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

  更多相關(guān)文章： 鋼絞線 腐蝕試驗(yàn) 應(yīng)力腐蝕 腐蝕疲勞 裂紋擴(kuò)展速率

【摘要】：國內(nèi)外斜拉橋斷索事故以及頻繁地?fù)Q索表明,人類在斜拉橋拉索損傷狀態(tài)評估和剩余壽命預(yù)測領(lǐng)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(fù)雜的應(yīng)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(yīng)力下引起的腐蝕疲勞極易導(dǎo)致拉索發(fā)生無預(yù)兆的脆性斷裂,從而造成巨大的傷亡事故以及經(jīng)濟(jì)損失。如何排除上述的隱患成為當(dāng)今各國科研人員研究的熱點(diǎn)。本文通過室內(nèi)鹽霧加速試驗(yàn),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(hù)套的鍍鋅鋼絞線試樣進(jìn)行不同的腐蝕時(shí)間以及不同加載狀況,來研究鋼絞線的腐蝕失重量、力學(xué)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(hù)套進(jìn)行不同形式的破壞,進(jìn)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(jìn)行觀察與分析,并測量蝕坑與裂紋尺寸,統(tǒng)計(jì)蝕坑密度。最后通過已有的研究,推導(dǎo)應(yīng)力腐蝕與腐蝕疲勞下裂紋擴(kuò)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(jìn)行模擬分析。本文主要內(nèi)容如下:①通過試驗(yàn)發(fā)現(xiàn),由于氧化產(chǎn)物的保護(hù)作用,試驗(yàn)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(guān)。②根據(jù)灰度直方圖所示,腐蝕時(shí)間相同的情況下,腐蝕程度表現(xiàn)為:無應(yīng)力靜態(tài)應(yīng)力交變應(yīng)力。③受拉性能退化的原因主要?dú)w于蝕坑的應(yīng)力集中效應(yīng)或截面削弱效應(yīng);但是,在腐蝕率相差不大的范圍內(nèi),蝕坑效應(yīng)的隨機(jī)特性導(dǎo)致上述受拉性能的退化程度與腐蝕率沒有明顯的對應(yīng)關(guān)系。④PE護(hù)套點(diǎn)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(yīng)力下腐蝕擴(kuò)展最為嚴(yán)重。⑤影響鋼絲斷口形狀的因素有兩個(gè),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(tuán)的排列方式。鋼絞線的極限抗拉強(qiáng)度是蝕坑的形態(tài)與蝕坑底部珠光體團(tuán)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(qiáng)度以及屈服強(qiáng)度的主要因素,在相同荷載作用下,深度越深裂尖應(yīng)力則越大;相反,長度與寬度越大,裂尖應(yīng)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(xué)位授予單位】：重慶交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：U446

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本文編號：1416988