提高钨合金铸铁磨球使用性能的研究

以我们新开发的钨合金铸铁磨球为基础，探讨了采用稀土变质处理以提高其使用性能的可靠性。研究结果表明，钨合金铸铁经适量稀土变质处理后，共晶碳化物内网状分布变成断网状分布，磨球冲击韧性显著提高，硬度略有上升，耐磨性明显改善，冲击疲劳寿命显著提高，磨球各项指标达到了甚至超过了高铬铸铁球的水平。     

变质处理及热处理对低合金白口铸铁组织和韧性的影响

通过三种变质剂对低合金白口铸铁进行了变质处理及热处理,从金相、硬度、冲击韧性等各方面进行了分析研究。结果表明:低合金白口铸铁可以通过变质处理来改变组织形态和分布,增强基体的连续性,提高材料的韧性;其中Zn+Ca-Si+Nb变质剂的变质效果最好,变质处理后再进行正火处理,能进一步改善性能。     

高镍奥氏体蠕墨铸铁活塞耐磨环的耐磨性与热疲劳性

研究了汽车用高镍奥氏体蠕墨铸铁活塞耐磨镶环的石墨形态、耐磨损及热疲劳性能的影响规律,为活塞耐磨镶环工件的合理选材提供试验依据。分析结果表明,针对高镍合金蠕化剂为0.4%-0.6%(Ni含量12%-15%)的蠕化效果良好,蠕虫状石墨形态较稳定,耐磨损及20-500℃热疲劳试验条件下,蠕墨铸铁镶环相比于原灰铸铁镶环的耐磨损及热疲劳性能更为优良。热疲劳试验中的微裂纹起源于石墨相边缘,主裂纹通常是沿着石墨和基体的界面扩展。     

变质处理提高钨渣低铬耐磨铸铁冲击韧性

研究变质处理对钨渣低铬（Ｃｒ≤２％）耐磨铸铁显微组织、力学性能及抗磨性的影响。结果表明，用含Ｖ、Ｘ和Ｂ的变质剂处理钨渣低Ｃｒ耐磨铸铁，可使其组织中的碳化物由连续网状粗大的板块状，转变为孤立细小的块状；冲击声望生提高１８０％；抗磨性提高８５％左右。     

钕变质处理对Mg-8Al合金显微组织和拉伸性能的影响

在Mg-8Al合金中加入不同含量(质量分数0~0.8%)的稀土钕对其进行变质处理,研究了钕变质处理对合金显微组织和拉伸性能的影响。结果表明:钕的加入改变了合金中初晶α-Mg的形态,使α-Mg树枝晶分支发达,但细化晶粒的效果不明显;加入钕变质前,合金的共晶组织为部分离异共晶,加入钕后的共晶组织为完全离异共晶,共晶组织由未变质时的连续网状分布变为断续分布;当加入钕的质量分数为0.4%时,合金的室温拉伸性能最佳,抗拉强度、屈服强度和伸长率分别较变质前提高了24%,11%和61%,此时的组织中开始有少量板条状稀土相Al11Nd3析出。     

热锻碾压轮稀土变质耐磨材料的应用

提出一种用于热锻碾压轮使用的新型稀土变质处理耐磨铸钢.研究了此材料的成分设计、金相组织、材料处理.生产实践表明,这种由稀土变质与热处理的复合作用构成的组织具有良好的性能,可作为热锻碾压轮替代材料.     

变质高碳硼钢的冲击磨料磨损行为研究

对高碳硼钢进行稀土变质处理,在MLD-10动载磨料磨损试验机上研究了变质高碳硼钢的冲击磨料磨损性能,并与高铬铸铁(Cr26)进行了比较.结果表明,适量稀土元素的加入,能有效提高高碳硼钢的耐磨性和冲击韧度;冲击功为2.0 J时,变质高碳硼钢的耐磨性不如高铬铸铁,冲击功为2.5 J时,变质高碳硼钢的耐磨性相当于高铬铸铁(Cr26);在磨损过程中,高碳硼钢的冲击磨损机制主要是塑性变形及疲劳剥落,切削所占的比例较小.     

HG80钢及其焊接接头的疲劳裂纹扩展

为适应大型工程机械焊接用钢需要，对低合金高强度钢HG80及其焊接接头的疲劳裂纹扩展速率进行了研究。结果表明，疲劳裂纹扩展速率对钢板的轧制方向不敏感，焊缝及热影响区疲劳裂纹扩展速率明显低于基材。在排除焊接残余应力导致的裂纹闭合效应后，焊缝及热影响区疲劳裂纹扩展速率与基材相当。     

Q690ZM中锰钢的焊接冷裂纹敏感性

采用Ar-CO2气体保护焊通过最高硬度试验和斜Y型坡口焊接冷裂纹试验,研究了Q690ZM中锰钢的焊接冷裂纹敏感性.结果表明:当焊接热输入由10 kJ·cm-1增加至20 kJ·cm-1或预热温度由20℃升高至200℃时,中锰钢焊接热影响区的显微硬度均略微降低,最高硬度均高于430 HV,焊接冷裂倾向严重;当焊接热输入为15 kJ·cm-1,预热温度由100℃升高至200℃时,斜Y型坡口焊接裂纹试验中试验焊缝的表面裂纹和根部裂纹逐渐消失,断面裂纹率降低至9.09％.为防止冷裂纹的产生,中锰钢焊前必须进行150～200℃的预热,并进行相应的焊后热处理;粗晶热影响区中粗大的马氏体板条晶体学取向差小,大角度晶界密度低,抵抗解理裂纹扩展的能力弱,因此焊接冷裂纹萌生后沿紧邻熔合线的粗晶热影响区扩展.     

碳含量及复合变质处理对白口铸铁组织和性能的影响

通过在铸造过程中对熔体进行复合变质处理,制备了变质白口铸铁,采用金相分析、碳化物定量分析、硬度测试和冲击韧度测试等研究了碳含量(2.2%~3.2%)及复合变质处理对白口铸铁组织和性能的影响,并研究了碳含量对复合变质效果的影响。结果表明:随着碳含量的增加,白口铸铁的显微组织由珠光体+离异共晶状渗碳体向少量珠光体+大块连续的莱氏体转变;通过复合变质处理可以有效改善碳化物的形态与分布,碳化物变得孤立、分散,部分网状结构消失,但随着碳含量的提高,复合变质效果变差;经过变质处理后,白口铸铁的硬度和冲击韧度都有所提高。     

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。     

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.     

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.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...