Response characteristics and impact resistance of composite laminates with shear stiffening gel under hypervelocity impact

To investigate the damage characteristics of spacecraft structures caused by external impacts and propose protective measures, this study utilizes two-stage light gas gun launcher with detonation capability. Hypervelocity impact experiments are conducted on composite laminates that incorporate varying proportions of shear stiffening gel (SSG). Polyvinylidene fluoride (PVDF) sensors are employed to collect response signals from the front corners, rear corners, and rear edges of the laminate, enabling an assessment of its behavior under impact conditions. By analyzing the signals acquired from the Polyvinylidene fluoride sensor, the study obtains the timefrequency response characteristics of the signals at various positions with different proportions of shear stiffening gel. The correlation between these response characteristics and the damage of the laminate is investigated. The analysis reveals that the vibration response at various positions of the laminate provides a comprehensive indication of internal delamination and surface damage. Moreover, this response is linked to the level of fragmentation of the projectile. The incorporation of shear stiffening gel in the laminate enhances its impact resistance and helps mitigate damage at the connection between the laminate and other components. Interestingly, the impact resistance does not follow a monotonic trend with respect to the proportion of shear stiffening gel. Based on the experimental results discussed in this article, the optimal proportion of shear stiffening gel is determined to be 5 %.