Fatigue Failure of Ductile Iron Crankshafts

Abstract

Automobile crankshafts can be produced as either steel forgings or ductile-iron castings. In the latter case, because of the high structure-sensitivity of fatigue strength, mechanical test requirements must be very specific. A detailed investigation of two series of crankshafts produced from pearlitic nodular-graphite iron, grade SG 60, is described. Normal tensile tests and microstructural examinations were supplemented by determination of fatigue life and fatigue limit. Fatigue tests under axial bending conditions were carried out on segments taken from two series (I, II) of machined crankshaft castings. Satisfactory bending moment and performance data were obtained for one series of samples. In the other series, sub-surface microporosity in the cast structure was exposed during subsequent machining and led to premature fatigue failure after less than 2 × 10⁵ cycles of testing.     

永存三叉动脉伴发脑血管性病变及其他脑部疾病

永存三叉动脉（PPTA）是成人最常见的一种永久性颈内动脉和基底动脉之间的异常吻合，是一种较罕见的脑血管变异。PPTA经常伴发脑血管性病变，并且可引起三叉神经痛，动眼神经、外展神经麻痹，蛛网膜下腔出血等症状，与临床关系较为密切。本文对１９８３年至今中英文文献报道的１１６例PPTA伴发脑血管性病变及其他脑部疾病的病例进行总结。     

特殊动脉导管未闭的介入治疗

目的分析特殊动脉导管未闭（PDA）的介入治疗方法，提高介入封堵的成功率及安全性。方法根据造影显示PDA形态及临床特点，选用合适封堵器和治疗方法，术后２４h、１、３、６个月时以心脏超声随访评价疗效。结果特殊类型PDA２３例，其中:①形态特殊型１２例，包括细小型５例，４例成功，１例５F导管无法通过PDA放弃介入治疗；粗大型３例；动脉瘤型２例；特殊投照体位２例，均成功封堵。②合并其他畸形２例:合并右位主动脉弓１例，合并右位心１例，均成功封堵。③合并重度肺动脉高压８例，６例成功。④外科术后再通１例，未封堵。结论特殊PDA采取不同的诊疗策略，大多可顺利完成介入封堵术     

Kontextbasierte Kooperation für mobile Geschäftsanwendungen

Realistic requirements of mobile business applications often exceed the capabilities of their respective local environments. In order to overcome such restrictions of specific mobile devices, services, and resources, this contribution introduces the concept of context-based cooperation. It is based on mobile processes which enable applications to cross boundaries of individual systems and thereby allow combining both mobile and stationary resources in order to realize highly dynamic individual applications. This contribution presents an approach for realizing context-based cooperation built upon on a respective context management infrastructure and execution environment. It also identifies specific requirements and proposes related enhancements for mobile business applications.     

Verbundstrangpressen von Titan‐Aluminium‐Verbindungen

Rod Extrusion of Titanium‐Aluminum Composites The combination of different metals enables the processing of materials with local optimized properties. Thus, the production of metallic composites is associated with high standards in manufacturing technologie. Focus of the following investigations is the rod extrusion process of titanium‐aluminum‐composites. Besides the mechanical properties, the formation of the bonding zone and the mechanisms of adhesion in the bonding zone were investigated. The influence of specimens’ preparation and of different coatings used improve bonding were a matter of particular interest. Whereas coatings of copper or nickel inhibit the formation of a strong bonding due to the formation of oxide layers, sealed titanium cores can reach a mechanical strength of up to 100 MPa after rod extrusion. Compared to other joining technologies, an impairment of the base metal via formation of heat affected zones, pores or grain coarsening does not occur.     

靶血管内留置导管持续化疗患者的护理

目的减少保留导管持续化疗患者留置导管期间的相关问题的发生。方法①加强对患者的宣教、指导；②规范护士护理操作；③制定合理的护理常规、流程；④护士要加强日常护理中的观察、巡视、记录。结果通过对留置导管患者的各种问题的分析及临床观察，总结了护理经验。结论合理、有效的护理可以减少留置导管持续化疗患者留置导管期间相关问题的发生。     

围肝移植并发症介入治疗的认识

大部分肝移植术后并发症与介入放射学有关。动脉和静脉并发症有较明确的介入治疗模式，胆道并发症一直是治疗的重点和难点。随着对介入放射学认识的深入和操作技术的提高，在经皮经肝胆道引流、内镜鼻胆管引流基础上围绕胆道并发症进行的系列治疗，能解决部分患者的黄疸并最终治愈，但对另一些患者胆道引流仍是主要的姑息性治疗手段，并将最终伴随患者一生。围绕胆道并发症制订肝移植术后并发症的临床治疗指引是亟需解决的课题。