發(fā)布時間：2018-01-13 02:10

  本文關鍵詞：鹽霧環(huán)境下斜拉索應力腐蝕與腐蝕疲勞試驗研究　出處：《重慶交通大學》2015年碩士論文　論文類型：學位論文

  更多相關文章： 鋼絞線 腐蝕試驗 應力腐蝕 腐蝕疲勞 裂紋擴展速率

【摘要】：國內(nèi)外斜拉橋斷索事故以及頻繁地換索表明,人類在斜拉橋拉索損傷狀態(tài)評估和剩余壽命預測領域的研究還很不充分。斜拉橋拉索在服役期間由于腐蝕環(huán)境和復雜的應力共同作用會使其使用壽命大大縮短,并且在腐蝕介質(zhì)與交變應力下引起的腐蝕疲勞極易導致拉索發(fā)生無預兆的脆性斷裂,從而造成巨大的傷亡事故以及經(jīng)濟損失。如何排除上述的隱患成為當今各國科研人員研究的熱點。本文通過室內(nèi)鹽霧加速試驗,模擬沿海地區(qū)斜拉橋拉索遭受氯離子的腐蝕。通過對熱包聚乙烯護套的鍍鋅鋼絞線試樣進行不同的腐蝕時間以及不同加載狀況,來研究鋼絞線的腐蝕失重量、力學性能、斷口特征等變化情況,分析其產(chǎn)生的原因。本文還創(chuàng)造性地提出,對聚乙烯護套進行不同形式的破壞,進而分析不同破壞形式對鋼絞線腐蝕的影響。通過工業(yè)數(shù)碼顯微鏡與圖像處理軟件GSA-Image Analyser對腐蝕后鋼絞線進行觀察與分析,并測量蝕坑與裂紋尺寸,統(tǒng)計蝕坑密度。最后通過已有的研究,推導應力腐蝕與腐蝕疲勞下裂紋擴展速度的算法,并利用有限元軟件ANSYS對不同長度、寬度、深度的裂紋進行模擬分析。本文主要內(nèi)容如下:①通過試驗發(fā)現(xiàn),由于氧化產(chǎn)物的保護作用,試驗腐蝕中后期腐蝕速率呈下降趨勢,并且與自然環(huán)境下的腐蝕速率線性無關。②根據(jù)灰度直方圖所示,腐蝕時間相同的情況下,腐蝕程度表現(xiàn)為:無應力靜態(tài)應力交變應力。③受拉性能退化的原因主要歸于蝕坑的應力集中效應或截面削弱效應;但是,在腐蝕率相差不大的范圍內(nèi),蝕坑效應的隨機特性導致上述受拉性能的退化程度與腐蝕率沒有明顯的對應關系。④PE護套點破壞與裂紋破壞會引起鋼絞線孔蝕與縫隙腐蝕,且這兩種腐蝕在交變應力下腐蝕擴展最為嚴重。⑤影響鋼絲斷口形狀的因素有兩個,宏觀上表現(xiàn)為蝕坑的幾何特征,微觀上表現(xiàn)為珠光體團的排列方式。鋼絞線的極限抗拉強度是蝕坑的形態(tài)與蝕坑底部珠光體團的位向共同作用下決定的。⑥裂紋的深度是影響鋼絲抗拉強度以及屈服強度的主要因素,在相同荷載作用下,深度越深裂尖應力則越大;相反,長度與寬度越大,裂尖應力則越小。
[Abstract]:The cable-stayed bridge is broken cable accident and frequently changing cable shows that humans in the cable-stayed bridge cable damage condition assessment and remaining life prediction research is still not sufficient. Cable stayed bridge during service due to corrosion and the complex stress interaction will make the service life is greatly shortened, and the corrosion fatigue in the corrosive medium and under alternating stress caused by cable can easily lead to brittle fracture without warning, causing huge casualties and economic losses. How to eliminate the risks has become a hot topic in today's research. This paper through indoor salt spray test, corrosion of chloride ions in simulated coastal areas of cable-stayed bridge cable. For different etching time and different loading conditions through the strands of heat pack polyethylene sheath of galvanized steel, corrosion of steel strand of the weight loss, mechanical properties, The changes of fracture characteristics, analysis of its causes. The paper also creatively proposed, different forms of damage to the polyethylene sheath, and analyses the influence of different failure modes on the corrosion of steel strand. Through industrial digital microscope and image processing software GSA-Image Analyser on the corrosion of steel strand were observed and analyzed, and the measurement of corrosion pits and crack size statistics, etch pit density. Finally through the existing research, corrosion and corrosion fatigue crack should be derived under the expansion speed algorithm, and the finite element software ANSYS of different length, width, depth of the crack were simulated and analyzed. The main contents of this paper are as follows: through the experiment, the protective effect of oxidation products. Corrosion tests in the late corrosion rate decreased, and the corrosion rate has nothing to do with the linear natural environment. According to the histogram shown, etching time Under the same conditions, the degree of corrosion performance: stress static stress alternating stress. The tensile performance degradation is mainly attributed to the pit stress concentration effect or weaken the effect of cross section; however, in the range of corrosion rate similar to that of the random characteristics of pit, the effect of the tensile properties the degree of degradation and corrosion rate was not significantly related. The PE sheath damage and crack damage point will cause pitting and crevice corrosion of steel strands, and two kinds of corrosion stress corrosion expansion is most serious in alternating. There are two factors affecting the wire fracture shape, exhibited the geometric characteristic of pits the micro performance of the pearlite arrangement. The ultimate tensile strength of steel strand is the common pit pit at the bottom of the pearlite morphology and orientation under the decision. The crack depth is the influence of tensile strength of steel wire and bend Under the same load, the deeper the deeper the depth of the crack tip stress is, the greater the length and width, the smaller the crack tip stress.

【學位授予單位】：重慶交通大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U446

【參考文獻】

相關期刊論文 前1條

1 龍廣成;邢鋒;余志武;謝友均;;氯離子在混凝土中的沉積特性研究[J];深圳大學學報(理工版);2008年02期

相關博士學位論文 前2條

1 徐俊;拉索損傷演化機理與剩余使用壽命評估[D];同濟大學;2006年

2 李富民;氯鹽環(huán)境鋼絞線預應力混凝土結構的腐蝕效應[D];中國礦業(yè)大學;2008年

相關碩士學位論文 前1條

1 梁雄;斜拉橋拉索腐蝕行為及使用壽命預測研究[D];重慶交通大學;2008年

，

本文編號：1416988