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Nonlinear dynamic analysis for elastic robotic arms

M. H. KORAYEM, H. N. RAHIMI

《机械工程前沿（英文）》 2011年 第6卷 第2期   页码 219-228 doi: 10.1007/s11465-011-0218-y

摘要：

The aim of the paper is to analyze the nonlinear dynamics of robotic arms with elastic links and joints. The main contribution of the paper is the comparative assessment of assumed modes and finite element methods as more convenient approaches for computing the nonlinear dynamic of robotic systems. Numerical simulations comprising both methods are carried out and results are discussed. Hence, advantages and disadvantages of each method are illustrated. Then, adding the joint flexibility to the system is dealt with and the obtained model is demonstrated. Finally, a brief description of the optimal motion generation is presented and the simulation is carried out to investigate the role of robot dynamic modeling in the control of robots.

关键词： robotic arms     elastic link     elastic joint     nonlinear dynamics     optimal control    

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using strain energy density as a function of stress triaxiality under quasi-static loading employing elastic-creep& elastic-plastic-creep deformation

Tahir MAHMOOD, Sangarapillai KANAPATHIPILLAI, Mahiuddin CHOWDHURY

《机械工程前沿（英文）》 2013年 第8卷 第2期   页码 181-186 doi: 10.1007/s11465-013-0257-7

摘要：

This paper demonstrates the application of a new multiaxial creep damage model developed by authors using stress traixiality to predict the failure time of a component made of 0.5%Cr-0.5%Mo-0.25%V low alloy steel. The model employs strain energy density and assumes that the uniaxial strain energy density of a component can be easily calculated and can be converted to multi-axial strain energy density by multiplying it to a function of stress trixiality which is a ratio of mean stress to equivalent stress. For comparison, an elastic-creep and elastic-plastic-creep finite element analysis (FEA) is performed to get multi-axial strain energy density of the component which is compared with the calculated strain energy density for both cases. The verification and application of the model are demonstrated by applying it to thin tube for which the experimental data are available. The predicted failure times by the model are compared with the experimental results. The results show that the proposed model is capable of predicting failure times of the component made of the above-mentioned material with an accuracy of 4.0%.

关键词： elastic-creep     elastic-plastic-creep     stress triaxiality     life prediction     pressure vessels     finite element analysis (FEA)    

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Analytical algorithms of compressive bending capacity of bolted circumferential joint in metro shield

《结构与土木工程前沿（英文）》   页码 901-914 doi: 10.1007/s11709-023-0915-8

摘要： The integrity and bearing capacity of segment joints in shield tunnels are associated closely with the mechanical properties of the joints. This study focuses on the mechanical characteristics and mechanism of a bolted circumferential joint during the entire bearing process. Simplified analytical algorithms for four stress stages are established to describe the bearing behaviors of the joint under a compressive bending load. A height adjustment coefficient, α, for the outer concrete compression zone is introduced into a simplified analytical model. Factors affecting α are determined, and the degree of influence of these factors is investigated via orthogonal numerical simulations. The numerical results show that α can be specified as approximately 0.2 for most metro shield tunnels in China. Subsequently, a case study is performed to verify the rationality of the simplified theoretical analysis for the segment joint via numerical simulations and experiments. Using the proposed simplified analytical algorithms, a parametric investigation is conducted to discuss the factors affecting the ultimate compressive bending capacity of the joint. The method for optimizing the joint flexural stiffness is clarified. The results of this study can provide a theoretical basis for optimizing the design and prediciting the damage of bolted segment joints in shield tunnels.

