基于加速老化试验的硅泡沫材料时变本构模型研究

Time-varying constitutive model of silicon foam based on accelerated aging test

硅泡沫材料的老化及力学性能退化是相关结构全寿命、可靠设计时须关注的重要因素。通过硅泡沫加速老化试验和老化后材料的单轴压缩试验,获得不同温度、不同时间老化后硅泡沫的应力-应变关系。以试验数据为基础,分别以Blatz-Ko模型、Ogden Hyperfoam模型为基础提出材料时变本构模型,基于阿伦尼乌斯加速关系和分子老化动力学方程,对本构模型参数与材料老化时间和温度关系用最小二乘法拟合,建立硅泡沫材料单轴压缩的时变本构模型。对建立的时变本构模型进行试验验证及有限元分析验证。结果表明:基于Ogden Hyperfoam模型建立的硅泡沫时变本构模型能表征硅泡沫在不同温度、不同老化时间后的压缩行为,为硅泡沫结构的性能退化仿真与寿命设计提供基础。

The aging and degradation of mechanical properties of silicon foam materials are important factors that must be paid attention to in the long‐life and high‐reliability design of its related structures.Through the accelerated aging test of silicon foam and the uniaxial compression test of the aged material,the stress‐strain relationship of the silicon foam after aged at different temperatures and for different times was obtained.Based on the experimental data,a time‐varying constitutive model of the material was proposed based on the Blatz‐Ko model and the Ogden Hyperfoam model.Based on the arrhenius acceleration relationship and the molecular aging kinetic equation,the correlation between constitutive model parameters and material aging time and temperature was fitted by the least square method,and a time‐varying constitutive model of silicon foam material under uniaxial compression was established.The established time‐varying constitutive model was verified by independent experiments and finite element analysis.The results show that the time‐varying constitutive model of silicon foam based on the Ogden Hyperfoam model can characterize the compressive mechanical behavior of silicon foam at different temperatures and aging times,and provide a basis for performance degradation simulation and life design of silicon foam structures.