發(fā)布時(shí)間：2018-04-14 12:19

  本文選題：空冷橋架 + 隨機(jī)振動(dòng)　； 參考：《西安建筑科技大學(xué)》2015年碩士論文

【摘要】：空冷系統(tǒng)具有明顯的環(huán)境效益,廣泛用于我國富煤缺水的北方地區(qū)�？绽浣Y(jié)構(gòu)的安全性直接影響到火電廠正常運(yùn)行,以往研究主要集中在整體結(jié)構(gòu)遭受風(fēng)荷載、地震作用等方面,關(guān)于風(fēng)機(jī)運(yùn)轉(zhuǎn)致振問題研究尚顯不足。空冷橋架和風(fēng)機(jī)系統(tǒng)屬于耦合體系,風(fēng)機(jī)運(yùn)轉(zhuǎn)必然引起橋架結(jié)構(gòu)振動(dòng),尤其在空冷結(jié)構(gòu)長(zhǎng)期工作狀態(tài)下風(fēng)機(jī)運(yùn)轉(zhuǎn)產(chǎn)生的擾力將使橋架結(jié)構(gòu)出現(xiàn)疲勞破壞。本文以現(xiàn)場(chǎng)實(shí)測(cè)空冷結(jié)構(gòu)橋架振動(dòng)結(jié)果為基礎(chǔ),建立橋架上風(fēng)機(jī)擾力荷載模型。在擾力荷載作用下進(jìn)行空冷結(jié)構(gòu)隨機(jī)振動(dòng)響應(yīng)分析,最后定量評(píng)價(jià)橋架結(jié)構(gòu)在服役期內(nèi)風(fēng)機(jī)擾力影響下的可靠性。(1)本文首先闡述了空冷結(jié)構(gòu)在我國發(fā)展的必然趨勢(shì),系統(tǒng)總結(jié)了空冷結(jié)構(gòu)目前的研究現(xiàn)狀,分別從頻域和時(shí)域角度介紹荷載識(shí)別方法。圍繞空冷結(jié)構(gòu)風(fēng)機(jī)橋架現(xiàn)場(chǎng)實(shí)測(cè)振動(dòng)呈現(xiàn)隨機(jī)特性,論述有關(guān)隨機(jī)過程的基本概念,窄帶隨機(jī)過程的統(tǒng)計(jì)特性以及結(jié)構(gòu)隨機(jī)振動(dòng)的計(jì)算分析方法。(2)針對(duì)不同轉(zhuǎn)速下現(xiàn)場(chǎng)實(shí)測(cè)的直接空冷系統(tǒng)風(fēng)機(jī)橋架振動(dòng)速度響應(yīng),分別在時(shí)域和頻域?qū)φ駝?dòng)響應(yīng)進(jìn)行分析,傳統(tǒng)簡(jiǎn)諧擾力荷載作用下的振動(dòng)響應(yīng)不能反映實(shí)測(cè)結(jié)果中幅度和相位緩慢變化的窄帶隨機(jī)特性。本文以實(shí)測(cè)振動(dòng)響應(yīng)為基礎(chǔ),建立基于載波理論的風(fēng)機(jī)隨機(jī)擾力模型,并以振動(dòng)響應(yīng)的功率譜為目標(biāo),識(shí)別擾力模型參數(shù),結(jié)果表明建立的擾力模型能夠很好地反映橋架振動(dòng)的隨機(jī)性。(3)根據(jù)結(jié)構(gòu)動(dòng)力學(xué)理論的振型疊加法,動(dòng)力反應(yīng)數(shù)值分析方法中的中心差分原理,推導(dǎo)已知橋架結(jié)構(gòu)振動(dòng)響應(yīng),反分析求解橋架上風(fēng)機(jī)擾力的計(jì)算方法�；趯�(shí)測(cè)各工況橋架結(jié)構(gòu)振動(dòng)輸出響應(yīng),結(jié)合有限元模態(tài)分析結(jié)果,采用反演方法識(shí)別風(fēng)機(jī)擾力,并在頻域和時(shí)域內(nèi)對(duì)比驗(yàn)證反分析結(jié)果的可靠性。結(jié)果表明識(shí)別的等效擾力荷載模型能夠反映實(shí)際不同工作條件下風(fēng)機(jī)運(yùn)行對(duì)支撐橋架的影響。(4)建立實(shí)際空冷結(jié)構(gòu)有限元模型,以諧波疊加法生成目標(biāo)功率譜下的風(fēng)機(jī)擾力時(shí)程樣本,計(jì)算擾力荷載作用下空冷結(jié)構(gòu)隨機(jī)振動(dòng)響應(yīng),并對(duì)計(jì)算結(jié)果進(jìn)行分析。提取多組風(fēng)機(jī)擾力荷載作用下橋架隨機(jī)振動(dòng)的應(yīng)力結(jié)果,采用雨流計(jì)數(shù)程序?qū)ζ鋺?yīng)力幅進(jìn)行統(tǒng)計(jì),計(jì)算橋架危險(xiǎn)點(diǎn)在不同服役期內(nèi)的疲勞累積損傷,給出相應(yīng)服役期內(nèi)結(jié)構(gòu)不發(fā)生疲勞失效的可靠度。
[Abstract]:Air-cooling system has obvious environmental benefits and is widely used in the north of China, which is rich in coal and short of water.The safety of air-cooled structures has a direct impact on the normal operation of thermal power plants. Previous studies focused on wind load and seismic action on the whole structure.The air-cooled bridge frame and fan system belong to the coupling system, the fan operation will inevitably cause the bridge structure vibration, especially under the air-cooled structure long-term operation disturbance force will cause fatigue damage to the bridge frame structure.Based on the measured results of vibration of air-cooled structure bridge, the model of disturbance load of fan on bridge frame is established in this paper.The random vibration response analysis of air-cooled structure under disturbance load is carried out. Finally, the reliability of bridge frame structure under the influence of blower disturbance force during service period is quantitatively