LAUSR

Silicone rubber gaskets are employed to keep fuel gases and oxidation in their own zones. Due to the viscosity and elasticity, the assembly force could relax when the silicone rubber is compressed in a proton exchange membrane fuel cell. In this work, the stress relaxation behavior of silicone rubber samples is studied under different temperatures and simulated operating conditions. The results show that the stress relaxes exponentially with time at 25% strain level, especially at higher temperature or with higher acid concentration solution. The three-term Prony series can simulate the viscoelastic behavior well, and the Master curves are established by applying a time-temperature superposition method to estimate the life of the samples. It can save approximately 50% and 78% of the test time when an operating temperature and acid solution are chosen appropriately.摘要硅橡胶材料在燃料电池中主要用于保持燃料气体与氧化气体在各自区域不因泄露而混合。由于 硅橡胶兼具黏性与弹性性质,在燃料电池中由于密封而处于压缩状态,所以预测力会随着时间的延长 而产生松弛。本论文针对硅橡胶试样在不同温度及不同模拟操作工况下的压缩应力松弛行为进行了研 究。结果表明,在25%应变状态下,材料的应力松弛行为随着时间的延长而呈指数下降趋势,特别是 当试样在温度较高或酸度较高的试验环境下老化之后。文中采用三参数Prony级数很好地模拟了硅橡 胶材料的黏弹性行为,并且基于时温等效原理构建主曲线预测试样寿命。当加速试验时老化温度与酸 浓度选择合适,相对于垫片材料在实际燃料电池环境中老化的力学损伤性能变化,可缩短50%甚至 78%老化时间。