clearly to have a good knowledge about the importance of laser polishing in the future.

关键词: laser polishing     surface roughness     process parameters     mechanism    

Numerical analysis of hydrodynamic process of circular-translational-moving polishing (CTMP)

ZHAI Wenjie, LIU Changxiong, LIANG Yingchun

《机械工程前沿(英文)》 2008年 第3卷 第4期   页码 441-448 doi: 10.1007/s11465-008-0074-6

摘要: By keeping a pad moving relative to a wafer along a circular path without rotation, we developed a polishing technique called circular-translational-moving polishing (CTMP), which permits multidirectional polishing of the work piece and thus bears the advantage of isotropic polishing and a potential increase of material removal rate (MRR) on the wafer. To illuminate the mechanisms of CTMP and determine the optimum process variables in a CTMP process, a three-dimensional hydrodynamic lubrication model for CTMP with a smooth and rigid pad under a quasi-stable state is established in a polar coordinate system. The model equations are further calculated numerically by the finite difference method. The instantaneous distribution of fluid pressure is obtained, which shows that a negative pressure exists. The reason for negative pressure in CTMP and its effect on polishing is discussed. Moreover, the nominal clearance of the fluid film, roll, and pitch angles under different working conditions are obtained in terms of the applied load, moments, and polishing velocity. The obtained numerical analysis can be used as guidance for choosing operation parameters in a practical CTMP application.

关键词: numerical analysis     practical CTMP     circular-translational-moving polishing     CTMP     different    

Advances in polishing of internal structures on parts made by laser-based powder bed fusion

《机械工程前沿(英文)》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0724-0

摘要: The internal structures of metallic products are important in realizing functional applications. Considering the manufacturing of inner structures, laser-based powder bed fusion (L-PBF) is an attractive approach because its layering principle enables the fabrication of parts with customized interior structures. However, the inferior surface quality of L-PBF components hinders its productization progress seriously. In this article, process, basic forms, and applications relevant to L-PBF internal structures are reviewed comprehensively. The causes of poor surface quality and differences in the microstructure and property of the surface features of L-PBF inner structures are presented to provide a perspective of their surface characteristics. Various polishing technologies for L-PBF components with inner structures are presented, whereas their strengths and weaknesses are summarized along with a discussion on the challenges and prospects for improving the interior surface quality of L-PBF parts.

关键词: laser-based powder bed fusion     polishing     internal structures     surface quality     surface features     post process     additive manufacturing    

Experimental study on high-efficiency polishing for potassium dihydrogen phosphate (KDP) crystal by using

Ziyuan LIU, Hang GAO, Dongming GUO

《机械工程前沿(英文)》 2020年 第15卷 第2期   页码 294-302 doi: 10.1007/s11465-019-0576-4

摘要: A high-efficiency polishing approach using two-phase air–water fluid (TAWF) is proposed to avoid surface contamination and solve the inefficiency of previous water-dissolution polishing techniques for potassium dihydrogen phosphate (KDP) crystal. In the proposed method, controllable deliquescence is implemented without any chemical impurity. The product of deliquescence is then removed by a polishing pad to achieve surface planarization. The mechanism underlying TAWF polishing is analyzed, a special device is built to polish the KDP crystal, and the effect of relative humidity (RH) on polishing performance is studied. The relationship between key parameters of polishing and surface planarization is also investigated. Results show that the polishing performance is improved with increasing RH. However, precisely controlling the RH is extremely difficult during TAWF polishing. Controllable deliquescence can easily be disrupted once the RH fluctuates, which therefore needs to be restricted to a low level to avoid its influence on deliquescence rate. The material removal of TAWF polishing is mainly attributed to the synergistic effect of deliquescence and the polishing pad. Excessive polishing pressure and revolution rate remarkably reduce the life of the polishing pad and the surface quality of the KDP crystal. TAWF polishing using IC-1000 and TEC-168S increase the machining efficiency by 150%, and a smooth surface with a root mean square surface roughness of 5.5 nm is obtained.

