基于循环载荷法评价聚乙烯管材性能的可靠性研究

Evaluation of Performance Reliability for Polyethylene Pipe by Cyclic Loading Method

为研究循环载荷法对加速表征聚乙烯(PE)管材耐慢速裂纹扩展(SCG)性能的可靠性,对5种不同等级的PE管材采用循环载荷缺口圆棒(CRB)试验和全切口拉伸蠕变(FNCT)试验的方法对其耐慢速裂纹扩展性能进行评估,同时对其试验结果进行相关性分析。此外,通过测量PE管材的分子量及其分布、结晶度和片晶厚度等高分子材料参数进一步佐证所选PE管材耐慢速裂纹扩展性能的优劣,进而验证CRB试验方法的可靠性。结果表明,循环载荷CRB试验方法不仅能可靠有效评估PE管材的耐SCG性能,且相比FNCT试验方法,其试验所需时长更短及试验条件要更贴近实际使用工况。

To investigate the performance reliability of polyethylene(PE)pipe under the slow crack growth(SCG)condition,five different graded PE pipes were selected for the evaluation of SCG resistance by a cyclic load gap(CRB)test and a full-notch tensile creep test(FNCT),and the correlation of experimental results was analyzed. Moreover,the macromolecular structural parameters of PE pipes including molecular weight and distribution,crystallinity and wafer thickness were investigated to further verify the performance reliability of selected PE tubes under the SCG condition,and meanwhile the reliability of CRB test method was also confirmed. The results indicated that the CRB test method not only could be used to reliably and effectively evaluate the SCG resistance of PE pipes,but also revealed a shorter test time and closer test conditions than the FNCT.