evaluated.) in this paper, the inevitable development trend of air-cooled structure in China is first expounded.The present research status of air-cooled structures is summarized systematically, and load identification methods are introduced from frequency domain and time domain respectively.Based on the random characteristics of field measured vibration of air-cooled structure fan bridge frame, the basic concepts of stochastic process are discussed.Statistical characteristics of narrow Band Stochastic process and calculation and Analysis method of structural Random Vibration. (2) aiming at the vibration velocity response of fan bridge of direct air-cooled system measured at different rotational speeds, the vibration response is analyzed in time domain and frequency domain, respectively.The vibration response under the traditional harmonic disturbance force can not reflect the narrow band random characteristic of the amplitude and phase in the measured results.Based on the measured vibration response, a random disturbance model of fan based on carrier theory is established in this paper. The parameters of the disturbance model are identified by taking the power spectrum of the vibration response as the target.The results show that the disturbance force model can well reflect the randomness of bridge vibration. According to the vibration superposition method of structural dynamics theory and the central difference principle in the numerical analysis method of dynamic response, the known vibration response of bridge frame structure is deduced.The calculation method for calculating the disturbance force of the blower on the bridge frame by inverse analysis.Based on the measured vibration output response of the bridge structure under different operating conditions, combined with the modal analysis results of finite element method, the inverse method is used to identify the disturbance force of the fan, and the reliability of the back-analysis results is verified by comparing the results in frequency domain with that in time domain.The results show that the identified equivalent disturbance load model can reflect the influence of fan operation on the supporting bridge under different actual working conditions.The harmonic superposition method is used to generate the time history samples of the disturbance force of the fan under the target power spectrum. The random vibration response of air-cooled structure under the disturbing force load is calculated, and the calculated results are analyzed.The stress results of random vibration of the bridge frame under the disturbance force load of many sets of fans were extracted. The stress amplitude of the bridge was counted by the rain flow counting program, and the fatigue cumulative damage of the dangerous point of the bridge in different service periods was calculated.The reliability of structure without fatigue failure during the corresponding service period is given.
【學(xué)位授予單位】：西安建筑科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU311.3

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