基于聚偏二氟乙烯(PVDF)压电薄膜的密封舱壁穿孔损伤识别技术

日益恶化的空间碎片环境将严重威胁空间站及航天员的在轨安全。文章基于聚偏二氟乙烯（polyvinylidene fluoride，PVDF）压电薄膜设计了一种密封舱壁穿孔损伤识别技术方案，用于识别空间碎片超高速撞击对航天器密封舱壁造成的损伤模式，可为航天员合理选择应急措施提供依据。首先，发射超高速弹丸穿透铝合金靶板以模拟密封舱壁被击穿损伤的情况，形成的碎片云撞击PVDF压电薄膜探头，利用信号采集设备获取高速撞击引起的去极化效应信号，识别该信号的频率特征；其次，对PVDF压电薄膜探头及其支撑结构进行敲击试验，模拟在轨运行时因碰撞产生的干扰信号，掌握此类干扰信号的频率特征。试验结果表明，当系统采样频率为20 MHz时：1）所获得的探头去极化效应信号具有极为陡峭的上升沿，且上升沿的时长为亚μs量级；2）去极化效应信号主要由1 MHz以下的信号组成，但也包含少量的3～10 MHz高频成分；3）敲击探头及其支撑结构所产生的干扰信号频率在20 kHz以下。可根据频率差异进行两种信号的识别。

A PVDF-based perforation damage pattern recognition method for sealed cabin

The deteriorating space debris environment continuously threatens the on-orbit spacecraft. In this paper, a perforation damage pattern recognition method is designed by using the polarized polyvinylidene fluoride （PVDF） piezoelectric film, for recognizing the damage pattern of the sealed cabin caused by the hypervelocity space debris impact, and it provides a warning for astronauts to take reasonable emergency measures. Firstly, the hypervelocity aluminum bullet is launched to penetrate the aluminum target to simulate the perforation of the sealed cabin, and the debris cloud produced after perforation punctures the PVDF detector, and the measurement equipment acquires the depolarization signal and its characteristics of the detector. Secondly, the knocking test on the detector and its support structure is made to simulate the on-orbit interference signals, and the signal feature is identified. A perforation damage pattern recognition scheme with anti-interference is designed for the sealed cabin. The experiment shows that： 1） the PVDF depolarization signal has a steep rising edge （shorter than microsecond level） when the sampling rate is sufficient; 2） the frequency of the depolarization signals is mostly lower than 1 MHz, and a few of them have frequencies in the range of 3~10 MHz. The interference signal frequency is usually lower than 20 kHz. The signal could be distinguished by the frequency difference.