考虑应力集中的吊车梁多轴疲劳寿命预测

钢结构吊车梁在工业建筑中被广泛应用,应力集中的存在导致几何不连续位置在复杂应力下服役.借助有限元法分析吊车梁应力-应变状态,确定危险点位置,并提取应力、应变分量;以应变能密度作为损伤参量并以最大平面为临界面,基于能量准则建立临界面位置数值计算方法,结合有限元结果给出吊车梁临界面位置;考虑吊车梁在非对称载荷下服役,借助Goodman方程进行平均应力修正,并结合Q355D钢近似S-N曲线计算疲劳寿命.该方法考虑了应力集中处多轴应力对疲劳损伤的影响,可以为复杂应力下几何不连续钢构件的疲劳寿命评估提供新方法.

Multiaxial fatigue life prediction of crane beams considering stress concentration

Steel structure crane beams have been widely used in industrial buildings. Due to the existence of stress concentration, parts of crane beams with geometric discontinuity are in service under multiaxial stress. In this paper, finite element method is used to analyze the stress and strain state of crane beam, determine the position of dangerous point, and extract its stress and strain component. Taking the plane with the highest energy density as the critical plane, a method to determine the critical plane based on energy criterion is proposed. Given that the crane beam works under asymmetric load, with the help of Goodman equation of mean stress correction, the fatigue life of crane beam is calculated by combining the approximate S-N curve of Q355D steel. The proposed method considers the effect of the multiaxial stress near the region of stress concentration on the fatigue damage and provides a new method for fatigue life evaluation of steel members with geometric discontinuous under complicated stress.