湿热环境下聚乙烯拉索护套应力-光氧老化性能

为探究服役环境下斜拉索HDPE护套的老化性能，开展了不同应力水平与环境耦合作用下的人工加速老化试验。通过电子万能试验机得到HDPE护套应力-应变曲线、断裂伸长率、拉伸强度和腐蚀失重等力学性能指标，揭示了HDPE护套的力学性能在湿热环境和荷载耦合作用下的宏观衰变规律，并借助工业电子显微镜从微观角度展示了HDPE护套损伤特征，推演了HDPE护套长期性能从宏观尺度向微观尺度发展的进程。研究表明：随着HDPE护套不断老化，其表面依次出现污渍、黑点、裂纹等损伤形式，致使其断裂强度、拉伸强度和断裂伸长率与老化时间呈指数衰减趋势；随应力水平的提高，衰减速率将进一步加快，尤其是耦合应力6.0MPa的试样，其断裂强度、拉伸强度和断裂伸长率的下降程度高达42.07%、23.62%和27.56%。

Stress-photo-oxygen Aging Performance of High Density Polyethylene Cable Sheath in Hygrothermal Environment

In order to investigate the aging performance of cable HDPE sheath in service environment, artificial accelerated aging tests were carried out under the coupling action of different stress levels and environment. HDPE sheath is obtained by electronic universal testing machine, stress-strain curve and elongation at break, tensile strength and corrosion weightlessness mechanics performance index, revealed that the mechanical properties of HDPE sheathed in hygrothermal environment and macro decay law of load under the action of coupling, and with the aid of industrial electronic microscope shows the HDPE sheath damage characteristic from the microscopic view. The long - term performance of HDPE sheath is deduced from macro - scale to micro - scale. The results show that with the continuous aging of HDPE sheath, the surface of HDPE sheath appears stains, black spots, cracks and other forms of damage, resulting in the fracture strength, tensile strength and elongation at break with the aging time of exponential decay trend. With the increase of stress level, the decay rate will be further accelerated, especially for the specimen with coupling stress of 6.0MPa, the fracture strength, tensile strength and elongation at break decrease as much as 42.07%, 23.62% and 27.56%.