基于物元模型分析方法的路面状况综合评价

针对目前路面状况等级评价方法中存在主观影响因素过多、权重不确定性等问题, 根据影响路面状况的路面状况指数、行驶质量指标、路面强度系数、路面抗滑能力系数等主要指标, 提出了一种基于物元模型的路面状况等级综合评价方法。以路面状况等级、评价指标及其特征值构造物元模型, 并根据计算出的综合关联度实现对各路面状况等级的综合评判。实例表明该模型能准确地反映路面状况, 是可行的, 有一定的推广应用价值。     

车桥回转件CAPP系统中零件信息的输入

零件信息输入是CAPP系统中的一个关X技术问题。本文介绍了一个基于AUt0CAD环境下开发的零件信息输入方法一特征形京法，对商品化CAD环境下实现CAPP信息输入作了一些探讨。     

The intelligent use of finite element methods

The structural analysis based on application of numerical methods used in the solution of complex structural problems, when applied correctly, is a powerful tool leading to rational structural design of ships. This paper discusses the practicalities of its application and indicates that in order to achieve the stated objective, the following are essential pre-requisites: a) full understanding of the problem; b) ability to solve the problem using currently available methods; and c) ability to interpret the results of the analysis correctly. Whilst there is still a lot of discussion on whether the structural analysis represents a structural design or a structural verification tool, the view expressed in this paper is that the structural analysis should mainly be used in the latter context. This means that a sound engineering solution ought to be established in the first phase of the analysis and used as a basis. The final results will then only be used to perfect the structural detail and modify the areas where rapid stress gradients occur. Any other approach would invariably require repetitive, time consuming and costly iterations which under normal circumstances may prove to be counter-productive. This paper presents a few examples of practical application, the methodology of achieving the solution and the way of interpreting the results.     

长江电子航道图航道要素脱密处理方法

长江电子航道图中涵盖了多种要素及其属性,是指导船舶安全航行的必备重要信息.但根据相关保密法律法规中的规定,部分要素及其属性属于涉密内容,不能对外公开.为了既保证数据的规范性又保证数据的安全性,在充分分析相关保密法律法规和航道要素及其属性的基础上,对长江电子航道图航道要素密级及脱密处理方法进行研究,规定涉密要素及其属性的取舍情况.在保证对外发布数据安全性的同时,确保长江电子航道图能够正确指导船舶用户安全航行.     

南海深水油气开发海洋工程方案选择策略探讨

深水油气开发的关键是基于油藏数据进行海洋工程方案的选择和确定,建立油藏、流体特性和海洋工程方案关键参数之间的联系是解决油藏和油气井的特性参数的不确定性的良好对策。深水油气开发海洋工程方案要素包括油藏地质和分布、油藏流体属性、钻完井及修井特性和场址特征等。海洋工程方案选择策略是确立功能需求、评价技术约束条件、进行生命周期的经济价值的风险比较和确定作业者的战略主导和其他决策的基本策略。南海深水油气开发海洋工程方案选择策略可借鉴美国墨西哥湾等深水开发经验,选择适合南海海域的浮式平台和外输方案。     

VIV response of a flexible cylinder with varied coverage by buoyancy elements and helical strakes

Many significant engineering challenges have emerged as the petroleum industry has moved their field development and production activities into increasingly deeper water depths. The design of deepwater marine risers presents the combined challenges to minimize top tensioning requirements, mitigate any flow-induced vibrations, and if possible to increase the expected fatigue life of these slender structural members. As part of the design process to achieve these goals external buoyancy modules and strakes have been employed. To gain insight into the complex multi-mode response behavior a recent experimental study was performed and the analysis of selected data sets is presented. In the experiments a horizontal cylinder with a length to diameter ratio of 263 was fitted with a variety of strake and buoyancy element configurations. The models were towed at uniform speeds ranging from 0.4 to 2.0 m/s and fiber optic strain gages were used to measure both in-line and cross-flow strain response. The resulting time series information was processed utilizing the method of time domain decomposition formulated for strain data input and the introduction of modal assurance criterion to resolve the modal strain information that included frequency, mode shape, and critical damping ratio information. The pre-tensioned cylinder without appendages was used as a base case and the results were basically consistent with expectations. In the case of 0.8 m/s low-tension test, multiple closely spaced non-overlapping peaks were observed in both in-line and cross-flow directions and were identified as being of the same mode with mode shapes distorted away from purely sinusoidal behavior. The test data for the 100% coverage by helical stakes demonstrated the effectiveness of that suppression device over the range of current velocities investigated. The most interesting case was that of a staggered combination of helical strakes and buoyancy element whose total for each type of coverage was equal. This effective asymmetric VIV suppression approach is presented and discussed in detail.     

桩板结构加固病害库岸挡墙稳定性研究*

采用Plaxis有限元分析软件,研究桩板结构加固病害库岸挡墙的稳定性,并定量分析了库岸挡墙整体稳定安全系数随水位的变化规律。结果表明采用桩板结构加固病害库岸挡墙能有效控制墙体变形,显著提高稳定安全系数。库岸挡墙的整体稳定安全系数并不随水位的升高一直降低,而是呈显著的下凹型,即在设计低水位和设计高水位间存在一个最不利水位,可以通过有限元方法进行搜索。该方法克服了因水位选择不当而错误确定挡墙最小安全系数的缺点,建议在重要水工结构计算中推广使用。     

基于土体弹塑性理论的复合桩基沉降特征有限元分析*

采用有限元软件,在考虑土的弹塑性及桩土接触特性的基础上,建立了复合桩基三维有限元模型。系统计算分析了在不同荷载P、桩长L、桩径d及桩间距S的条件下,复合桩基群桩基础的沉降及差异沉降的变化趋势,得到了可供设计参考的结论。     

某大型低速柴油机曲轴的全生命周期疲劳计算与分析

以大型低速柴油机曲轴为研究对象,在传统动力学计算的基础上,利用UG和ANSYS软件建立曲轴有限元计算模型,运用全寿命法对曲轴进行疲劳计算,获得曲轴的安全系数和疲劳寿命,提出改进危险区域疲劳强度的结构措施和工艺措施。     

铁道车辆橡胶弹性元件设计仿真与校验

通过详细介绍一种铁道车辆转向架用橡胶关节的结构设计与疲劳试验设计过程中运用虚拟样机仿真分析的技术手段,说明设计仿真中利用有限元仿真分析技术和实际试验相关联的方法确定产品结构参数;利用车辆系统动力学仿真分析技术和随机载荷统计分析技术确定产品的载荷条件和疲劳载荷谱,通过实际疲劳试验校验设计仿真的可行性和可靠性。