Force and stress for electromechanical integrated toroidal drive

Lizhong Xu,Jin Huang 국제구조공학회 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.3

Vibration characteristic analysis of high-speed railway simply supported beam bridge-track structure system

Lizhong Jiang,Yulin Feng,Wangbao Zhou,Binbin He 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.31 No.6

Based on the energy-variational principle, a coupling vibration analysis model of high-speed railway simply supported beam bridge-track structure system (HSRBTS) was established by considering the effect of shear deformation. The vibration differential equation and natural boundary conditions of HSRBTS were derived by considering the interlayer slip effect. Then, an analytic calculation method for the natural vibration frequency of this system was obtained. By taking two simply supported beam bridges of high-speed railway of 24 m and 32 m in span as examples, ANSYS and MIDAS finite-element numerical calculation methods were compared with the analytic method established in this paper. The calculation results show that two of them agree well with each other, validating the analytic method reported in this paper. The analytic method established in this study was used to evaluate the natural vibration characteristics of HSRBTS under different interlayer stiffness and length of rails at different subgrade sections. The results show that the vertical interlayer compressive stiffness had a great influence on the high-order natural vibration frequency of HSRBTS, and the effect of longitudinal interlayer slip stiffness on the natural vibration frequency of HSRBTS could be ignored. Under different vertical interlayer stiffness conditions, the subgrade section of HSRBTS has a critical rail length, and the critical length of rail at subgrade section decreases with the increase in vertical interlayer compressive stiffness.

Studies on restoring force model of concrete filled steel tubular laced column to composite box-beam connections

Lizhong Jiang,Zhi Huang,Wang-Bao Zhou,Shan Chen 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.22 No.6

Mega composite structure systems have been widely used in high rise buildings in China. Compared to other structures, this type of composite structure systems has a larger cross-section with less weight. Concrete filled steel tubular (CFST) laced column to box-beam connections are gaining popularity, in particular for the mega composite structure system in high rise buildings. To enable a better understanding of the destruction characteristics and aseismic performance of these connections, three different connection types of specimens including single-limb bracing, cross bracing and diaphragms for core area of connections were tested under low cyclic and reciprocating loading. Hysteresis curves and skeleton curves were obtained from cyclic loading tests under axial loading. Based on these tested curves, a new trilinear hysteretic restoring force model considering rigidity degradation is proposed for CFST laced column to box-beam connections in a mega composite structure system, including a trilinear skeleton model based on calculation, law of stiffness degradation and hysteresis rules. The trilinear hysteretic restoring force model is compared with the experimental results. The experimental data shows that the new hysteretic restoring force model tallies with the test curves well and can be referenced for elastic-plastic seismic analysis of CFST laced column to composite box-beam connection in a mega composite structure system.

Analysis on natural vibration characteristics of steel-concrete composite truss beam

Lizhong Jiang,Yulin Feng,Wangbao Zhou,Binbin He 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.26 No.1

In order to study the natural vibration characteristics of steel-concrete composite truss beam (SCCTB), the influence of multiple factors such as interface slip, shear deformation and moment of inertia are considered. Afterwards, based on the Hamilton principle the vibration control differential equation and natural boundary conditions of SCCTB are deduced. By solving SCCTB differential equations of vibration control, an analytical calculation method is proposed for analyzing the natural vibration characteristics of SCCTB. The natural frequencies of SCCTBs with different degrees of shear connection and effective lengths are calculated by using the analytical method, and the results are compared against those obtained from ANSYS finite element numerical calculation method. The results show that the analytical method considering the influence factors such as interface slip, shear deformation and moment of inertia are in good agreement with those obtained from ANSYS finite element numerical calculation method. This evidences the correctness of the analytical method and show that the method proposed exhibits improvement over the previously developed theories for the natural vibration characteristics of SCCTB. Finally, based on the analytical method, the influence factors of SCCTB natural vibration characteristics are analyzed. The results indicate that the influence of interface slip stiffness on SCCTB's natural frequency is more than 10% and therefore cannot be neglected. Moreover, shear deformation has an effect of more than 35% on SCCTB’s natural frequency and the effect cannot be ignored either in this case too.

