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Size-dependent axisymmetric bending and buckling analysis of functionally graded sandwich Kirchhoff nanoplates using nonlocal strain gradient integral model

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Applied Mathematics and mechanics(English Edition) 2025年第3期46卷 467-484页

作者： Chang LI Hai QING State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China

This paper extends the one-dimensional(1D)nonlocal strain gradient integral model(NStraGIM)to the two-dimensional(2D)Kirchhoff axisymmetric nanoplates,based on nonlocal strain gradient integral relations formulated along both the radial and circumferential *** transforming the proposed integral constitutive equations into the equivalent differential forms,complemented by the corresponding constitutive boundary conditions(CBCs),a well-posed mathematical formulation is established for analyzing the axisymmetric bending and buckling of annular/circular functionally graded(FG)sandwich *** boundary conditions at the inner edge of a solid nanoplate are derived by L'H?spital's *** numerical solution is obtained by the generalized differential quadrature method(GDQM).The accuracy of the proposed model is validated through comparison with the data from the existing literature.A parameter study is conducted to demonstrate the effects of FG sandwich parameters,size parameters,and nonlocal gradient parameters.

关键词： size effect nonlocal strain gradient integral model(NStraGIM) bending buckling Kirchhoff annular/circular nanoplate functionally graded(FG)sandwich material

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Mass-spring model for elastic wave propagation in multilayered van der Waals metamaterials

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Applied Mathematics and mechanics(English Edition) 2024年第7期45卷 1107-1118页

作者： Yabin JING Lifeng WANG Yuqiang GAO State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing210016China

Multilayered van der Waals(vdW)materials have attracted increasing interest because of the manipulability of their superior optical,electrical,thermal,and mechanical properties.A mass-spring model(MSM)for elastic wave propagation in multilayered vdW metamaterials is reported in this *** dynamics(MD)simulations are adopted to simulate the propagation of elastic waves in multilayered vdW *** results show that the graphene/MoS_(2)metamaterials have an elastic wave bandgap in the terahertz *** MSM for the multilayered vdW metamaterials is proposed,and the numerical simulation results show that this model can well describe the dispersion and transmission characteristics of the multilayered vdW *** MSM can predict elastic wave transmission characteristics in multilayered vdW metamaterials stacked with different two-dimensional(2D)*** results presented in this paper offer theoretical help for the vibration reduction of multilayered vdW semiconductors.

关键词： multilayered van der Waals(vd W)metamaterial molecular dynamics(MD) mass-spring model(MSM) dispersion relation transmission characteristic

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Dynamic characteristics of multi-span spinning beams with elastic constraints under an axial compressive force

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Applied Mathematics and mechanics(English Edition) 2024年第2期45卷 295-310页

作者： Xiaodong GUO Zhu SU Lifeng WANG State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China

A theoretical model for the multi-span spinning beams with elastic constraints under an axial compressive force is *** displacement and bending angle functions are represented through an improved Fourier series,which ensures the continuity of the derivative at the boundary and enhances the *** exact characteristic equations of the multi-span spinning beams with elastic constraints under an axial compressive force are derived by the Lagrange *** efficiency and accuracy of the present method are validated in comparison with the finite element method(FEM)and other *** effects of the boundary spring stiffness,the number of spans,the spinning velocity,and the axial compressive force on the dynamic characteristics of the multi-span spinning beams are *** results show that the present method can freely simulate any boundary constraints without modifying the solution *** elastic range of linear springs is larger than that of torsion springs,and it is not affected by the number of *** an increase in the axial compressive force,the attenuation rate of the natural frequency of a spinning beam with a large number of spans becomes larger,while the attenuation rate with an elastic boundary is lower than that under a classic simply supported boundary.

关键词： multi-span spinning beam elastic constraint improved Fourier series free vibration semi-analytical solution

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Vibration of black phosphorus nanotubes via orthotropic cylindrical shell model

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Theoretical & Applied mechanics Letters 2024年第3期14卷 166-173页

作者： Minglei He Lifeng Wang State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Black phosphorus nanotubes(BPNTs)may have good properties and potential *** thevibration property of BPNTs is essential for gaining insight into the mechanical behaviour of BPNTs and designingoptimized *** this paper,the mechanical behaviour and vibration property of BPNTs are studied viaorthotropic cylindrical shell model and molecular dynamics(MD)*** vibration frequencies of twochiral BPNTs are analysed *** to the results of MD calculations,it is revealed that thenatural frequencies of two BPNTs with approximately equal sizes are unequal at each order,and that the naturalfrequencies of armchair BPNTs are higher than those of zigzag *** addition,an armchair BPNTs witha stable structure is considered as the object of research,and the vibration frequencies of BPNTs of differentsizes are *** comparing the MD results,it is found that both the isotropic cylindrical shell modeland orthotropic cylindrical shell model can better predict the thermal vibration of the lower order modes of thelonger BPNTs ***,for the vibration of shorter and thinner BPNTs,the prediction of the orthotropiccylindrical shell model is obviously superior to the isotropic shell model,thereby further proving the validity ofthe shell model that considers orthotropic for BPNTs.

