虚拟装配技术及应用

虚拟制造是一种新兴的先进制造概念和理论，虚拟装配是虚拟制造研究领域重要的研究分支。虚拟装配可帮助产品摆脱对于试制物理样机并装配物理样机的过度依赖，可以有效地提高产品装配建模的质量与速度，有助于降低产品开发成本，缩短产品开发周期。介绍了虚拟装配的国内外现状，分析了虚拟装配的特征和关键，探讨了虚拟装配的实施方案和步骤。     

原位TiB2颗粒增强铝基复合材料及其力学性能

对原位反应合成TiB2／A356铝基复合材料微观组织和力学拉伸性能进行了研究。结果表明，原位反应生成的颗粒增强相在复合材料基体中分布均匀，基体与颗粒间的界面洁净。复合材料强度随着颗粒含量的增加显著提高，与基体合金相比，TiB2质量分数为8％的TiB2／A356复合材料强度和弹性模量的提高幅度约为28％，TiB2质量分数为16％的TiB2／A356复合材料强度和弹性模量的提高幅度约为35％。复合材料的断裂主要是由于基体与颗粒界面脱粘，在拉伸应力作用下由此萌生微裂纹并扩展，导致界面处的基体撕裂，从而降低复合材料塑性。     

AlTiB纳米细化剂对ZL101合金力学及阻尼性能的影响

利用原位自生法合成的纳米晶粒细化剂,成功的克服了颗粒团聚,有效的抑制了颗粒的沉降。本试验用其对ZL101合金的细化行为进行了研究。试验结果表明:加入量为0.2%(质量分数)时,纳米晶粒细化剂可有效地细化初晶α-Al,改善共晶硅的形貌及尺寸,细化后铸态α-Al枝晶尺寸由44μm减小至23μm;经T6处理的细化后试样其拉伸断口为韧窝断口,且韧窝明显多于未细化试样;加入细化剂后保温30min,与未细化合金相比,抗拉强度提高了28MPa,屈服强度提高了22MPa,延伸率增加了2.6%;同时细化后合金的阻尼性能较未细化合金有了大幅提高,0.5Hz时细化后室温阻尼性能Q-1=13×10-3,较之细化前Q-1提高了5×10-3。     

Microdefects and electron densities in NiTi shape memory alloys studied by positron annihilation

1Introduction NiTi alloys are the most successful shape memory alloys as a result of their combination of good functional properties and excellent mechanical strength[1,2].The thermal and mechanical shape memory behavior in these alloys is dependent upon …     

Elastic properties of polycrystalline gold thin films: Simulation and X-ray diffraction experiments

The elastic behavior of supported gold thin films has been studied using a framework in which the elastic interaction between grains and the actual structure of the film (i.e. preferential grain orientation and grain shape) are taken into account. Experiments were carried out using synchrotron X-ray diffraction combined with in-situ tensile testing and thereafter, no assumptions on the residual stress state and on the stress-free lattice parameter a₀ have to be made. Modeling of grain elastic interactions is based on the extension of Eshelby-Kröner model, which allows for estimating the elastic behavior of polycrystals considering the texture and the shape of the crystallites. Flat-disc shaped grains arrangement is shown to yield the best representation of the elastic behavior of the fiber-textured gold thin films composed of columnar grains. This non-intuitive representation results from free-surface effect.     

A double linear driving force approximation for non-isothermal mass transfer modeling through bi-disperse adsorbents

The aim of this paper is to derive a double LDF non-isothermal model to describe mass transfer through a fixed bed of bi-disperse adsorbent pellets. Firstly, we perform an analysis concerning the different way the composition within the pellets can be described and the consequence on the model structure and compactness. Secondly, we present a bed model including a simplified intra-particle model that is based on a double LDF approximation. This bi-disperse pellet model reduces the number of variables and parameters that are needed. This simplified model is used to simulate breakthroughs of a methane/carbon dioxide mixture over a 5 A zeolite and of a 2,2-dimethylbutane/2-methylpentane mixture over a silicalite molecular sieve. It is also compared with a more detailed model based on Stefan-Maxwell theory that we have previously developed.     

船用柴油机轴瓦巴氏合金离心浇注工艺优化

分析目前大功率低速船用柴油机轴瓦的巴氏合金浇注技术难题和常见质量缺陷,通过对巴氏合金浇注工艺技术及浇注后变形规律进行研究,对浇注工艺进行改进和优化,确保轴瓦合金层具有均匀的金相组织、较高的结合强度、足够的承载能力、以及良好的力学性能,达到大功率低速船用柴油机专利公司的要求,获得生产许可认证.     

基于材料吸附机理的抑尘沥青路面改性剂选择与试验研究

为了选择性能更优的抑尘吸附改性剂,通过对抑尘吸附材料的吸附机理进行分析,研究了比表面积、表面张力两项指标对纤维素系吸附材料、无机物系吸附材料和无机盐系吸附材料的影响.通过吸湿增重试验、比表面积测定、表面自由能测定对抑尘吸附改性剂的性能进行评估;通过抑尘沥青混合料吸湿效果试验对抑尘吸附改性剂的性能进行了验证.结果表明:玉米芯粉、天然沸石粉及无水氯化钙都可作为吸尘吸附改性剂且具有良好的吸附性能.吸附性能:无水氯化钙沸石粉玉米芯粉.     

基于旋转电弧立焊装置设计与轨迹规划

设计了一种基于旋转电弧的竖直焊缝焊接机器人机构,采用了工业计算机与运动控制卡进行控制;水平和竖直滑块各采用一个步进电机进行控制,利用滚珠丝杠传动,竖直电机带有刹车,防止竖直滑块下滑,以此提高各滑块的精度和焊接跟踪质量;焊枪由步进电机控制旋转,因此可以在焊接过程中进行焊接姿态调节,能够焊接上下两端的角点,增加操作的灵活性,提高使用性能。焊接过程较为平稳,焊缝成形良好。     

室温离子液体在萃取中的应用

综述了室温离子液体在萃取中的应用研究,包括液—液萃取,液相微萃取,固相微萃取,超临界CO2萃取。