Experimental studies of the deflection of the hydraulic cylinder as a result of its operational loading

2021 ◽  
pp. 21-26
Author(s):  
V.G. Gubanov
Keyword(s):  
Contact Stress ◽  
Experimental Studies ◽  
Hydraulic Cylinder ◽  
Longitudinal Plane ◽  
Compressive Loads ◽  
Hydraulic Cylinders ◽  
Bending Loads

Two-way hydraulic cylinders with a one-way rod are widely used on Transport and technological machines. During operation, compressive loads act on such a hydraulic cylinder, as a result of which there are deformations of the hydraulic cylinder in the longitudinal plane, i.e., there is an operational deflection. As a result of the appearance of such a deflection, the bending loads and reactions acting on the hydraulic cylinder and its elements significantly increase, which leads to an acceleration of the process of wear of the hydraulic cylinder elements such as the piston and the guide sleeve and an increase in the probability of the hydraulic cylinder failure. Keywords: hydraulic cylinder, deformation, contact, stress, deflection

scholarly journals Design and Experimental Analyses of Hybrid Piston Rods Used in Hydraulic Cylinders under Axial Load

2021 ◽  
Vol 11 (18) ◽  
pp. 8552
Author(s):  
Praveen Kumar S P ◽  
Seok-Soon Lee
Keyword(s):  
Axial Load ◽  
Compressive Loading ◽  
Experimental Studies ◽  
Hydraulic Cylinder ◽  
Design Parameters ◽  
Buckling Strength ◽  
Compressive Loads ◽  
Hydraulic Cylinders ◽  
And Behavior ◽  
The Given

Composite hydraulic cylinders are used to reduce the weight of construction equipment such as aerial work platforms or excavators. The weight is compensated by manufacturing hydraulic cylinders from Carbon Fiber Reinsforced Plastic (CFRP), but this is expensive. Therefore, this study investigated a hybrid hydraulic cylinder, which is a combination of CFRP and steel, considering both performance and cost. The conventional hydraulic cylinder rods are made of steel, which can prevent failure due to buckling under push load (Push) or failure under alternating push–pull load (Push–Pull) or pull only. In this paper, we discuss how the failure threshold for these two mechanisms can be increased by making the piston rod from a hybrid material. In order to develop this lightweight hybrid piston rod for hydraulic cylinders that meets the buckling strength requirements of the original steel rod, CFRP is used as a substitute, which has significant buckling strength against compressive loading and, most importantly, is lighter than steel. The substitution is done either by replacing steel completely with CFRP or by reducing the volume of steel and sheathing it with CFRP. Numerical and experimental studies are carried out to understand the strength and behavior of piston rods when they are replaced by different combinations of composite materials for the given load. For this study, two different piston rod designs with various design parameters were considered, and their respective behavior under loading was discussed. The effect of compressive loads on CFRP wrapped steel parts and buckling strength as a function of fiber orientation, stacking angle and number of CFRP layers was investigated using experiments. The study demonstrated the usefulness of steel-CFRP composites to reduce weight and their influence on buckling load in hydraulic cylinders.

scholarly journals Volumetric hydraulic drive with series connection of hydraulic actuators

2020 ◽  
Vol 1 (4) ◽  
pp. 61-69
Author(s):  
V.N. Pil'gunov ◽  
◽  
K.D. Yefremova ◽  
Keyword(s):  
Single Channel ◽  
Production Systems ◽  
Experimental Studies ◽  
Hydraulic Drive ◽  
Hydraulic Cylinder ◽  
Series Connection ◽  
Power Characteristics ◽  
Serial Number ◽  
Piston Speed ◽  
Hydraulic Cylinders

