基于修正力磁模型的混凝土结构压磁疲劳模拟

Piezomagnetic fatigue simulation of concrete structures based on modified magneto-mechanical model

为了通过混凝土梁内钢筋在力磁效应下的磁信号来定量分析混凝土梁的疲劳状态,整合几种力磁模型的优缺点和适用范围,提出了适用于铁磁性材料弹塑性阶段的力磁本构模型,并通过ANSYS定量模拟分析了混凝土梁在弹性和弹塑性阶段的磁化特征;对混凝土结构在拟动力和疲劳加载过程中的力磁效应进行了有限元模拟,得到了测点处磁感应强度的时变曲线,并与试验和隐式微分模型所得结果进行对比。结果表明:修正后的力磁模型在弹性阶段的应用能够准确反映试验观察到的3个阶段变化规律,即梁开裂前的平直段、开裂后的迅速磁化段和加载后期的磁化饱和段;该模型的磁场模拟结果还能反映箍筋、纵筋的相对位置和梁的受载情况;在疲劳阶段,模拟结果与试验观察的规律一致,精度较高,并与试验结果在同一数量级;该修正力磁模型不仅具有应力与磁学属性的直观映射关系,而且相较于隐式微分模型更易于应用,可作为力磁效应的定量化研究工具。

In order to quantitatively analyze the fatigue state of concrete beams by the magnetic signal of steel bars in concrete beams under the magneto-mechanical effect,the advantages,disadvantages and application scope of several magneto-mechanical models were integrated,and a magneto-mechanical constitutive model suitable for the elastoplastic stage of ferromagnetic materials was proposed.The magnetization characteristics of concrete beams in the elastic and elastoplastic stages were quantitatively simulated and analyzed by ANSYS.The magneto-mechanical effect of concrete structures during pseudo-dynamic and fatigue loading was simulated by finite element method,and the time-varying curve of magnetic induction intensity at the measuring point was obtained,which was compared with the results obtained by experiment and implicit differential model.The results show that the modified magneto-mechanical model accurately captures the observed three-stage variation pattern during the elastic phase,including a linear segment before beam cracking,a rapid magnetization stage post-cracking,and a saturation stage in the late loading period.Moreover,the magnetic field simulation results of this model can reflect the relative positions of stirrups,longitudinal bars,and the loading conditions of the beam.In the fatigue phase,the simulation results exhibit consistency with observed experimental patterns,demonstrating high precision and agreement with experimental results on the same scale.The modified magneto-mechanical model not only establishes an intuitive mapping relationship between stress and magnetic properties but also proves to be more user-friendly compared to the implicit differential model.Thus,the model can be used as a quantitative tool for investigating magneto-mechanical effects.