起重机生命周期载荷谱预测及基于疲劳寿命的结构优化设计

Prediction of load spectrum for crane life cycle and structural optimal design based on fatigue life

起重机在服役期间长期承受具有不同特征的交变载荷的作用,其结构因疲劳而导致承载能力下降。为了研究在实际工作过程中载荷及应力变化对起重机结构疲劳寿命的影响,首先,利用神经网络对起重机在服役期间的载荷谱进行分析,准确预测其载荷特征,并结合预测的载荷谱及其结构承载特性分析起重机在服役期间的应力—时间历程;其次,利用Miner线性损伤累积理论和线弹性断裂力学法,预测起重机结构关键部位的疲劳寿命;最后,以起重机结构关键部位的疲劳寿命及结构承载能力为约束,建立考虑起重机服役期间载荷特征的优化设计模型,采用智能优化算法在全局范围内搜索最优设计变量组合,获取满足疲劳寿命和承载能力设计要求的起重机结构最佳设计参数。研究结果表明了结构疲劳寿命计算与智能优化算法相结合的方法在起重机结构优化设计中的可行性,为起重机结构的轻量化设计提供了全新的思路。

Crane has been subjected to alternating loads with different characteristics for a long time during service,resulting in a decrease in load-bearing capacity due to structure fatigue.In order to study the impact of load and stress changes on the fatigue life of crane structure during actual work,firstly,a neural network was used to analyze the load spectrum of crane during service and accurately predict the load characteristics,and the stress-time history of the crane during service was analyzed by combining the accurately predicted load spectrum and structural bearing characteristics;secondly,Miner's linear damage accumulation theory and linear elastic fracture mechanics method were used to predict the fatigue life of the key parts of the crane structure;finally,with the fatigue life and structural bearing capacity of the key parts of the crane structure as constraints,an optimization design model considering the load characteristics of the crane during service was established.Intelligent optimization algorithm was used to search for the optimum design variable combination globally to obtain the optimum design parameters of the crane structure that met the design requirements of fatigue life and bearing capacity.The research results showed the feasibility of the method combining the calculation of structural fatigue life with intelligent optimization algorithm in the optimization design of crane structure,providing a new approach for the lightweight design of crane structure.