Experimental and Numerical Assessment of Demisable Joints for Controlled Break-up of Large Sandwich Panel Structures

Kurzfassung

This work investigates the influence of demisable joints (DJs) on the atmospheric re-entry and ground-impact risk of the EarthCARE satellite using the SCARAB simulation framework. A high-fidelity reference model of the satellite was developed and adapted to incorporate demisable joints at selected primary structural interfaces. Different joint-triggering conditions and resulting structural separation scenarios were simulated to assess their effects on the re-entry process, breakup sequence, surviving debris mass, and Debris Casualty Area (DCA).

In parallel, bracket-type demisable joint samples developed at the German Aerospace Center (DLR) were successfully tested in a plasma wind tunnel (PWT). These tests provided an experimental assessment of the thermal response and demisability of the developed joint concept under representative re-entry heating conditions, complementing the numerical investigations.

In addition to evaluating the overall simulation results, a subsystem-level analysis methodology was developed to trace surviving fragments back to their subsystems of origin. This enables the quantification of absolute DCA changes for individual subsystems and provides insight into their respective contributions to ground-impact casualty risk. The approach supports the identification of critical structural interfaces and the assessment of different joint configurations and triggering conditions.

The results demonstrate the applicability of simulation-based analyses for investigating the potential benefits and limitations of demisable joints in satellite structures. However, the numerical findings are subject to the assumptions and limitations of the model and do not constitute experimental validation of joint functionality within the simulated EarthCARE configuration or a prediction of the actual satellite re-entry event. Further work should address the refinement of joint separation modelling, sensitivity to key simulation parameters, and integration of experimental test results to enable a more robust assessment of the potential of demisable joints to reduce surviving debris and associated ground-impact casualty risk.