Characterisation of the Scratch Deformation Mechanisms for Poly(methylmethacrylate) using Surface Optical Reflectivity

A novel technique using surface local optical reflectivity measurements for characterising the modes of surface mechanical damage of polymers is described. The technique utilises the sensed laser reflectivity of polymer surfaces, after damage, as a means of measuring the relative extent of brittle and plastic deformation modes for polymers. The polymeric surface used in this paper is a commercial poly(methylmethacrylate). The surface damage is produced by scratching with rigid conical indenters under different contact conditions of strain and load. The results show that the local optical reflectivity of a surface depends upon the topography of the surfaces, which varies for different modes of deformation. The reflectivity of a brittle fractured surface is significantly lower in comparison with that for a plastically deformed surface. © 1997 SCI     

单颗磨粒超声振动辅助划擦C/SiC复合材料三维有限元仿真

采用有限元分析软件ABAQUS建立反映C/SiC复合材料编织结构的三维仿真模型,模拟单颗金刚石磨粒划擦C/SiC复合材料的去除过程,获得划擦过程中材料上的应力、应变分布与磨削力变化曲线.通过试验获得相同划擦条件下的磨削力值,与模拟值比较,平均轴向力误差值为8.9％,平均切向力误差值为11.2％.仿真结果解释了试验中有、...     

直缝焊管成形过程划伤问题的数值仿真分析

基于弹塑性有限元法建立了激光直缝焊管成型过程的有限元分析模型,分析了焊管表面深度划伤的产生原因和解决措施.结果表明,深度划伤产生的根本原因是由于板带与水平辊下辊接触点位置线速度与轧辊旋转速度不匹配.通过数值分析,在合理控制水平辊辊缝保证焊缝成型的基础上,获得板带与下辊辊面接触弧的平均辊径,并计算了避免焊管表面划伤的合理的下辊旋转速度.     

减少气垫炉表面划伤废品

结合生产实际，阐述了气垫式连续热处理炉14#技术废品的产生原因，并提出解决措施，并取得了良好的效果。     

电力送电线路工程高空划印技术的改进

在电压等级比较高的送电线路工程施工中，传统的划印方法已不适应发展需要，为此，在学习和借鉴的基础上，对传统的划印方法进行改进，提出一种新的方法--导线带张力高空划印法。改进后的高空划印施工方法具有划印准确、调整弧垂方便、导线弧垂精确度高的优点，使用效果较好。     

基体表面纳织构化对AlCrN涂层刀具界面结合强度影响的研究

为了探讨基体表面不同预处理工艺对涂层界面结合强度的影响,利用研磨抛光、喷砂和织构化等三种不同的预处理工艺对基体表面进行处理后涂覆Al Cr N涂层,制备出三种不同的Al Cr N涂层试样。对试样进行划痕试验,研究并比较各试样的界面结合强度。研究结果表明:与研磨抛光和喷砂两种预处理方式相比,织构化工艺能在基体表面有效加工出规则、连续的纹理,增加基体表面的粗糙度,有利于增加涂层与基体间的界面结合强度。     

Preliminary study on theory and experiment of photo-mechanics manufacturing and detecting technologies based on laser thermal stress

Mechanical effects of laser thermal stress is a new manufacturing technology, which is made use of thermal stress by high power laser acted on the surface of metal material to generate stress field. The technologies such as formation by laser thermal stress, measurement by laser scratch, measurement by XRD and so on are formed based on mechanics effects of laser thermal stress. The mechanisms of formation by laser thermal stress, measurement by laser scratch and measurement by XRD are analyzed. The theory of photo-mechanics manufacturing based on laser thermal stress is originally put forward whose experiment is primitively researched, and the manufacturing theory by mechanics effects of laser thermal stress is established.     

基于纳米划痕仪的单晶锗纳米沟槽加工实验研究

为了提高纳米锗器件的制造精度,使用纳米划痕仪对单晶锗进行纳米沟槽刻划加工实验,采用扫描电子显微镜对沟槽形貌进行观察,并通过三维白光干涉表面形貌仪测量其三维形貌尺寸,研究了切削速度、施加的垂直载荷及刻划次数对单晶锗纳米沟槽形貌的影响。建立了垂直载荷和刻划次数与沟槽深度及宽度的线性拟合曲线和幂函数拟合曲线,并进行分析。结果表明,单晶锗纳米沟槽的宽度和深度随切削速度的变化非常小,随着垂直载荷的增大,刻划次数的增多而逐渐增大。曲线的拟合度很高,能够对制造纳米沟槽的深度和宽度进行较为准确的预测,从而可以降低工件表面粗糙度,提高工件表面质量。     

高温阀门设计中的关键技术

高温条件下金属材料的强度、硬度、塑性、以及蠕变、断裂的失效形式等各种物理性能、机械性能都将发生明显的变化，因此高温阀门在结构设计和材料选择上与低温阀门或常温阀门相比具有很大的差别。通过分析材料的机械性能、热胀量、热交变化及擦伤问题对高温阀门的影响，总结出高温阀门在结构设计和材料选择上的关键技术。     

Comparative study of the effect of surface texturing on cutting tool in dry cutting

Recent researches in the field of dry machining have indicated that surface texture has the potential to influence tribological conditions. Researchers have studied the application of controlled surface microtextures on cutting tool surfaces to improve machining performance by changing the tribological conditions at the interfaces of tool–chip and tool–work piece. An experiment to study the performance of the microtextured high-speed steel cutting implement within the machining of steel and aluminum samples was performed. Surface textures were introduced using Rockwell hardness tester, Vickers hardness tester, and by scratching with diamond dresser on the face of single point cutting tool. Machining in dry conditions was applied on mild steel (EN3B) and aluminum (AA 6351) samples using lathe machine with microtextured and traditional cutting tool for the constant range of feed, depth of cut, and for varying range of cutting speeds. Measurement of cutting force, cutting temperature, and surface roughness of the work surfaces after machining were made. The results showed reduction in cutting forces and cutting temperature with textured tools in comparison with those of the untextured tool. Chips collected from different samples were studied under a microscope and the results showed that textures created on the tool surface by various methods exhibited variations in chip formation. Cutting tools without texture and with texture were comparatively studied and the outcomes of the experimental study are presented in this paper.