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摘要: 基于动态三轴被动加载实验技术，建立了一种可测量吉帕量级及以下低体模量材料压强-体应变关系的被动围压SHPB实验设计方法。在该实验设计中确定了样品、封装垫块、围压套管的尺寸以及尺寸间的匹配，并对实验压强进行了限制。通过比较传统SHPB实验和被动围压SHPB实验测量LC4铝合金等效应力的方式，验证了被动围压SHPB实验压强测量的有效性；通过实验和数值模拟分析，验证了体应变测量的有效性。将设计的被动围压SHPB实验方法应用于铈，得到了铈在伽马→阿尔法相变区间完整显示的压强-体应变演化信息，且相变起始和终止压强、相变体积变化量均与静高压实验结果基本一致。这说明设计的被动围压SHPB实验方法适用于测量低体模量材料的压强-体应变关系。Abstract: Based on dynamic triaxial passive loading techniques, a new passive confined SHPB experiment technique was designed for measuring the responses of pressure and volume strain of materials with bulk modulus of giga pascal or less.In the experiment design, the dimensions of the specimens, encapsulated pads and confinement tube were determined as well as their matching.And the upper limit of pressure load was given.The pressure result from this design was validated by the deviation of equivalent pressure of LC4 aluminum alloy measured by the passive confined SHPB experiment and SHPB experiment.The volume strain result from this design is approximately equal to the axial strain measured by the SHPB experiment.And based on the analysis of experiment and numerical simulation, the radial strain can be omitted compared with the volume strain.Cerium was tested by the designed passive confined SHPB setup.The result shows the entire response of pressure and volume strain during the phase transition of gamma to alpha.The variety of volume strain during phase transition and the pressures of the beginning and ending of phase transition are similar to those by hydrostatic-pressure experiments.So the designed passive confined SHPB technique is feasible for measuring the pressure-volume strain relation of materials with low bulk modulus.
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图 2 LC4铝合金的应力应变曲线与模型曲线的对比
Figure 2. Stress-strain curves of LC4 aluminum alloy from SHPB experiment and simulation model
图 3 不同长径比的LC4铝合金样品“虚拟实验”压强相对偏差
Figure 3. Relative deviation of pressure by numerical experiments for LC4 aluminum alloy specimens with different length-to-diameter ratios
图 4 不同长径比的LC4铝合金样品“虚拟实验”应变结果对比
Figure 4. Strain results by numerical experiment for LC4 aluminum alloy specimens with different length-to-diameter ratios
图 5 不同长径比的LC4铝合金样品被动围压SHPB实验结果
Figure 5. Experimental results by passive confined SHPB for LC4 aluminum alloy specimens with different length-to-diameter ratios
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