汽车6061铝合金材料切削加工理论及实验研究

以汽车6061铝合金材料为研究对象,采用冶金技术通过添加强化相粉煤灰制备样品,基于灰色多响应优化理论建立不同工艺参数下切削加工理论模型,同时进行不同工艺参数的实验,运用理论及实验方法研究了不同工艺参数对汽车6061铝合金材料切削加工的影响。研究表明:汽车6061铝合金材料硬度随着强化相粉煤灰增加而增加,其密度却呈现相反趋势;切削加工过程中复合汽车材料表面粗糙度随着切削速度、填充物增加而逐渐降低,表面粗糙度随着进给量增加而增加; PCD刀具切削加工的复合汽车材料表面粗糙度明显低于K10硬质合金钢刀具;理论计算值与实验值相对误差较小,验证该理论及试验方法正确性和为其在新型汽车铝合金复合材料制备及切削工艺改善等工程应用提供可行性。     

旋转摩擦挤压法制备CNTs/5A06铝基复合材料的摩擦磨损行为

添加体积分数3%碳纳米管(CNTs),应用旋转摩擦挤压(RFE)法制备了CNTs/5A06铝基复合材料,研究了其显微组织、显微硬度和耐磨性能,并与RFE加工前后5A06铝合金的进行了对比。结果表明:RFE加工后铝合金组织由RFE加工前的粗大长条状晶粒变为细小等轴晶,但显微硬度增幅不明显,复合材料的晶粒进一步细化,硬度明显增加;RFE加工对铝合金摩擦因数与磨损率的影响较小,复合材料的摩擦因数与磨损率则分别比RFE加工前铝合金的降低了17.6%,34.7%;复合材料磨损表面光滑完整,存在塑性变形和少量犁沟,磨损机制为表面塑性变形和轻微的磨粒磨损,RFE加工前后铝合金的磨损表面均存在较多凹坑和犁沟,磨损机制为黏着磨损和磨粒磨损。     

ZL101A铝合金表面微弧氧化陶瓷层的摩擦磨损性能

在ZL101A铝合金表面制备了微弧氧化陶瓷层,采用扫描电镜、X射线衍射仪、显微硬度计、高温摩擦磨损试验机等研究了该陶瓷层的显微组织、物相组成、显微硬度和摩擦磨损性能。结果表明:微弧氧化陶瓷层主要由α-Al_2O_3和γ-Al_2O_3相组成,其层厚约60μm,表层疏松、内层致密;该陶瓷层的平均硬度为1 740.9HV,远高于ZL101A铝合金的150.2HV,摩擦因数与磨损质量损失均小于ZL101A铝合金的,其磨损机理主要为磨粒磨损。     

0Cr18Ni9/ZL107网络互穿复合材料加工表面缺陷研究

对0Cr18Ni9/ZL107网络互穿复合材料进行了车削试验研究。研究结果表明,网络互穿复合材料两相材料界面处的车削加工缺陷主要表现为增强相与基体相之间的裂纹以及增强相与基体相的分离翘曲,复合材料表面的加工缺陷主要表现为增强相凹凸、基体撕裂以及基体表面微裂纹。试验证明,减小进给量和切削深度,增大切削速度能够有效控制车削加工表面缺陷。     

ZL109铝合金切削加工表面粗糙度演变研究

轻质高强ZL109铝合金应用广泛，切削加工过程中易形成积屑瘤，导致加工表面粗糙度不受控。对ZL109铝合金切削加工表面粗糙度演变进行研究，通过改变背吃刀量和进给量，进行ZL109铝合金棒材切削加工，分析表面粗糙度的演变规律，并分析切削温度、表面微观形貌、切屑形态、刀刃损伤对切削表面粗糙度的影响规律。研究结果表明，加工表面粗糙度值随背吃刀量和进给量的增大而增大，且背吃刀量对表面粗糙度的影响较大。当进给量为0.25～0.5 mm/r,背吃刀量为0.25 mm时，加工表面粗糙度值最小，表面完整性最好，并且刀刃损伤程度最轻。     

