基于精细算法的焊接结构疲劳寿命预测方法研究

Study of Fatigue Life Prediction Method of Welded Structure based on Precise Algorithm

针对现有随机振动疲劳分析方法的局限性,在随机振动精细分析方法的基础上引入等效结构应力新方法来研究随机振动疲劳寿命问题.以随机振动的虚拟激励法结合分体耦合式振型分解法为基础的求解方法大幅提高了随机振动分析的计算效率,不必将计算模型大幅简化,保证了有限元模型的完整性.等效结构应力疲劳评估新方法是一种相对准确的计算焊接结构焊缝处疲劳寿命的方法,可有效解决现有分析方法的不足.通过建立某平车包括走行部结构在内的车辆整体结构动力学精细有限元模型,以轨道不平顺谱作为输入激励载荷进行随机振动计算,结合主S-N疲劳曲线法完成疲劳寿命评估,以工程实例证明该方法的可行性.

The limitations of existing methods of random vibration fatigue analysis are introduced,and a new method of equivalent structural stress is proposed to study the random vibration fatigue life based on the method of random vibration fine analysis. The calculation method based on the random vibration virtual excitation method combined with the split-coupled vibration mode decomposition method greatly improves the computational efficiency of random vibration analysis,and it is not necessary to simplify the computational model significantly to ensure the integrity of the finite element model. The new method of stress fatigue assessment of equivalent structures is a relatively accurate method for calculating the fatigue life of welded joints,which can effectively solve the deficiencies of the existing analytical methods. Through building a precise finite element model of the overall vehicle structure including the walking part structure of a flat car,the random vibration calculation is made by using the track irregularity spectrum as the input excitation load,and the fatigue life assessment is completed according to the main SN fatigue curve method. Finally,the feasibility of this method is proved by engineering example.