王  欣¹，蔡福海¹，張占杰²，黃邵軍¹，徐金帥^3
1（大連理工大學(xué)，大連 100190）  ²（中海油能源發(fā)展股份有限公司油田建設(shè)工程公司，天津 300450)  ³（大連益利亞工程機(jī)械有限公司，大連，116085)

　　摘要：從中小噸位到大噸位移動(dòng)式起重機(jī)的桁架臂進(jìn)行了軸力有限元提取，發(fā)現(xiàn)其底節(jié)危險(xiǎn)處弦桿和腹桿軸向力的比例均在40:1左右，這是起重機(jī)桁架臂受力的一個(gè)典型特征。針對(duì)起重機(jī)桁架臂中K型管的受力特點(diǎn)，對(duì)K型管常用的幾何參數(shù)進(jìn)行分析，建立了45個(gè)適應(yīng)于起重機(jī)桁架臂幾何參數(shù)的K型管有限元模型。其次，采用熱點(diǎn)應(yīng)力法并考慮K型管的彎曲次應(yīng)力，對(duì)K型管焊縫周圍應(yīng)力集中系數(shù)隨幾何參數(shù)的分布規(guī)律進(jìn)行了數(shù)值計(jì)算分析。通過(guò)對(duì)管節(jié)點(diǎn)的應(yīng)力測(cè)試及疲勞壽命分析，驗(yàn)證了數(shù)值模擬分析的準(zhǔn)確性。通過(guò)分析可知，在起重機(jī)典型載荷形式下，K型管焊縫周圍的應(yīng)力集中系數(shù)受幾何參數(shù)影響，最大應(yīng)力集中系數(shù)出現(xiàn)在跟點(diǎn)處，并且冠點(diǎn)處與跟點(diǎn)處應(yīng)力集中系數(shù)接近，而鞍點(diǎn)處最小。腹桿與弦桿的壁厚比值、腹桿外徑與弦桿外徑的比值這兩個(gè)參數(shù)均對(duì)焊縫跟點(diǎn)和冠點(diǎn)處的應(yīng)力集中系數(shù)值有明顯的影響，而對(duì)鞍點(diǎn)附近的應(yīng)力集中系數(shù)值無(wú)明顯影響，因此適當(dāng)減小腹桿的壁厚，相對(duì)增加腹桿的外徑，均可提高臂架的疲勞壽命。弦桿外徑與壁厚的比值參數(shù)對(duì)鞍點(diǎn)處的應(yīng)力集中系數(shù)有一定的影響，對(duì)冠點(diǎn)處影響很小；在50°~70°范圍內(nèi)，腹桿與弦桿的夾角幾乎對(duì)應(yīng)力集中系數(shù)沒(méi)有影響，故在起重機(jī)桁架臂的抗疲勞設(shè)計(jì)中，可以將角度參數(shù)不作為主要因素進(jìn)行研究。
　　關(guān)鍵詞：起重機(jī)，桁架臂，K型管，熱點(diǎn)應(yīng)力，分布規(guī)律

 Stress Distribution Along Weld Toe For Tubular K-Joins Of Crane’s Lattice Boom
Wang Xin¹，Cai Fuhai¹，Zhang Zhanjie²，Huang Shaojun¹，Xu Jinshuai^3
1 (Dalian University of Technology, Dalian 116024, China)
²（CNOOC Energy Technology &Services-Oilfield Construction Engineering Co., Tianjin 300450, China）
³（Dalian Yiliya Construction Machinery Co.,Ltd., Dalian 116025, China)

　　Abstract:Axial forces are analysed by finite element extraction method from small to large tonnage lattice boom mobile crane. It is found that the proportion at critical areas of chords and brace of the bottom section of the axial force were about 40:1, which is a typical feature of the lattice boom cranes. Since the loads type exerts an influence on the stress distribution around tubular K-node, 45 finite element models subjected to axial loads are analyzed, of these the geometry parameters and loads type are adjusted to fit cranes well. And then, considering of the influence of secondary bending moments in lattice girders, the distribution of stress concentration factors along the weld toe are obtained with using the hot spot stress method. By stress and fatigue life tests on K-nodes, the accuracy of the numerical simulation analysis is verified. It is found that, the distribution of stress concentration factors along the weld toe is determined by some main geometrical parameters. Under the typical loads of cranes, the maximal stress concentration factor is at the location of the heel, while the minimal is near the location of the saddle. Besides, the stress concentration factor of the crown is almost equal to the heel. Two parameters which are wall thickness ratio of braces and chords, the outside diameter ratio of braces and chords have a significant effect on the SCF value at the location of the heel and heel. It has no significant effect on the saddle point. Thus reducing the wall thickness of the brace and increasing the outer diameter of the brace can increase the fatigue life of the boom. The ratio of outside diameter and wall thickness parameter of the chord has a certain influence on the SCF at the saddle point but have little impact at the crown point; within the range of 50 ° ~ 70 ° angle between the braces and chords, it has little effect on SCF, so for the fatigue design of lattice boom cranes, the angle parameter may not be studied as a major factor.
　　Key words:crane, lattice boom, tubular K-node, hot spot stress, stress distribution
　　聯(lián)系方式
　　蔡福海：caifuhai@dlyiliy.com

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