Ductile crack initiation behavior in steels with compressive prestrain

It is well known that compressive prestrain reduces ductility in steels. On the other hand, it has also been found that high stress triaxiality reduces equivalent plastic strain at the onset of ductile fracture. In this research, plate specimens and notched bar specimens, which were prestrained in compression with bending, were used in reversed bending tests, and the effect of compressive prestrain on ductile crack initiation in steels was investigated. It was found that small ductile cracks occurred from the microscopic wrinkles which were formed on the concave surface with compressive prestrain. The critical relationship between stress triaxiality and equivalent plastic strain at ductile crack initiation was investigated by finite-element analysis. It was found that ductile crack initiation in steels with compressive prestrain can be estimated qualitatively by the relationship between stress triaxiality and equivalent plastic strain.     

舰船能量管理系统技术研究

随着全电力舰船的发展,能量管理系统的应用逐渐为人所重视.本文介绍了舰船能量管理系统(PMS)的功能模块、信息流、网络结构.并着重介绍了PMS对推进系统的管理.     

舰船科研院所知识型员工绩效考核优化

通过对舰船科研院所知识型员工绩效考核存在问题分析,提出了要按照知识型员工的特点,着力实现绩效考核向绩效管理转变,推进绩效考核与科研院所战略导向的有机结合,确保个体绩效与团队绩效相互协同的优化思路.同时,从建立合理的考核指标体系、设计科学优化的考核量表、注重绩效考核全过程沟通、实现考核与激励的有机结合等四个方面,阐述了知识型员工绩效考核优化的重点.     

取货看板在船厂车间的应用研究

看板管理是准时生产的一个重要工具,而取货看板是其主要内容之一,因此,着重研究了取货看板,列举了取货看板在船厂车间的应用例子,提出了推行取货看板的方法和要求,从而使造船达到准时生产,提高经济效益.     

大型邮轮安全管理系统设计

为满足安全返港理念下安全管理系统的设计要求,以安全管理系统设计过程中适用的法规及相关设计要求为基础,分析所有与邮轮安全相关联的接入业务,结合安全管理系统处理流程,提出安全管理系统架构设计方案.设计冗余的配电及通信网络方案,并分析安全返港场景下设计方案潜在的损失情况.     

Application of analytical model in the prediction of dynamic responses and fatigue damage of flexible risers: Part II – Dynamic analysis of flexible risers in large-scale domain using a direct moment correction method

In recent years, the dynamic responses of flexible risers have been the focus of many researchers. Most flexible risers undergo a substantial level of irregular motion from environmental loadings, which involves a continuous slip of helical wires. The slip of helical wires especially leads to a hysteretic effect by reducing the bending stiffness, making it hard to predict the dynamic responses of flexible risers. The current study, as an extension to Part I, presents a new large-scale dynamic analysis method for flexible risers. The suggested method creates a large-scale model for the dynamic analysis that considers a geometric and bending nonlinearity of flexible risers. The kinematics of each beam element is formulated based on a Green-Lagrangian strain and the interaction with the seabed, providing a realistic analysis of flexible risers. In particular, the current study introduces a direct moment correction method that modifies the internal force vector using an improved analytical model. The improved analytical model is assigned at each node of the large-scale model and estimates an accurate bending hysteresis curve considering the effect of shear deformation and varying tension. The suggested method corrects the bending moment and shear force of all beam elements based on the bending hysteresis curves obtained from the improved analytical model, by which a complex bending behavior of flexible risers is reflected in a large-scale domain. As a result, this study achieves a more accurate prediction of the dynamic responses and fatigue damage of flexible risers. A new dynamic analysis program, called OPFLEX, is developed herein based on the suggested analysis method. Using the developed program, the current study conducts several numerical investigations to identify the effect of the shear deformation and varying tension. Consequently, it is confirmed that the shear deformation of internal layers reduces the fatigue damage of helical wires by delaying the increase of internal stress. It is also identified that the effect of varying tension deteriorates the fatigue life of flexible risers through a continuous change of contact pressure during bending.     

振动状态下桥面铺装采用商品混凝土施工出现的裂缝问题研究

通过近几年石家庄-安阳高速公路处理单板受力桥梁的施工,对桥面铺装在通车振动状态下采用商品混凝土施工出现的裂缝问题进行分析,找出产生裂缝的原因,总结和制定了行之有效的措施,为确保桥面铺装的施工质量奠定了良好基础。     

某高端商用车车架裂纹分析与解决方案

汽车车架是汽车的核心部分之一,它承载各种载荷,也是汽车能安全行驶的重要保证。本文就某新开发的高端商用车车架由于结构更改和载荷变化在试验中出现裂纹进行了分析。经过静力学分析、基于实际工况下的有限元仿真分析,得到了出现裂纹的主要原因。同时根据实际情况采取了增加横梁、减少通孔等措施。经过实验检验和用户反映,车架上的裂纹不再出现,整车安全性和可靠性得到保障。     

矩阵项目型管理在整车研发过程中的解析及优化

汽车行业的竞争日益激烈,新车型层出不穷,如何高效地推动新车型的研发进度,成为现今汽车研发机构思考的一大难题。通过对汽车整车新产品研发项目管理现状的调研,发现主要有3种管理模式,文章结合整车项目管理的理论与实践,阐明某一车型研发的一种管理模式——矩阵型,并对其优点和缺点进行了阐述,同时针对矩阵型管理模式不足之处进行成因分析,提出针对性的解决措施。     

浅析建设项目供应商的选择及存在问题

在建设项目管理的全过程中,供应商的考察和选择是非常关键的环节之一。供应商的选择直接影响到项目的质量、成本和进度。目前项目的业主及从事项目管理的单位对项目供应商的选择都有一定的重视,而且制定了相关供应商考察和评价的工作流程。该文主要分析了建设领域对供应商选择的几种方法并对其中存在的不足提出了自己的看法。