Design of a Hydraulic Damper for Heavy Machinery

Engineering and Technology Journal, 2018

It is generally accepted that the vibration of fluid power systems considered to be one of the major problems that is normally occurred in the hydraulic system, which causes a noise and short life of its components. Accordingly, it should be reduced the efficiency as well as an increase leakage system. Hence, present study pays more attention to investigate a bladder an accumulator which was successfully added to the hydraulic system in order to reduce the vibrations that might be generated by the system and decelerate the actuator at the end stroke. Which variables are measured before relief and directional valve and at the linear cylinder body. It was found that the maximum percentage damping in vibration velocity at a position before relief and directional control valve and at cylinder body was 20%, 20.8% and 55% at 20 and 15 bar pressure supply respectively. Whereas, it was observed the acceleration was 11.3%, 12.5% and 50% at 40 bar pressure supply. Also, it was found that the piston begins decelerate gradually from distance 25cm in which equal to 1/6 of total stroke length with a period of time 5 seconds.

The automotive damper is one of the important components of a vehicle suspension system. It controls spring motion by damping energy from the spring, and it is used for the optimization of driving comfort and driving safety. Many automotive dampers have non-linear asymmetric characteristics to accommodate the incompatible requirements between ride comfort and road handling, the engineer requires techniques that can characterize this non-linear behavior and provide models of the dampers for use in ride performance simulations of the full suspension system. In this paper, experimental characterization is done by developing a mathematical model of the front wheel gas-filled hydraulic damper of Maruti Suzuki swift corresponding to road conditions. The dampers have tested under both sinusoidal and ramp excitations on the dynamic material test platform. To accurately predict damping force experimental data is used to fit the equation of curve using the least square curve fitting method in Matlab software interface and components of the mathematical force model is identified. Finally, results of a mathematical model are verified with experimental results. The results of the mathematical model show good correlation with experimental data with precision above 90%. Though some error has been found. It is mainly due to hysteresis effect which is present because of damper compliance.

2002

The objective of this research is to develop a new semi-active control device for displacement control of structures with long period. A new device, named as accumulated semi-active hydraulic damper (ASHD), is designed to improve the function of passive control system for seismic resistance. This device is composed of hydraulic jack, directional valve and accumulator. In order to achieve the optimal rate of energy dissipation, the acting direction of the device is regulated by controlling the flow of oil in hydraulic jack. The test results show that rate of energy dissipation of ASHD is extremely good with the minimum requirement of energy supply. In this paper, the authors will describe the construction of three different versions of dampers in detail. An analytical model describing the hysteresis behavior is proposed. Finally, results of a series of dynamic tests on shaking table will demonstrate the accuracy of the proposed analytical model for ASHD energy dissipation behavior an...

Methodology used to minimizing suspension of a vehicle for different velocities. Investigate effect of orifices on the damping force at different velocities. Three different orifices opening to conduct experiment analysis. Auto mobile damper results of two, six, and ten-orifice opening are compared. a b s t r a c t The liquid flow through orifices produces larger damping, whereas the cushioning effect comes from the fluid's compressibility. The hydraulic damper design is subjected to constant high pressure necessary to achieve the required forces, which drastically increases during the dynamic operation. Damper has different orifices or piston valves that lead to different flow losses. The main objective behind this work is to investigate the effect of number of orifices on the damping force at different velocities for rear side two-wheeler automobile mono tube damper. Three different orifice opening cases are considered for simulations and experiments such as two-orifice opening, six-orifice opening and ten-orifice opening.

Nonlinear Dynamics, 2012

A nonlinear model of monotube hydraulic dampers is presented with an emphasis on the shim stack properties and their effects on the overall damper performance. There has been no published detailed analysis of the effects of shim stack design in a hydraulic damper to date. Other damper models have used simplifying assumptions for the shim stack deflection and effects of the shim stack have not been completely studied. Various parameters affecting the nonlinear characteristics of monotube dampers such as the hysteresis region are studied. The model presented in this paper can be used for design purposes and helps in developing controllable valvings based on shim stacks. It can also be used to design controllable bypasses in hydraulic dampers. The mathematical model is validated by comparison against experimental test results carried out on an OHLINS CCJ 23/8 monotube damper, in CVeSS test facilities.

Sadhana, 2010

A relief valve parallel to the throttle valve is added to a Velocity dependent hydraulic damper (VDHD) so that the orifice size that regulates the oil flow can be adjusted. This device adjustment will allow the damper to have an adaptive control of damping by changing its damping coefficient. A mathematical model including a serial friction model and a small damper that is parallel to the friction model added to the Maxwell model for simulating the actual energy-dissipating behaviour of the VDHD was proposed in this research. To extend the useful value of VDHD, a numerical analysis model based on the SAP2000 nonlinear analysis program was applied to simulate the energy-dissipating characteristics of VDHD in this study. The analysis results obtained by using the mathematical model and the proposed SAP2000 numerical model conform to the seismic resistant test results, and confirm that the SAP2000 nonlinear analysis program can accurately describe the actual energy-dissipating behaviour of the VDHD installed on structures under various energy-dissipating situations.

Journal of Dynamical Systems and Geometric Theories, 2006

The semi-active control does not consume a huge quantity of electricity because its controlling force comes from the oscillation of the structure system. Furthermore, it is adaptable that the control over the structure can be changed. Therefore, the optimum solutions are available to resolve the problems of the electric power system conditions and the adaptability of the controlling force, commonly found in other control methods. The damper used in this research is the Accumulated Semi-Active Hydraulic Damper, ASHD, developed on the basis of the Displacement Dependent Semi-Active Hydraulic Damper by means of installing the accumulator. The damper and the bracing series are connected together to the structure; the displacement of structure can drive the bracing series distortion to engender the action power of ASHD. When the action power passes through ASHD, the energy dissipation behaviors occur, which can form the fullest hysteresis loop. This research establishes the mathematical analysis model to analyze its energy dissipation capability based on the hysteresis loop of ASHD, obtained from the experiment. The analysis results show that no matter what energy dissipation period, ASHD perform high energy dissipation capability.

Engineering Transactions, 2006

Streszczenie angielskie: The main focus is on the hydraulic shock absorbers employed in vehicles, in the context of parameters associated with the damping force control for the given direction of action and with the energy dispersion. Two types of shock absorbers are examined: those with constant and variable parameters of damping force adjustment. Shock absorbers that were subject to research investigations included a commercially-available shock absorber with fixed parameters and an experimental absorber with variable ...

Mechanical Systems and Signal Processing, 2010

The research presented in this paper investigates the possibility of precise experimental identification of steady damper characteristics. The paper considers velocity sensitive and nominally symmetric hydraulic dampers. The proposed identification methodology is based on a piecewise constant velocity excitation. One goal of the paper is to analyze the transient nature of the damper response in the context of finite permissible piston displacements and first order transient effects due to elastic elements in the damper structure. The proposed methodology is formalized in a framework suitable for experimental design, allowing the detailed study of steady state damper performance. The second goal of the paper is to demonstrate the practical application of the proposed methodology. It is applied to the case of a safety critical hydraulic damper used for stability augmentation in production helicopters. The research work presented shows that this methodology can be used for identification in a finite but relatively wide range of piston velocities. The case study demonstrates a successful example of damper property identification where the resulting characteristics prove useful as a tool for model validation. Finally, the identification results are related to the results of a more traditional test with harmonic piston excitation.