以在80℃老化不同时间（120，240，360 h）的聚乙烯（PE）管为对象，通过冲击强度的变化分析其老化状态；利用短时傅里叶变换（STFT）获取不同热老化试样的超声声速谱和衰减谱，建立超声声速、超声衰减系数与冲击强度间的关系，并计算得到聚乙烯的相对冲击强度以进行老化评价。结果表明：随着热老化时间的延长，聚乙烯的冲击强度以及超声声速和衰减系数均减小，冲击强度与超声声速和衰减系数均满足一定的二次函数关系；由超声声速和衰减系数计算得到的冲击强度与试验测试结果的相对误差均在2%以内，说明可以利用超声检测参量对聚乙烯的热老化程度进行无损评价。

Aging conditions of polyethylene (PE) pipes aged at 80℃ for different times (120, 240, 360 h) were analyzed by change of impact strength. The ultrasonic velocity spectrum and attenuation spectrum of different thermal aged samples were obtained by short-time Fourier transform (STFT), and then the relationship between the ultrasonic velocity, the attenuation coefficient and the impact strength was established. The relative impact strength of polyethylene was calculated to evaluate the aging degree. The results show that with the extension of thermal aging time, the impact strength, ultrasonic velocity and attenuation coefficient of polyethylene decreased. The relationship between impact strength and ultrasonic velocity, and between impact strength and attenuation coefficient satisfied a certain quadratic function. The relative errors between the impact strength calculated by the ultrasonic velocity or by the attenuation coefficient and the test result were both below 2%, indicating that the thermal aging degree of polyethylene can be non-destructively evaluated with ultrasonic parameters.