The aim of the proposed work is theoretical and experimental studies of the performance of a single-channel hydraulic drive with a series connection of executive hydraulic cylinders and the de-velopment of recommendations for predicting their characteristics. The authors of the paper carried out a set of experimental studies and obtained the numerical kinematic, speed and power characteristics of a single-channel hydraulic drive with five hydraulic cylinders connected in series. It is shown that the nature of the kinematic connection is determined by the differentiation of the hydraulic cylinders. The speed of advancement of the piston of an indi-vidual hydraulic cylinder is determined by its serial number in the chain of hydraulic cylinders, while the highest speed of the piston movement is developed by the first hydraulic cylinder. The relative unevenness of the piston movement in comparison with the speed of the piston movement of the first hydraulic cylinder is determined by the differentiation of the hydraulic cylinder, while the hydraulic drive with the differentiation D = 2 has the greatest unevenness. It is shown that by the selection of the differentiation of the hydraulic cylinders, their stepwise arrangement and the displacement of the location of the bottom of the hydraulic cylinder, that it is possible to realize complex forms of the total trajectory of the points of attachment of the hydraulic cylinder rods. In the hydrostatic (power) hydraulic drive in the rod cavities of the hydraulic cylinders, depend-ing on the serial number of the hydraulic cylinder, the thrust on its rod and the differentiation set different pressure levels, and the lowest pressure will be in the piston cavity of the last hydraulic cylinder. With uniformly loaded hydraulic cylinders, the pressure in the piston cavities depends only on the number of the hydraulic cylinder and its differentiation. In a hydraulic drive with hydraulic cylinders of equal power, the last hydraulic cylinder will develop the greatest force at the lowest piston speed. In addition, the work also shows that the reproducibility of the positions of unloaded rods of hy-draulic cylinders of equal differentiation is not less than 1%. As a result of the experimental studies, a method was developed for the design of a volumetric hydraulic drive with sequential switching on of executive hydraulic cylinders, which can be used to solve the problems of hydrofication of me-chanical engineering production (bending presses, sheet stamping), in shipbuilding (ship slipways), in flexible production systems, industrial and warehouse logistics.

scholarly journals Electro-Hydraulic Drive of the Variable Ratio Lifting Device under Active Load

2021 ◽  
pp. 599-610
Author(s):  
Andrzej Kosucki ◽  
Łukasz Stawiński ◽  
Adrian Morawiec ◽  
Jarosław Goszczak
Keyword(s):  
Asynchronous Motor ◽  
Experimental Studies ◽  
Hydraulic Drive ◽  
Hydraulic Cylinder ◽  
Open Loop ◽  
Control Mode ◽  
Gear Pump ◽  
Hydraulic Systems ◽  
Energy Recuperation ◽  
Hydraulic Cylinders

Hydraulic systems fed by fixed displacement pumps driven by frequency-controlled electric motors can replace conventional throttling systems due to their ability to control the speed of hydraulic cylinders regardless of the value and direction of the load. These systems can improve the energy efficiency of the drive or even provide the possibility of energy recuperation during lowering. This paper presents experimental studies of the new drive system with volumetric control of the speed of the lifted/lowered payload using the example of a scissor lift. The system uses a reversible gear pump driven by an asynchronous motor fed by a frequency inverter operating in field-oriented control mode. Comparative studies of the mapping of the assumed speed of the hydraulic cylinder and platform are presented, as well as studies of the influence of the load change on the speed and positioning of the mechanism driven by the open-loop controlled system.

The Lower Extremity Exoskeleton Coordinated Control Method Based on Human Electromechanical Coupling

2012 ◽  
Vol 220-223 ◽  
pp. 1012-1017
Author(s):  
Qing Guo ◽  
Dan Jiang
Keyword(s):  
Lower Extremity ◽  
Electromechanical Coupling ◽  
Position Control ◽  
Control Method ◽  
Angular Displacement ◽  
Stability Margin ◽  
Hydraulic Cylinder ◽  
Load Force ◽  
Hydraulic Cylinders ◽  
Coupling Characteristics

This paper has introduced electromechanical coupling characteristics in the lower extremity exoskeleton systems, considered model ,according to legs supporting gait when people walking, established the load torque compensation model , and a mathematical model of knee position control system which is made of the servo valve, hydraulic cylinders and other hydraulic components, designed hydraulic cylinder position control loop in case of existing load force interference compensation, and used the method of combining the PID and lead correction network for frequency domain design ,ensured system to meet a certain stability margin. The simulation results show that this position control method can servo on the knee angular displacement of normal human walking, reached a certain exoskeleton boost effect, at the same time, met the needs of human-machine coordinated motion.

