THE INFLUENCE OF THE LENGTHS OF THE LINKS OF THE HINGED FOUR-LINK ON THE ANGLE OF HEIGHT, RETURN ANGLE AND RELATIVE DISPLACEMENT OF LINKS CONNECTED BY THE ELASTIC ELEMENT DURING THE OUTPUT LINK STABILITY

2020 ◽  
Author(s):  
Tat'yana Balabina ◽  
Mariya Karelina ◽  
Aleksey Mamaev
Keyword(s):  
Elastic Element ◽  
Variable Structure ◽  
Relative Displacement ◽  
Technological Equipment ◽  
Output Link ◽  
Periodic Rotation ◽  
Link Stability ◽  
Wide Possibility ◽  
The One ◽  
Automatic Action

Toothed-lever and cam-toothed-lever mechanisms are widely used in technological equipment of automatic and semi-automatic action to convert the one-way rotational motion of the input link into one-way rotary motion of the output link with periodic stops. To ensure periodic rotation with a precise fixed length, an elastic element with a preload of two-sided action is introduced into the mechanism, as a result of which the mechanism has a variable structure. Compared to other mechanisms of periodic rotation, in gear-link mechanisms there is a wide possibility of influencing the function of the position of the output link, the angle of reverse rotation and the relative displacements of the links connected to each other by an elastic element by changing the lengths of the links of the basic hinged four-link

Nonlinear Dynamics of One-Way Clutches in Belt-Pulley Systems

2003 ◽  
Author(s):  
Farong Zhu ◽  
Robert G. Parker
Keyword(s):  
Nonlinear Dynamics ◽  
Degrees Of Freedom ◽  
Piecewise Linear ◽  
Primary Resonance ◽  
Harmonic Balance Method ◽  
Excitation Amplitude ◽  
Relative Displacement ◽  
Second Primary ◽  
Arc Length ◽  
The One

One-way clutches are frequently used in the serpentine belt accessory drives of automobiles and heavy vehicles. The clutch plays a role similar to a vibration absorber in order to reduce belt/pulley vibration and noise and increase belt life. This paper analyzes a two-pulley system where the driven pulley has a one-way clutch between the pulley and accessory shaft that engages only for positive relative displacement between these components. The belt is modeled with linear springs that transmit torque from the driving pulley to the accessory pulley. The one-way clutch is modeled as a piecewise linear spring with discontinuous stiffness that separates the driven pulley into two degrees of freedom (DOF). The harmonic balance method (HBM) combined with arc-length continuation is employed to illustrate the nonlinear dynamic behavior of the one-way clutch. HBM with arc-length continuation yields the stable and unstable periodic solutions for given parameters. These solutions are examined across a range of excitation frequencies. The results are confirmed by numerical integration and the widely used bifurcation software AUTO. At the first primary resonance, most of the responses are aperiodic, including quasiperiodic and chaotic solutions. At the second primary resonance, the peak bends to the left with classical softening nonlinearity because clutch disengagement decouples the pulley and the accessory over portions of the response period. The dependence on system parameters such as clutch stiffness, excitation amplitude, and inertia ratio between the pulley and accessory is studied to characterize the nonlinear dynamics across a range of conditions.

scholarly journals The use of pneumatic cylinders with a return spring to compensate for balance losses in mechanical regenerative drives for reciprocating movements

2019 ◽  
Vol 287 ◽  
pp. 01027
Author(s):  
Wen Zhao ◽  
Victor Leonidovich Zhavner
Keyword(s):  
Energy Recovery ◽  
Design Parameters ◽  
Energy Costs ◽  
Technological Equipment ◽  
Output Link ◽  
Pneumatic Actuators ◽  
Return Spring ◽  
Linear Spring ◽  
Mechanical Spring ◽  
Pneumatic Cylinders

Mechanical spring drives with energy recovery are designed to produce return-rotational movements in various technological equipment and reduce energy costs by several times compared with traditional electromechanical, hydraulic and pneumatic drives. The use of pneumatic motors in spring drives to compensate for dissipative losses, fixing the drive in extreme positions and the primary charging of spring batteries is considered. The class of tasks in which spring drives with energy recovery are created using only pneumatic cylinders with return springs is highlighted. This study examines mechanical spring drives with energy recovery, based on nonlinear spring batteries with spring preload in the middle position of the output link. The use of pneumatic actuators with return springs in mechanical drives based on linear spring batteries with two springs is proposed. Mechanical spring drives with energy recovery are designed to produce return-rotational movements in various technological equipment and reduce energy costs by several times compared with traditional electromechanical, hydraulic and pneumatic drives. The amount of energy expended in spring recuperative drives is actually determined by the energy expended on compensating for dissipative losses in kinematic pairs. The results of the study allow the designers of such drives to consciously approach the choice of their schemes and design parameters.

