Numerical modeling of impacts of twisted-pair data cables

Data wire cable runs are a significant presence on the exterior of the International Space Station (ISS), and continued ISS mission support requires detailed assessment of cables due to micrometeoroid and orbit debris (MMOD) impact. These data wire cables are twisted-pair cables consisting of two 22 gauge stranded conductors inside a tight-fitting, braided-copper shield and jacket having a nominal outer diameter of 3.76 mm. Previous work has documented a total of 97 impact experiments that were performed into these cables to develop an empirical, statistical model for the failure of these cables in reliability studies; however, the experimental work left open the internal behaviors that contribute to the probabilistic findings. To address this shortcoming, numerical impact simulations have been performed to expand the understanding of the acquired dataset. This paper summarizes the dependence of impact location and speed to the penetration of wire jackets based upon particle size and provides an empirical ballistic limit equation based on the assumption that exposed conductors may lead to a short circuit. This work is consolidated with the previous experimental work for design and reliability assessments to cover projectile types, speeds and obliquities.