关键词： Orthotropic cylindrical shell Molecular dynamics simulation Black phosphorus nanotube Vibration

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Analytical libration control law for electrodynamic tether system with current constraint

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Astrodynamics 2024年第2期8卷 237-246页

作者： Shidong Xu Ti Chen Hao Wen Dongping Jin State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing210016China

This study focuses on stabilizing the libration dynamics of an electrodynamic tether system(EDTS)using generalized torques induced by the Lorentz *** contrast to existing numerical optimization methods,a novel analytical feedback control law is developed to stabilize the in-plane and out-of-plane motions of a tether by modulating the electric current *** saturation constraint on the current is accounted for by adding an auxiliary dynamic system to the *** enhance the robustness of the proposed controller,multiple perturbations of the orbital dynamics,modeling uncertainties,and external disturbances are approximated using a neural network in which the weighting matrix and approximation error are estimated simultaneously,such that these perturbations are well compensated for during the control design of the ***,a dynamically scaled generalized inverse is utilized to address the singular matrix in the control *** closed-loop system is proven to be ultimately bounded based on Lyapunov stability ***,numerical simulations are performed to demonstrate the effectiveness of the proposed analytical control law.

关键词： electrodynamic tether system(EDTS) libration dynamics analytical control current constraint

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Dynamic response of sandwich panel attached with a double mass-spring-damping system to shallow-buried explosion:Analytical modeling

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Science China(Technological Sciences) 2024年第2期67卷 568-586页

作者： ZHANG DuJiang ZHAO ZhenYu GAO HuiYao LU TianJian State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China MIIT Key Laboratory of Multifunctional Lightweight Materials and Structures(MLMS) Nanjing University of Aeronautics and AstronauticsNanjing 210016China

How to ensure the safety of occupants has become a challenge for protective design of armored vehicles against intensive blast *** this study,for armored vehicles subjected to shallow-buried explosions,an analytical model was established to characterize the dynamic performance of an all-metallic sandwich floorboard attached with a double mass-spring-damping system(mimicking seat and occupant),with the former consisting of a front face,a core and a rear *** validation,numerical simulations with the method of finite elements(FE)were *** agreement between analytical predictions and numerical results was *** analytical model was then employed to quantify the effects of explosive mass,yield stress of material make,configurational parameters of sandwich panel,spring stiffness,and damping coefficient on dynamic response of the sandwich panel and double mass-spring-damping *** increasing explosive mass and decreasing yield stress of material make,the peak displacements of rear face,seat and occupant were all found to *** core relative density was increased,these peak displacements also increased when the ratio of face thickness to core height was relatively *** the ratio of face thickness to core height led to increased peak accelerations of seat and *** peak displacement of rear face was insensitive to the increase of either spring stiffness or damping coefficient,while the peak acceleration of occupant increased with increasing spring *** increasing the damping coefficient between the rear face and seat or that between the seat and occupant or both,the peak acceleration of occupant *** occupant safety duly considered,the proposed analytical model provides useful guidance for designing high-performance protective structures for armored vehicles subjected to intensive blast loadings.

关键词： analytical model shallow-buried explosion sandwich panel occupant safety mass-spring-damping system

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Variable-Diameter Deployable Structure Composite Preforms Made by Braiding and Needle-Punching Integrated Forming Technology

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Chinese Journal of Mechanical Engineering 2024年第6期37卷 649-665页

作者： Zhengxi Zhou Zitong Guo Zhongde Shan Zheng Sun Jun Zhang Fengchen Geng Yaoyao Wang Tianzheng Yang Zhiqi Zhuang Nanjing University of Aeronautics and Astronautics Nanjing 210016China State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing 210016China

