高压复合绝缘子用GFRP材料吸湿特性及湿应力分布数值模拟

Numerical Simulation of Hygroscopic Characteristic and Wet Stress Distribution of GFRP Material Used in High Voltage Composite Insulators

在我国南方长期高温高湿环境下,外界水分逐渐侵入复合绝缘子芯棒内部,会造成芯棒酥朽劣化甚至会使整支绝缘子断裂,因此准确模拟及分析水分入侵过程对于解决此类问题至关重要。该文仿真计算外界环境温度分别为10℃、20℃和30℃,相对湿度为90%下高压复合绝缘子用玻璃纤维增强环氧树脂(GFRP)材料的瞬态吸湿扩散过程及材料内部的湿应力变化情况。结果显示,水分在GFRP材料内部的扩散过程满足Fick定律,且吸湿扩散率和饱和吸湿率均随环境温度的升高而有所增大;在GFRP材料内部纤维分布密集处和纤维-基体界面处存在较大的湿应力和湿失配应力,且其与吸湿量正相关。当饱和吸湿率在0.008%~0.4%时,材料内部最大湿应力可达到48.07~66.06MPa。进一步研究分析得出,材料内部吸湿和脱湿周期性循环且湿应力水平较高的情况下,易产生微裂纹、微孔洞、纤维-基体界面脱粘开裂等缺陷,并进一步促进材料的吸湿。该文将计算值与已有文献中的试验值进行比较,相对误差在±5%以内,验证了模型的合理性和计算结果的正确性。研究结论对揭示复合绝缘子芯棒酥朽断裂机理、提高复合绝缘子使用寿命具有重要的参考价值。

On the condition of the long-term high temperature and high humidity environment in southern China,external moisture gradually penetrates into the composite insulator core rod,causing the core rod to decay-like deterioration and even the entire insulator to break.Therefore,accurate simulation and analysis of the moisture intrusion process is essential.This paper simulates and calculates the transient hygroscopic diffusion process inside glass fiber reinforced plastic(GFRP)material used in high voltage composite insulators and the change of the wet stress in the material at the external environment temperature of 10℃,20℃and 30℃,and the relative humidity of 90%.The results show that the diffusion process of water inside the GFRP material satisfies Fick’s law,and both the hygroscopic diffusion rate and the saturated hygroscopic rate increase with the increase of external environment temperature.In the GFRP material,the wet stress and wet mismatch stress at the densely distributed areas of the fiber distribution and fiber-matrix interface are large,and they are positively correlated with the moisture absorption.When the saturated hygroscopic rate is 0.008%~0.4%,the maximum wet stress inside the material can reach 48.07~66.06 MPa.Further analysis shows that when the moisture absorption and dehumidification cycle periodically and the wet stress level is high inside the material,defects such as micro cracks,micro holes,fiber-matrix debonding and cracking are likely to occur,and the moisture absorption of the material is further promoted.The relative error between the calculated value of this paper and the experimental value of the existing literature is within±5%.The conclusions have important reference value for revealing the decay-like fracture of the composite insulator core rod and improving the service life of composite insulators.