基于刚塑性有限元法和最优化方法的锻件预成形设计系统及其应用

将正向有限元数值模拟和最优化方法相结合,以Digital Visual Fortran为编译平台,开发了基于FEM和最优化方法并与锻件充填缺陷相关的预成形设计系统,并对程序实现过程中的若干关键技术进行了探讨.应用所建立的锻件预成形设计原型系统,对FGH95合金涡轮盘锻件开式锻造过程进行预成形坯料及模具设计,取得了满意的结果.     

锻造技术课程教学改革

锻造技术是是根据金属塑性成形原理,研究利用各种锻造工艺有效生产锻件的技术科学,具有较强的理论性和实践性。从合理安排教学内容,改进教学方法,引入思维导图,运用比较法以及计算机数值模拟技术等方面,对锻造技术课程教学进行了改革。     

大型长轴类GH4169合金锻件的成形工艺

介绍了大型长轴类GH4169合金锻件的成形工艺,分析了锻件锻造成形存在的困难.在工艺制定及模具设计上采用特殊优化工艺和相应的措施,成功地锻造了外形尺寸和各项性能均合格的锻件,为同类产品的锻造生产提供了参考依据.     

纯钼的多向锻造数值模拟及实验研究

采用DEFORM–3D有限元模拟软件对纯钼坯体多向锻造大塑性变形过程进行数值模拟,结合锻造实验,研究了变形温度、锻造压下量及锻造工步等对锻件等效应变及其均匀性分布的影响,优选出了反复拔长–镦粗的锻造工艺.研究发现,随着锻造的进行,等效应变分布趋于均匀,在第三次拔长过后,锻件心部等效应变值可达到3.75以上,锻件整体相对...     

锻造成形数值模拟中的关键技术

锻造成形机理非常复杂,数值模拟是目前塑性成形分析最有效的方法.本文介绍锻造成形数值模拟基本理论,对几项直接影响计算精度及效率的关键技术进行了分析和探讨,包括模具结构描述、动态摩擦条件、动态边界识别以及网格的划分与再划分,并给出了利用DEFORM软件进行数值模拟的实例.     

等温锻造工艺对GH4720Li合金盘锻件组织的影响

采用物理模拟得到了GH4720Li合金的热变形特征,同时利用数值模拟研究了不同锻造工艺对GH4720Li盘锻件温度场、应力场、设备载荷等参数的影响规律,并通过实际锻造Ф150mm的GH4720Li合金盘锻件进行了验证。结果表明,GH4720Li合金变形组织对温度、应变等参数非常敏感,采用普通锻造会造成温度应力分布不均,...     

中国大型铝合金等关键件模锻工艺取得重大进展

日前,作为"高档数控机床与基础制造装备"国家科技重大专项的重要内容之一,由中国第二重型机床集团公司承担的"大型关键件模锻工艺技术"课题研究取得了重大进展.该课题重点围绕大型航空模锻件热模锻近净成形技术,结合正在建设的800MN大型模锻压机,开发出复杂精密航空锻件的近净成形新技术,解决了大型模锻工艺基础共性技术和关键技术问题.突破了大型钛合金、铝合金锻件的整体成形技术,在航空用典型钛合金、铝合金、高强钢的基础数据测试,锻造成形过程的无网格法模拟技术研究,钛合金典型结     

Deform在锻造中的应用

介绍了Deform软件在锻件锻造成形过程的选型和应用，并通过实例分析介绍了该软件在网格划分、应力和应变分析、点的跟踪等方面的应用，并提出了其存在的问题。     

锻造对喷射成形Al-8.5Fe-1.3V-1.7Si合金组织和性能的影响

采用喷射成形和锻造工艺制备了Al-8.5Fe-1.3V-1.7Si合金．通过金相、扫描电镜和力学性能测试等实验，对锻件组织和性能进行了分析。结果表明：“闷车＋包套锻造”工艺对喷射成形Al-8.5Fe-1.3V-1.7Si合金坯件的致密化效果好于用自由锻造和包套锻造致密化的合金，采用该工艺可以制备出组织和性能优良的耐热铝合金材料。“闷车＋包套锻造”锻件在室温下的抗拉强度（σb）达到407MPa，屈服强度（σ0.2）达到344MPa，延伸率（δ5）为7．6％；在315℃，锻件的σb，σ0.2，σ5分别为222，216MPa，7．2％。     

叉形铝合金锻件锻造工艺研究

介绍了2A50铝合金叉形锻件的生产工艺,针对叉形锻件成形特点,确定了锻造生产工艺,经生产验证,成功的生产出外形尺寸、组织性能均合格的2A50铝合金叉形锻件,对类似模锻件的生产工艺编制及锻模设计有一定的参考意义.     