ON FINITENESS PROPERTIES ON ASSOCIATED PRIMES OF LOCAL COHOMOLOGY MODULES AND EXT-MODULES

Lizhong Chu,Xian Wang 대한수학회 2014 대한수학회지 Vol.51 No.2

Let R be a commutative Noetherian (not necessarily local) ring, I an ideal of R and M a finitely generated R-module. In this paper, by computing the local cohomology modules and Ext-modules via the injective resolution of M, we proved that, if for an integer t > 0, dim R H i I (M) ≤ k for ∀i < t, then [수식] for ∀j ≤ t and ∀n > 0. This shows that [수식] is a finite set for ∀i ≤ t. Also, we prove that [수식] if x 1 ,x 2 ,...,x r is M-sequences in dimension > k and n 1 ,n 2 ,...,n r are some positive integers. Here, for a subset T of Spec(R), set T ≥i = {p ∈ T | dimR/p ≥ i}.

A New Method to Assign Computer Network Link Capacities

LiZhong Yuan 대한전자공학회 1991 ICEIC:International Conference on Electronics, Inf Vol.1991 No.8

Forced response of the inertial piezoelectric rotary motor to electric excitation

Lizhong Xu,Jichun Xing 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.11

For a novel inertial piezoelectric rotary motor, the equation of the voltage response on the piezo-ceramic bimorph under the excitationsignals is deduced and the dynamic equation of the motor rotor is given. Using the equations, the voltage responses on the piezo-ceramicbimorph and the responses of the displacement, velocity and acceleration on the rotor to the sawtooth voltage excitation are investigated. The results show that when the frequency of the excitation signal is quite low, the waveform of the displacement response of the rotor isidentical to one of the excitation signal; the outer diameter of the rotor, its length and thickness, etc., have obvious effects on the inertialmoment applied to the rotor. The results are useful for design and control of the operating performance of the motor.

Effects of eccentricity on dynamic behavior of electromechanical integrated electrostatic harmonic actuator

Lizhong Xu,Xu Shi 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.9

The authors earlier invented an electromechanical integrated electrostatic harmonic actuator consisting of a flexible ring and segmented stator. As the dimension of the actuator decreases, the effect of ring eccentricity on the dynamic behavior of the actuator becomes significant. In this paper, the equations for the displacements of the flexible ring and the electromechanical coupled dynamic equations under eccentricity are deduced. Using these equations, changes of the natural frequencies and vibrating modes as a function of the eccentric center distance are analyzed. For different eccentric center distances, changes of the forced response along with the system parameters are given. Results show that the ring eccentricity causes significant changes of the natural frequencies and vibrating amplitudes of the flexible ring, which could cause loss of the load-carrying ability for the actuator. The flexible ring radius, thickness, and clearance and voltage between the flexible ring and stator influence the relationship between the eccentricity and the dynamic behavior of the actuator.

Distortional and local buckling of steel-concrete composite box-beam

Lizhong Jiang,Jingjing Qi,Andrew Scanlon,Linlin Sun 국제구조공학회 2013 Steel and Composite Structures, An International J Vol.14 No.3

Distortional and local buckling are important factors that influences the bearing capacity of steel-concrete composite box-beam. Through theoretical analysis of distortional buckling forms, a stability analysis calculation model of composite box beam considering rotation of steel beam top flange is resented. The critical bending moment calculation formula of distortional buckling is established. In addition, mechanical behaviors of a steel beam web in the negative moment zone subjected separately to bending stress, shear stress and combined stress are investigated. Elastic buckling factors of steel web under different stress conditions are calculated. On the basis of local buckling analysis results, a limiting value for height-to thickness ratio of a steel web in the elastic stage is proposed. Numerical examples are presented to verify the proposed models.

Dynamic analysis of a short cylinder piezo motor

Lizhong Xu,Shanjie Du 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.8

The bar-type traveling wave ultrasonic motor is simple, inexpensive, easy to use, and suitable for miniaturization. Its operating performanceis significantly affected by the dynamic behavior of the vibrator. In this work, the analytical equations for calculating the dynamicbehavior of the motor vibrator are presented using the ring model. The natural frequencies and vibrating modes of the motor areinvestigated using the analytical equations. Changes in the natural frequencies along with the motor parameters are analyzed. The forcedresponses of the vibrator to two input signals with a phase difference of 90º are given. A FEM analysis in ANSYS is used to simulate thenatural frequencies and vibrating modes of the vibrator. A test is conducted to illustrate the analytical calculative results.