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摘要: 分离式霍普金森压杆(SHPB)实验常被用来获得混凝土类材料的动态压缩强度, 所得数据对建立本构方程有重要作用，因此需要对其进行正确解释或分析。利用最新的混凝土材料模型研究了SHPB实验中试件尺寸的影响。藉由混凝土试件的体积考虑动态尺寸效应的影响，并提出了一个计算由于惯性(约束)效应引起的动态增强因子的新经验公式。结果表明：新经验公式与不同尺寸混凝土的SHPB模拟结果吻合得很好，且惯性(约束)效应引起的动态增强因子随着试件尺寸的增大而增大。
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关键词:
- 分离式霍普金森压杆实验 /
- 混凝土 /
- 惯性(约束)效应 /
- 试件尺寸效应 /
- 数值模拟
Abstract: The split Hopkinson pressure bar (SHPB) tests are often conducted to obtain the dynamic compressive strengths of concrete-like materials which need to be interpreted or analyzed correctly as these data are very important for the construction of reliable constitutive equations used in numerical simulations.In the present work, a numerical study is performed on the influence of specimen size on concrete in SHPB tests using a rate-independent material model.A new empirical equation for the dynamic increase factor due to inertia (confinement) effect is also proposed which took account of specimen size effect through its volume.It is shown that the empirical formula agrees well with the numerical results for the SHPB tests on concrete with different specimen sizes, and the dynamic increase factor due to inertia (confinement) effect increases with the increase of specimen size.-
Key words:
- SHPB test /
- concrete /
- inertia (confinement) effect /
- specimen size effect /
- numerical simulation
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Figure 3. Comparison of Eq.(6) with numerical results fordynamic increase factor due to inertia (confinement)effect for concrete specimens with the same volumeof different length/diameter ratios
Figure 4. Comparison of Eq.(6) with numerical results fordynamic increase factor due to inertia (confinement)effect for concrete specimens with different volumeof the same length/diameter ratio
Figure 5. Variation of normalized numericallyobtained dynamic increase factor due to inertia(confinement) effect with strain rate
Table 1. Material parameters of concrete[1]
Parameters of EOS Parameters of constitutive model ρ0/(kg·m-3) ρs0/(kg·m-3) pcrush/MPa plock/GPa n K1/GPa K2/GPa K3/GPa Strength surface Shear damage Tensile damage Lode effect fc'/MPa ft/MPa B N G/GPa λs l r λm c1 c2 εfrac e1 e2 e3 2 400 2 680 15.2 3 3 13.9 30 10 45.6 3.8 1.7 0.7 10.5 4.6 0.45 0.3 0.3 3 6.93 0.007 0.65 0.01 5 
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Table 2. Load function parameters for direct compression analyses
t1/μs t2/μs t3/μs ppeak/MPa 25 200 25 Varies
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Table 3. Values of various parameters in Eq.(6) and Eq.(7)
$ {{{\dot \varepsilon }_0}} $/s-1 Fi Si Wi Gi W β 1.0 6.0 0.8 2.8 8.5 2.8 2.7
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