Development of hydraulic cylinder diagnostic methods by modeling methods

2021 ◽  
pp. 41-45
Author(s):  
Keyword(s):  
Hydraulic Drive ◽  
Hydraulic Cylinder ◽  
Technical Condition ◽  
Diagnostic Methods ◽  
Technical Diagnostics ◽  
Remaining Service Life ◽  
Construction Machine ◽  
Piston Speed ◽  
Variable Nature ◽  
Hydraulic Cylinders

The hydraulic drive of a construction machine is a complex dynamic system that is subjected to many dynamic loads of a variable nature and operates under conditions of variable external influences caused by various factors. During operation, these loads cause failure of the hydraulic transmission elements. To prevent these malfunctions, technical diagnostics should be applied by determining their current technical condition and remaining service life. The article assesses the working condition of hydraulic cylinders using a mathematical model. Using matlab/simulink software to simulate the hydraulic cylinder and hydraulic piston speed when changing the hydraulic cylinder clearance. The simulation results are presented. Keywords: diagnostic, hydraulic cylinder, simulation, development

Three Dimensional Seismic Isolation System Using Hydraulic Cylinder

2002 ◽  
Author(s):  
Shinichiro Kajii ◽  
Naoki Sawa ◽  
Nobuhiro Kunitake ◽  
K. Umeki
Keyword(s):  
Seismic Isolation ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Hydraulic Cylinder ◽  
Seismic Load ◽  
3D Seismic ◽  
Isolation System ◽  
Response Characteristics ◽  
Seismic Motion ◽  
Hydraulic Cylinders

A three-dimensional (3D) seismic isolation system for FBR building is under development. The proposed vertical isolation system consists form hydraulic cylinders with water-based liquid and accumulators to support large vertical static load and to realize low natural frequency in the vertical direction. For horizontal isolation, laminated rubber isolator or sliding type isolator will be combined. Because the major part of the feasibility of this isolation system depends on the sealing function and durability of the hydraulic cylinder, a series of feasibility tests of the hydraulic cylinder have been conducted to verify the reliability against seismic load and seismic motion. This paper describes the specification of the seismic isolations system, seismic response characteristics and the results of the feasibility tests of the seal. This study was performed as part of a government sponsored R&D project on 3D seismic isolation.

scholarly journals Some Aspects Concerning The Impact Of The End Of Stroke On Hydraulic Cylinders

2015 ◽  
Vol 21 (3) ◽  
pp. 821-824
Author(s):  
Niculai Hauk
Keyword(s):  
Numerical Simulation ◽  
Mechanical Systems ◽  
Hydraulic Cylinder ◽  
Important Variable ◽  
Mechanical Impact ◽  
Hydraulic Cylinders ◽  
The Masses ◽  
The Impact ◽  
Simulation Systems ◽  
Classical Calculation

Abstract The increase of speeds for mechanical systems operated with hydraulic cylinder raises risks of mechanical impact of the end of the race. We are considering a number of measures to limit the impact intensity. Its size is estimated according to the masses in motion, to work pressures and to the geometry of the mechanism. Elasticity of the components is also an important variable. This paper presents a method which combines the classical calculation with numerical simulation systems.

scholarly journals Modeling Study on Stiffness Characteristics of Hydraulic Cylinder under Multi-Factors

2017 ◽  
Vol 63 (7-8) ◽  
pp. 447 ◽  
Author(s):  
Hao Feng ◽  
Qungui Du ◽  
Yuxian Huang ◽  
Yongbin Chi
Keyword(s):  
Mechanical System ◽  
Volume Expansion ◽  
Hydraulic Cylinder ◽  
Experimental Results ◽  
Axial Deformation ◽  
Response Characteristics ◽  
Stiffness Model ◽  
Hydraulic Cylinders ◽  
Stiffness Characteristics ◽  
Cylinder Barrel

