Search results for "cylinder"

A Self-Contained Electro-Hydraulic Cylinder: Modeling, Control Design, Simulation and Experimental Validation

2018

Master's thesis Mechatronics MAS500 - University of Agder 2018 In the constant effort to improve the efficiency of hydraulic systems, the pressure drop over hydraulic valves has been one of the major obstacles. In the Self-Contained Electro-Hydraulic Cylinder, the directional valve and the hydraulic power unit have been replaced by a bi-directional axial piston pump and a Permanent Magnet Synchronous Motor. Actuation of the cylinder is performed by controlling the direction of rotation and the velocity of the motor. Originally the purpose of this project was to: "Design a proper control algorithm for an existing novel selfcontained electro-hydraulic cylinder, implement it on the main boom o…

Stability of melt flow due to a traveling magnetic field in a closed ampoule

2004

The linear three-dimensional instability of the flow due to a low frequency traveling magnetic field in a regular cylinder is studied numerically for height-to-diameter ratios in the range [0.5:2.5]. The first instability has the form of an azimuthal wave with wave numbers between 1 and 6 depending on the aspect ratio. It is shown that the flow is stable if the Reynolds number is below 290. Even stronger stationary flows may be obtained in a flattened cylinder.

Complex analysis for the solution of torsion problems: a comparison among three methods

2009

Application of Model Predictive Control in Discrete Displacement Cylinders to Drive a Knuckle Boom Crane

2018

In this paper, two Discrete Displacement Cylinders (DDCs) are used to drive the boom of a knuckle boom crane. DDCs operate by connecting one of several available pressure levels to each chamber in order to produce different forces. A trade-off exists with such systems, between the accuracy of tracking and energy dissipation due to switching. A popular way to approach this problem is a Force Shifting Algorithm (FSA). However, in this paper, the trade-off is managed by use of a Model Predictive Control (MPC) algorithm. The tracking accuracy and energy efficiency of the MPC and FSA strategies for DDCs are compared to a PID strategy for standard cylinders. The comparison is obtained by use of a…

A method for smoothly disengaging the load-holding valves of energy-efficient electro-hydraulic systems

2020

A novel self-contained, electro-hydraulic cylinder drive capable of passive load-holding, four-quadrant operations, and energy recovery was presented recently and implemented successfully. This solution improved greatly the energy efficiency and motion control in comparison to state-of-the-art, valve-controlled systems typically used in mobile or offshore applications. The passive load-holding function was realized by two pilot-operated check valves placed on the cylinder ports, where their pilot pressure is selected by a dedicated on/off electro valve. These valves can maintain the actuator position without consuming energy, as demonstrated on a single-boom crane. However, a reduced drop o…

Study of a Self-Contained Electro-Hydraulic Cylinder Drive

2018

Self-contained electro-hydraulic cylinders that can be powered just by an electrical wire will be popular in the coming years. Combining electrical-drives and hydraulic cylin- ders exploits some excellent properties of these two technologies and enables flexible implementation. To fully benefit from such a drive solution, there is the need to develop electro-hydraulic cylinders capable of operating independently as opposed to standard hydraulic systems that are connected to a central power supply. Therefore, this paper presents a numerical investigation of a self-contained electro-hydraulic cylinder with passive load- holding capability. The corresponding dynamic model is proposed and used …

Behavior in compression of concrete cylinders externally wrapped with basalt fibers

2015

Abstract This paper gives additional information on the use of new class of composites constituted by Basalt Fiber Reinforced Polymer (BFRP) bonded with epoxy resin to concrete specimens as an alternative confinement material for compressed concrete members with respect to carbon or glass fibers. From the experimental point of view, concrete cylinders are wrapped with continuous fibers, in the form of sheets, applying both full and partial discrete wrapping with BFRP straps, and then tested in compression. For comparison, few other concrete cylinders are wrapped with Carbon Fiber Reinforced Polymer (CFRP) sheets and tested in compression. The number and type of plies (full or partial wrappi…

Fractional visco-elastic Euler–Bernoulli beam

2013

Abstract Aim of this paper is the response evaluation of fractional visco-elastic Euler–Bernoulli beam under quasi-static and dynamic loads. Starting from the local fractional visco-elastic relationship between axial stress and axial strain, it is shown that bending moment, curvature, shear, and the gradient of curvature involve fractional operators. Solution of particular example problems are studied in detail providing a correct position of mechanical boundary conditions. Moreover, it is shown that, for homogeneous beam both correspondence principles also hold in the case of Euler–Bernoulli beam with fractional constitutive law. Virtual work principle is also derived and applied to some c…

An experimental investigation on two different methods for swirl induction in a multivalve engine

2005

This paper describes an experimental investigation aimed at comparing the swirl effect induced by unbalancing the mass flow through the two intake ports of a multivalve engine head using two different methods: the first one reduced the curtain area of one of the intake valves [different lifts (DL) method]; the second one adopted a sluice-gate-shaped valve, installed upstream of the intake valves [swirl control valve (SCV) method] in order to cause a pressure drop. A steady-flow test rig (equipped with instrumentation for the discharge coefficient and swirl intensity measurement) was realized in order to compare and evaluate the results of both methods and determine their respective validit…

Onset of convective rolls in a circular porous duct with external heat transfer to a thermally stratified environment

2011

A horizontal circular duct filled with a fluid saturated porous medium is studied. The external wall is assumed to exchange heat with an external environment thermally stratified in the vertical direction. The external heat transfer is modeled through a third kind boundary condition, and a Biot number associated with the external heat transfer coefficient is defined. The linear stability of the basic state where the velocity field is zero is studied numerically. The condition of neutral stability is determined, by solving the system of elliptic governing equations for the disturbances through a Galerkin finite-element method. The neutral stability curves, together with the critical values o…