scholarly journals About the weight and size parameters of electromagnetic stiffness correctors

2021 ◽  
Vol 2131 (5) ◽  
pp. 052003
Author(s):  
V Y Gross ◽  
A V Zharov ◽  
A M Baranovskiy ◽  
S N Reutov
Keyword(s):  
Relative Position ◽  
Elastic Element ◽  
Relative Displacement ◽  
Negative Stiffness ◽  
Stiffness Coefficient ◽  
Power Characteristic ◽  
Negative Coefficient ◽  
Static Stiffness ◽  
Vibration Isolators ◽  
Mathematical Expressions

Abstract A significant reduction in the levels of general ship vibrations can be achieved by using vibration isolators with a “floating” section of zero stiffness in vibration protection suspensions. In such devices, in parallel to the main elastic element, the so-called stiffness corrector (compensator) is switched on - a device with a negative coefficient of static stiffness, equipped with a restructuring system that ensures the retention of the corrector elements when the relative position of the vibrating and protected objects, caused by a change in static forces acting on these objects. One of the variants of the corrector is an electromagnetic stiffness corrector, in which the power characteristic with a negative stiffness coefficient is provided by two electromagnets with a common armature turned on in opposite directions. The disadvantage of such correctors is the dependence of their overall dimensions on the value of the permissible relative displacement of the vibrating and protected objects. The article deduced mathematical expressions that approximately determine the dependence of the overall dimensions of the stiffness corrector electromagnets on the value of the calculated relative displacement of the vibrating and protected objects, the possible field of application of vibration isolators Xwith electromagnetic stiffness correctors is determined.

scholarly journals Problems of Working Women in the Rural Informal Sector of Punjab (Pakistan)

1999 ◽  
Vol 4 (2) ◽  
pp. 89-99
Author(s):  
Karamat Ali ◽  
Abdul Hamid Abdul Hamid
Keyword(s):  
Developing Countries ◽  
Informal Sector ◽  
Working Women ◽  
Variable Structure ◽  
Policy Instrument ◽  
Small Scale ◽  
Formal Sector ◽  
Economic Activities ◽  
The One

The informal sector plays a significant role in Pakistan’s economy as well as in other developing countries. The role of the informal sector in solving the unemployment problem of Third World countries has become the focus of a conceptual and empirical debate in recent years. Most of the research takes a favourable view of this sector and suggests that it should be used as a policy instrument for the solution of the most pressing problems of developing countries, such as unemployment, poverty, income inequalities, etc. Before proceeding further, we will define the informal sector and differentiate it from the formal sector. There are various definitions, but the one given in an ILO report (1972) is generally considered the best. According to this report, informal sector activities are ways of doing things characterised by a heterogeneous array of economic activities with relative ease of entry, reliance on indigenous resources; temporary or variable structure and family ownership of enterprises, small scale of operation, labour intensive and adapted technology, skills acquired outside the formal school system, not depending on formal financial institutions for its credit needs; unregulated and unregistered units, and not observing fixed hours/days of operation.

Description of matrix converter in frequency domain

2013 ◽  
Vol 62 (3) ◽  
pp. 387-400
Author(s):  
Dariusz Borkowski ◽  
Tadeusz J. Sobczyk
Keyword(s):  
Frequency Domain ◽  
Linear Equations ◽  
Harmonic Balance Method ◽  
Variable Structure ◽  
Matrix Converter ◽  
Multiphase System ◽  
Calculation Results ◽  
Cascade Method ◽  
The One ◽  
Infinite Set

Abstract The paper presents abilities and advantages following from the use of the harmonic balance method for analysis of steady state of a multiphase system with switching devices on example of a matrix converter. Switching elements are modelled as resistances with step-wise variable parameters, what allows to describe the converter by a linear infinite set of equations. The analysis in frequency domain is presented on example of the one-periodic control strategy. External systems were also added using the Thevenin method approach. The numerical calculation results of a linear equations set were verified by the variable structure method in a time domain and the numerical convergence was confirmed. Furthermore, the exemplary complex system was analysed using the cascade method and current waveforms were obtained.

scholarly journals SUPPORT FOR VIBRATION ISOLATION OF THE TECHNOLOGICAL EQUIPMENT

