On Flexible Pin Shafts and Clearance Interaction for the Dynamic Response of Planar Mechanisms

1992 ◽  
Author(s):  
Wu DeRong
Keyword(s):  
Dynamic Response ◽  
Perturbation Method ◽  
Dynamic Interaction ◽  
Dynamic Equations ◽  
Unperturbed System ◽  
Gyroscopic System ◽  
Planar Mechanisms ◽  
Major Objective ◽  
Analytical Technique ◽  
Insight Into

Abstract The dynamic equations of planar mechanisms with flexible pin shafts and clearance connections is developed here using Lagrangian formulation. The general flexible-connection planar mechanism can be described by a damped, circulatory, gyroscopic system. Quite often, damping and circulatory forces are small, one may regards them as the perturbations. Indeed, a perturbation method for obtaining the eigensolution and dynamic response is presented by regarding the undamped, non-circulatory, gyroscopic system as the unperturbed system. The procedure may be used to investigate the fundamental nature of dynamic interaction between the elastic deflection of pin shafts and clearance connections. A major objective of this paper, in addition to the development of the analytical technique, was to obtain some insight into the phenomenon at flexible-connection, so that these effects may be included during the designing of mechanisms.

scholarly journals Second Approximate Solution of Duffing Equation with Strong Nonlinearity by Homotopy Perturbation Method

1970 ◽  
Vol 30 ◽  
pp. 59-75
Author(s):  
M Alhaz Uddin ◽  
M Abdus Sattar
Keyword(s):  
Approximate Solution ◽  
Nonlinear Systems ◽  
Perturbation Method ◽  
Differential System ◽  
Homotopy Perturbation Method ◽  
Approximate Solutions ◽  
Second Order ◽  
Strong Nonlinearity ◽  
Analytical Technique ◽  
Homotopy Perturbation

 In this paper, the second order approximate solution of a general second order nonlinear ordinary differential system, modeling damped oscillatory process is considered. The new analytical technique based on the work of He’s homotopy perturbation method is developed to find the periodic solution of a second order ordinary nonlinear differential system with damping effects. Usually the second or higher order approximate solutions are able to give better results than the first order approximate solutions. The results show that the analytical approximate solutions obtained by homotopy perturbation method are uniformly valid on the whole solutions domain and they are suitable not only for strongly nonlinear systems, but also for weakly nonlinear systems. Another advantage of this new analytical technique is that it also works for strongly damped, weakly damped and undamped systems. Figures are provided to show the comparison between the analytical and the numerical solutions. Keywords: Homotopy perturbation method; damped oscillation; nonlinear equation; strong nonlinearity. GANIT J. Bangladesh Math. Soc. (ISSN 1606-3694) 30 (2010) 59-75  DOI: http://dx.doi.org/10.3329/ganit.v30i0.8504

Effect of payloads contact upon the coupled dynamic response of two cooperating robots

Robotica ◽  
1996 ◽  
Vol 14 (6) ◽  
pp. 659-665
Author(s):  
G. Shagal ◽  
S.A. Meguid
Keyword(s):  
Dynamic Response ◽  
Function Method ◽  
Search Algorithm ◽  
Contact Region ◽  
Dynamic Equations ◽  
Penalty Function Method ◽  
The Finite Element Method ◽  
Contact Search ◽  
Cooperating Robots ◽  
Lagrange’S Method

The coupled dynamic response of two cooperating robots handling two flexible payloads is treated using a new algorithm. In this algorithm, the dynamic equations describing the system are obtained using Lagrange's method for the rigid robot links and the finite element method for the flexible payloads. The contact between the flexible payloads is modelled using the penalty function method and a contact search algorithm is employed to identify the contact region.

scholarly journals Dynamic Response Analysis on the Interaction Between Flexible Bodies of Large-Sized Wind Turbine Under Random Wind Loads

2018 ◽  
Author(s):  
Yilun Li ◽  
Shuangxi Guo ◽  
Min Li ◽  
Weimin Chen ◽  
Yue Kong
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Elastic Deformation ◽  
Dynamic Interaction ◽  
Response Analysis ◽  
Flexible Bodies ◽  
Dynamic Response Analysis ◽  
Dynamic Behaviors ◽  
Energy Consuming ◽  
Turbine Model

As the output power of wind turbine increasingly gets larger, the structural flexibility of elastic bodies, such as rotor blades and tower, gets more significant owing to larger structural size. In that case, the dynamic interaction between these flexible bodies become more profound and may significantly impact the dynamic response of the whole wind turbine. In this study, the integrated model of a 5-MW wind turbine is developed based on the finite element simulations so as to carry out dynamic response analysis under random wind load, in terms of both time history and frequency spectrum, considering the interactions between the flexible bodies. And, the load evolution along its transmitting route and mechanical energy distribution during the dynamic response are examined. And, the influence of the stiffness and motion of the supporting tower on the integrated system is discussed. The basic dynamic characteristics and responses of 3 models, i.e. the integrated wind turbine model, a simplified turbine model (blades, hub and nacelle are simplified as lumped masses) and a rigid supported blade, are examined, and their results are compared in both time and frequency domains. Based on our numerical simulations, the dynamic coupling mechanism are explained in terms of the load transmission and energy consumption. It is found that the dynamic interaction between flexible bodies is profound for wind turbine with large structural size, e.g. the load and displacement of the tower top gets around 15% larger mainly due to the elastic deformation and dynamic behaviors (called inertial-elastic effect here) of the flexible blade; On the other hand, the elastic deformation may additionally consume around 10% energy (called energy-consuming effect) coming from external wind load and consequently decreases the displacement of the tower. In other words, there is a competition between the energy-consuming effect and inertial-elastic effect of the flexible blade on the overall dynamic response of the wind turbine. And similarly, the displacement of the blade gets up to 20% larger because the elastic-dynamic behaviors of the tower principally provides a elastic and moving support which can significantly change the natural mode shape of the integrated wind turbine and decrease the natural frequency of the rotor blade.

