Thermo-Mechanical Coupling Characteristics of SMA-Actuated Morphing Stratospheric Airships

A shape memory alloy (SMA)-actuated morphing stratospheric airship configuration is proposed, in which SMA members serve simultaneously as actuation elements and primary load-carrying structures. A partitioned sequential coupling strategy is adopted, integrating a station-keeping thermal model, a nonlinear structural finite-element model, and a vertical dynamics model to establish a thermo-mechanical coupling computational method for the rigid-flexible hybrid structure. The morphing performance analysis indicates that the configuration with 16 longitudinal ribs can achieve the 2 km altitude-regulation design target under the specified conditions, while the corresponding structural stress and deformation responses are characterized. The diurnal station-keeping characteristics are then examined, revealing a 4.1% volume variation and a 290 m altitude fluctuation for the design configuration, with notable fluctuations in temperature, stress, and deformation driven by the thermal environment. Finally, short-term altitude-regulation processes are analyzed for descent and ascent initiated at different times. Compared with the case without the station-keeping thermal environment, the altitude-regulation capability varies from a 1.5% reduction to a 7.4% improvement during descent, while an improvement of 1.8%–5.4% is observed during ascent. These results indicate that the influence of the station-keeping thermal environment on altitude-regulation performance depends on the initiation time and regulation direction. The results demonstrate that thermo-mechanical coupling plays an essential role in the morphing capability, long-duration station-keeping stability, and short-term altitude-regulation performance.