关键词： shield tunnel     segment joint     joint structural model     failure mechanism    

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Out-of-plane elastic buckling load and strength design of space truss arch with a rectangular section

Senping WANG; Xiaolong LIU; Bo YUAN; Minjie SHI; Yanhui WEI

《结构与土木工程前沿（英文）》 2022年 第16卷 第9期   页码 1141-1152 doi: 10.1007/s11709-022-0866-5

摘要： The out-of-plane stability of the two-hinged space truss circular arch with a rectangular section is theoretically and numerically investigated in this paper. Firstly, the flexural stiffness and torsional stiffness of space truss arches are deduced. The calculation formula of out-of-plane elastic buckling loads of the space truss arch is derived based on the classical solution of out-of-plane flexural-torsional buckling loads of the solid web arch. However, since the classical solution cannot be used for the calculation of the arch with a small rise-span ratio, the formula for out-of-plane elastic buckling loads of space truss arches subjected to end bending moments is modified. Numerical research of the out-of-plane stability of space truss arches under different load cases shows that the theoretical formula proposed in this paper has good accuracy. Secondly, the design formulas to predict the out-of-plane elastoplastic stability strength of space truss arches subjected to the end bending moment and radial uniform load are presented through introducing a normalized slenderness ratio. By assuming that all components of space truss circular arches bear only axial force, the design formulas to prevent the local buckling of chord and transverse tubes are deduced. Finally, the bearing capacity design equations of space truss arches are proposed under vertical uniform load.

关键词： torsional stiffness     strength design     elastic buckling     space truss arches     out-of-plane    

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Finite element analysis on the seismic behavior of side joint of Prefabricated Cage System in prefabricated

Yunlin LIU, Shitao ZHU

《结构与土木工程前沿（英文）》 2019年 第13卷 第5期   页码 1095-1104 doi: 10.1007/s11709-019-0538-2

摘要： The Prefabricated Cage System (PCS) has the advantages of high bearing capacity and good ductility. Meanwhile, it is convenient for factory production and it is beneficial to the cost savings, construction period shortening. Side joint is the weak region of PCS concrete frame and has great influence on seismic behavior of the whole structure. Thus systematically study on the seismic behavior of PCS concrete side joint is necessary. This paper presents a finite element study on behavior of the side joint under seismic loading. In the finite element model, PCS concrete and the reinforced concrete (RC) is modeled by the solid element and fiber-beam element, respectively. The numerical results is compared with the experimental results and it is found that the results of model based on fiber-beam element is in better agreement with the experimental results than solid element model. In addition, the overall seismic behavior of the side joints in PCS concrete is better than that of the RC with the same strength.

关键词： PCS concrete side joint     numerical simulation     fiber-beam element joint model     solid element joint model     seismic behavior    

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Effects of elastic support on the dynamic behaviors of the wind turbine drive train

Shuaishuai WANG, Caichao ZHU, Chaosheng SONG, Huali HAN

《机械工程前沿（英文）》 2017年 第12卷 第3期   页码 348-356 doi: 10.1007/s11465-017-0420-7

摘要：

The reliability and service life of wind turbines are influenced by the complex loading applied on the hub, especially amidst a poor external wind environment. A three-point elastic support, which includes the main bearing and two torque arms, was considered in this study. Based on the flexibilities of the planet carrier and the housing, a coupled dynamic model was developed for a wind turbine drive train. Then, the dynamic behaviors of the drive train for different elastic support parameters were computed and analyzed. Frequency response functions were used to examine how different elastic support parameters influence the dynamic behaviors of the drive train. Results showed that the elastic support parameters considerably influenced the dynamic behaviors of the wind turbine drive train. A large support stiffness of the torque arms decreased the dynamic response of the planet carrier and the main bearing, whereas a large support stiffness of the main bearing decreased the dynamic response of planet carrier while increasing that of the main bearing. The findings of this study provide the foundation for optimizing the elastic support stiffness of the wind turbine drive train.

关键词： wind turbine drive train     elastic support     dynamic behavior     frequency response function    

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Frequencies of circular plate with concentric ring and elastic edge support

null

《机械工程前沿（英文）》 2014年 第9卷 第2期   页码 168-176 doi: 10.1007/s11465-014-0299-5

摘要：

Exact solutions for the flexural vibrations of circular plates having elastic edge conditions along with rigid concentric ring support have been presented in this paper. Values of frequency parameter for the considered circular plate are computed for different sets of values of elastic rotational and translation restraints and the radius of internal rigid ring support. The results for the first three modes of plate vibrations are computed and are presented in tabular form. The effects of rotational and linear restraints and the radius of the rigid ring support on the vibration behavior of circular plates are studied over a wide range of non-dimensional parametric values. The values of the exact frequency parameter presented in this paper for varying values of restraint parameters and the radius of the rigid ring support can better serve in design and as benchmark solutions to validate the numerical methods obtained by using other methods of solution.

