镍基合金粉末的选择性激光烧结试验研究

分析了金属粉末选择性激光烧结的工艺特点，通过镍基合金粉末F105的系列选择性激光烧结试验及其产物的微观结构分析，研究了金属粉末在激光作用下的熔凝过程以及各烧结参数对其熔凝过程的影响；对镍基F105合金粉末的激光烧结工艺进行了初步优化，通过多层烧结试验对获得的烧结工艺进行了试验验证。研究结果表明，采用优化工艺制备的烧结制件内部组织主要由大量微米量级的等轴晶与少量枝晶组成，结构致密。     

烧结碳化钨增强激光熔敷涂层耐磨性研究

选择烧结碳化钨为增强材料,通过激光熔敷的方法制备烧结碳化钨增强镍基合金;研究碳化钨与镍基合金的结合方式,考察碳化钨增强合金在磨料磨损条件下的磨损性能,并探讨其磨损机制。结果表明:烧结碳化钨的加入显著提高镍基激光熔覆合金的耐磨性,且在烧结碳化钨颗粒表面还获得一层具有良好的耐磨性能和耐蚀性能的组织。原因是碳化钨颗粒与镍基合金在激光加热过程中结合到一起,同时Ni、Cr等基体元素扩散进入碳化钨-钴系统中,形成的新WC黏结相,从而获得一种耐磨、耐蚀性很好的组织。     

改善镍基合金铸造性能的研究

研究了稀土元素用于改善镍基合金铸造性能的可能性和效果。试验结果表明，在镍基合金中加入适量的稀土，可提高合金的流动性，降低其热裂倾向，对合金的线收缩率影响不大。     

Fe-P-C三元系粉末合金的研究

Fe-P二元系合金具有较好的综合机械性能。但是,当磷含量提高时,合金的烧结收缩也随之增加,尤其当磷含量高于0.6%时,烧结收缩值较大,这对于要求高强度、高精度的铁基零件来说,将受到某些限制。在Fe-P二元系合金中加入碳元素,即建立Fe-P-C三元系合金,不仅可以进一步提高合金的强度,而且还能显著减小烧结收缩,和更好地控制铁基零件的精度。本文着重讨论了在Fe-P-C三元系合金中,磷含量碳含量对其性能和烧结收缩的影响,并从理论上进行了分析。     

镍基合金粉末的选择性激光烧结试验研究

分析了金属粉末选择性激光烧结的工艺特点 ,通过镍基合金粉末 F1 0 5的系列选择性激光烧结试验及其产物的微观结构分析 ,研究了金属粉末在激光作用下的熔凝过程以及各烧结参数对其熔凝过程的影响 ;对镍基 F1 0 5合金粉末的激光烧结工艺进行了初步优化 ,通过多层烧结试验对获得的烧结工艺进行了试验验证。研究结果表明 ,采用优化工艺制备的烧结制件内部组织主要由大量微米量级的等轴晶与少量枝晶组成 ,结构致密。     

Fe-Mo-Mn-Sn-Ce-C烧结合金体系与强化烧结工艺研究

研究了合金成分，烧结气氛对Fe-Mo-Mn-Sn-Ce-C系合金的力学性能与烧结温度的影响以及在烧结合金中的作用机理，结果表明：适量的Mn、Sn、混合稀土和氨燃烧氮基保护气氛均可加速该系合金的烧结进程，降低其烧结温度，改善其力学性能，而且具有协同、叠加强化效果。其强化作用主要体现在稀土元素的脱氧保碳、变质夹杂物，细化晶粒，Mn,Sn元素的固溶强化以及氨燃烧氮基保护气氛对烧结热效率，合金表层脱碳状况，烧结活化能的改善等方面，该系合金在氨燃烧氮基保护气氛中的合适烧结温度范围为1025～1075℃，比Fe-Mo-Ni-C系合金的烧结温度降低了120～180℃。     

TiAl基合金的制备及其摩擦磨损性能

以钛粉、铝粉和铬粉为原料,采用机械合金化放电等离子烧结技术制备了TiAl基合金,分析了球磨时间和烧结温度对其物相组成、显微组织以及硬度的影响;用SiC砂轮为对偶件对TiAl基合金的摩擦磨损性能进行了研究.结果表明:混合粉经150 h球磨,1 173 K烧结9 min后所制备的合金具有较好的性能,其显微组织均匀细小,平均晶粒尺寸小于10μm,硬度达到68.2 HRC;与304不锈钢相比,烧结TiAl基合金具有更低的摩擦因数和更高的耐磨性,磨损机理为磨粒磨损.     

放电等离子烧结温度对Ti-45Al-6Nb-0.3W合金显微组织和力学性能的影响

在不同温度下(1 150,1 200,1 250℃)对氩气雾化Ti-45Al-6Nb-0.3W合金粉末进行放电等离子烧结,研究了烧结温度对合金显微组织和力学性能的影响。结果表明:放电等离子烧结合金由γ相和α2相组成,随烧结温度升高,组织形态由片层和等轴状转变为全片层状,同时晶粒尺寸增大,γ相含量增加;合金密度随烧结温度升高略有增加,硬度变化不大;不同温度烧结合金的压缩性能均优于铸态合金的,1 200℃下烧结合金的室温压缩性能最好,抗压强度、压缩率分别为3 012 MPa,40.8%。     

选择性激光烧结金属粉末制作微型部件

本文提出对金属粉末进行选择性激光烧结制作微型部件，用微细镍基合金粉末、铜粉进行了实验，把镍粉、铜粉选择性烧结在一个微型部件中，证明在一个微型部件中进行多种材料的集成是可行的。     

碳、镍元素对铁-锰合金的阻尼性能与相变行为的影响

应用倒扭摆内耗议、热机械分析仪和光学显微镜研究了碳和镍对铁-锰基减振合金γ→ε转变行为和阻尼性能影响。结果表明：碳增加γ→ε相变的阻力，降低合金的M3温度，减少合金中ε马氏体的数量；碳的钉扎作用能够使合金中γ／ε相界面的滑移性能变差，从而恶化了合金的阻尼性能。镍降低了合金的相变温度，但不会对合金阻尼性能产生不利影响。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.