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一种基于能量耗散的对接接头疲劳寿命快速预测模型

A rapid fatigue life prediction model of butt joints based on energy dissipation

  • 摘要: 通过引入ISV(internal state variable)本构模型中的αβ变量,建立了一种与对接接头高周疲劳滞弹性和非弹性行为相关的能量耗散模型,并定义了两个特征应力幅,即标志着可恢复滞弹性和不可恢复非弹性行为开始形成的关键应力幅σc0σc1(疲劳极限);借助该能量耗散模型,研究了不同应力幅下的对接接头能量耗散响应情况,发现能量耗散在疲劳极限附近呈现从线性响应到非线性响应的过渡;在此基础上,考虑到当应力幅高于疲劳极限时,全寿命周期的能量耗散存在临界值,结合与损伤相关的非弹性耗散,研发了一种基于损伤累积的疲劳寿命预测模型,并对接头的疲劳寿命进行了快速预测. 结果表明,经预测数据和试验数据拟合的中值S-N曲线一致程度较好,从而证明了模型可用于实现对接接头的疲劳寿命快速、精确预测.

     

    Abstract: An energy dissipation model for high cycle fatigue linked to anelastic and inelastic behavior of butt joints is developed by introducing α and β variables of the internal state variable (ISV) constitutive model. The crucial stress amplitudes, σc0 and σc1 (fatigue limit), corresponding to the onset of recoverable anelastic and unrecoverable inelastic behavior, are defined as two characteristic stress amplitudes. The energy dissipation response of butt joints under different stress amplitudes is examined using this energy dissipation model. The results demonstrate that when stress levels are close to the fatigue limit, the energy dissipation exhibits a transition from a linear response to a nonlinear response. On this basis, considering that when the stress amplitude is above the fatigue limit, there is a critical value for the energy dissipation during the fatigue duration, a fatigue life prediction model based on damage accumulation is developed in combination with the damage-related inelastic dissipation, thereby reaching a rapid fatigue life prediction. The results show that the median S-N curve fitted by the predicted data and the test data is in good agreement, and this validates that the proposed model can be utilized to realize a rapid and accurate prediction of the fatigue life of butt joints.

     

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