重型车辆变速器齿轮轮毂断裂失效分析及改进措施

针对变速器一挡主动齿轮在试验过程中发生断齿这一早期失效问题,进行了失效齿轮轮毂的化学成分检验、断口分析和金相组织形貌检测分析等失效机理研究.分析结果表明,花键槽圆角过小、轮缘厚度不足及齿根喷丸强化不足是造成失效齿轮轮毂异常断裂的主要原因.采用有限元建模进行失效齿轮的接触应力分析,并提出了改进措施.     

农用车发动机球墨铸铁曲轴断裂失效分析

采用断口分析、硬度检测、化学分析、金相组织检测等方法对球墨铸铁曲轴断裂的原因进行了综合分析.结果表明曲轴颈与曲臂圆角处光洁度差,原加工痕未磨削消失是疲劳断裂的主要原因.     

汽车半轴断裂失效分析

通过宏观分析、显微组织和断口形貌观察以及硬度测试等方法对汽车半轴的断裂原因进行了分析.结果表明,汽车半轴的断裂是由于拆换轴承不当导致半轴表面损伤产生裂纹源,后经反复的磨损及受力,其裂纹不断扩展,并最终断裂.     

石油钻铤开裂失效分析

一根直径为Φ159 mm的油田钻铤在使用时发生开裂,通过对失效钻铤进行化学成分分析、金相组织分析、SEM分析及力学性能测试等,研究了该钻铤的失效机制.结果表明:该钻铤失效属于疲劳断裂破坏,疲劳裂纹形成于钻铤内螺纹消失处最后1个～2个螺扣部位,该处存在较大应力集中,同时单位面积受力较大,应力状态复杂,使用过程中容易萌生疲劳裂纹,最终导致裂纹的贯穿.     

高压高速下摆线马达输出轴的疲劳寿命研究

BM系列摆线马达在各个行业运用潜力越来越显著,特别是高压化、小型化改进后的产品更受欢迎,但高压化技术推广过程中输出轴疲劳断裂的问题也相应增多。根据用户反应的情况,马达大致的失效情况为:键齿破坏、轴头断裂。为提高疲劳分析的效率与准确性,根据失效形式,结合国外先进的疲劳分析技术,以传统理论为基础,建立新的疲劳分析方法,对输出轴的失效进行分析。通过对比真实失效情况,验证新的疲劳分析方法的可行性,并且具有实际意义,可以为今后机械零件的可靠性研究提供参考。     

复合板封头开裂失效原因分析

通过宏观分析、微观组织分析和扫描电镜分析等方法分析了DN6200复合板封头开裂的原因.结果表明,不锈钢板双面焊中心连续分布的线型缺陷是DN6200复合板封头加工时开裂的一个重要源头;碳钢基材内部大量的空洞是过载断裂时大韧窝的来源,是造成材料组织不均匀的重要原因之一.     

副励磁机轴断裂失效分析

通过分析副励磁机轴断裂的宏观、微观组织形貌 ,得出该轴断裂的主要原因是夹杂物和其所受的附加弯曲应力 ,最好的改进办法是通过热处理或更换材质。     

泵轴失效的分析

本文通过电镜、金相显微镜、硬度仪、光谱仪等检测手段,对扬子石化炼油厂输送蜡油泵的断裂轴进行了检测,并对检测结果进行分析,结果表明泵轴断裂属疲劳失效.造成疲劳的主要原因是泵轴的倒角半径R值过小.为此,提出相应的改进措施,效果良好.     

压缩机高压气缸的断裂失效分析

应用断裂失效分析方法,对6MD32压缩机断裂高压气缸进行了形态分析（包括断口形态、裂纹形态和组织形态）、性能分析（包括机械性能、物理性能和化学性能）、材料成分和工艺分析,找出了裂纹扩展规律,确认了断裂性质。在此基础上,对断裂原因进行了分析,为解决高压气缸断裂提供了依据。     

350兆瓦汽轮机叶片断裂失效分析

通过金相、化学分析、透射电镜、扫描电镜及Ｘ射线衍射仪等分析手段对３５０兆瓦汽轮机叶片的失效进行了分析。结果表明,该叶片的失效是由于疲劳断裂而不是由于腐蚀环境下的疲劳断裂。     

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.     

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.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.