关键词： circular plate     frequency     elastic edge     rigid ring     mode switching    

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基于同步波动原理的抗冲蚀弹性涂层设计

郭源君,肖华林,徐大清,李文斌

《中国工程科学》 2008年 第10卷 第9期   页码 60-63

摘要：

基于过流面冲蚀波纹形貌特征与流体边界层扰动波参数的对应关系，提出了实现弹性涂层边壁与边界层扰动波的同步波动，从而变边壁被动承受粒子冲击为主动回避与粒子的碰撞的抗冲蚀设计思想；分析了实现弹性涂层边壁与边界层扰动波同步波动的条件，并由此确定出弹性涂层的材料常数。

关键词： 冲蚀     边界层     弹性边壁     弹性涂层     同步波动    

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Nonlinear elastic model for compacted clay concrete interface

R. R. SHAKIR, Jungao ZHU

《结构与土木工程前沿（英文）》 2009年 第3卷 第2期   页码 187-194 doi: 10.1007/s11709-009-0033-2

摘要： In this paper, a nonlinear elastic model was developed to simulate the behavior of compacted clay concrete interface (CCCI) based on the principle of transition mechanism failure (TMF). A number of simple shear tests were conducted on CCCI to demonstrate different failure mechanisms; i.e., sliding failure and deformation failure. The clay soil used in the test was collected from the “Shuang Jang Kou” earth rockfill dam project. It was found that the behavior of the interface depends on the critical water contents by which two failure mechanisms can be recognized. Mathematical relations were proposed between the shear at failure and water content in addition to the transition mechanism indicator. The mathematical relations were then incorporated into the interface model. The performance of the model is verified with the experimental results. The verification shows that the proposed model is capable of predicting the interface shear stress versus the total shear displacement very well.

关键词： interface modeling     friction     soil structure interface     soil structure interaction     simple shear test    

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Semi-analytical approach for free vibration analysis of cracked beams resting on two-parameter elastic

null

《机械工程前沿（英文）》 2014年 第9卷 第2期   页码 191-202 doi: 10.1007/s11465-014-0293-y

摘要：

In present study, free vibration of cracked beams resting on two-parameter elastic foundation with elastically restrained ends is considered. Euler-Bernoulli beam hypothesis has been applied and translational and rotational elastic springs in each end considered as support. The crack is modeled as a mass-less rotational spring which divides beam into two segments. After governing the equations of motion, the differential transform method (DTM) has been served to determine dimensionless frequencies and normalized mode shapes. DTM is a semi-analytical approach based on Taylor expansion series that converts differential equations to recursive algebraic equations. The DTM results for the natural frequencies in special cases are in very good agreement with results reported by well-known references. Also, the DTM procedure yields rapid convergence beside high accuracy without any frequency missing. Comprehensive studies to analyze the effects of crack location, crack severity, parameters of elastic foundation and boundary conditions on dimensionless frequencies as well as effects of elastic boundary conditions on cracked beams mode shapes are carried out and some problems handled for first time in this paper. Since this paper deals with general problem, the derived formulation has capability for analyzing free vibration of cracked beam with every boundary condition.

