Uniform wall thickness plays an essential role in avoiding forming failure in incremental sheet forming. However, it is challenging to promote the uniform distribution of wall thickness in single-pass forming of high wall angle and complex three-dimensional thin-walled parts using flexible dieless incremental sheet forming technology. In this article, based on the hydraulic support single-point incremental sheet forming technology, the finite element software is used to simulate and analyze the influence of different support pressure on the wall thickness distribution and the uniform critical angle of single-pass incremental sheet forming truncated pyramid parts. The results show that the hydraulic support can effectively improve the thickness uniformity and critical forming angle. In addition, a single-point increment experiment system of hydraulic support is designed, and the uniform critical angle of wall thickness corresponding to different support pressure is obtained. The experimental results are consistent with the finite element simulation results. Therefore, this article provides guidance for manufacturing high wall angles and complex parts with uniform wall thickness in single-pass incremental sheet forming.
Based on the new high-modulus carbon fiber CCM40J-6k, which is the critical raw material of a solar panel, the molding process of a mesh face sheet combined with epoxy resin, the overall mechanical performance of a mesh face sheet combined with aluminum honeycomb, the compatibility with polyimide insulation film + solar cell circuit, and the space environment adaptability must pass a test verification and assessment as the premise for large-scale orbit applications. Therefore, based on the traditional carbon fiber M40JB-6k as a reference, a systematic verification project was conducted to apply the CCM40J-6k carbon fiber composite at the process, component, and assembly levels. Six aspects of testing and verifying items were conducted, including mechanical properties under room temperature and thermal shock conditions, bonding force of mesh nodes, comparison of the adaptability of domestic and imported carbon fiber substrates to high–low temperature alternation, the ability of domestic carbon fiber substrates to adapt to the thermal environment after laying solar cell circuits, and in-orbit lifespan of solar panels. Based on the verification results, the mechanical properties of the substrate are the same as those of the imported M40JB-6k, and the actual molding process for M40JB-6k can be utilized. Sample pieces of the substrates can withstand the thermal shock and thermal cycling tests. The bending stiffness of the sample pieces before and after the tests is 3.5%~9.6% higher, and the bending strength is 4.2%~7.2% lower. The tensile strength of mesh nodes made of domestic carbon fiber is 18.9% higher than that of mesh nodes made of imported carbon fiber. The CCM40J-6k substrate is similar to triple-junction GaAs solar cells. The change rates of the open-circuit voltage and the short-circuit current of solar panels based on domestic carbon fiber after fatigue thermal cycling with 2070 cycles are 0.55% and 0.24%, respectively. The above results indicate that the comprehensive performance of the domestic carbon fiber CCM40J-6k meets the requirements and can be applied to solar panels for solar arrays.
6 April 2024 in Journal of Magnetism and Magnetic Materials
The multidimensional deployment of large-scale spatial solar arrays has been the basis for high-power advanced spacecraft and a symbol of the leaps forward in aerospace technology. Activated and passive drives have often been used in combination to implement the driving mechanism of large-scale solar arrays, which can reduce the impact of the deployment and locking process. For the first time, a novel active speed-limit mechanism was introduced into the two-dimensional secondary deployable drive system of a large-scale spatial solar array, achieving a balance between large deployable driving torque and small locking impact load. A highly integrated and lightweight drive system has been designed, integrating motor drive, gear drive, and adaptive torque limiting device to achieve adaptive control of the deployment torque of the solar array. A dynamic simulation system for the entire process of a large-scale spatial solar array based on the Kane method and ADAMS model has been established. A two-dimensional secondary deployable motion control law for a large-scale solar array using an active speed-limit mechanism has been established, and the dynamic characteristic parameters of the active speed-limit driving mechanism have been determined, such as driving torque, driving mode, and driving speed. The results can be used to guide the design of the deployable driving mechanism for large-scale spatial solar arrays.
This paper proposes a multilevel three-dimensional constitutive model based on a microscopically phenomenological approach from the domain rotation mechanism, which is a fully coupled self-consistent homogenization scheme considering the interactions between elastic–inelastic strain and hysteresis. Considering the interactions among magnetic domains, grains, polycrystalline complexes, and macroscopic phenomenology, we predict the nonlinear magnetostrictive response of Terfenol-D under different types of external force loads and magnetic excitations in various thermal environments involving multi-fields of coupled magnetic, elastic, thermal, and mechanical phenomena. The average values of the mechanical bulk strains for different magnetization states are obtained at the grain scale utilizing Boltzmann functions and a self-consistent homogenization scheme. A Taylor series expansion of the Gibbs function concerning the field variables and an adapted Jiles–Atherton model are used to construct the hysteresis coupled constitutive relations at the macroscopic scale. The results associated with the experiments show that the established model can reasonably predict the magnetostrictive response under different external mixed stimuli. It can provide theoretical guidance for the precise control of nonlinear vibrations and the optimal design of the rotating giant magnetostrictive transducers at both microscopic and macroscopic multiple scales.
12 July 2023 in Journal of Science: Advanced Materials and Devices