硅橡胶动态压缩性能SHPB测试方法及其本构模型研究

SHPB Test Method for the Dynamic Compressive Properties and Dynamic Constitutive Model of Silicon Rubber

为了采用分离式霍普金森压杆测试硅橡胶的动态力学性能,首先实验分析波形整形器厚度对入射波形的影响,根据柔性粘弹性试样的应力应变均匀化条件,确定合适的波形整形器厚度。然后采用实验与数值模拟相结合的方法,分析试样厚度对其变形特征和动态力学性能测试结果的影响。结果表明,厚度超过3mm的试样在冲击测试过程中难以达到力平衡状态,试样的非均匀变形会导致应力应变曲线上出现应力平台甚至是应力软化现象。最后测试了硅橡胶在不同应变率条件下的力学性能,采用超-粘弹性本构模型表征其动态力学性能,并提出新的粘弹性参数拟合方法,能很好地拟合所测试柔性硅橡胶的粘弹性参数。

In order to test the dynamic mechanical propertyof silicon rubber materials using split Hopkinson pressure bar, theeffects of the thickness of pulse shaper on thecharacteristics of incident stress wave were experimentally examined. Based on the analysis on the stress and strainuniformity in the soft viscoelastic specimens, the proper thickness of pulse shaper was determined. The experiment tests and numerical simulations were carried out to analyze the effects of specimen size on the deformation characteristics and dynamic mechanical properties of silicon rubber. The results showed that for the specimens with thickness higher than 3 mm, it is hard to achieve the equilibrium state of contact pressures on the two ends of the specimen to the pressure bars. The nonuniform deformation of specimen can cause the stress plateau and even stress softening in the tested stress-strain curves at high strain rate deformation. The dynamical mechanical properties of the soft silicon rubber at different strain rate deformation were tested. A hyper-viscoelastic constitutive modelconsisting of hyperelasitic and viscoelastic constitutive equationswas used to describe the dynamic mechanical behavior of the rubbermaterial. A new parameter fitting method was put forward for the viscoelastic parameter calculation of the viscoelastic model, and they could be conveniently calculated by the proposed method.