For a complex mechanical system driven by hydraulic cylinders, the dynamic response characteristics of the mechanical system are significantly affected by the stiffness characteristics of hydraulic cylinders. This paper comprehensively studies the impacts of various factors on the stiffness characteristics of the hydraulic cylinders, including the oil bulk modulus, the air content in the hydraulic oil, the axial deformation of the piston rod, the volume expansion of the cylinder barrel, the volume expansion of the metal pipes and the flexible hoses, and the deformation of the hydraulic cylinder sealing. By combining the theoretical analysis and the experimental results, the level of each impacting factor was quantified, and the stiffness model of the hydraulic cylinder was established. Finally, comparative analysis of the stiffness was conducted by taking the experimental hydraulic cylinder as an example; it was verified that the calculated results of the proposed hydraulic cylinder stiffness model approximated the experimental results. Compared with stiffness models presented in current literature, the average accuracy was improved by more than 15 %.

scholarly journals A Self-Contained Electro-Hydraulic Cylinder with Passive Load-Holding Capability

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 292 ◽  
Author(s):  
Damiano Padovani ◽  
Søren Ketelsen ◽  
Daniel Hagen ◽  
Lasse Schmidt
Keyword(s):  
Energy Efficiency ◽  
Cost Efficiency ◽  
Tracking Error ◽  
Hydraulic Cylinder ◽  
Position Tracking ◽  
Hydraulic Systems ◽  
Practical Applications ◽  
Hydraulic Cylinders ◽  
External Loads ◽  
Boom Crane

Self-contained electro-hydraulic cylinders have the potential to replace both conventional hydraulic systems and the electro-mechanical counterparts enhancing energy efficiency, plug-and-play installation, and reduced maintenance. Current commercial solutions of this technology are limited and typically tailor-made, whereas the research emphasis is primarily on cost efficiency and power applications below five [kW]. Therefore, there is the need of developing more flexible systems adaptable to multiple applications. This research paper offers a contribution in this regard. It presents an electro-hydraulic self-contained single-rod cylinder with passive load-holding capability, sealed tank, capable of recovering energy, and scalable up to about eighty [kW]. The system implementation on a single-boom crane confirms its feasibility: The position tracking error remains well within ±2 [mm], oscillations are limited, and the overall energy efficiency is about 60 [%] during actuation. Concerning the passive load-holding devices, it is shown that both vented and non-vented pilot-operated check valves achieve the desired functioning and can hold the actuator position without consuming energy. Additional observations about the size and the arrangement of the load-holding valves are also provided. In conclusion, this paper demonstrates that the proposed self-contained cylinder can be successfully extended to several practical applications, especially to those characterized by overrunning external loads and the need of securing the actuator position.

Internal leakage identification of hydraulic cylinder based on intrinsic mode functions with random forest

2019 ◽  
Vol 233 (15) ◽  
pp. 5532-5544 ◽  
Author(s):  
Lin Li ◽  
Yixiang Huang ◽  
Jianfeng Tao ◽  
Chengliang Liu
Keyword(s):  
Random Forest ◽  
Hydraulic Cylinder ◽  
Support Vector ◽  
Hydraulic Systems ◽  
Intrinsic Mode Functions ◽  
Random Forest Algorithm ◽  
Mode Decomposition ◽  
Empirical Mode Decomposition Method ◽  
Hydraulic Cylinders ◽  
Experimental Pressure

Monitoring for internal leakage of hydraulic cylinders is vital to maintain the efficiency and safety of hydraulic systems. An intelligent classifier is proposed to automatically evaluate internal leakage levels based on the newly extracted features and random forest algorithm. The inlet and outlet pressures as well as the pressure differences of two chambers are chosen as the monitoring parameters for leakage identification. The empirical mode decomposition method is used to decompose the raw pressure signals into a series of intrinsic mode functions to obtain the essence in experimental signals. Then, the features extracted from intrinsic mode functions in terms of statistical analysis are formed the input vector to train the leakage detector. The classifier based on random forest is established to categorize internal leakage into proper levels. The accuracy of the internal leakage evaluator is verified by the experimental pressure signals. Moreover, an internal leakage evaluator is established based on the support vector machine algorithm, in which the wavelet transform is applied for feature extraction. The accuracy and efficiency of different classifiers are compared based on leakage experiments. The results show that the classifier trained by the intrinsic mode function features in terms of random forest algorithm may more effectively and accurately identify internal leakage levels of hydraulic cylinders. The leakage evaluator provides probability for online monitoring of the internal leakage of hydraulic cylinders based on the inherent sensors.

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