关键词: potassium dihydrogen phosphate (KDP) crystal     controllable deliquescence     two-phase air–water fluid     high-efficiency polishing     material removal    

面向大幅面金属增材抛光的激光扫描振镜与伺服台协同控制系统 Article

崔梦嘉, 卢立斌, 张震, 管迎春

《工程(英文)》 2021年 第7卷 第12期   页码 1732-1740 doi: 10.1016/j.eng.2020.06.028

摘要:

为了满足高品质金属增材制造的迫切需求,本文创新地提出了一种以激光扫描振镜与精密伺服台协同控制为核心的大幅面激光精密抛光方法,以实现大幅面选区激光熔化(SLM)成形镍合金精密抛光。我们提出的协同控制系统主要包括主从式新型协同控制架构、运动矢量分解和误差合成等核心模块。研究实验结果表明,与传统步进-扫描方法相比,该协同控制系统实现了激光光斑连续运动,避免了拼接误差,加工效率提升了38.24%。由于激光扫描路径更流畅,相应能量分布更均匀,因此,大幅面抛光质量得到显著改善。本协同系统为大幅面、高精度、高效率的激光精密加工提供了重要途径,在航空航天、新能源、高端模具、医疗器械等精密制造领域具有广阔的应用前景。

关键词: 协同控制     激光制造     拼接误差     激光抛光     大幅面    

Laboratory and field evaluation of asphalt pavement surface friction resistance

Zhong WU, Chris ABADIE

《结构与土木工程前沿(英文)》 2018年 第12卷 第3期   页码 372-381 doi: 10.1007/s11709-017-0463-1

摘要:

Pavement surface friction is a significant factor for driving safety and plays a critical role in reducing wet-pavement crashes. However, the current asphalt mixture design procedure does not directly consider friction as a requirement. The objective of this study was to develop a surface friction prediction model that can be used during a wearing course mixture design. To achieve the objective, an experimental study was conducted on the frictional characteristics of typical wearing course mixtures in Louisiana. Twelve wearing course mixtures including dense-graded and open-graded mixes with different combinations of aggregate sources were evaluated in laboratory using an accelerated polishing and testing procedure considering both micro- and macro texture properties. In addition, the surface frictional properties of asphalt mixtures were measured on twenty-two selected asphalt pavement sections using different in situ devices including Dynamic Friction Tester (DFT), Circular Texture Meter (CTM), and Lock-Wheel Skid Trailer (LWST). The results have led to develop a procedure for predicting pavement end-of-life skid resistance based on the aggregate blend polish stone value, gradation parameters, and traffic, which is suited in checking whether the selected aggregates in a wearing course mix design would meet field friction requirements under a certain design traffic polishing.

关键词: friction skid resistance     polishing     PSV     LWST     micro-texture     macro-texture    

Mechanical performance analysis and stiffness test of a new type of suspension bridge

《结构与土木工程前沿(英文)》 2021年 第15卷 第5期   页码 1160-1180 doi: 10.1007/s11709-021-0760-6

摘要: A new type of suspension bridge is proposed based on the gravity stiffness principle. Compared with a conventional suspension bridge, the proposed bridge adds rigid webs and cross braces. The rigid webs connect the main cable and main girder to form a truss that can improve the bending stiffness of the bridge. The cross braces connect the main cables to form a closed space truss structure that can improve the torsional stiffness of the bridge. The rigid webs and cross braces are installed after the construction of a conventional suspension bridge is completed to resist different loads with different structural forms. A new type of railway suspension bridge with a span of 340 m and a highway suspension bridge with a span of 1020 m were designed and analysed using the finite element method. The stress, deflection of the girders, unbalanced forces of the main towers, and natural frequencies were compared with those of conventional suspension bridges. A stiffness test was carried out on the new type of suspension bridge with a small span, and the results were compared with those for a conventional bridge. The results showed that the new suspension bridge had a better performance than the conventional suspension bridge.

