Numerical investigation on dynamic tensile fracture in concrete material by non-ordinary state-based peridynamics
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摘要: 为了准确预测冲击爆炸荷载作用下混凝土材料的动态拉伸断裂破坏,基于非常规态近场动力学理论框架,本文首先建立了修正的Monaghan人工体积粘性计算方法用于消除数值振荡,然后将前期建立的等效计算应变率方法植入到课题组前期研发的Kong-Fang模型中,用以准确计算应变率突变时的应变率效应。在此基础上,开展了一维杆中的弹性波传播的数值模拟,发现在力矢量状态上额外附加修正的Monaghan人工体积粘性力矢量状态,可有效地抑制由变形梯度近似导致的非物理数值振荡现象,进而讨论分析了人工体积粘性参数的影响并给出参数建议值。最后将模型用于混凝土试件层裂的数值模拟,对比分析了人工体积粘性、不同应变率效应计算方法对动态拉伸断裂预测结果的影响规律,数值模拟结果表明,准确预测混凝土材料动态拉伸断裂破坏需同时考虑人工体积粘性和等效计算应变率,建立的考虑人工体积粘性和等效计算应变率的非常规态近场动力学模型可以较好地预测裂缝位置和数量,为冲击爆炸荷载作用下混凝土材料动态拉伸断裂破坏的数值模拟提供了新思路。
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Abstract: To accurately predict the dynamic tensile fracture in concrete materials subjected impact and blast loadings, this study firstly establishes a modified Monaghan artificial bulk viscosity calculated method within the framework of a non-ordinary state-based peridynamics theory to eliminate numerical oscillations. And then, the previously developed corrected strain-rate method is implemented into the Kong-Fang model recently proposed to accurately calculate the strain-rate effect during sudden changes in strain-rate. Based on the two methods above, numerical simulations of elastic wave propagation in a one-dimensional rod are conducted, and the numerical simulations demonstrate that the modified Monaghan artificial bulk viscosity could effectively suppress the non-physical numerical oscillations caused by the deformation gradient approximation. Furthermore, the influence of the artificial bulk viscosity parameters is investigated, and recommended values of parameters are provided. Finally, the model is used to numerically simulate of the spall test in concrete specimens, in which effects of artificial bulk viscosity and different strain-rate computation methods on the predictions of dynamic tensile fracture are compared. The numerical simulation results demonstrate that accurately predicting the dynamic tensile fracture in concrete materials requires simultaneous considerations of artificial bulk viscosity and corrected strain-rate. The established non-ordinary state-based peridynamics model that accounts for both artificial bulk viscosity and corrected strain-rate shows a good capability in predicting crack locations and quantities. This work gains new insights for the numerical simulation of dynamic tensile fracture in concrete materials under impact and blast loadings. -
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