本文關(guān)鍵詞：基于等效臨界距離法的焊接鋼結(jié)構(gòu)疲勞強(qiáng)度預(yù)測　出處：《長沙理工大學(xué)》2013年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 焊接鋼結(jié)構(gòu) 焊接殘余應(yīng)力 疲勞強(qiáng)度 等效臨界距離法 有效應(yīng)力集中 S-N曲線

【摘要】：疲勞破壞是導(dǎo)致結(jié)構(gòu)失效的一種主要方式,所以對結(jié)構(gòu)的疲勞失效進(jìn)行研究有著重要的意義。由于焊接過程中不均勻瞬態(tài)熱輸入，焊后不可避免的在結(jié)構(gòu)內(nèi)部產(chǎn)生殘余應(yīng)力，而殘余應(yīng)力的存在使焊接鋼結(jié)構(gòu)的疲勞強(qiáng)度降低。本文在考慮殘余應(yīng)力影響的基礎(chǔ)上對焊接鋼結(jié)構(gòu)的疲勞性能進(jìn)行了研究，運(yùn)用臨界距離理論探討了焊接鋼結(jié)構(gòu)疲勞強(qiáng)度與S-N曲線的理論預(yù)測方法。本文研究的主要內(nèi)容有： 利用有限元分析技術(shù)，考慮材料的熱物理性能和力學(xué)性能隨溫度的變化，使用APDL語言功能編寫程序動態(tài)模擬焊接過程中金屬的熔敷；針對焊接熱應(yīng)力場的材料非線性瞬態(tài)問題，選用彈塑性力學(xué)的增量理論進(jìn)行計算，運(yùn)用“生死單元技術(shù)”，動態(tài)模擬焊接過程中焊料的填入和凝固，建立了焊接溫度場和殘余應(yīng)力場的有限元理論計算模型。分別對對接板接頭、錯位板接頭和T型板接頭的焊接溫度場和殘余應(yīng)力場進(jìn)行了數(shù)值計算分析，得到了幾類典型焊接鋼結(jié)構(gòu)的焊接溫度場和殘余應(yīng)力場。 采用斷裂力學(xué)理論，，探討了含貫通裂紋的無限大板在均勻拉伸荷載作用下裂紋尖端附近的應(yīng)力場，在研究Taylor等人提出的臨界距離法（含點法、線法、面法、體積法）的基礎(chǔ)上，建立了臨界距離的圓柱法和橢圓柱法。并研究焊接殘余應(yīng)力對疲勞強(qiáng)度的影響，建立了焊接鋼結(jié)構(gòu)疲勞強(qiáng)度預(yù)測的等效臨界距離理論（包括等效臨界距離的點法、線法、面積法、半橢圓面積法、圓柱法和橢圓柱法）。這種理論考慮了結(jié)構(gòu)幾何形式、焊接接頭類型、焊縫局部幾何形狀、應(yīng)力集中、尺寸效應(yīng)、殘余應(yīng)力等因素對結(jié)構(gòu)疲勞性能的影響。利用所建立的等效臨界距離方法對對接板接頭、錯位板接頭和T型板接頭的疲勞強(qiáng)度進(jìn)行了理論預(yù)測，并與疲勞試驗結(jié)果進(jìn)行了比較，驗證了本文所建立的理論方法的正確性。 以等效臨界距離理論預(yù)測的疲勞強(qiáng)度為基礎(chǔ)，采用有效應(yīng)力集中系數(shù)和S-N曲線理論預(yù)測模型，建立了基于等效臨界距離理論的焊接鋼結(jié)構(gòu)有效應(yīng)力集中系數(shù)和S-N曲線預(yù)測的方法。并將理論計算值與疲勞試驗結(jié)果進(jìn)行了比較，驗證了理論方法的有效性。
[Abstract]:Fatigue failure is one of the main causes of structural failure, so it is of great significance to study the fatigue failure of structure, because of the uneven transient heat input in welding process. It is inevitable to produce residual stress inside the structure after welding. The fatigue strength of welded steel structure is reduced by the existence of residual stress. In this paper, the fatigue properties of welded steel structure are studied on the basis of considering the influence of residual stress. The theoretical prediction method of fatigue strength and S-N curve of welded steel structures is discussed by using the critical distance theory. The main contents of this paper are as follows: By using the finite element analysis technology, considering the variation of the thermal and mechanical properties of the material with temperature, the APDL language is used to compile a program to dynamically simulate the deposition of metals in the welding process. Aiming at the material nonlinear transient problem of welding thermal stress field, the incremental theory of elastic-plastic mechanics is used to calculate, and the "birth and death element technique" is used to dynamically simulate the filling and solidification of solder during welding process. The finite element theory model of welding temperature field and residual stress field is established. The welding temperature field and residual stress field of butt plate joint, staggered plate joint and T type plate joint are numerically calculated and analyzed respectively. The welding temperature field and residual stress field of several typical welded steel structures are obtained. Using the theory of fracture mechanics, the stress field near the crack tip of an infinite plate with a through-through crack under uniform tensile load is discussed. The critical distance method (including point method) proposed by Taylor et al. On the basis of linear method, surface method and volume method, the critical distance cylindrical method and elliptical column method are established, and the effect of welding residual stress on fatigue strength is studied. The equivalent critical distance theory for fatigue strength prediction of welded steel structures is established, including point method, line method, area method and semi-elliptical area method. This theory takes into account the geometry of the structure, the type of welded joint, the local geometric shape of the weld, the stress concentration and the size effect. Using the method of equivalent critical distance, the fatigue strength of butt plate joint, staggered plate joint and T-type plate joint is predicted theoretically. Compared with the fatigue test results, the correctness of the theoretical method established in this paper is verified. Based on the fatigue strength predicted by the equivalent critical distance theory, the effective stress concentration factor and the S-N curve theory are used to predict the fatigue strength. An effective stress concentration factor and S-N curve prediction method for welded steel structures based on the equivalent critical distance theory is established, and the calculated values are compared with the fatigue test results. The validity of the theoretical method is verified.
【學(xué)位授予單位】：長沙理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2013
【分類號】：TU391

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 王向明,劉文s

本文編號：1400123