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A two-step unconditionally stable explicit method with controllable numerical dissipations

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Earthquake Engineering and Engineering Vibration 2019年第2期18卷 285-299页

作者： Li Jinze yu kaiping Li Xiangyang Department of Astronautic Science and Mechanics Harbin Institute of Technology

A family of unconditionally stable direct integration algorithm with controllable numerical dissipations is proposed. The numerical properties of the new algorithms are controlled by three parameters α, β and γ. By the consistent and stability analysis, the proposed algorithms achieve the second-order accuracy and are unconditionally stable under the condition that α≥-0.5, β≤ 0.5 and γ≥-(1+α)/2. Compared with other unconditionally stable algorithms, such as Chang's algorithms and CR algorithm, the proposed algorithms are found to be superior in terms of the controllable numerical damping ratios. The unconditional stability and numerical damping ratios of the proposed algorithms are examined by three numerical examples. The results demonstrate that the proposed algorithms have a superior performance and can be used expediently in solving linear elastic dynamics problems.

关键词： direct integration method unconditional stability numerical dissipation dynamic analysis

On minimum cavitation number of the ventilated supercavity in water tunnel

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Science China(Physics,Mechanics & Astronomy) 2013年第10期56卷 1945-1951页

作者： ZOU Wang yu kaiping ARNDTREA KAWAKAMIE The School of Astronautics Harbin Institute of Technology Saint Anthony Falls Laboratory University of Minnesota

A numerical method consisted of the cavitation number correction and the model coefficient correction algorithms is presented to simulate the supercavity in water tunnel considering blockage and gravity effects based on the Logvinovich model.A model of the minimum cavitation number is also proposed based on the dimensional analysis theory,and the minimum cavitation number is formulated based on the model and numerical results using the nonlinear least square method(NLLS).The formula is verified by experiment to some extent.

关键词： supercavity minimum cavitation number Froude number blockage ratio NLLS

Nonlinear system identification framework of folding fins with freeplay using backbone curves

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Chinese Journal of Aeronautics 2022年第10期35卷 183-194页

作者： Shuaishuai LIU Rui ZHAO kaiping yu Bowen ZHENG Department of Astronautical Science and Mechanics Harbin Institute of TechnologyHarbin 150001China

Due to wear and manufacturing tolerance,the freeplay is unavoidable in the hinges of folding fins,which exerts significant effects on the aerodynamic *** paper proposes a backbone-curve-based framework for the dynamical identification of folding fins containing the freeplay *** no need to measure the input force signal and the response signals of nonlinear related Degrees of Freedom(DOFs),the proposed method is more direct and elegant than most existing nonlinear identification approaches,and it contains three steps:Firstly,the underlying linear model of the folding fin structure is obtained through the modal test on its linear sub-parts,and then,the harmonic approximation solves the analytical expressions of the backbone curves of measurable ***,response data measured from the sine-sweep test are used to extract the fitting points of backbone curves for these ***,the curve fitting approach is applied to identify the freeplay parameters.A series of numerical experiments verify the effectiveness of the proposed method.A real-life folding fin structure is also employed to illustrate how the method can be *** examples demonstrate that the identification framework can give an accurate dynamic model of the folding fin structure.

关键词： Backbone curves Folding fin Freeplay nonlinearity Harmonic approximation Indirect estimation Output-only identification

Nonlinear aeroelastic analysis of the folding fin with freeplay under thermal environment

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Chinese Journal of Aeronautics 2020年第9期33卷 2357-2371页

作者： Haonan HE Hong TANG kaiping yu Jinze LI Ning YANG Xiaolei ZHANG Department of Astronautical Science and Mechanics.Harbin Institute of Technology Harbin 150001China Beijing Institute of Electronic System Engineering Beijing 100854China

The nonlinear aeroelastic behavior of a folding fin in supersonic flow is investigated in this *** finite element model of the fin is established and the deployable hinges are represented by three torsion springs with the freeplay *** aerodynamic grid point is assumed to be at the center of each aerodynamic box for *** aerodynamic governing equation is given by using the infinite plate spline method and the modified linear piston *** improved fixed-interface modal synthesis method,which can reduce the rigid connections at the interface,is developed to save the problem size and computation *** uniform temperature field is applied to create the thermal *** the linear flutter analyses,the flutter speed increases first and then decreases with the rise of the hinge stiffness due to the change of the flutter coupling *** the nonlinear analyses,a larger freeplay angle results in a higher vibration divergent *** different types of limit cycle oscillations and a multiperiodic motion are observed in the wide range of airspeed under the linear flutter *** linear flutter speed shows a slight descend in the thermal environment,but the effect of the temperature on the vibration divergent speed is different under different hinge stiffnesses when there exists freeplay.

关键词： Aeroelasticity Fixed-interface modal synthesis method Folding fin Freeplay Thermal environment

Sliding mode control of supercavitating vehicles in the vertical plane using guaranteed cost theory

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High Technology Letters 2011年第2期17卷 186-190页

作者：吕瑞 Wei Yingjie Zhang Jiazhong yu kaiping Wang Jinghua School of Astronautics Harbin Institute of Technology Harbin 150001 P.R. China

This paper focuses on robust control problems for supercavitating vehicles in the vertical plane. Firstly, for the mathematical model with mismatched uncertainties, the robust sliding mode function is designed based on the guaranteed cost theory, and a sufficient condition for the existence is given in terms of linear matrix inequality （LMI）. Secondly, a continuous sliding mode controller is proposed to handle the nonlinear, time - varying behavior of the vehicles. Simulation results demonstrate that the system responds rapidly and has good robust stability. Therefore, it provides theoretical references for further study on control problems of supercavitating vehicles.

