随着清洁可再生能源的不断发展,利用洋流能为水下微型无线传感器提供电能已成为研究热点。水下涡激振动能量俘获系统是一种在浅海低流速条件下利用涡激振动效应俘获洋流能的发电装置。本文将非线性恢复力、单向轴承及齿轮齿条机构与振...随着清洁可再生能源的不断发展,利用洋流能为水下微型无线传感器提供电能已成为研究热点。水下涡激振动能量俘获系统是一种在浅海低流速条件下利用涡激振动效应俘获洋流能的发电装置。本文将非线性恢复力、单向轴承及齿轮齿条机构与振动钝体结合,提出一种新型基于洋流能的涡激振动能量俘获系统。采用Van der Pol方程描述流体和钝体间的耦合效应,建立系统流-固-电耦合动力学方程。对系统进行稳定性分析,得到系统在单稳、双稳及三稳态情况下的参数数值范围,将3种稳态下系统的振幅比进行对比,发现系统处于三稳态时具有较强的发电优势。借助数值仿真,通过钝体振动的时域图、相图、分岔图及庞加莱截面详细研究流体参数(水流流速)和结构参数(质量比和阻尼比)对系统位移响应的影响,并分析单向轴承对传动轴转速的影响。分析质量比和阻尼比对发电功率的影响。结果表明,三稳态系统拥有非常丰富的非线性动力学行为,出现混沌运动、多周期运动及准周期运动,阻尼比的变化主要影响发电功率的峰值,而质量比的变化主要影响涡激振动的共振区间范围。展开更多
This paper aims to explore and quantify the nonlinear vibration response of tri-directional functionally graded sandwich(3D-FGSW)plates partially supported by a Pasternak foundation(PF)subjected to blast loading(BL).A...This paper aims to explore and quantify the nonlinear vibration response of tri-directional functionally graded sandwich(3D-FGSW)plates partially supported by a Pasternak foundation(PF)subjected to blast loading(BL).A key objective is to develop a computationally efficient finite element framework capable of accurately capturing the complex behavior of 3D-FGSW plates.The studied configuration features a two-dimensional functionally graded material(2D-FGM)core between two threedimensional functionally graded material(3D-FGM)face layers.Nonlinear geometric effects,including mid-plane stretching,are modeled using von K arm an-type assumptions,and the governing equations are formulated via Hamilton's principle within an improved first-order shear deformation theory(iFSDT).The accuracy and computational efficiency of the proposed method are validated through comparison with existing benchmark solutions.Subsequently,a comprehensive parametric study is carried out to examine the effects of geometric dimensions,material properties,foundation sizes,and boundary conditions(BCs)on the nonlinear vibration of 3D-FGSW plates.The findings of this work are expected to provide valuable insights for the design and manufacturing of advanced sandwich structures subjected to BL.展开更多
Magnetorheological(MR)bearings,with their field-controllable rheological properties,offer new possibilities for control of rotor instabilities.However,their nonlinear dynamic behaviors and the underlying physical mech...Magnetorheological(MR)bearings,with their field-controllable rheological properties,offer new possibilities for control of rotor instabilities.However,their nonlinear dynamic behaviors and the underlying physical mechanisms governing these instabilities remain insufficiently understood.This work develops a coupled MR bearingrotor system model,where the oil film force is derived from a novel bilinear constitutive equation to capture the field-sensitive shear behaviors of MR fluids.Complex nonlinear dynamic behaviors including period doubling,quasi-period,and chaos are revealed,which emerge from the interaction between oil film vortex dynamics and magnetic excitation.The critical instability mechanism is identified from the evolution of intrinsic dynamic characteristics of MR bearings.When the whirl speed within the oil film reaches approximately half of the rotor speed,the damping force balances the destabilizing force,thereby defining a critical threshold beyond which the system transitions to instability.This threshold can be effectively tuned by adjusting the excitation current,which modifies the yield stress of MR fluids and consequently regulates the damping force.As a result,the nonlinear vibrations of oil whirl and whip can be suppressed,and the system stability can be significantly enhanced.These findings provide both theoretical insight and practical guidance for the design and control of MR bearing supported rotor systems.展开更多
