本文選題：鋼絲　切入點(diǎn)：腐蝕速率　出處：《東南大學(xué)》2015年碩士論文

【摘要】：索體是纜索承重體系橋梁中重要的傳力和承載構(gòu)件,在橋梁設(shè)計(jì)基準(zhǔn)期內(nèi),索體鋼絲易受到環(huán)境和力學(xué)等因素的影響發(fā)生腐蝕損傷導(dǎo)致其力學(xué)性能退化。本文通過(guò)鋼絲的電化學(xué)腐蝕試驗(yàn)、表面腐蝕特征分析、力學(xué)拉伸試驗(yàn)和疲勞試驗(yàn)研究了鋼絲的腐蝕特征和力學(xué)性能,主要研究過(guò)程和研究成果如下：1)首先,探討了鋼絲腐蝕機(jī)理,然后利用電化學(xué)腐蝕試驗(yàn)研究了溫度、應(yīng)力、氯鹽濃度、pH值四種單因素對(duì)鋼絲基體腐蝕速率的影響,建立了腐蝕速率與各單因素間的函數(shù)關(guān)系式；最后基于響應(yīng)面法試驗(yàn)設(shè)計(jì),研究了溫度、應(yīng)力、氯鹽濃度、pH值交互作用對(duì)鋼絲基體腐蝕速率的影響,建立鋼絲基體腐蝕速率與多因素間的函數(shù)關(guān)系式。研究表明,各單因素都會(huì)影響鋼絲基體的腐蝕速率,且各因素間存在顯著的交互作用。2)其次,對(duì)舊索腐蝕鋼絲的蝕坑尺寸進(jìn)行了量化檢測(cè),然后利用數(shù)理統(tǒng)計(jì)方法研究了蝕坑尺寸的分布特征,并分析了蝕坑尺寸與均勻腐蝕之間的關(guān)系。研究表明,平均腐蝕深度、蝕坑深度服從廣義極值分布,蝕坑長(zhǎng)度、寬度服從對(duì)數(shù)正態(tài)分布。3)第三,通過(guò)對(duì)新鋼絲和舊鋼絲進(jìn)行了力學(xué)拉伸試驗(yàn),得到了新、舊鋼絲力學(xué)性能參數(shù),研究了鋼絲力學(xué)性能參數(shù)分布規(guī)律,并分析了鋼絲拉伸斷口特征。研究表明,鋼絲延伸率、屈服強(qiáng)度、極限強(qiáng)度都隨著腐蝕程度的增加而下降,且鋼絲極限強(qiáng)度下降速率大于屈服強(qiáng)度；對(duì)鋼絲力學(xué)性能的退化評(píng)價(jià)采用最大蝕坑深度作為參數(shù)比采用平均腐蝕深度更加合理和準(zhǔn)確。4)第四,通過(guò)對(duì)新鋼絲、表面無(wú)腐蝕損傷鋼絲、預(yù)制蝕坑鋼絲進(jìn)行疲勞試驗(yàn),擬合得到了各鋼絲試樣的S-N曲線,研究了鋼絲疲勞壽命變化規(guī)律,并分析了鋼絲疲勞斷口特征。研究結(jié)果表明：在低應(yīng)力幅值下,表面無(wú)腐蝕損傷鋼絲疲勞壽命下降較小,但有腐蝕損傷鋼絲疲勞壽命隨著腐蝕程度的增加下降幅度較大；在低應(yīng)力幅值下,預(yù)制蝕坑鋼絲疲勞壽命隨腐蝕時(shí)間的增加、蝕坑深度的增加而下降；在高應(yīng)力幅值下表面無(wú)腐蝕損傷鋼絲、預(yù)制蝕坑鋼絲疲勞壽命與新鋼絲相比都出現(xiàn)了明顯的下降,且疲勞壽命離散性增加。
[Abstract]:Cable body is one of the most important load-transfer and load-carrying components in cable-bearing system. During the reference period of bridge design, steel wire of cable body is susceptible to corrosion damage caused by environmental and mechanical factors, resulting in degradation of mechanical properties.In this paper, the corrosion characteristics and mechanical properties of steel wire are studied by electrochemical corrosion test, surface corrosion characteristic analysis, mechanical tensile test and fatigue test.The corrosion mechanism of steel wire was discussed, and the influence of four factors, temperature, stress, chloride concentration and pH value, on the corrosion rate of steel wire substrate was studied by electrochemical corrosion test, and the functional relationship between corrosion rate and each single factor was established.Finally, based on the experimental design of response surface method, the effects of temperature, stress, chloride concentration and pH value on the corrosion rate of steel wire matrix are studied, and the functional relationship between the corrosion rate of steel wire matrix and multiple factors is established.The results show that each single factor will affect the corrosion rate of steel wire matrix, and there is a significant interaction between each factor. Secondly, the corrosion pit size of corroded steel wire with old cables is measured quantitatively.Then the distribution of the size of the pit is studied by means of mathematical statistics, and the relationship between the size of the pit and the uniform corrosion is analyzed.The results show that the average corrosion depth, the depth coat of the pit is distributed from the generalized extreme value, the length and width of the pit are distributed from the logarithmic normal distribution. Third, the new steel wire and old steel wire are obtained through mechanical tensile tests on the new steel wire and the old steel wire.The distribution of mechanical property parameters of old steel wire was studied, and the tensile fracture characteristics of steel wire were analyzed.The results show that the elongation, yield strength and ultimate strength of steel wire decrease with the increase of corrosion degree, and the decreasing rate of ultimate strength of steel wire is higher than that of yield strength.The degradation evaluation of steel wire mechanical properties using the maximum pit depth as the parameter is more reasonable and accurate than the average corrosion depth. Fourth, the fatigue test is carried out on the new steel wire, the steel wire without corrosion damage on the surface, and the prefabricated corrosion pit steel wire.The S-N curves of each steel wire sample were obtained, the fatigue life of steel wire was studied, and the fatigue fracture characteristics of steel wire were analyzed.The results show that the fatigue life of non-corrosion-free surface steel wire decreases slightly under low stress amplitude, but the fatigue life of corroded steel wire decreases greatly with the increase of corrosion degree, and at low stress amplitude, the fatigue life of corrosion-free steel wire decreases with the increase of corrosion degree.The fatigue life of prefabricated corrosion-pit steel wire decreases with the increase of corrosion time and decreases with the increase of corrosion depth, and the fatigue life of prefabricated pit steel wire decreases obviously compared with that of new steel wire under high stress amplitude.And the fatigue life dispersion increases.
【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：U443.38

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