scholarly journals Performance assessment of fluid power drive at stage of its design using evolutionary simulation

2015 ◽  
Vol 2015 (4) ◽  
pp. 135-140
Author(s):  
Валерий Казаков ◽  
Valeriy Kazakov ◽  
Павел Казаков ◽  
Pavel Kazakov
Keyword(s):  
Dynamic Properties ◽  
Transient Behavior ◽  
Fluid Power ◽  
Damping Coefficient ◽  
Hydraulic Actuator ◽  
Operating Characteristics ◽  
Design Data ◽  
Power Drive ◽  
Evolutionary Simulation ◽  
Static Fluid

In a number of engineering problems in the development of automated systems arises a necessity in the computation and design of a fluid power drive (FPD) in conformity with particular technological schemes for which there are no finished industrial products or it is necessary to carry out a sufficiently exact correspondence of operating characteristics with specified engineering data. In this case one does not carry out the selection of standard elements for a fluid power drive, but performs their designing, where there were used modern approaches and methods of the computeraided design. As operation results show, a designed fluid power drive in most cases cannot possess required for system functioning dynamic properties: performance, capacity for a decrement, sensitivity and so on. According to the investigations, they depend in many respects upon such characteristics of a hydrosystem as static fluid of a hydrocylinder and piping, time constant of transient and damping coefficient. If we consider the process of FPD designing as a procedure of a parametric synthesis, then the research of its variants with different combinations of parameter values gives a possibility not only to choose geometrical dimensions for a unit, but to estimate its potential operational functionalities. At present time as one of the effective approaches in the realization of such a solution may be the application of methods for the evolutionary simulation, where each object analyzed is considered as an individual. As an example of the evolutionary simulation there are considered the results of FPD servicing characteristics estimate computed on bases of design data for a forklift truck. The graphic dependences obtained establish the extreme correlations of hydraulic actuator operational characteristics which stipulate for a stable work of the fluid power drive in the transient behavior without special damping devices. Results of the evolutionary simulation allow analyzing the influence of parameters mentioned upon the damping coefficient changes and drawing a conclusion for decision making for the choice of such a design variant of a fluid power drive at which there would be ensured the best servicing characteristics of the plant.

A Theory of Mixed Lubrication

1972 ◽  
Vol 186 (1) ◽  
pp. 421-430 ◽  
Author(s):  
H. Christensen
Keyword(s):  
Hydrodynamic Lubrication ◽  
Dynamic Properties ◽  
Mixed Lubrication ◽  
Rapid Rise ◽  
Operating Characteristics ◽  
Lubrication Regime ◽  
Lubricated Contact ◽  
Mixed Lubrication Regime ◽  
Lubrication Conditions ◽  
Lubrication Properties

The phenomena observed when a lubricated contact or bearing is operating under mixed lubrication conditions are assumed to arise from an interaction of the surface asperities or roughness as well as from hydro-dynamic action of the sliding surfaces. It is shown how one of the previously published stochastic models of hydrodynamic lubrication can be extended or generalized to deal with mixed lubricating conditions. As an illustration of the application of the theory to a concrete example the influence on the operating characteristics of a plane pad, no side-leakage bearing is analysed. It is found that in the mixed lubrication regime friction is mainly controlled by the boundary lubrication properties of the liquid–solid interface. Load, on the other hand, is almost entirely controlled by the hydro-dynamic properties of the bearing. It is demonstrated how transition to mixed lubrication conditions will cause a rapid rise in friction thereby producing a minimum point in the Stribeck type diagram.

Experimental Investigation of the Transient Behavior of MR Fluids

2011 ◽  
Author(s):  
Ju¨rgen Maas ◽  
Dirk Gu¨th
Keyword(s):  
Magnetic Field ◽  
Experimental Investigation ◽  
Response Time ◽  
Dynamic Properties ◽  
Transient Behavior ◽  
Current Control ◽  
Large Signal ◽  
Carrier Fluid ◽  
Mr Fluids ◽  
The Magnetic Field

The transient behavior of MRF actuators is an important property for certain applications that is mainly affected by three delays, occurring from the dynamic properties of the coil current, the magnetic field and the torque generation by the MRF. In order to investigate the transient behavior of the generated torque with respect to the magnetic field, which is mainly affected by the motion of the MR particles in the carrier fluid, the mentioned response time of the electrical and magnetic domains must be in an appropriated ratio in comparison to the MRF response time to obtain reliable results by experiments. Therefore a special disc-type test actuator with outstanding dynamics is designed that minimizes the delays by the use of an ultrafast current control and a magnetic core made of soft ferrite material for preventing the effects of eddy currents. For the experimental investigation of the transient behavior of MR fluids, the small signal as well as the large signal behavior is analyzed for different test signals and load conditions of the actuator. Various results of the investigated transient behavior are shown finally for two different MR fluids featuring response times of about 1 ms for the fluid itself and switching times of about 4 ms for the MRF actuator.