2019 ◽  
Vol 15 (6) ◽  
pp. 866-876
Author(s):  
V. N. Sorokin ◽  
I. Yu. Efimov
Keyword(s):  
Mathematical Model ◽  
Elastic Element ◽  
Vibration Isolation ◽  
Negative Impact ◽  
Road Construction ◽  
Dynamic Loads ◽  
Toroidal Shell ◽  
Technological Equipment ◽  
Support Design ◽  
The Mathematical Model

Introduction. The most urgent tasks of road construction is to improve the sustainability of the roadway, on which the durability of the road surface largely depends and vibration processes are widely used. Moreover, the mechanization of production processes in  construction, the growth of power and speed of technological equipment lead to increasing in dynamic loads on its parts and assemblies. To reduce the dynamic loads in the parts and assemblies of construction machines and equipment, as well as to reduce the negative impact of vibration on the staff, it is necessary to isolate the vibration-generating units and assemblies from the base part of the machine.Materials and methods. The vibro-supports of various designs are used to isolate the vibro-active elements of machines. The authors propose the vibration support design with a quasi-zero stiffness effect, in which the rubber-cord shell of the I-09 type is used as a supporting elastic element, and also the toroid-shaped rubber shell that relies on four identical support segments. In addition, each segment represents the fourth part of the annular tube and cut into two parts by a vertical  cylindrical plane. The outer parts of each segment are connected with hinges to the posts and fixed on the support base, and the inner parts of each segment are also connected to a supporting elastic element and a  vibration-proof mass is connected by means of hinges. The authors describe the working procedure of the proposed construction and compile the mathematical model of vibration support with a quasi-zero stiffness  effect.Results. As a result, the equations of the mathematical model are performed in Matlab with the Simulink extension. The values of the equations are used to plot the strain variation of the toroidal shell of the corrector, which depends on the mass displacement, as well as on the motion patterns of a vibrationproof object of 100 kg for variants of the carrier spring without additional volume and with additional volume of the 1 - 10 Hz pneumatic spring carrier.Discussion and conclusions. The authors determine the pressure in the corrector shell, depending on the isolated object mass. Therefore, the deformation of the corrector shell could be provided with a support structure due to the elasticity of the shell material. The usage of additional volume together with the stiffness corrector allows to obtain a wider area of the load characteristics with quasi-zero stiffness and to improve the vibration-protective properties of the support.

Machines on the Basis of Variable Structure Mechanisms (VSM)

2006 ◽  
Author(s):  
Samudin Abdraimov ◽  
Nazira Samudinovna Abdraimova
Keyword(s):  
Power Consumption ◽  
Variable Structure ◽  
Output Link ◽  
Considerable Part ◽  
Unique Possibility ◽  
New Type ◽  
Machine Parts ◽  
Laws Of Motion ◽  
Force Displacement

The new type of mechanisms — the variable structure mechanisms (VSM) possess a unique possibility of rapid and practically instantaneous transformation of the motion law of actuating link under influence of insignificant non-force displacement of one of the kinematical elements without breaking up the entire kinematical chain. The main feature of VSM is in its ability to fulfill two and more laws of motion by output link. The change of motion law for lever mechanisms occurs without disruption in the kinematical chain and thus enables to expend less effort and time. Whereas the couplings, brakes and other power impact elements control the block of interacting mechanisms till now, this results in disruption of entire kinematical chain. A considerable part of power will be required to put these elements into action. This results in decrease of machine efficiency and, especially, extremely influences the machine parts’ durability. The variable structure mechanisms (VSM) exclude such supplementary operative power consumption elements.

A Modal Analysis of Eccentric Shaft of Caster Vibration Device

2012 ◽  
Vol 605-607 ◽  
pp. 1176-1180 ◽  
Author(s):  
Jia Lian Shi ◽  
Xu Yang ◽  
Da Dong Ma
Keyword(s):  
Finite Element ◽  
Harmonic Analysis ◽  
Modal Analysis ◽  
Natural Frequency ◽  
Elastic Element ◽  
The Other ◽  
Finite Element Software ◽  
Eccentric Shaft ◽  
The One ◽  
Elastic Constraints

The model of eccentric shaft of caster vibration device is built by finite element software ANSYS, and bearings are regarded as rigid constraints and elastic constraints.Firstly, regarding the bearings as rigid constraints, the nodes on the parts of eccentric shaft, which match with bearing,are exerted full constraints. Secondly, regarding bearings as elastic constraints, spring, which is built by elastic element combination 14, are used to replace the bearings. In addition, the full constraints are exerted on the one side of spring,and axial constraint are exerted on the other side. Afterwards make the modal analysis of eccentric shaft.Solve and extract the first six natural frequency and modal shape.Watch and analyse the breaking formal of eccentric shaft as it is in different mode. The basis are settled for instantaneous and harmonic analysis.

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