文摘随着清洁可再生能源的不断发展,利用洋流能为水下微型无线传感器提供电能已成为研究热点。水下涡激振动能量俘获系统是一种在浅海低流速条件下利用涡激振动效应俘获洋流能的发电装置。本文将非线性恢复力、单向轴承及齿轮齿条机构与振动钝体结合,提出一种新型基于洋流能的涡激振动能量俘获系统。采用Van der Pol方程描述流体和钝体间的耦合效应,建立系统流-固-电耦合动力学方程。对系统进行稳定性分析,得到系统在单稳、双稳及三稳态情况下的参数数值范围,将3种稳态下系统的振幅比进行对比,发现系统处于三稳态时具有较强的发电优势。借助数值仿真,通过钝体振动的时域图、相图、分岔图及庞加莱截面详细研究流体参数(水流流速)和结构参数(质量比和阻尼比)对系统位移响应的影响,并分析单向轴承对传动轴转速的影响。分析质量比和阻尼比对发电功率的影响。结果表明,三稳态系统拥有非常丰富的非线性动力学行为,出现混沌运动、多周期运动及准周期运动,阻尼比的变化主要影响发电功率的峰值,而质量比的变化主要影响涡激振动的共振区间范围。
文摘This paper aims to explore and quantify the nonlinear vibration response of tri-directional functionally graded sandwich(3D-FGSW)plates partially supported by a Pasternak foundation(PF)subjected to blast loading(BL).A key objective is to develop a computationally efficient finite element framework capable of accurately capturing the complex behavior of 3D-FGSW plates.The studied configuration features a two-dimensional functionally graded material(2D-FGM)core between two threedimensional functionally graded material(3D-FGM)face layers.Nonlinear geometric effects,including mid-plane stretching,are modeled using von K arm an-type assumptions,and the governing equations are formulated via Hamilton's principle within an improved first-order shear deformation theory(iFSDT).The accuracy and computational efficiency of the proposed method are validated through comparison with existing benchmark solutions.Subsequently,a comprehensive parametric study is carried out to examine the effects of geometric dimensions,material properties,foundation sizes,and boundary conditions(BCs)on the nonlinear vibration of 3D-FGSW plates.The findings of this work are expected to provide valuable insights for the design and manufacturing of advanced sandwich structures subjected to BL.
基金Project supported by the National Natural Science Foundation of China(Nos.52575093 and 12202229)the China Postdoctoral Science Foundation(No.2025M771368)the Fundamental Research Funds for the Central Universities of China(Nos.buctrc202405 and JD2522)。
文摘Magnetorheological(MR)bearings,with their field-controllable rheological properties,offer new possibilities for control of rotor instabilities.However,their nonlinear dynamic behaviors and the underlying physical mechanisms governing these instabilities remain insufficiently understood.This work develops a coupled MR bearingrotor system model,where the oil film force is derived from a novel bilinear constitutive equation to capture the field-sensitive shear behaviors of MR fluids.Complex nonlinear dynamic behaviors including period doubling,quasi-period,and chaos are revealed,which emerge from the interaction between oil film vortex dynamics and magnetic excitation.The critical instability mechanism is identified from the evolution of intrinsic dynamic characteristics of MR bearings.When the whirl speed within the oil film reaches approximately half of the rotor speed,the damping force balances the destabilizing force,thereby defining a critical threshold beyond which the system transitions to instability.This threshold can be effectively tuned by adjusting the excitation current,which modifies the yield stress of MR fluids and consequently regulates the damping force.As a result,the nonlinear vibrations of oil whirl and whip can be suppressed,and the system stability can be significantly enhanced.These findings provide both theoretical insight and practical guidance for the design and control of MR bearing supported rotor systems.
