Multifunctional charging and thermal–mechanical performance of double-layer sandwich structure with PCM

To address the demands of renewable energy devices facing complex service environments, this study proposes a double-layer corrugated-core sandwich structure (DCSS) that integrates energy storage, thermal management, and mechanical load-bearing functions. The DCSS is designed in three configurations: S1 (pores filled with phase change material (PCM)), S2 (pores containing cold fluid), and S3 (PCM in the upper pores and cold fluid in the lower pores). To systematically analyze the performance of the DCSS, a three-dimensional numerical model, validated by experimental data, was developed. The results show that S3 demonstrates excellent temperature regulation. The PCM in S3 absorbs substantial energy via latent heat, reducing the heating rate and maintaining its solid-phase temperature lower than that of S2 for an extended period. When the Reynolds number increases from 500 to 2000, the lower temperature duration decreases by 74.03 % (from 1644 s to 427 s), but the full charging time of PCM increases by 21.11 % (from 947 s to 1147 s). Therefore, the velocity of the cold fluid in S3 can further control the phase transition of PCM and the temperature of the DCSS. In terms of mechanical performance, the DCSS undergoes multi-stage deformation under quasi-static compression, with initial failure occurring at a nominal stress peak of 16.98 MPa. Moreover, coupled thermo-mechanical analysis of DCSS is carried out under different boundary conditions. These findings provide valuable guidance for designing and optimizing multifunctional structures.