关键词: new type of suspension bridge     stiffness test     mechanical performance     railway bridge     space truss    

Mixed mode properties of CNT reinforced composites using Arcan test rig

Jacob MUTHU

《结构与土木工程前沿(英文)》 2015年 第9卷 第4期   页码 397-404 doi: 10.1007/s11709-015-0321-y

摘要: Composite materials reinforced with carbon nanotubes were mechanical tested using Arcan test rig under Mode-I, Mode-II and mixed mode loading conditions to obtain their fracture properties. The butterfly composite specimens were fabricated with 0.02, 0.05 and 0.1 wt % CNTs. The polyester/CNT composite was fabricated using VRTM (Vacuum Resin Transfer Molding) where the CNTs were first functionalised to reach an optimum properties. Arcan test rig was designed and fabricated to work with the Shimadzu testing machine. The results show that the functionalised CNTs have improved the fracture behavior by acting as bridge between the cracked face. In addition, the fracture properties were not improved for the higher weight fraction of 0.1 wt% CNTs.

关键词: CNT     composites     Arcan test rig     stress intensity factor    

Accelerated life-time test of MEA durability under vehicle operating conditions in PEM fuel cell

Tian TIAN, Jianjun TANG, Wei GUO, Mu PAN

《能源前沿(英文)》 2017年 第11卷 第3期   页码 326-333 doi: 10.1007/s11708-017-0489-z

摘要: In this paper, a novel accelerated test method was proposed to analyze the durability of MEA, considering the actual operation of the fuel cell vehicle. The proposed method includes 7 working conditions: open circuit voltage (OCV), idling, rated output, overload, idling-rated cycle, idling-overload cycle, and OCV-idling cycle. The experimental results indicate that the proposed method can effectively destroy the MEA in a short time (165 h). Moreover, the degradation mechanism of MEA was analyzed by measuring the polarization curve, CV, SEM and TEM. This paper may provide a new research direction for improving the durability of fuel cell.

关键词: polymer electrolyte membrane fuel cell     accelerated life-time test     load cycling test     durability    

Review on the progress of ultra-precision machining technologies

Julong YUAN, Binghai LYU, Wei HANG, Qianfa DENG

《机械工程前沿(英文)》 2017年 第12卷 第2期   页码 158-180 doi: 10.1007/s11465-017-0455-9

摘要:

Ultra-precision machining technologies are the essential methods, to obtain the highest form accuracy and surface quality. As more research findings are published, such technologies now involve complicated systems engineering and been widely used in the production of components in various aerospace, national defense, optics, mechanics, electronics, and other high-tech applications. The conception, applications and history of ultra-precision machining are introduced in this article, and the developments of ultra-precision machining technologies, especially ultra-precision grinding, ultra-precision cutting and polishing are also reviewed. The current state and problems of this field in China are analyzed. Finally, the development trends of this field and the coping strategies employed in China to keep up with the trends are discussed.

关键词: ultra-precision grinding     ultra-precision cutting     ultra-precision polishing     research status in China     development tendency    

XB高精度火箭橇试验滑轨

杨兴邦

《中国工程科学》 2000年 第2卷 第10期   页码 98-104

摘要:

火箭橇试验滑轨是一种大型地面动态模拟试验设备,用于研究试验件在空中高速度、高加速度运行时所遇到的诸多技术问题,其技术核心是一百万分之一的轨道直线性相对精度。它要求具有稳定的滑轨基础、高直线度准直基准线和光滑平顺的钢轨作为基本条件,需要采用钢轨精密机械加工、钢轨焊接、焊缝超声波探伤、轨道张拉锚固锁定、轨道直线度调整等新工艺技术。我国已成功地建成世界上唯一的、钢轨经精密机械加工后再全程焊接的XB高精度火箭橇试验滑轨。文章论述了它的诞生背景、设计思路、技术方案、技术与建造特点以及应用展望,该滑轨直线度达到世界先进水平。

关键词: 火箭滑橇     试验滑轨     地面动态模拟试验    

Application of metal magnetic memory test in failure analysis and safety evaluation of vessels

