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由于悬挂吊车荷载的随机性,螺栓球节点网架结构的疲劳实属变幅疲劳。针对常用的M20、M30两种规格20个高强螺栓的疲劳试件,在自行设计的专用加载装置上,首次进行了“低→高”、“高→低”、“低→高→低”、“高→低→高”以及“随机加载”5种典型加载模式下的变幅疲劳性能试验研究,获得了20个变幅疲劳破坏试验数据;在国内已有的高强度螺栓常幅疲劳数据基础上,应用线性累积损伤理论三种方法(Miner法则、修正Miner法则和Corten-Dolan理论),对两种规格的高强度螺栓进行变幅疲劳寿命估算;对比三种方法得出D值的平均值和分布区间,并综合分析三种方法的前提及影响因素,确定合理的估算方法,并提出这三种方法的建议公式。研究结果可为进一步建立螺栓球节点网架结构的变幅疲劳设计方法及疲劳寿命估算方法提供参考。
Due to the randomness of hoisting crane load, the fatigue of the bolt ball grid structure is actually fatigue. According to the commonly used fatigue specimens of 20 high-strength bolts of M20 and M30, the “low-high”, “high-low”, “low” High-low-low “,” high-low-high-high “and” random loading "under five kinds of typical loading modes of luffing fatigue performance test, obtained 20 amplitude fatigue failure test data; Based on the fatigue data of some high-strength bolts, the linear cumulative damage theory (Miner’s rule, modified Miner’s law and Corten-Dolan’s theory) were used to estimate the luffing fatigue life of two kinds of high strength bolts. The three methods derive the average value and distribution interval of D values, and comprehensively analyze the preconditions and influencing factors of the three methods to determine the reasonable estimation method and propose the formulas for the three methods. The research results can provide a reference for further design of the luffing fatigue design method and the fatigue life estimation method of the bolted ball grid frame structure.