scholarly journals Development of a Lever Mechanism for Loading a Suspended Conveyor

2021 ◽  
Vol 346 ◽  
pp. 03053
Author(s):  
Ildar Kutlubaev ◽  
Elena Macko ◽  
Igor Usov ◽  
Olga Panfilova
Keyword(s):  
Rock Bolt ◽  
Fluid Power ◽  
Force Analysis ◽  
Parametric Synthesis ◽  
Power Drive ◽  
Linear Dimensions ◽  
Lever Mechanism ◽  
Crank Mechanism

The issue of mechanization of hanging of long components of self-installing rock bolt (SIRB) type has been considered. The possibility of usage of slider-crank mechanism for these purposes has been proved. Linear dimensions of lever mechanism that meet the requirements defined by the applied motor and SIRB parameters have been determined on the ground of parametric synthesis. The performed force analysis has proved the application of fluid power drive.

scholarly journals Contextual Learning Module Based on Multiple Representations: The Influence on Students’ Concept Understanding

2018 ◽  
Vol 3 (1) ◽  
pp. 11 ◽  
Author(s):  
Ummul Uslima ◽  
Chandra Ertikanto ◽  
Undang Rosidin
Keyword(s):  
Conceptual Understanding ◽  
Multiple Representations ◽  
T Test ◽  
Contextual Learning ◽  
Control Group ◽  
Homogeneity Test ◽  
Design Data ◽  
Control Group Design ◽  
Learning Module ◽  
Static Fluid

This study aims to describe the effect of using contextual learning module based on multiple representations of static fluid material toward students' conceptual understanding. The sample of this research was the students of class XI IPA 2 and XI IPA 3 in SMA N 1 Trimurjo, Central Lampung. This research was conducted using Pretest-Posttest Control Group Design. Data were tested with N-gain analysis, normality test, homogeneity test and Independent Sample T-test. Results from the Independent Sample T-test value of the Sig value. (2-Tailed) was less than 0.05 which is 0.036, then it can be stated that there is a significant influence of contextual learning module based on multiple representations toward the students’ conceptual understanding. Based on the N-gain value, the average N-gain concept comprehension in the experimental class was 0.56 (medium category), while the control class was 0.46 (medium category). Contextual learning modules based on multiple representations can improve students’ conceptual understanding.

Digital Motion Control and Profile Planning for Pneumatic Servos

1992 ◽  
Vol 114 (4) ◽  
pp. 634-640 ◽  
Author(s):  
J. Pu ◽  
R. H. Weston ◽  
P. R. Moore
Keyword(s):  
Motion Control ◽  
Transient Behavior ◽  
Performance Characteristics ◽  
Motion Controller ◽  
Operating Characteristics ◽  
Servo Systems ◽  
Pneumatic Actuators ◽  
Control Scheme ◽  
Conventional Methods ◽  
The Stability

This paper considers the use of “profile-planning” to (i) improve/optimize certain performance characteristics of pneumatic servos and (ii) simplify procedures associated with their tuning. The underlying approach is to preplan the transient behavior of the system thereby generating an appropriate command profile. To assist in applying this technique to the control of air-powered servo-systems, the paper highlights important knowledge derived previously with regard to the stability and operating characteristics of pneumatic drives. Preliminary rules for conducting such planning are then proposed with reference to a series of experimental observations. This approach can be employed to significantly reduce or prevent overshoot and instability of servo-driven pneumatic actuators (cylinders in particular) which are difficult to overcome by using conventional methods. At the same time, increased operating speeds and improved positioning can be attained. The proposed control scheme has been implemented in prototype form through using a proprietary programmable motion controller which incorporates software mechanism for generating gearbox and cam-like motion profiles.

scholarly journals Fatigue Effect on the Dynamic Properties of Cfrp Composites

1994 ◽  
Vol 3 (4) ◽  
pp. 096369359400300 ◽  
Author(s):  
L. Vellios ◽  
V. Kostopoulos ◽  
S. A. Paipetis
Keyword(s):  
Free Vibration ◽  
Dynamic Modulus ◽  
Composite Laminates ◽  
Mechanical Response ◽  
Dynamic Properties ◽  
Damping Coefficient ◽  
Damage Development ◽  
Damage State ◽  
Fatigue Effect ◽  
Damping Coefficients

Damage developing during fatigue of composite laminates affects both dynamic modulus of elasticity and damping coefficient of the material. It has been shown that the effect of fatigue on the damping coefficient is of particular importance. The damping variation could be used to characterise the damage state of the material, produced by fatigue. A model relating damage with damping was developed to correlate damage development to mechanical response. The damping coefficients of the composite of the fatigue test were measured at various stages, using the flexural free vibration of the test coupon hi cantilever configuration. The method was applied both in multidirectional and unidirectional laminates.