关键词： free vibration     cracked beam     elastic foundation     restrained ends     differential transform method    

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Conformal analysis of fundamental frequency of vibration of elastic clamped plates

QI Hongyuan, ZHU Hengjun

《机械工程前沿（英文）》 2007年 第2卷 第4期   页码 429-432 doi: 10.1007/s11465-007-0073-z

摘要： To calculate the fundamental frequency of vibration of special-shaped and elastic clamped plates, the conformal mapping theory is adopted to separate the interpolating points of a complicated boundary into odd and even sequences, both of which can be mutually iterated, so that the conformal mapping function between the complicated region and the unit dish region is established. Trigonometric interpolation and convergence along the normal direction methods are provided, and the complex coefficients of the conformal mapping function are calculated. Galerkin method is used to obtain the solution of fundamental frequency in the vibrating differential function of the complicated vibrating region. Finally, taking ellipse elastic clamped plates as an example, the effects on fundamental frequency coefficient caused by eccentric ratio and area size are analyzed.

关键词： direction     theory     vibration     odd     complicated boundary    

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Vibration analysis of multi-walled carbon nanotubes embedded in elastic medium

Pattabhi R. BUDARAPU,Sudhir Sastry YB,Brahmanandam JAVVAJI,D. Roy MAHAPATRA

《结构与土木工程前沿（英文）》 2014年 第8卷 第2期   页码 151-159 doi: 10.1007/s11709-014-0247-9

摘要： We propose a method to estimate the natural frequencies of the multi-walled carbon nanotubes (MWCNTs) embedded in an elastic medium. Each of the nested tubes is treated as an individual bar interacting with the adjacent nanotubes through the inter-tube Van der Waals forces. The effect of the elastic medium is introduced through an elastic model. The mathematical model is finally reduced to an eigen value problem and the eigen value problem is solved to arrive at the inter-tube resonances of the MWCNTs. Variation of the natural frequencies with different parameters are studied. The estimated results from the present method are compared with the literature and results are observed to be in close agreement.

关键词： natural frequencies     multi-walled carbon nanotubes (MWCNTS)     elastic medium    

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Reliability analysis of kinematic accuracy for the elastic slider-crank mechanism

TUO Yaofei, CHEN Jianjun, ZHANG Chijiang, CHEN Yongqin

《机械工程前沿（英文）》 2007年 第2卷 第2期   页码 214-217 doi: 10.1007/s11465-007-0037-3

摘要： This paper deals with the static and dynamic output kinematic accuracy of a group of elastic slider-crank mechanisms with the same design parameters by taking the bar length, the joint-gaps, the mass density, and the sectional and the physical parameters as random variables. According to the principle of linear pile-up of small displacement, the static and dynamic output kinematic errors are synthesized, and the reliability model of the kinematic accuracy of the mechanism is built. Through an example, a study of the influencing factors on the reliability of the output kinematic accuracy of the mechanism is made. The results obtained reveal the following facts: with the increase of the crank s rotating speed, the dynamic elastic deformation of the mechanism becomes the principal factor that greatly affects the reliability of the output kinematic accuracy of the mechanism.

关键词： output kinematic     group     slider-crank     kinematic accuracy     displacement    

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Dynamic characteristics of a magnetorheological pin joint for civil structures

Yancheng LI,Jianchun LI

《机械工程前沿（英文）》 2014年 第9卷 第1期   页码 15-33 doi: 10.1007/s11465-014-0283-0

摘要：

Magnetorheological (MR) pin joint is a novel device in which its joint moment resistance can be controlled in real-time by altering the applied magnetic field. The smart pin joint is intended to be used as a controllable connector between the columns and beams of a civil structure to instantaneously shift the structural natural frequencies in order to avoid resonance and therefore to reduce unwanted vibrations and hence prevent structural damage. As an intrinsically nonlinear device, modelling of this MR fluid based device is a challenging task and makes the design of a suitable control algorithm a cumbersome situation. Aimed at its application in civil structure, the main purpose of this paper is to test and characterise the hysteretic behaviour of MR pin joint. A test scheme is designed to obtain the dynamic performance of MR pin joint in the dominant earthquake frequency range. Some unique phenomena different from those of MR damper are observed through the experimental testing. A computationally-efficient model is proposed by introducing a hyperbolic element to accurately reproduce its dynamic behaviour and to further facilitate the design of a suitable control algorithm. Comprehensive investigations on the model accuracy and dependences of the proposed model on loading condition (frequency and amplitude) and input current level are reported in the last section of this paper.

