Speaker
Description
We have established and applied the software tool “PHILOS-SOPHIA” that enables a non-expert user to perform hydrocode simulations of hypervelocity collisions on orbit. It relies on high-fidelity hydrocode simulations, which is the best method for systematically studying the processes and effects of orbit fragmentations for a wide range of impact conditions and for complex space systems. Other numerical methods such as empirical tools or analytical models are limited to a narrow validity range. Their computing time is much faster due to their simplifying nature, but they cannot meet the quality and precision of physics-based methods, nor do they allow complex modelling.
“PHILO-SOPHIA” includes a graphical user interface that can be used to 1) setup complex collision scenarios, 2) start the simulations using the existing FE/SPH solver SOPHIA, 3) monitor its outputs, and 4) visualize and analyze the results. The software tool outputs the characteristics of the generated fragments, including mass, size and the velocity vector of each fragment.
We performed comprehensive numerical simulations using “PHILOS-SOPHIA”. This includes the simulation of 1) spacecraft shielding performance on component level, 2) simple validation with experimental results, and 3) complex collisions using ESA LOFT spacecraft. The spacecraft shielding analysis demonstrated the tool capability for studying specific hypervelocity features but also showed the demand for adequate material models when new materials like Kevlar and CFRP structures come into play.
The validation against experimental data and a commercial general-purpose hydrocode showed very good performance of PHILO-SOPHIA in terms of quality and computing time. Since the existing experimental data (high-speed images) allow for a more qualitative comparison of the fragment cloud size and its evolution in time and space, we propose to perform new experiments using advanced particle methods to gain quantitative data for validation.
We performed detailed fragmentation analyses for different complex scenarios using the LOFT spacecraft. When comparing the results with the empirical NASA Standard Satellite Breakup Model, we found both good agreements and clear deviations. Due to the strong influence of the collision geometry, we did not find a strongly noticeable breakup limit depending only on the energy-to-mass ratio. More research is recommended to define generalized criteria for catastrophic collision conditions. PHILOS-SOPHIA, thoroughly backed by advanced experiments, can be the tool for this purpose.
