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The thermochromic properties of vanadium dioxide (VO 2) hold great promise for applications in smart glass windows. VO 2 films exhibit a high phase transition temperature (T c), low visible transmission (T lum), and low solar modulating ability (ΔT sol), making them inadequate for the requirements of smart glass windows. While some improvement in VO 2 film performance can be achieved through single-element doping, these limited enhancements still fall short of ideal results. Therefore, there is a pressing need for the improvement of VO 2 films. In this study, we utilized the sol-gel method to prepare VO 2 samples simultaneously doped with three elements: W, Sn, and Zr. Microscopic characterization confirmed the successful incorporation of these elements. Optical measurements, including ultraviolet–visible–near-infrared spectroscopy, were conducted to assess the optical properties of the films. Ultimately, outstanding T lum (69%) and ΔT sol (14%) were achieved, along with an appropriate T c (27.6 °C). Energy consumption simulations were performed using the EnergyPlus model with experimental data, revealing that compared to conventional glass, VO 2 glass reduces total cooling energy consumption by 9.8%. In comparison to previous work, the multi-element-doped films push the performance limits of VO 2 films, offering a viable approach for fabricating superior VO 2 smart glass windows. [Display omitted] [ABSTRACT FROM AUTHOR]

Composite thin-walled lenticular tube (CTLT) is a lightweight foldable and deployable structural material that enables large-scale deployable mechanisms for various space missions. A key step toward the structural design of CTLT is to understand its folding, stowage, and deployment behaviors. This work presents an integrated experimental and numerical investigation of the dynamic deployment behavior of CTLT that wraps around a central hub, with emphasis on the effect of long-term storage. A two-meter-long CTLT prototype was manufactured, and a gravity compensation system was designed and built for the on-ground dynamic deployment experiments. The deployment experiments were performed on the CTLT prototype both before and after it had been stowed for extended storage periods. The results indicate that after being stowed for 6 and 10.5 months the CTLT is deployed slower and the deployment time increases by 8.2% and 15.0%, respectively. Furthermore, a high-fidelity numerical model was constructed using the explicit dynamic finite element method, where the CTLT was modeled as a deformable part and the folding/deployment mechanisms were modeled as rigid bodies to perform the folding, stowage, and deployment simulations. The long-term storage effect was accounted for in the numerical analyses with the use of a viscoelastic fiber-reinforced composite material model, and a good agreement has been achieved between the experimental and numerical results. • Dynamic deployment tests of CTLT are conducted using a gravity unloading system. • FE simulations are performed to analyze the folding and deployment behavior of CTLT. • The effect of long-term stowage is revealed both in experiments and simulations. [ABSTRACT FROM AUTHOR]

Deployable rib-mesh reflector antennas, known for their ultralight nature and high deployment-to-stowage ratio, have been attracting attention from both the aerospace industry and academia. Form finding is a critical step in determining the equilibrium shape of the reflector under a specific internal stress distribution, which is a prerequisite in evaluating the surface accuracy of these antennas. This paper presents a comprehensive methodology for iteratively implementing the nonlinear finite element method for form finding of cable-membrane structures supported by flexible frames. The method is integrated into the commercial finite element code ABAQUS with Python scripts, and its accuracy and efficiency are validated through a few benchmark examples. Subsequently, the proposed method is applied to analyze the surface accuracy of umbrella-like rib-mesh reflector antennas. The effect of key design parameters such as the number and rigidity of ribs, the magnitude and anisotropy of membrane stress, and the amount of pretension force in boundary cables on the antenna's surface accuracy has been highlighted. The effort not only establishes a robust and user-friendly strategy for form finding of cable-membrane structures supported by flexible frames but also provides valuable insights into the surface accuracy of umbrella-like rib-mesh reflector antennas. To facilitate the application of the FEM-based form-finding method, the source code for this paper is publicly available via a permanent link on GitHub https://github.com/SCU-An-Group/FEM-based-Form-Finding. • FEM techniques for form finding of tensile cable-membrane structures are detailed. • Elastic deformation of supporting frames is included in the form finding procedure. • Benchmark cases are solved to validate the accuracy of the proposed method. • Surface accuracy analysis is conducted for umbrella-like rib-mesh reflectors. [ABSTRACT FROM AUTHOR]

Fluid-elastic instability (FEI) poses a particularly significant challenge to the safety of steam generators, given its potential to cause substantial damage in short periods. The tube bundle system model is inherently complex, resulting in expensive costs for experiments and numerical simulations during the design process. In this study, a substantial volume of FEI experimental data, conducted by various scholars, was compiled to create FEI surrogate model. The accuracy and feasibility of this surrogate model were demonstrated and compared to experimental results. This work represents the pioneering reference on the optimization of tube array configurations, achieved by combining FEI deep neural network (DNN) surrogate model with genetic algorithm (GA). The design variables for optimization encompassed tube array configurations and structural parameters. The optimization objective is to achieve a tubular array structure exhibiting a higher critical velocity, U r , enabling safe operation of the heat exchanger tube bundle across a wider range of flow rates without any FEI accident. The developed approach holds promise for data-driven FEI analysis and optimized tube bundle design, resulting in substantial time and cost savings. We publicly share all code implementations, and we believe that our efforts open a door for the surrogate-model-assisted structural optimization of tube arrays. • The FEI surrogate model is established by training extensive experimental data. • The tube array configurations are first set as input variables in the FEI-DNN model. • The first refernce on tube bundle FEI optimization combined DNN with GA (GA-DNN). [ABSTRACT FROM AUTHOR]

The composite tape-spring hinge (CTSH) is a lightweight structural connector widely employed in space structures, including spacecraft and satellites, due to its high specific strength and stiffness. Introducing cutouts enables CTSH to possess folding and deployment capability, while optimizing the cutouts finely to optimize the performance of CTSH. However, the interaction between cutout size and the dynamic deployment of CTSH is a novel topic. To address this, a multi-objective optimization problem is formulated, aiming to minimize both the maximum overshoot angle and deployment time while considering mass constraints. An accelerated size optimization is achieved by integrating data-driven surrogate modeling and size optimization. The optimized CTSH design exhibits a significant improvement in performance, with a 26.3% reduction in the maximum overshoot angle and a 12.6% reduction in the deployment time compared to the initial design. The proposed optimization strategy is highly adaptable and can be applied to various optimization problems, offering valuable insights for future designing space deployable structures with desirable performance. [Display omitted] • Employed a combination of dynamic testing and high-fidelity finite element modeling for accurate characterization of dynamic unfolding behavior of CTSH. • Highlighted the potential of cutouts size optimization in enhancing the dynamic behavior of composite tape spring hinges. • Proposed an accelerated size optimization strategy using data-driven surrogate modeling. • Optimized CTSH design reduces overshoot angle and deployment time by 12.6% and 26.3% respectively, while saving 97% in computational costs. [ABSTRACT FROM AUTHOR]