A Theory for the Identification of a Single Degree-of-Freedom Machine From its Periodic Operating Characteristics

1983 ◽  
Vol 105 (3) ◽  
pp. 445-451 ◽  
Author(s):  
J. L. Wiederrich
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Dynamic Analysis ◽  
Dynamic Properties ◽  
Degree Of Freedom ◽  
Operating Characteristics ◽  
Energy Potential ◽  
Single Degree Of Freedom ◽  
Single Degree

The dynamic properties of a machine are defined by its kinetic energy, potential energy, and dissipation functions. These functions form the basis for the dynamic analysis of a machine. This paper presents a theory whereby these functions may be determined from the observed forced periodic operating response of a single degree of freedom machine. This method may have applications in machinery development and diagnosis.

Experimental Investigation of the Influence of the Supporting Mechanism of a Self-Energizing Hydraulic Brake on Torque Oscillations

2015 ◽  
Author(s):  
Matthias Hirtz ◽  
Julian Ewald ◽  
Hubertus Murrenhoff
Keyword(s):  
Experimental Investigation ◽  
Dynamic Properties ◽  
Dynamic Pressure ◽  
Scientific Work ◽  
Pressure Control ◽  
Control Mode ◽  
Brake Disc ◽  
Hydraulic Actuator ◽  
Brake Torque ◽  
Hydraulic Brake

Friction force oscillations caused by changes in the properties of the contact zone between brake disc and pad are well known from various applications. Resulting effects like brake judder are known phenomena in brake technologies and in the scope of various scientific work. A new potential measure to reduce brake torque oscillations is the active compensation with the use of the control system of a self-energizing hydraulic brake (SEHB). The SEHB for railway application developed at the Institute for Fluid Power Drives and Controls (IFAS) of RWTH Aachen University offers high dynamic properties with its capability to reduce brake torque oscillations actively. New — in comparison to other braking systems — is the fact that the brake torque is measured by sensing the pressure in an additional supporting cylinder. Within this paper the influence of the hydraulic-mechanical system of the supporting cylinder on the oscillation properties of the SEHB is analyzed. The experimental investigation is conducted using a full scale brake test for railway applications. The brake disc is driven by hydraulic motors in secondary control mode. Measurement results will be used to define requirements of a superimposed dynamic pressure control to minimize brake torque oscillations. Future work will be experimental investigation of the influence of the self-energizing effect and the development of measures to compensate brake torque oscillations actively with the hydraulic actuator of the SEHB.

Analysis of dynamics of fluid power drive‐trains for variable speed wind turbines: parameter study

2014 ◽  
Vol 8 (4) ◽  
pp. 398-410 ◽  
Author(s):  
Antonio Jarquin Laguna ◽  
Niels F.B. Diepeveen ◽  
Jan Willem Wingerden
Keyword(s):  
Wind Turbines ◽  
Fluid Power ◽  
Parameter Study ◽  
Variable Speed ◽  
Power Drive ◽  
Drive Trains ◽  
Analysis Of Dynamics

The twist axis of frames with particular application to motorcycles

2016 ◽  
Vol 230 (17) ◽  
pp. 3026-3039 ◽  
Author(s):  
Alberto Doria ◽  
Luca Taraborrelli
Keyword(s):  
Dynamic Properties ◽  
Critical Role ◽  
Point Of View ◽  
Experimental Results ◽  
General Definition ◽  
Hydraulic Actuator ◽  
Laser Sensors ◽  
Definition Of ◽  
Stiffness And Damping ◽  
Reference Plate

The static and dynamic properties of the frame and the front fork of a single track vehicle play a critical role from the point of view of vehicle stability. A turning point in the study of motorcycle stability was established by the introduction of lumped stiffness elements to characterize the critical compliances of the motorcycle elements, this approach being still in use with advanced multibody codes. Nonetheless, up to now very few scientific studies have been carried out to identify the parameters that account for the stiffness and damping properties of motorcycle front forks and frames. This work addresses the problem of identifying the parameters needed for developing lumped element models of motorcycles from experimental results. Two motorcycle frames are studied performing static, dynamic, and modal tests by means of a specific testing equipment. The frames have been tested in two different conditions: fixing them at the steering head or at the swing-arm pivot. In the first section of the paper a general definition of the twist axis, based on the concept of “Mozzi” or instantaneous screw axis, is presented. The twist axis is used for characterizing the deformation patterns of the tested frames. The static twist axis is identified loading the frames at low rate by means of a servo-hydraulic actuator and measuring the deformation of a reference plate by means of three laser sensors; the dynamic twist axis is identified exerting an impulsive excitation and measuring the vibration of a reference plate by means of three accelerometers. In the last section of the paper, experimental results obtained on motorcycle frames are shown. A method to identify the stiffness properties of the frames from the measured twist axes is presented. Results obtained with the proposed method are in good agreement with the ones presented in literature.

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