Residual mechanical properties of a carbon fibers/PEEK space robotic arm after simulated orbital debris impact

• Orbital debris impacts were simulated on four carbon fibers/PEEK cylinders.
• Laminates impacted at hypervelocities were subsequently tested in fatigue bending.
• A correlation between the visible and internal damage to the booms was obtained.
• Damage propagation during fatigue was observed with the ∼4.5 kNm load amplitude.
• Considerations on the safe utilization of impacted space structured were provided.

The robotic arm on the International Space Station, Canadarm2, is susceptible to damage by orbital debris impact; evaluating its residual stiffness and resistance is thus of prime importance. Four cylinders, made of 19-ply carbon fiber IM7/PEEK laminates, each with a diameter of 35 cm, representative of the structure of Canadarm2, were subjected to hypervelocity impacts. Aluminum projectiles with diameters of 5.56 mm and 7.94 mm and velocities of ∼7 km/s were used for the tests. Imaging of the damaged zones was performed and the cylinders were thereafter subjected to fatigue tests by bending them under load amplitudes of ∼2.5 kNm or ∼4.5 kNm. The damaged zones were positioned close to the neutral plane in one test and far from the neutral plane in three tests. Damage propagation was detected using ∼4.5 kNm load amplitude for the damage that was far from the neutral plane, demonstrating that impacts of this nature on Canadarm2 could be problematic for its continued use at this level of loading.