关键词： supercavitating vehicles mismatched uncertainties guaranteed cost control linear matrix inequality (LMI) sliding mode control

Vibration and Acoustic Response of Sandwich Panels with Flexible Core Under Thermal Environments

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Journal of Harbin Institute of Technology(New Series) 2017年第5期24卷 20-31页

作者： Jingyong Han kaiping yu Haiyang Song Xiangyang Li School of Astronautics Harbin Institute of Technology China Academy of Launch Vehicle Technology

Sandwich panels are increasingly used in the aerospace industry in recent years. Aircrafts are always affected by the thermal and noise environment during their life in service. Analytical studies on the sound vibration response of the sandwich panels with flexible core under thermal environments are performed in the paper. Governing equations are obtained by applying Hamilton 's principle with both anti-symmetric and symmetric motions taken into consideration. Natural frequencies,mode shape and critical temperature are acquired with thermal stresses considered. The forced vibration response and sound radiation are obtained based on the mode superposition principle and the Rayleigh integral. The model is validated compared with the results in literature. Natural frequencies for both anti-symmetric and symmetric motions decrease with temperature *** order flexural mode and higher-order dilatational mode are sensitive to the temperature change. Symmetric motion induces the anti-resonance frequencies move to the low frequency range. The peaks of sound vibration response remove to the low frequency range as the temperature rise and the amplitude of the peaks decrease due to the enhanced *** proposed model may serve as an effective guideline for the application of sandwich panels in thermal environments.

关键词： sandwich panels symmetric motion vibration sound radiation thermal environment

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考虑测量误差影响的改进随机激励辨识方法

振动．测试与诊断 2020年第6期40卷 1105-1111,1231页

作者：盖晓男于开平哈尔滨工业大学航天学院哈尔滨150001

为研究考虑测量误差影响的随机激励辨识方法,首先,在逆虚拟激励法中引入模型测量误差和响应测量误差,推演总结影响随机激励辨识精度的因素;其次,分析提高辨识精度的途径;最后,引入系数矩阵来减弱频率响应函数矩阵的条件数对随机激励辨... 详细信息

为研究考虑测量误差影响的随机激励辨识方法,首先,在逆虚拟激励法中引入模型测量误差和响应测量误差,推演总结影响随机激励辨识精度的因素;其次,分析提高辨识精度的途径;最后,引入系数矩阵来减弱频率响应函数矩阵的条件数对随机激励辨识精度的影响。以悬臂梁结构为对象进行多点随机激励辨识的数值仿真研究;以复合板结构为对象,进行多点随机振动试验研究。结果表明,与传统的逆虚拟激励法相比,此改进方法在考虑测量误差的同时能有效地提高某些固有频率附近的识别精度。

关键词：随机振动激励辨识测量误差系数矩阵

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识别时变结构模态参数的改进子空间方法

应用力学学报 2005年第2期22卷 184-188,i004页

作者：庞世伟于开平邹经湘哈尔滨工业大学哈尔滨150001

给出了基于整体数据子空间方法的改进算法,原方法对噪声的影响极为敏感,基于原方法的关键是计算一个与原系统的广义能观阵的特征值相同的矩阵的基本事实,将求矩阵的过程转化为最小二乘的问题,然后用广义能观阵替换输出矩阵,对数据进行滤... 详细信息

给出了基于整体数据子空间方法的改进算法,原方法对噪声的影响极为敏感,基于原方法的关键是计算一个与原系统的广义能观阵的特征值相同的矩阵的基本事实,将求矩阵的过程转化为最小二乘的问题,然后用广义能观阵替换输出矩阵,对数据进行滤波,从而有效地降低了算法对噪声敏感性,但同时增加了计算量。利用奇异向量矩阵的正交性,将最小二乘问题中求矩阵伪逆的过程简化为求该矩阵的转置,从而降低了计算量,改进后的算法能够在提高算法对噪声的敏感性的同时降低计算量。最后利用改进后的方法辨识出一个两自由度弹簧质量块模型在三种不同的刚度变化形式下的伪模态参数,并通过与使用原方法所得的结果比较,验证了以上结论。

关键词：模态参数识别子空间方法时变结构系统

用于线性时变系统辨识的固定长度平移窗投影估计递推子空间方法

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机械工程学报 2005年第10期41卷 117-122页

作者：庞世伟于开平邹经湘哈尔滨工业大学航天科学与力学系哈尔滨150001

给出了一个新的用于线性时变参数结构系统模态参数识别的基于固定长度平移窗投影估计的递推子空间方法。首先推得基于平移窗投影估计的子空间跟踪算法,以代替奇异值分解,再推得系统数据矩阵的一阶修正形式,从而得到新的基于平移窗投影... 详细信息

给出了一个新的用于线性时变参数结构系统模态参数识别的基于固定长度平移窗投影估计的递推子空间方法。首先推得基于平移窗投影估计的子空间跟踪算法,以代替奇异值分解,再推得系统数据矩阵的一阶修正形式,从而得到新的基于平移窗投影估计的递推子空间方法。该方法可有效地降低算法的计算量。最后通过刚度随时间变化的3自由度系统和一具有移动质量的机械臂系统的时变模态频率辨识仿真表明该方法可有效地辨识线性时变系统的伪模态参数。

关键词：平移窗投影估计线性时变系统递推子空间方法模态参数识别