本文關(guān)鍵詞：焊接管節(jié)點應(yīng)力分布規(guī)律評估新方法研究　出處：《大連理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： T型焊接管節(jié)點 零點結(jié)構(gòu)應(yīng)力 應(yīng)力梯度 應(yīng)力集中系數(shù) 參數(shù)方程

【摘要】：圓管焊接節(jié)點在海洋工程領(lǐng)域有著極其廣泛的應(yīng)用。由于管節(jié)點在焊縫交線處結(jié)構(gòu)形式非常復(fù)雜,會產(chǎn)生嚴(yán)重的局部應(yīng)力集中,加上焊接過程引入的宏觀和微觀缺陷,使得管節(jié)點在風(fēng)、浪、流等各種隨機(jī)環(huán)境載荷的聯(lián)合作用下處于非常復(fù)雜的交變應(yīng)力狀態(tài),容易出現(xiàn)疲勞破壞；并且,疲勞評估的最危險點可能出現(xiàn)在沿焊縫交線的任意位置。工程上常用的基于表面插值算法的熱點應(yīng)力法無法對焊趾位置復(fù)雜的應(yīng)力狀態(tài)進(jìn)行準(zhǔn)確的描述：首先,目前的絕大部分工作均集中于熱點應(yīng)力峰值的計算而忽略了其沿管壁厚度方向及焊縫交線的分布規(guī)律；其次,研究中多采用殼單元對管節(jié)點進(jìn)行模擬,無法充分考慮焊趾尺寸對焊縫位置應(yīng)力分布產(chǎn)生的影響。因而,對于受到多軸疲勞載荷作用的復(fù)雜焊接管節(jié)點,傳統(tǒng)的疲勞評估應(yīng)力計算方法仍存在一些問題。為保證海洋平臺整個服役過程中的安全,研究焊接管節(jié)點在復(fù)雜載荷作用下的應(yīng)力分布規(guī)律,建立能夠應(yīng)用于實際工程結(jié)構(gòu)的多軸疲勞強(qiáng)度評估方法,在海洋工程領(lǐng)域具有非常重要的意義。本文以T型管節(jié)點為例,將一種新的零點結(jié)構(gòu)應(yīng)力法用于其疲勞評估應(yīng)力的計算。計算過程中,為更加準(zhǔn)確的考慮焊縫尺寸對管節(jié)點應(yīng)力分布產(chǎn)生的影響,文中采用三維的20節(jié)點塊體單元對管節(jié)點的支管、主管以及焊縫進(jìn)行了詳細(xì)建模；新方法充分考慮裂紋的擴(kuò)展方向,以管壁厚度方向上非線性峰值應(yīng)力為零的一點作為疲勞評估點,以該點處的結(jié)構(gòu)應(yīng)力作為疲勞評估應(yīng)力。該結(jié)構(gòu)應(yīng)力可直接通過有限元計算結(jié)果后處理得到,方便用于管節(jié)點的多軸疲勞壽命預(yù)測；另外,由于評估位置取在管壁外表面下方一點,可在一定程度上考慮應(yīng)力梯度對疲勞壽命的影響。在此基礎(chǔ)上,通過與公開發(fā)表的疲勞試驗數(shù)據(jù)進(jìn)行比較,驗證了本文方法應(yīng)用于管節(jié)點疲勞強(qiáng)度評估的適用性和正確性。最后,本文基于大量的有限元數(shù)值計算,提出了T型管節(jié)點在各基本載荷作用下的應(yīng)力集中系數(shù)參數(shù)方程,并對參數(shù)方程的精度進(jìn)行了驗證。
[Abstract]:Circular pipe welded joints are widely used in the field of offshore engineering. Due to the very complex structure form of pipe joints at the weld intersections, serious local stress concentration will occur. Combined with the macroscopic and microcosmic defects introduced in the welding process, the pipe joints are subjected to very complex alternating stress states under the combined action of wind, wave, flow and other random environmental loads, which are prone to fatigue failure. And... The most dangerous point of fatigue assessment may appear anywhere along the intersection line of weld seam. The hot spot stress method based on surface interpolation algorithm can not accurately describe the complex stress state of weld toe position in engineering: firstly. At present, most of the work focuses on the calculation of the peak stress of hot spot and neglects the distribution law along the direction of pipe wall thickness and the intersecting line of weld. Secondly, the shell element is often used to simulate the pipe joints, which can not fully consider the influence of weld toe size on the weld stress distribution. Therefore, for the complex welded pipe joints subjected to multiaxial fatigue load. There are still some problems in the traditional fatigue assessment stress calculation method. In order to ensure the safety of offshore platform during the whole service process, the stress distribution law of welded pipe joints under complex loads is studied. It is of great significance to establish a multiaxial fatigue strength evaluation method which can be applied to practical engineering structures. In this paper, T-tube joints are taken as an example. A new 00:00 structural stress method is used to calculate the fatigue assessment stress. In the calculation process, the effect of weld size on the stress distribution of pipe joints is considered more accurately. In this paper, the three-dimensional 20-node block element is used to model the branch pipe, the supervisor and the weld seam of the pipe joint in detail. The new method takes the crack propagation direction into account and takes the point where the nonlinear peak stress is zero in the direction of pipe wall thickness as the fatigue assessment point. The structural stress at this point is taken as the fatigue assessment stress, which can be obtained directly by the post-processing of the finite element calculation results, which is convenient for predicting the multiaxial fatigue life of pipe joints. In addition, the influence of stress gradient on fatigue life can be considered to some extent because the evaluation position is below the outer surface of pipe wall. On this basis, the fatigue test data are compared with published data. The applicability and correctness of the proposed method applied to the fatigue strength assessment of pipe joints are verified. Finally, a large number of finite element numerical calculations are carried out in this paper. The parameter equation of stress concentration factor for T-tube joints under various basic loads is proposed and the accuracy of the equation is verified.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TG404