Yiliang ZHANG, Song YANG, Xuedong XU

《机械工程前沿(英文)》 2009年 第4卷 第1期   页码 40-48 doi: 10.1007/s11465-009-0003-3

摘要: Metal magnetic memory test (MMMT), which is a new subject in the field of nondestructive examination, can determine regions of stress concentration by testing the distribution of the magnetic field of metal structures so as to effectively diagnose premature defects. MMMT and other test methods are applied in the study to put a propylene purifier of a temperature-jump accident and a leaked ammonia vessel through safety evaluation. Results are as follows: The margin of safety declines after the purifier is overburnt; several stress concentrations are observed within the overburnt area and the level of stress concentration rises after one-month operation; and overpressure operation of the purifier must be strictly avoided and carefully monitored during later operation. Cracks are observed on the ammonia vessel after one year’s service. Extremely high residual stress is the primary cause of cracks. After four years in service, the residual stresses existing in the area of the base metal and weld zone are still greater than 0.5 , which results in numerous cracks due to stress corrosion. From the MMMT result of the ammonia vessel’s defects, it can be seen that the derivative of magnetic density (d p/d ) is an important reference variable. Within the 31 leakage points, 67.7% of them whose dHp/dx values are more than 10, and 96.8% of them whose dHp/dx values are more than 8.

关键词: Metal magnetic memory test (MMMT)     nondestructive testing (NDT)     residual stress     propylene purifier     ammonia vessel    

Investigating the raveling test for full-depth reclamation

Robert HILL, Andrew BRAHAM

《结构与土木工程前沿(英文)》 2018年 第12卷 第2期   页码 222-226 doi: 10.1007/s11709-017-0423-9

摘要: Full-Depth Reclamation (FDR) is a sustainable method of building pavement structure compared to more traditional rehabilitation methods. Traffic is generally returned to an FDR project before a surface course is applied, as water in the FDR needs time to evaporate from the structure. This should not be done too quickly or raveling occurs. Currently, there is no test to quantify the timing of return to traffic. In this study, the “Raveling test of cold mixed bituminous emulsion samples” (ASTM D7196) was used to compare asphalt emulsion and asphalt foam FDR. Asphalt emulsion samples were cured at ambient and 40 °C temperatures, while asphalt foam samples were cured at ambient temperatures. Raveling test data was collected from 0 to 48 hours of curing, however, samples were often not able to withstand fifteen minutes of testing. Therefore, the “time lasted” (the time the raveling head loses contact with the surface of the sample) was recorded. In general, the asphalt emulsion samples that were cured in the oven at 40 °C had a longer time lasted and showed higher potential for determination of return to traffic. In addition, the asphalt emulsion samples had a longer time lasted than the asphalt foam samples at ambient temperatures.

关键词: raveling     full depth reclamation    

标题 作者 时间 类型 操作

Study on micro-texture and skid resistance of aggregate during polishing

Zhenyu QIAN, Lingjian MENG

期刊论文

静电自组装制备复合磨粒及其对铜的抛光特性研究

黄亦申,许雪峰,姚春燕,胡建德,彭伟

期刊论文

Review on mechanism and process of surface polishing using lasers

Arun KRISHNAN, Fengzhou FANG

期刊论文

Numerical analysis of hydrodynamic process of circular-translational-moving polishing (CTMP)

ZHAI Wenjie, LIU Changxiong, LIANG Yingchun

期刊论文

Advances in polishing of internal structures on parts made by laser-based powder bed fusion

期刊论文

Experimental study on high-efficiency polishing for potassium dihydrogen phosphate (KDP) crystal by using

Ziyuan LIU, Hang GAO, Dongming GUO

期刊论文

面向大幅面金属增材抛光的激光扫描振镜与伺服台协同控制系统

崔梦嘉, 卢立斌, 张震, 管迎春

期刊论文

Laboratory and field evaluation of asphalt pavement surface friction resistance

Zhong WU, Chris ABADIE

期刊论文

Mechanical performance analysis and stiffness test of a new type of suspension bridge

期刊论文

Mixed mode properties of CNT reinforced composites using Arcan test rig

Jacob MUTHU

期刊论文

Accelerated life-time test of MEA durability under vehicle operating conditions in PEM fuel cell

Tian TIAN, Jianjun TANG, Wei GUO, Mu PAN

期刊论文

Review on the progress of ultra-precision machining technologies

Julong YUAN, Binghai LYU, Wei HANG, Qianfa DENG

期刊论文

XB高精度火箭橇试验滑轨

杨兴邦

期刊论文

Application of metal magnetic memory test in failure analysis and safety evaluation of vessels

Yiliang ZHANG, Song YANG, Xuedong XU

期刊论文

Investigating the raveling test for full-depth reclamation

Robert HILL, Andrew BRAHAM

期刊论文