关键词： Magnetorheological pin joint     hyperbolic hysteresis model experimental testing frequency dependence    

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基于人体髋关节转动中心分析的髋关节外骨骼仿生设计 Article

Wei YANG,Can-jun YANG,Ting XU

《信息与电子工程前沿（英文）》 2016年 第17卷 第8期   页码 792-802 doi: 10.1631/FITEE.1500286

摘要： 为了改善外骨骼穿戴舒适性，本文提出了一种基于人机物理交互优化的外骨骼设计方法。该方法通过设计外骨骼髋关节，使其保证人体髋关节运动时外骨骼髋关节转动中心能跟随人体髋关节转动中心的运动轨迹。当人体髋关节运动时，通过实验测量和计算可以得到其转动中心轨迹。本文设计的外骨骼髋关节运动机构能在人体髋关节屈曲/伸展和外展/内收时，保证转动中心都能够包容人体髋关节转动中心运动范围。同时，所设计的外骨骼髋关节被应用到下肢步行康复训练外骨骼中。通过人机接触力实验可知，与传统设计外骨骼髋关节进行相比，本文设计的仿生髋关节外骨骼在髋关节屈曲/伸展和内收/外展时分别可以减小24.1%和76.0%的人机接触力。这一结果证明仿生设计髋关节外骨骼更具穿戴舒适性，更符合人机工程学的设计要求。最后，本文通过建立人机闭式链模型进一步分析了仿生设计对于人体髋关节内力的影响，并验证该设计能减少关节内力作用。

关键词： 髋关节外骨骼；髋关节中心；柔顺关节；人机交互力    

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标题 作者 时间 类型 操作

Nonlinear dynamic analysis for elastic robotic arms

M. H. KORAYEM, H. N. RAHIMI

期刊论文

using strain energy density as a function of stress triaxiality under quasi-static loading employing elastic-creep& elastic-plastic-creep deformation

Tahir MAHMOOD, Sangarapillai KANAPATHIPILLAI, Mahiuddin CHOWDHURY

期刊论文

Analytical algorithms of compressive bending capacity of bolted circumferential joint in metro shield

期刊论文

Out-of-plane elastic buckling load and strength design of space truss arch with a rectangular section

Senping WANG; Xiaolong LIU; Bo YUAN; Minjie SHI; Yanhui WEI

期刊论文

Finite element analysis on the seismic behavior of side joint of Prefabricated Cage System in prefabricated

Yunlin LIU, Shitao ZHU

期刊论文

Effects of elastic support on the dynamic behaviors of the wind turbine drive train

Shuaishuai WANG, Caichao ZHU, Chaosheng SONG, Huali HAN

期刊论文

Frequencies of circular plate with concentric ring and elastic edge support

null

期刊论文

基于同步波动原理的抗冲蚀弹性涂层设计

郭源君,肖华林,徐大清,李文斌

期刊论文

Nonlinear elastic model for compacted clay concrete interface

R. R. SHAKIR, Jungao ZHU

期刊论文

Semi-analytical approach for free vibration analysis of cracked beams resting on two-parameter elastic

null

期刊论文

Conformal analysis of fundamental frequency of vibration of elastic clamped plates

QI Hongyuan, ZHU Hengjun

期刊论文

Vibration analysis of multi-walled carbon nanotubes embedded in elastic medium

Pattabhi R. BUDARAPU,Sudhir Sastry YB,Brahmanandam JAVVAJI,D. Roy MAHAPATRA

期刊论文

Reliability analysis of kinematic accuracy for the elastic slider-crank mechanism

TUO Yaofei, CHEN Jianjun, ZHANG Chijiang, CHEN Yongqin

期刊论文

Dynamic characteristics of a magnetorheological pin joint for civil structures

Yancheng LI,Jianchun LI

期刊论文

基于人体髋关节转动中心分析的髋关节外骨骼仿生设计

Wei YANG,Can-jun YANG,Ting XU

期刊论文