Variable-diameter deployable carbon fiber reinforced polymer(CFRP)composites possess deformation and load-bearing functions and are composed of stiff-flexible coupled preforms and *** stiff-flexible coupled preform,serving as the reinforcing structure,directly determines the deployable properties,and its forming technology is currently a research *** paper designs a braiding and needle-punching(BNP)composite preform forming technology suitable for stiff-flexible coupled *** forming,the preform is partitioned into flexible and rigid zones,with braiding and needle-punching performed layer by layer in the respective zones.A retractable rotating device is developed to form the stiff-flexible coupled preform,achieving a diameter variation rate of up to 26.6%for the BNP preform.A structural parameter model is also established to describe the geometric parameter changes in the deformation and load-bearing areas of the preform during deployment as a function of the braiding *** on experiments,this paper explains the performance changes of BNP composites concerning the structural parameters of the *** analysis shows that as the braiding angle increases,the tensile performance of BNP composites significantly decreases,with the change rate of tensile strength first decreasing and then ***,when the braiding angle is less than 21.89°,the impact toughness of BNP composites remains within the range of 83.66±2 kJ/m^(2).However,when the braiding angle exceeds 21.89°,the impact toughness of BNP composites gradually decreases with increasing braiding ***,a hybrid agent model based on Latin hypercube sampling and error back-propagation neural network is developed to predict the tensile and impact properties of BNP composites with different structural parameters,with maximum test relative errors of 1.89%for tensile strength and 2.37%for impact toughness.

关键词： Variable-diameter deployable structure Composites preform Braiding and needle-punching process Parametric model Composites mechanics Prediction model

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Nonlocal stress gradient formulation for damping vibration analysis of viscoelastic microbeam in thermal environment

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Applied Mathematics and mechanics(English Edition) 2023年第5期44卷 773-786页

作者： Hai QING Huidiao SONG State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China

An integral nonlocal stress gradient viscoelastic model is proposed on the basis of the integral nonlocal stress gradient model and the standard viscoelastic model,and is utilized to investigate the free damping vibration analysis of the viscoelastic BernoulliEuler microbeams in thermal ***'s principle is used to derive the differential governing equations and corresponding boundary *** integral relations between the strain and the nonlocal stress are converted into a differential form with constitutive *** size-dependent axial thermal stress due to the variation of the environmental temperature is derived *** Laplace transformation is utilized to obtain the explicit expression for the bending deflection and *** the boundary conditions and constitutive constraints,one can get a nonlinear equation with complex coefficients,from which the complex characteristic frequency can be determined.A two-step numerical method is proposed to solve the elastic vibration frequency and the damping *** effects of length scale parameters,viscous coefficient,thermal stress,vibration order on the vibration frequencies,and critical viscous coefficient are investigated numerically for the viscoelastic Bernoulli-Euler microbeams under different boundary conditions.

关键词： damping vibration size effect integral nonlocal stress gradient model standard viscoelastic model Laplace transformation

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Adaptive fault-tolerant control for non-minimum phase hypersonic vehicles based on adaptive dynamic programming

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Chinese Journal of aeronautics 2024年第3期37卷 290-311页

作者： Le WANG Ruiyun QI Bin JIANG State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China

In this paper,a novel adaptive Fault-Tolerant control(FTC)strategy is proposed for non-minimum phase Hypersonic Vehicles(HSVs)that are affected by actuator faults and parameter *** strategy is based on the output redefinition method and Adaptive Dynamic Programming(ADP).The intelligent FTC scheme consists of two main parts:a basic fault-tolerant and stable controller and an ADP-based supplementary *** the basic FTC part,an output redefinition approach is designed to make zero-dynamics stable with respect to the new ***,Ideal Internal Dynamic(IID)is obtained using an optimal bounded inversion approach,and a tracking controller is designed for the new output to realize output tracking of the nonminimum phase HSV *** the ADP-based compensation control part,an ActionDependent Heuristic Dynamic Programming(ADHDP)adopting an actor-critic learning structure is utilized to further optimize the tracking performance of the HSV control ***,simulation results are provided to verify the effectiveness and efficiency of the proposed FTC algorithm.

关键词： Hypersonic vehicle Fault-tolerant control Non-minimum phase system Adaptive control Nonlinear control Adaptive dynamic programming

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An embedded piezoelectric actuator for active vibration control:Concept,modeling,simulation,and investigation

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Chinese Journal of aeronautics 2025年第4期38卷 244-256页

作者： Rui QI Liang WANG Jiamei JIN Lusheng YUAN Ziyu SHEN Yuning GE State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing 210016China College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Piezoelectric active vibration control holds paramount importance in space *** embedded piezoelectric actuator with a sandwich configuration is proposed,which enhances control accuracy by integrating various ***,the electromechanical coupling characteristics of the actuator are revealed,and the model is ***,the equivalent model of a cylindrical cantilever beam is investigated as the object,and the feasibility of the vibration control of the actuator is verified by ***,the prototype comprised of two actuators,which respectively use the proposed embedded actuators for producing the vibration and suppressing the vibration,is developed,and the measurement system is *** results demonstrate the excellent control efficiency in two orthogonal directions,achieving a minimum vibration amplitude control of 0.00102 mm and a maximum vibration control of-42.74 d *** integrated structure offers fast response,lightness,adaptability,and high control efficiency,which is conducive to enhancing the vibration control.

关键词： Piezoelectric actuators Vibration control Disturbance rejection Actuators Bending vibration

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