转炉炉壳热应力分析

根据实际转炉建立实体模型。以有限元为手段,考虑了炉衬和炉壳材料的物性参数随温度变化的特点和炉衬与炉壳之间膨胀间隙,计算了转炉炉壳在温度载荷和炉衬膨胀压力同时作用下的热应力。所得结果可为转炉炉壳设计提供依据。     

焦炭热性能指标意义浅析

通过对焦炭在高炉内的历程及其变化规律的剖析,阐述焦炭热性能指标的意义,形象地把焦炭在高炉内的损耗分为三部分(M1,M2,M3)。指出M2对焦比及焦炭价格有一定的指导作用。     

Results of treatment of cancer of the cardia

Cancer of the cardia is traditionally discussed with cardiac cancer of the lower portion of the esophagus and upper gastric cancer invading the esophagus, and the specific characteristics of cancer of the cardia have never been clearly defined. We reviewed the outcome of 172 patients with adenocarcinoma of the cardia who had undergone radical surgery between 1949 and 1994 in the Division of Gastrointestinal Surgery of the Cancer Institute Hospital. The centers of the tumors were located within 2 cm above and below the boundary between the esophagus and the stomach, and their longitudinal diameter was less than 8 cm. We divided the patients into an early period (1949-1979; n = 79) and a late period (1980-1994; n = 93), and focused on the historical transition. There were no differences in patient gender or histology between the two periods. However, the late period was associated with fewer cases of esophageal invasion and shorter longitudinal diameter, as the age of the population advanced. The number of advanced cancers such as the localized and infiltrative type had decreased, and early cancer and early clinical stage had become more common, but despite the fact that the number of early cancers had increased, extended dissection, such as thoracic and paraaortic lymph node dissection, was performed more frequently. By clinical stage, the long-term outcome markedly improved in Stage I patient in the late period, and tended to improve in Stage II and III patients. This appears to have been attributable to the prevention of micrometastasis by extended dissection, although the number of early cancers is another major potential cause. There were no differences in the outcome of Stage IV patients between the two periods, and further advances in multimodality therapy must be awaited. The range of resection is basically proximal gastrectomy, and if there are adequate indications, the prognosis is favorable. In view of the status of lymphatic flow and lymph node metastasis, and long-term results, lateroaortic lymph node dissection is important. Since the number of early cancer patients has been increasing, if intraabdominal recurrence is prevented, intrathoracic lymph node dissection will contribute greatly to the outcome of such patients.     

The effect of amount of possession of the trait of hostility on accuracy of perception of hostility in others.

Some theories of personality hold that an individual's perception of others is influenced by his own personality characteristics; more specifically, that a trait of low social value will be projected more into others, and that insight into the possession of these characteristics reduces this distortion. These 2 hypotheses were tested by having a group of college students rate each other (including themselves) on degree of friendliness or hostility. Agreement with group rating about self yielded the insight score. In general, the hypotheses were supported; the "friendly" Ss were most accurate in their perception of others, and insight was positively associated with accurate perception. From Psyc Abstracts 36:04:4HL16M. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of rates of infection of two methods of emergency ventricular drainage

The rates of infection of two methods of external ventricular drainage in use at Atkinson Morley's Hospital--namely, (a) percutaneous drainage with Rickham reservoirs and (b) tunnelled ventriculostomies--were compared in this retrospective review. Percutaneous drainage of CSF with Rickham reservoirs was associated with a 27% rate of infection as identified by positive microbiological cultures; tunnelled ventriculostomy catheters had a 10% infection rate. The difference in the infection rate between the two methods was statistically significant (P < 0.015). Other variables examined, including the age and sex of the patients and the reasons for ventricular drainage, were not associated with an increased rate of infection. Most infections from either method were caused by a coagulase negative staphylococcus. The average duration of ventricular drainage before identification of positive cultures was 5.7 days for Rickham reservoirs and 6.0 days for ventriculostomies.     

浅析《野草》的版画特征

鲁迅先生一生热爱美术作品,对版画中木刻兴趣尤甚.<野草>作为其"写心之作",亦呈现出一些与木刻版画一致的审美特征:一是具有木刻版画的色彩特征,多对比、多冷色,有阴郁的美感;二是具有木刻版画的力度特征,环境描写、人物刻画处处刀锋毕现,遒劲有力,有一种"力之美".     

四辊破碎机车刀架的改造

针对四辊破碎机车刀架车削中存在的几个问题,详细介绍了电动车刀架的结构和工作原理,建立主要设计参数的数学表达式,并进行适当的分析。改造后,这种电动车刀架运行平稳、可靠、方便、省力,取得了预期的效果。     

Effect of antibiotics of chemotaxis of human leukocytes

The effect of 20 different antibiotics on chemotaxis by human neutrophils was studied. Human leukocytes incubated with chloramphenicol, rifampin, sodium fusidate, and tetracyclines in vitro showed markedly depressed migration. The mechanisms by which these antibiotics affect leukotaxis are discussed.