scholarly journals Hyphenated Mass Spectrometry versus Real-Time Mass Spectrometry Techniques for the Detection of Volatile Compounds from the Human Body

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7185
Author(s):  
Oliver Gould ◽  
Natalia Drabińska ◽  
Norman Ratcliffe ◽  
Ben de Lacy Costello
Keyword(s):  
Mass Spectrometry ◽  
Volatile Compounds ◽  
Real Time ◽  
Qualitative Data ◽  
Method Development ◽  
Complex Matrices ◽  
Analytical Technique ◽  
Monitoring Drug ◽  
Highly Sensitive ◽  
Insight Into

Mass spectrometry (MS) is an analytical technique that can be used for various applications in a number of scientific areas including environmental, security, forensic science, space exploration, agri-food, and numerous others. MS is also continuing to offer new insights into the proteomic and metabolomic fields. MS techniques are frequently used for the analysis of volatile compounds (VCs). The detection of VCs from human samples has the potential to aid in the diagnosis of diseases, in monitoring drug metabolites, and in providing insight into metabolic processes. The broad usage of MS has resulted in numerous variations of the technique being developed over the years, which can be divided into hyphenated and real-time MS techniques. Hyphenated chromatographic techniques coupled with MS offer unparalleled qualitative analysis and high accuracy and sensitivity, even when analysing complex matrices (breath, urine, stool, etc.). However, these benefits are traded for a significantly longer analysis time and a greater need for sample preparation and method development. On the other hand, real-time MS techniques offer highly sensitive quantitative data. Additionally, real-time techniques can provide results in a matter of minutes or even seconds, without altering the sample in any way. However, real-time MS can only offer tentative qualitative data and suffers from molecular weight overlap in complex matrices. This review compares hyphenated and real-time MS methods and provides examples of applications for each technique for the detection of VCs from humans.

Insight into dynamic interaction of molten MgCl2-NaCl-KCl with impurity water via FPMD simulations

2020 ◽  
Vol 314 ◽  
pp. 113596
Author(s):  
Xuejiao Li ◽  
Weihua Liu ◽  
Zhongfeng Tang ◽  
Tingrui Xu ◽  
Jianqiang Wang
Keyword(s):  
Dynamic Interaction ◽  
Insight Into

Allocation of Dimensional Tolerances for Multiple Loop Planar Mechanisms

1989 ◽  
Vol 111 (4) ◽  
pp. 465-470 ◽  
Author(s):  
R. G. Fenton ◽  
W. L. Cleghorn ◽  
Jing-fan Fu
Keyword(s):  
Planar Mechanisms ◽  
Analytical Technique ◽  
Input Parameters

A method is presented to determine tolerance bands for the dimensions of multiple loop planar mechanisms such that output motions will be kept within specified allowable limits. The kinematic equations of mechanisms are generated by combining various link groups. A preliminary set of estimated tolerance bands is calculated using an analytical technique. An optimization and checking routine is then employed to determine the set of input parameters which satisfies the prescribed output motion requirements. Examples have been included to illustrate the method.

Dynamic Response of a Cylindrical Shell in a Potential Fluid

1979 ◽  
Vol 46 (4) ◽  
pp. 772-778 ◽  
Author(s):  
G. E. Cummings ◽  
H. Brandt
Keyword(s):  
Cylindrical Shell ◽  
Dynamic Response ◽  
Circular Cylindrical Shell ◽  
Time History ◽  
Experimental Results ◽  
Scale Model ◽  
Solution Technique ◽  
Analytical Technique ◽  
Forcing Function ◽  
Potential Fluid

A numerical solution technique is presented for determining the dynamic response of a thin, elastic, circular, cylindrical shell of constant wall thickness and density, in a potential fluid. The shell may be excited by any radial forcing function with a specified time history and spatial distribution. In addition, a pressure history may be specified over a segment of the fluid outer boundary. Any of the natural shell end conditions may be prescribed. The numerical results are compared to experimental results for a 1/12-scale model of a nuclear-reactor core-support barrel. Natural frequencies and modes are determined for this model in air, water, and oil. The computed frequencies are within 15 percent of experimental results. A sample application compares the numerical technique to an analytical solution for shell beam modes. The comparison resolves an uncertainty concerning the proper effective mass to use in the analytical technique.

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