Predictive model and physical interpretation of asymmetric features in pyroshock signals

In aerospace engineering, electronic devices can be easily damaged under pyroshock environments, and therefore, shock testing is required. The shock response spectrum (SRS) is the widely adopted specification tool to compare shock severities between field pyroshocks and testing shocks. However, two shocks with almost the same SRS but different temporal features could still lead to large differences in the failure of a device. The test specification should consider temporal features of shocks in order to be more representative of the field shocks. During shock propagation, shock signal evolves from an exponentially decaying shape to an asymmetric shape with an increased initial rise stage, which is characterized by the temporal moment or asymmetric basis functions. This study explains the evolution mechanism of shock asymmetry based on elastic wave propagation theory and proposed a predictive model. The theoretical foundation for the application of signal asymmetry in pyroshock characterization, device failure analysis and SRS reconstruction is provided.