The dynamics of beams subjected to moving loads are of practical importance since the responses caused by these loads can be greater than those under equivalent static loads in some cases.In this work,a novel inertial...The dynamics of beams subjected to moving loads are of practical importance since the responses caused by these loads can be greater than those under equivalent static loads in some cases.In this work,a novel inertial nonlinear energy sink(NES)is applied for the first time to achieve vibration suppression in beams under moving loads.Based on the Timoshenko beam theory,the nonlinear motion equations of a beam with an inertial NES are derived using the energy method and Lagrange equations.The Newmark-βmethod combined with the Heaviside step function is adopted to calculate the responses of the beam under moving loads of constant amplitude and harmonic excitation.The accuracy of the modelling derivation and solution methodology are validated through comparisons with results from other studies.The results demonstrate that the velocity and excitation frequency of the moving load significantly affect the response of the beam as well as the performance of the inertial NES.To enhance its effectiveness under various moving load conditions,parametric optimization is numerically performed.The optimized inertial NES can achieve good performance by efficiently reducing the maximum deflection of the beam.The findings of this study contribute to advancing the understanding and application of NESs in mitigating structural vibrations caused by moving loads.展开更多
To thoroughly examine the complex relationships between tire and pavement vibrations,a sophisticated vehicle-pavement coupled system is proposed,incorporating a non-uniform dynamic friction force between the tire and ...To thoroughly examine the complex relationships between tire and pavement vibrations,a sophisticated vehicle-pavement coupled system is proposed,incorporating a non-uniform dynamic friction force between the tire and the pavement.According to the Timoshenko beam theory,a dynamic model of pavement structure with a finite length beam was formulated on a nonlinear Pasternak foundation.To more accurately describe the coupling relationship between the tire and the pavement,and to take into account the vibration state under vehicle-pavement interaction,the load distribution between the tire and the pavement is modeled as a dynamic non-uniform contact.Combined with the classic LuGre tire model,the adhesion between the tire and the pavement is calculated.The Galerkin truncation method is employed to transform the pavement vibration partial differential equation into a finite ordinary differential equation,and the integral expression of the nonlinear foundation beam term is derived using the product to sum formula.By using the Runge-Kutta method,the tire-road coupled system can be numerically calculated,thus determining tire adhesion.This research demonstrates that compared with tire force under the traditional static load distribution,load distribution has a significant influence on adhesion.This study offers valuable insights for pavement structure design and vehicle performance control.展开更多
Based on the Timoshenko beam theory,this paper proposes a nonlocal bi-gyroscopic model for spinning functionally graded(FG)nanotubes conveying fluid,and the thermal–mechanical vibration and stability of such composit...Based on the Timoshenko beam theory,this paper proposes a nonlocal bi-gyroscopic model for spinning functionally graded(FG)nanotubes conveying fluid,and the thermal–mechanical vibration and stability of such composite nanostructures under small scale,rotor,and temperature coupling effects are investigated.The nanotube is composed of functionally graded materials(FGMs),and different volume fraction functions are utilized to control the distribution of material properties.Eringen’s nonlocal elasticity theory and Hamilton’s principle are applied for dynamical modeling,and the forward and backward precession frequencies as well as 3D mode configurations of the nanotube are obtained.By conducting dimensionless analysis,it is found that compared to the Timoshenko nano-beam model,the conventional Euler–Bernoulli(E-B)model holds the same flutter frequency in the supercritical region,while it usually overestimates the higher-order precession frequencies.The nonlocal,thermal,and flowing effects all can lead to buckling or different kinds of coupled flutter in the system.The material distribution of the P-type FGM nanotube can also induce coupled flutter,while that of the S-type FGM nanotube has no impact on the stability of the system.This paper is expected to provide a theoretical foundation for the design of motional composite nanodevices.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12102015 and 12472003)the General Program of Science and Technology Development Project of the Beijing Municipal Education Commission(Grant No.KM202110005030)the Key Research Project of Zhejiang Market Supervision Administration(Grant No.ZD2024013).
文摘The dynamics of beams subjected to moving loads are of practical importance since the responses caused by these loads can be greater than those under equivalent static loads in some cases.In this work,a novel inertial nonlinear energy sink(NES)is applied for the first time to achieve vibration suppression in beams under moving loads.Based on the Timoshenko beam theory,the nonlinear motion equations of a beam with an inertial NES are derived using the energy method and Lagrange equations.The Newmark-βmethod combined with the Heaviside step function is adopted to calculate the responses of the beam under moving loads of constant amplitude and harmonic excitation.The accuracy of the modelling derivation and solution methodology are validated through comparisons with results from other studies.The results demonstrate that the velocity and excitation frequency of the moving load significantly affect the response of the beam as well as the performance of the inertial NES.To enhance its effectiveness under various moving load conditions,parametric optimization is numerically performed.The optimized inertial NES can achieve good performance by efficiently reducing the maximum deflection of the beam.The findings of this study contribute to advancing the understanding and application of NESs in mitigating structural vibrations caused by moving loads.
基金financially supported by the National Natural Science Foundation of China(Grant No.12072204).
文摘To thoroughly examine the complex relationships between tire and pavement vibrations,a sophisticated vehicle-pavement coupled system is proposed,incorporating a non-uniform dynamic friction force between the tire and the pavement.According to the Timoshenko beam theory,a dynamic model of pavement structure with a finite length beam was formulated on a nonlinear Pasternak foundation.To more accurately describe the coupling relationship between the tire and the pavement,and to take into account the vibration state under vehicle-pavement interaction,the load distribution between the tire and the pavement is modeled as a dynamic non-uniform contact.Combined with the classic LuGre tire model,the adhesion between the tire and the pavement is calculated.The Galerkin truncation method is employed to transform the pavement vibration partial differential equation into a finite ordinary differential equation,and the integral expression of the nonlinear foundation beam term is derived using the product to sum formula.By using the Runge-Kutta method,the tire-road coupled system can be numerically calculated,thus determining tire adhesion.This research demonstrates that compared with tire force under the traditional static load distribution,load distribution has a significant influence on adhesion.This study offers valuable insights for pavement structure design and vehicle performance control.
基金National Natural Science Foundation of China,12372025,Feng Liang,12072311,Feng Liang.
文摘Based on the Timoshenko beam theory,this paper proposes a nonlocal bi-gyroscopic model for spinning functionally graded(FG)nanotubes conveying fluid,and the thermal–mechanical vibration and stability of such composite nanostructures under small scale,rotor,and temperature coupling effects are investigated.The nanotube is composed of functionally graded materials(FGMs),and different volume fraction functions are utilized to control the distribution of material properties.Eringen’s nonlocal elasticity theory and Hamilton’s principle are applied for dynamical modeling,and the forward and backward precession frequencies as well as 3D mode configurations of the nanotube are obtained.By conducting dimensionless analysis,it is found that compared to the Timoshenko nano-beam model,the conventional Euler–Bernoulli(E-B)model holds the same flutter frequency in the supercritical region,while it usually overestimates the higher-order precession frequencies.The nonlocal,thermal,and flowing effects all can lead to buckling or different kinds of coupled flutter in the system.The material distribution of the P-type FGM nanotube can also induce coupled flutter,while that of the S-type FGM nanotube has no impact on the stability of the system.This paper is expected to provide a theoretical foundation for the design of motional composite nanodevices.
