弹性接触问题的位移-力法有限元解法研究

本文根据接触状态下的有限元基本方程,通过对定解条件、约束条件的分析应用,得出了仅与接触点有关的定解方程。 运用所编制的电算程序对某柴油机副连杆销及孔在最大载荷下的失圆变形进行了计算。通过采用空心及实心销两种简化模型计算得出了实际副连杆销的失圆变形范围。     

Global cutting-path optimization considering the minimum heat effect with microgenetic algorithms

This article considers microgenetic algorithms (GAs), which explore in a small population with a few genetic operators, for cutting-path optimization problems. The major difference between GAs and simple genetic algorithms (SGAs) is how to make a reproductive plan for an improved searching technique because of population choice. It is shown that GAs implementation reaches the near-optimal region much earlier than the SGAs approach, and the GAs give a better solution than simulated annealing (SA). The main objective was to determine what temperature distribution can be obtained from the solution of a travelling distributed heat source. The solution of the travelling heat source on nested raw plate provides information about the vertices of each nested part of the raw plate. From the fact that the initial temperature at a piercing point strongly depends on the heat flow which stems from the previous cutting contour, the temperature of all piercing points must be lower than the critical temperature after each cutting of the components of a part. The critical temperature is identified as the mechanical melting temperature of steels. A heuristic back-tracking method is introduced to find the near-optimum cutting path considering the minimum heat effect on deformation. The heuristic back-tracking method is incorporated with the GAs.     

Digital exchange of design models between marine equipment libraries using hybrid neutral formats

The selection of marine equipment is a time-consuming process for a ship outfitting designer. The inefficiency originates from the paper-based exchange of design information between shipyards and equipment manufacturers. We propose a method to exchange equipment models for electronic commerce. Shipyard practices were investigated to find out how the outfitting CAD library is being used. We also surveyed international standards for the exchange of digital equipment models, and analyzed the macroparametric methodology. We propose a hybrid method to represent the geometric information using STEP AP203 or the macroparametric method. The nongeometric information is defined according to the Parts Library (PLIB) standard. We implement a pilot system and test it with a ship design data set. The equipment model proposed can be used in the design process with heterogeneous shipbuilding CAD systems. The equipment model can improve the design and purchase process in shipyards.     

砂卵石地层台阶法施工隧道围岩-支护结构应力应变特性三维离散元分析

为了解砂卵石地层隧道围岩和支护结构的应力应变特性，以青海循隆高速公伯峡隧道为依托，借助PFC3D离散元软件对公伯峡隧道穿越砂卵石地层进行三维模拟，重点研究以密排短管棚预支护为根本前提，以三台阶预留核心土为施工方法的砂卵石地层围岩和支护结构的应力应变特性，并与现场实测进行对比分析。研究结果表明： 隧道台阶开挖时，围岩应力集中范围逐渐从拱顶过渡到拱腰，直到拱脚，对应的塑性区范围不断扩大，且密排短管棚对塑性区的发展有一定的“遮拦效应”； 围岩横纵向变形规律一致，主要是向隧道临空面产生收敛变形，且密排短管棚形成的梁拱效应限制了掌子面前方位移发展； 2种方法得到的初期支护变形规律一致，均呈阶段性变化，拱顶下沉累计值大于周边收敛累计值，且两者的最终变形量均满足规范限值要求。     

深长桩荷载-位移曲线计算研究

近年来，城市及交通建设发展迅速，随着上部结构荷载的增大及容许沉降的减小，深长桩的应用越来越广泛。深长桩的力学性态分析成为桩基础研究中一个非常重要的组成部分，桩顶荷载一位移曲线是桩基础设计的核心内容。     

天津富民桥锚碇及箱梁过渡段构造施工

天津富民桥主桥为单塔空间索面自锚式悬索桥结构,介绍该桥主跨自锚式锚碇、边跨重力式锚碇及钢-混凝土过渡段的施工特点以及根据现场实际情况采取的有效措施.     

CFC复频电导法与TEM瞬变电磁法在某隧道中的应用对比

CFC复频电导法与TEM瞬变电磁法是我国目前较为先进的隧道超前探水技术。以CFC与TEM在我国某铁路隧道中的应用为例,简述CFC与TEM的方法原理,并结合开挖实际情况进行对比。试验对比表明,CFC探水技术抗干扰能力更强,探水预报结果更为准确,特别是在电磁环境复杂的隧道。     

复杂电磁环境下装备指挥效能评估分析

应用模糊综合评判法,通过定性评估与定量评估相结合的分析方法,对复杂电磁环境下的装备指挥效能评估进行了研究.针对复杂电磁环境下装备指挥的特点,设计了装备指挥效能评估指标体系模型,通过分析计算得出的结果表明,模糊综合评判法应用于复杂电磁环境下装备指挥效能评估是可行的.     

沥青混凝土热铺层厚度测量仪设计

针对在公路养护与沥青混凝土路面摊铺过程中,沥青混凝土的厚度控制对施工成本、路面平整度、路面质量及验收结果的影响,设计了一种能够精确测量沥青混凝土热铺层厚度的实用新型厚度测量仪,克服了目前公路工程施工中沥青混凝土热铺层厚度测量技术中的缺点与不足     

牌楼长江大桥“梁重转移”法施工钢箱梁临时锁定区域受力优化

牌楼长江大桥主桥为主跨730m的双塔混合梁斜拉桥,主跨扁平钢箱梁采用桥面吊机整体吊装、悬臂拼装法施工,施工中采用“梁重转移”技术将待拼装节段与已安装节段分2次进行临时锁定,并提出采用特制的压力调节装置调节该区域受力。为分析该装置对临时锁定区域的受力调节效果,采用ANSYS软件建立钢箱梁节段模型,模拟施工中临时锁定区域的压力调节过程,分析压力调节前、后临时锁定区域的受力及变形,并对实际应用效果进行对比分析。结果表明:压力调节装置对临时锁定区域的水平受力优化效果明显,对临时锁定区的相对高差影响不明显;该压力调节装置的实际应用效果较好。