EPDM非线性力学行为及其拉伸速率特性研究

Study on EPDM nonlinear mechanical behaviorand tensile rate characteristic

为研究三元乙丙(ethylene propylene diene monomer, EPDM)力学行为的拉伸速率依赖性,分别开展了拉伸速率为3、30、300、500 mm/min下EPDM的单轴拉伸实验,分析了EPDM非线性力学行为规律及其拉伸速率特性。基于分数阶Kelvin-Vogit模型、ZWT模型和OGDEN模型,对应变160%时不同拉伸速率的实验曲线进行了拟合,对比研究了模型的表征能力。结果表明,EPDM全程加载曲线呈典型“S”型,具有显著的非线性迟滞特性,且拉伸速率越大迟滞环面积越大,阻尼损耗能力越强;在应变大于68%阶段,EPDM力学行为的拉伸速率特性显著,并呈现硬化现象。分数阶Kelvin-Vogit模型和OGDEN模型适用于EPDM在低拉伸速率下、应变低于68%阶段黏弹性材料的力学行为的表征;ZWT模型适用于EPDM在高拉伸速率下应变高于100%阶段黏弹性材料的力学行为的表征,且ZWT模型在低拉伸速率下也具有较好的拟合效果。研究结果可为EPDM制品的性能评估及优化提供有益参考。

In order to study the tensile rate dependence of EPDM mechanical behavior,uniaxial tensile tests of EPDM at 3 mm/min,30 mm/min,300 mm/min and 500 mm/min were carried out,respectively.The nonlinear mechanical behavior laws and tensile rate characteristics of EPDM were analyzed.Based on the fractional-order Kelvin-Vogit,ZWT and OGDEN models,the experimental curves of different tensile rates at 160%strain were fitted,and the characterization ability of the models was compared and studied.The results show that the whole loading curve of EPDM presents a typical“S”shape,and has significant nonlinear hysteresis characteristics.The larger the tensile rate,the larger the area of hysteresis loop,and the stronger the damping loss capacity.When the strain is greater than 68%,the tensile rate has a significant effect on the mechanical properties of EPDM,and hardening occurs.The fractional Kelvin-Vogit and OGDEN models are suitable for the characterization of mechanical behavior of viscoelastic materials of EPDM when the strain is less than 68%at a low tensile rate,while the ZWT model is suitable for the characterization of mechanical behavior of viscoelastic materials of EPDM when the strain is more than 100%at a high tensile rate.The ZWT model also has a good fitting effect at low tensile rate.The results can provide a useful reference for the performance evaluation and optimization of EPDM products.