论文部分内容阅读
为了研究复杂应力场对焊接接头疲劳寿命的影响规律,针对不同倾角(θ=0°,15°,30°,45°)全熔透承载角焊缝十字形焊接接头,进行了轴向拉伸疲劳试验和有限元数值模拟。采用线性外推法、二次外推法和1mm法来计算焊趾处的热点应力,通过有限元网格敏感性分析确定合适的网格尺寸,得到了热点正应力和热点剪应力集中系数随倾角的变化规律。分别基于等效应力法、相互作用方程法和双参数临界面法对焊接接头的疲劳寿命进行评估,并与试验结果进行对比。结果表明:当最小网格尺寸分别小于0.1t和0.03t时,外推法和1mm法可以忽略其对热点应力的影响;热点剪应力集中系数普遍大于热点正应力集中系数;随着焊缝倾角的增大,疲劳寿命越来越大,15°,30°和45°倾角的疲劳寿命试验结果分别是0°倾角的1.26,1.52和2.38倍;当焊缝倾角为30°和45°时,相互作用方程法和双参数临界面法预测的疲劳寿命误差较大且偏于危险,而等效应力法预测的疲劳寿命与试验值吻合较好且偏于安全,因此推荐采用线性外推法计算热点应力,用等效应力法来预测复杂应力场下焊接接头的疲劳寿命。
In order to study the influence of complex stress field on the fatigue life of welded joints, axial cross-section welded joints of full penetration fillet weld fillets with different inclination (θ = 0 °, 15 °, 30 °, 45 °) Fatigue test and finite element numerical simulation. Linear extrapolation method, quadratic extrapolation method and 1mm method were used to calculate the hot spot stress at weld toe, and the appropriate mesh size was determined by FEM mesh sensitivity analysis. The hot spot normal stress and hot spot shear stress concentration factor Inclination of the law. The fatigue life of welded joint was evaluated based on equivalent stress method, interaction equation method and two-parameter critical surface method, respectively, and compared with the experimental results. The results show that when the minimum grid size is less than 0.1t and 0.03t respectively, the extrapolation method and 1mm method can ignore the impact on the hot spot stress. The hot spot shear stress concentration factor is generally larger than the hot spot normal stress concentration factor. And the fatigue life is increasing. The fatigue life test results of 15 °, 30 ° and 45 ° inclination are 1.26, 1.52 and 2.38 times of 0 ° inclination, respectively. When the inclination angle of welding seam is 30 ° and 45 °, The fatigue life predicted by the interaction equation method and the two-parameter critical surface method is larger and more dangerous than the equivalent stress method, and the fatigue life predicted by the equivalent stress method is in good agreement with the experimental values and is therefore recommended to be calculated by linear extrapolation Hot stress, equivalent stress method to predict the fatigue life of welded joints under complex stress field.