Ground simulation of hypervelocity space debris impacts on polymers

Hypervelocity space debris impacts can lead to degradation of satellite performance and, in extreme cases, might cause a total loss of a spacecraft. The increase in space debris population provides the motivation for this study, which focuses mainly on the mechanical behavior of space-qualified polyimide Kapton films impacted by simulated hypervelocity debris. Kapton is used extensively on spacecrafts, especially in thermal control blankets. Kapton films 25, 50, and 125 mu m-thick were studied at different impact velocities of up to 2900 m center dot s(-1) generated by a laser driven flyer (LDF) system. The Kapton-impacted sites revealed ductile-type fractures for low-velocity debris, which changed gradually into mixed ductile-brittle fractures with crack formation when debris impact velocity was increased. Fractures created by impacts at velocities above 1700 m center dot s(-1) showed central impact regions which experienced the highest strain rate and revealed a ductile-type fracture, while the outer regions which experienced a lower strain rate failed through brittle cracking. A model explaining this phenomenon, based on the temperature profile developed within the impacted region at the time of impact, is presented.