With the development of the aerospace industry,space missions are becoming more complicated and diversified,and there is a demand for antenna mechanisms with a larger physical aperture.In this paper,a planar deployabl...With the development of the aerospace industry,space missions are becoming more complicated and diversified,and there is a demand for antenna mechanisms with a larger physical aperture.In this paper,a planar deployable mechanism is proposed,which can form a flat reflection surface with a small gap between plates.To this end,a novel large-scale two-dimensional deployable nine-grid planar antenna mechanism is designed.First,two antenna folding schemes and four supporting mechanism schemes are proposed.Through comparison analysis,the antenna configuration scheme with the best comprehensive performance is selected.A kinematic model of the deployable mechanism is established,and its kinematic characteristics are analyzed.Then,the correctness of the kinematic model is verified by comparing the analytical and simulation results of the kinematic model.Subsequently,a finite element model of the antenna is developed.Based on the response surface method,the structural parameters of the support rods of the antenna are optimized,and a set of optimized solutions with lightweight and high fundamental frequency characteristics are obtained.Finally,a prototype of the proposed nine-grid planar antenna is fabricated.The feasibility of the deployment principle and the rationality of the designed mechanism are verified by deployment experiments.展开更多
Although forbidden band effect in perfectly periodic phononic crystals(PC)is very attractive,random disordered(i.e.detuning)phenomenon is inevitable in engineering processing,thus explor-ing the effect of detuning on ...Although forbidden band effect in perfectly periodic phononic crystals(PC)is very attractive,random disordered(i.e.detuning)phenomenon is inevitable in engineering processing,thus explor-ing the effect of detuning on the wave characteristics of PC becomes a necessity.In this study,fundamental governing equa-tions and boundary conditions are derived from the principle of virtual work.Wave characteristics and localization factor of one-dimensional(1D)detuned nano-PC are investigated based on the transfer matrix method,with flexoelectric effect duly accounted for.Subsequently,with BaTiO_(3)SrTiO_(3) nano-PC taken for illustration,forbidden band properties and localization factor of 1D elastic waves in harmonic and detuned states are systematically character-ized.It is demonstrated that localization factor can characterize the energy band structure of 1D PC perfectly.Flexoelectric effect tends to widen the width of forbidden band with increasing detuning,and detuning is linearly related to the bandwidth.The forbidden band is more sensitive to flexoelectric coefficient detuning than thickness detuning.The research results provide useful theoretical guidance for designing high-frequency nanoscaled devices with the function of filtering based on band gap effect of nano-PC.展开更多
基金supported by the National Natural Science Foundation of China(No.52075467).
文摘With the development of the aerospace industry,space missions are becoming more complicated and diversified,and there is a demand for antenna mechanisms with a larger physical aperture.In this paper,a planar deployable mechanism is proposed,which can form a flat reflection surface with a small gap between plates.To this end,a novel large-scale two-dimensional deployable nine-grid planar antenna mechanism is designed.First,two antenna folding schemes and four supporting mechanism schemes are proposed.Through comparison analysis,the antenna configuration scheme with the best comprehensive performance is selected.A kinematic model of the deployable mechanism is established,and its kinematic characteristics are analyzed.Then,the correctness of the kinematic model is verified by comparing the analytical and simulation results of the kinematic model.Subsequently,a finite element model of the antenna is developed.Based on the response surface method,the structural parameters of the support rods of the antenna are optimized,and a set of optimized solutions with lightweight and high fundamental frequency characteristics are obtained.Finally,a prototype of the proposed nine-grid planar antenna is fabricated.The feasibility of the deployment principle and the rationality of the designed mechanism are verified by deployment experiments.
基金This work is supported by the National Natural Science Foundation of China(11502110,11972185,and 12002156)the Open Fund of the State Key Laboratory for Strength and Vibration of Mechanical Structures,Xi’an Jiaotong University(No.SV2018-KF-01,No.SV2018-KF-22)the Open Project of Space Structure and Mechanism Technology Laboratory of China Aerospace Science and Technology Group Co.,Ltd.
文摘Although forbidden band effect in perfectly periodic phononic crystals(PC)is very attractive,random disordered(i.e.detuning)phenomenon is inevitable in engineering processing,thus explor-ing the effect of detuning on the wave characteristics of PC becomes a necessity.In this study,fundamental governing equa-tions and boundary conditions are derived from the principle of virtual work.Wave characteristics and localization factor of one-dimensional(1D)detuned nano-PC are investigated based on the transfer matrix method,with flexoelectric effect duly accounted for.Subsequently,with BaTiO_(3)SrTiO_(3) nano-PC taken for illustration,forbidden band properties and localization factor of 1D elastic waves in harmonic and detuned states are systematically character-ized.It is demonstrated that localization factor can characterize the energy band structure of 1D PC perfectly.Flexoelectric effect tends to widen the width of forbidden band with increasing detuning,and detuning is linearly related to the bandwidth.The forbidden band is more sensitive to flexoelectric coefficient detuning than thickness detuning.The research results provide useful theoretical guidance for designing high-frequency nanoscaled devices with the function of filtering based on band gap effect of nano-PC.
基金supported by the National Natural Science Foundation of China(Grant Nos.12172214 and 12102252)the China Postdoctoral Science Foundation(Grant No.2021M692070)the Industry-University-Research Cooperation Fund of Shanghai Institute of Aerospace System Engineering(Grant No.USCAST2021-12).
