混凝土动态力学行为数值模拟研究

NUMERICAL ANALYSIS ON DYNAMIC MECHANICAL BEHAVIOR OF CONCRETE

  • 摘要: 混凝土动态强度的增强效应DIF(dynamic increase factor)一般由混凝土霍普金森杆SHPB(split Hopkinson pressure bar)试验进行测量,而基于不同应变率\dot \varepsilon 条件下的试块尺度的SHPB试验结果得到的宏观DIF- \dot\varepsilon 关系不能直接应用于数值模型定义。运用ANSYS /LS-DYNA有限元软件和K&C混凝土模型,对混凝土SHPB直接拉伸、劈裂和层裂试验进行了模拟研究。提出了局部和非局部损伤模型中引入网格和应变率\dot \varepsilon 双修正的DIF-\dot \varepsilon 模拟方案,并对混凝土非局部损伤模型中非局部特征长度L在数值模拟中的应用方案进行了讨论。SHPB和混凝土梁冲击试验模拟研究和试验数据的比较结果均表明,提出的分别基于局部和非局部损伤混凝土模型的双修正DIF-\dot \varepsilon 模拟方案能够较为准确描述混凝土动态力学行为。

     

    Abstract: The dynamic increasing factor (DIF) of concrete is normally measured via split Hopkinson pressure bar (SHPB) tests. However, the tested macro-scale DIF-\dot \varepsilon relationship from the specific SHPB test specimens under different strain rates \dot \varepsilon cannot be directly introduced to finite element (FE) modelling. Based on the ANSYS/LS-DYNA and K&C concrete damage model, the SHPB direct tension, split and spalling tests were modelled, and a modified DIF-\dot \varepsilon relationship with both mesh and \dot \varepsilon corrections for dynamic mechanic behaviour of concrete material was proposed for local and non-local damage modelling of concrete respectively, also the numerical application of the nonlocal characteristic length L was detailed discussed. The comparison between the SHPB/impact test modelling and the relevant test results indicated that the proposed doubly corrected DIF-\dot \varepsilon numerical application schemes could properly capture the concrete dynamic mechanical property.

     

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