铝硅钛合金疲劳裂纹扩展行为研究

以电解铝硅钛中间合金为主要原料，熔炼与ZL101A合金成分基本相同的合金AST101，对比研究了AST101和ZL101A合金的疲劳裂纹扩展行为。在应力比R=0.1和0.5的试验条件下，AST101合金的抗疲劳裂纹扩展能力不如ZL101合金。金相分析表明，AST101合金的铁含量较高，在合金中形成了脆性针状富铁相，该相自身的断裂和与基体的脱粘促进了合金疲劳裂纹的扩展，此外，AST101合金的微观组织特性影响了疲劳裂纹的闭合程度，也降低了合金的抗疲劳裂纹扩展能力。     

激光诱导氧化辅助微细铣削TiB_2基陶瓷复合材料试验研究

陶瓷复合材料具有高硬度、高弹性模量、耐磨、抗化学腐蚀等诸多优异性能,在航空航天、微电子、汽车、切削刀具和生物医学等领域具有广泛应用前景,但其微细铣削加工中存在铣削力高、刀具磨损严重等问题。本文提出了一种激光诱导氧化辅助微细铣削的复合加工方法,并用该方法制备了TiB_2基陶瓷复合材料微结构。在激光辐照下,TiB_2基陶瓷复合材料氧化生成具有一定厚度的、疏松易去除的氧化层;在此基础上,利用微细铣削工艺依次去除氧化层、热影响层和少量基体材料,以获得高加工效率和加工质量。主要研究了铣削深度和每齿进给量对铣削力和表面粗糙度的影响规律,结果表明,随着铣削深度和每齿进给量的增大,铣削力逐渐增大;在铣削深度为2μm、每齿进给量为0.3μm/z时,已加工表面粗糙度最小,S_a为0.06μm;随着铣削深度和每齿进给量的增大,材料去除方式先后经历弹性滑动摩擦、延性模式和脆性模式三个阶段。     

对切削加工性能的影响

为分析过共晶铝硅合金组织对其切削加工性能的影响,对两种化学成分相同但是组织结构不同的过共晶铝硅合金进行了切削试验研究并探讨了其切削机理.试验结果表明:过共晶铝硅合金经变质处理后组织中初晶硅的大小、形状和分布状况对切削刀具寿命和合金的切削加工表面质量影响极大,具有细小、分散而形状圆钝化初晶硅的合金有比较好的切削性能.造成这种影响的主要原因在于细小的硅粒比较容易协同基体塑性变形和被刀具压入切屑和已加工表面,而粗大的硅块往往发生解理破碎、脱落和位移,直接与刀具发生强烈摩擦并使已加工表面存留许多缺陷.     

过共晶铝硅合金组织对切削加工性能的影响

为分析过共晶铝硅合金组织对其切削加工性能的影响,对两种化学成分相同但是组织结构不同的过共晶铝硅合金进行了切削试验研究并探讨了其切削机理。试验结果表明：过共晶铝硅合金经变质处理后组织中初晶硅的大小、形状和分布状况对切削刀具寿命和合金的切削加工表面质量影响极大,具有细小、分散而形状圆钝化初晶硅的合金有比较好的切削性能。造成这种影响的主要原因在于细小的硅粒比较容易协同基体塑性变形和被刀具压入切屑和已加工表面,而粗大的硅块往往发生解理破碎、脱落和位移,直接与刀具发生强烈摩擦并使已加工表面存留许多缺陷。     

铝钎焊用锌基合金钎料的制备及钎焊接头的组织和抗剪强度

采用高频感应加热装置制备了锌基合金钎料,并以纯铝为母材进行润湿试验,并采用该钎料分别对2A12铝合金、55%SiCp/Al复合材料进行钎焊,分析了合金钎料的显微组织、成分、熔化温度范围,并对合金钎料及钎焊接头的拉剪强度进行了测试。结果表明:自制锌基合金钎料主要由α-Al固溶体、η-Zn固溶体和共晶组织组成,熔化温度区间为361~398℃;锌基合金钎料在纯铝上具有较好的润湿性;使用锌基合金钎料钎焊铝合金,其钎缝组织为η-Zn相、细小的共晶组织、树枝状及块状的α-Al相;钎焊55%SiCp/Al复合材料,其钎缝组织由铝的共析组织、η-Zn相、条纹状共晶组织及细小的共晶组织组成;钎料、2A12铝合金钎焊接头以及55%SiCp/Al复合材料钎焊接头的抗剪强度分别为237,127,109 MPa。     

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...     

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。     

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...     

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.     

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.     

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.     

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.