钢材表面涂漆前的喷丸清理(三)

七、表面清洁度和表面粗糙度 1.表面清洁度喷丸清理的主要目的是根据不同涂层系统的要求使钢材表面获得相应的表面清洁度,以最大限度地发挥涂层的防护能力。钢材表面喷丸处理后所能达到的表面清洁程度取决于所使用的磨料、清理时间和其他一些工艺条件。表面清洁度的评定难以用文字表达,故各国通常都以瑞典的《涂漆前钢材表面清洁度标准照片》(SIS 055900)作为依据,采用直观比较法作为评定清洁度等级和解决争议的手段。     

2006年我国港口国监督检查和我国国际航行船舶履约情况

2006年．中国海事局港口国监督检查外籍船舶3986艘次，发现并纠正缺陷24234项，滞留缺陷严重的船舶315艘。与2005年相比，单船缺陷率由5.3个增加到7．1个，滞留率增加到7．9％。     

A review of the effect of a／W ratio on fracture toughness （Ⅰ）—experimental investigation in EPFM

Many experimental investigations have previously been performed and recently done on different shipbuilding structural steels where the specimens size and crack depth/specimen width (a/W) were varied. A series of interesting results have been gained. It is worthwhile to have a review on the effect of a/W ratio on fracture toughness, and further theoretical analysis is necessary. In this paper, experimental work in elasticplastic fracture mechanics (EPFM) was discussed. Tests had been carried out on 10 kinds of strength steels. Results showed that J _i and δ₁ values increased with decreasing a/W when a/W<0.3 for three-point bend specimens and that shallow crack specimens which have less constrained flow field give markedly higher values of toughness than deeply notched specimens. However, for a/W>0.3, the toughness was found to be independent of a/W. Slip line field analysis shows that for shallow cracks, the hydrostatic stress is lower than that from standard deeply cracked bend specimen which develops a high level of crack tip constraint, provides a lower bound estimate of toughness, and will ensure an unduly conservative approach when applied to structure defects especially if initiation values of COD/J-integral are used.     

含挠率的标量——张量引力理论的暴涨宇宙模型

本文从有挠率的Brans—Dicke引力理论出发,并假定在足够早期宇宙是以标量场为主,我们求得了Robertson—Walker宇宙模型的解析解,并讨论了两种暴涨的存在。     

浅析CP-3型列尾装置使用中存在的问题及解决办法

1 原因分析 CP-3型列尾安全防护装置(以下简称列尾装置),是用于无守车货物列车的安全装置.投入使用以来,由于其查询信号及接收语音信号的功能都是借助无线列调机车电台完成的,因而机车电台的一些固有特性使得使用中的列尾装置对其他机车电台形成干扰.     

轮胎纵向附着特性数学模型

本文提出两种由试验数据建立轮胎纵向附着特性数学模型的方法，介绍其具体算法，对其精度和适用范围进行了比较。     

型砂紧实率自动控制的研究

型砂紧实率是反映铸型用砂含水量的一个重要指标.本文对与不同紧实率要求的铸件型砂相关的自动调整与控制系统从理论上进行了具体的分析研究,并成功地应用于生产实践.