【共引文獻(xiàn)】

相關(guān)期刊論文 前2條

1 秦林肖;潘穎;張鵬舉;;基于ANSYS的KKT型相貫節(jié)點承載力性能研究[J];輕工機(jī)械;2014年04期

2 王欣;張占杰;黃邵軍;金三強(qiáng);蔡福海;;桁架結(jié)構(gòu)K形節(jié)點焊縫應(yīng)力分布規(guī)律的研究[J];起重運輸機(jī)械;2015年03期

相關(guān)會議論文 前1條

1 劉剛;趙曉玲;黃一;;一種新的海洋平臺管節(jié)點應(yīng)力評估方法[A];中國鋼結(jié)構(gòu)協(xié)會海洋鋼結(jié)構(gòu)分會學(xué)術(shù)論文集[C];2015年

相關(guān)博士學(xué)位論文 前1條

1 蔡福海;起重機(jī)桁架臂疲勞壽命與可靠性研究[D];大連理工大學(xué);2014年

相關(guān)碩士學(xué)位論文 前7條

1 陳成;焊接圓鋼管節(jié)點抗火性能研究[D];煙臺大學(xué);2013年

2 韓超帥;導(dǎo)管架式海上風(fēng)機(jī)支撐結(jié)構(gòu)疲勞性能研究[D];哈爾濱工程大學(xué);2013年

3 何樹賓;焊接K型圓鋼管節(jié)點抗火性能研究[D];煙臺大學(xué);2014年

4 來佳雯;某體育場罩棚結(jié)構(gòu)整體分析及節(jié)點的有限元分析[D];鄭州大學(xué);2014年

5 李娜;海上風(fēng)機(jī)基礎(chǔ)結(jié)構(gòu)管節(jié)點應(yīng)力集中系數(shù)研究[D];大連理工大學(xué);2014年

6 黃邵軍;基于熱點應(yīng)力法的履帶起重機(jī)臂架壽命評估[D];大連理工大學(xué);2014年

7 秦林肖;空間KKT型圓管相貫節(jié)點的承載力性能研究[D];上海工程技術(shù)大學(xué);2015年

，

本文編號：1372728