The unsteady aerodynamic loads generated by the thin-shell object separating from aircraft affects flying safety.To investigate the loads,a method combining numerical simulation and experiment is proposed.Firstly,the ...The unsteady aerodynamic loads generated by the thin-shell object separating from aircraft affects flying safety.To investigate the loads,a method combining numerical simulation and experiment is proposed.Firstly,the motional tendency of the thin-shell object separating from aircraft is calculated,and then the high-speed air blowing test on ground is designed.Thereafter,the external store is employed to avoid colliding with the thin-shell object in air.Finally,the hanging and flight test is conducted by a high-speed unmanned aerial vehicle(UAV),and the feasibility of the thin-shell object separating from aircraft at high speed is proved.Consequently,the separating problem of a thin-shell object with an unconventional aerodynamic configuration is solved,and the collisions with aircraft is prevented.展开更多
In this study,we conduct an analysis of traversable wormhole solutions within the framework of linear f(Q,T)=αQ+βT gravity,ensuring that all energy conditions hold for the entire spacetime.The solutions presented in...In this study,we conduct an analysis of traversable wormhole solutions within the framework of linear f(Q,T)=αQ+βT gravity,ensuring that all energy conditions hold for the entire spacetime.The solutions presented in this paper are derived through a comprehensive analytical examination of the parameter space associated with the wormhole model.This involves considering the exponents governing the redshift and shape functions,as well as the radius of the wormhole throat(r_(0)),the redshift function value at the throat(∅_(0)),and the model parameters(αandβ).Moreover,we establish bounds on these free parameters,which guarantee the satisfaction of the energy conditions throughout spacetime and also provide two solutions.Furthermore,we use the Israel junction condition to observe the stability of a thin-shell around the wormhole.Finally,we calculate the null energy condition criteria as well as the potential for the thin-shell and how it varies with the chosen shape function.展开更多
Cellular thin-shell structures are widely applied in ultralightweight designs due to their high bearing capacity and strength-to-weight ratio.In this paper,a full-scale isogeometric topology optimization(ITO)method ba...Cellular thin-shell structures are widely applied in ultralightweight designs due to their high bearing capacity and strength-to-weight ratio.In this paper,a full-scale isogeometric topology optimization(ITO)method based on Kirchhoff-Love shells for designing cellular tshin-shell structures with excellent damage tolerance ability is proposed.This method utilizes high-order continuous nonuniform rational B-splines(NURBS)as basis functions for Kirchhoff-Love shell elements.The geometric and analysis models of thin shells are unified by isogeometric analysis(IGA)to avoid geometric approximation error and improve computational accuracy.The topological configurations of thin-shell structures are described by constructing the effective density field on the controlmesh.Local volume constraints are imposed in the proximity of each control point to obtain bone-like cellular structures.To facilitate numerical implementation,the p-norm function is used to aggregate local volume constraints into an equivalent global constraint.Several numerical examples are provided to demonstrate the effectiveness of the proposed method.After simulation and comparative analysis,the results indicate that the cellular thin-shell structures optimized by the proposed method exhibit great load-carrying behavior and high damage robustness.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(No.XZA14027)
文摘The unsteady aerodynamic loads generated by the thin-shell object separating from aircraft affects flying safety.To investigate the loads,a method combining numerical simulation and experiment is proposed.Firstly,the motional tendency of the thin-shell object separating from aircraft is calculated,and then the high-speed air blowing test on ground is designed.Thereafter,the external store is employed to avoid colliding with the thin-shell object in air.Finally,the hanging and flight test is conducted by a high-speed unmanned aerial vehicle(UAV),and the feasibility of the thin-shell object separating from aircraft at high speed is proved.Consequently,the separating problem of a thin-shell object with an unconventional aerodynamic configuration is solved,and the collisions with aircraft is prevented.
基金supported by the University Grants Commission(UGC),New Delhi,India,for awarding National Fellowship for Scheduled Caste Students(UGC-Ref.No.201610123801)supported by the Council of Scientific and Industrial Research(CSIR),Government of India,New Delhi,for junior research fellowship(File No.09/1026(13105)/2022-EMR-I)supported by the National Board for Higher Mathematics(NBHM)under the Department of Atomic Energy(DAE),Govt.of India for financial support to carry out the research project(No.02011/3/2022 NBHM(R.P.)/R&D II/2152 Dt.14.02.2022)
文摘In this study,we conduct an analysis of traversable wormhole solutions within the framework of linear f(Q,T)=αQ+βT gravity,ensuring that all energy conditions hold for the entire spacetime.The solutions presented in this paper are derived through a comprehensive analytical examination of the parameter space associated with the wormhole model.This involves considering the exponents governing the redshift and shape functions,as well as the radius of the wormhole throat(r_(0)),the redshift function value at the throat(∅_(0)),and the model parameters(αandβ).Moreover,we establish bounds on these free parameters,which guarantee the satisfaction of the energy conditions throughout spacetime and also provide two solutions.Furthermore,we use the Israel junction condition to observe the stability of a thin-shell around the wormhole.Finally,we calculate the null energy condition criteria as well as the potential for the thin-shell and how it varies with the chosen shape function.
基金supported by the National Key R&D Program of China(Grant Number 2020YFB1708300)China National Postdoctoral Program for Innovative Talents(Grant Number BX20220124)+1 种基金China Postdoctoral Science Foundation(Grant Number 2022M710055)the New Cornerstone Science Foundation through the XPLORER PRIZE,the Knowledge Innovation Program of Wuhan-Shuguang,the Young Top-Notch Talent Cultivation Program of Hubei Province and the Taihu Lake Innovation Fund for Future Technology(Grant Number HUST:2023-B-7).
文摘Cellular thin-shell structures are widely applied in ultralightweight designs due to their high bearing capacity and strength-to-weight ratio.In this paper,a full-scale isogeometric topology optimization(ITO)method based on Kirchhoff-Love shells for designing cellular tshin-shell structures with excellent damage tolerance ability is proposed.This method utilizes high-order continuous nonuniform rational B-splines(NURBS)as basis functions for Kirchhoff-Love shell elements.The geometric and analysis models of thin shells are unified by isogeometric analysis(IGA)to avoid geometric approximation error and improve computational accuracy.The topological configurations of thin-shell structures are described by constructing the effective density field on the controlmesh.Local volume constraints are imposed in the proximity of each control point to obtain bone-like cellular structures.To facilitate numerical implementation,the p-norm function is used to aggregate local volume constraints into an equivalent global constraint.Several numerical examples are provided to demonstrate the effectiveness of the proposed method.After simulation and comparative analysis,the results indicate that the cellular thin-shell structures optimized by the proposed method exhibit great load-carrying behavior and high damage robustness.
