Damper Valve Research Articles

Structural design and multi-objective optimization of an MR isolator based on flow valve-cone rubber structure

Due to the distinctive working environment of high precision machining and manufacturing field, it poses challenges in meeting the isolation requirements, including limited installation space, multi-dimensional vibration, and a wide range of vibration frequencies. To tackle these obstacles, this paper introduces a magnetorheological (MR) isolator that offers adjustable vertical damping characteristics while guaranteeing three-axis vibration isolation through an inclined cone structure. First, the structure of the isolator was designed by combining a flow valve damper with a conical rubber structure. Second, in pursuit of lightweight design and enhanced magnetic field strength, collaborative simulations using ANSYS and Maxwell are conducted to subject the critical components of the isolator to multi-objective optimization. The optimization results demonstrate that the mass of the isolator has been reduced by approximately 27.7%, while the magnetic field intensity has increased by around 20%. Finally, the performance of the MR isolator was verified through static testing and dynamic testing, respectively. The experimental results demonstrate that the isolator can generate a maximum damping force of approximately 778[Formula: see text]N when exposed to a current of 1.5[Formula: see text]A. Compared to the initial value of 445.06[Formula: see text]N at 0[Formula: see text]A, there has been an approximate increase of 1.74 times.

Multi-Physical Field Simulation of Magnetorheological Fluid Flow State in Valve Magnetorheological Damper

Magnetorheological fluid (MRF) is a kind of magnetic field responsive intelligent fluid, which is widely concerned in the field of damping and vibration reduction. The flow state of MRF plays a key role in vibration control in dampers. In this work, the flow behavior. of magnetorheological fluid (MRF) in a valve damper is studied through multi-physical field simulations. The objective is to comprehensively comprehend the influence of the magnetic field on the velocity distribution and pressure drop of the MRF within the damper channel. The magnetic field is generated by creating an electrified coil, and the magnetic flux density is subsequently changed by adjusting the current. The magnetic field calculation shows that the magnetic field is almost perpendicular to the MRF flow direction at the narrowest part of the damper channel. Next, based on the coupling calculation of multiple physical fields between fluid flow, electric field, and magnetic field, the flow velocity and pressure characteristics of MRF in the flow channel were calculated and analyzed. The results indicate that at the slit where the MRF flow direction is perpendicular to the magnetic field direction, the volume force acting on the MRF reduces its flow velocity, resulting in a significant pressure difference between the left and right sides of the flow channel. Additionally, the flow rate of MRF exhibits a decrease as the magnetic field strength increases. When the magnetic field strength increases from 0. 5T to 1. 5T, the flow rate of MRF fluid at the narrowest part of the flow channel decreases by about 0. 18m/s.

Research of time lag characteristics of Pilot-operated Solenoid Valve Damper based on multi-physics field

The development of semi-active suspensions has introduced Pilot-operated Solenoid Valve Dampers (PSVD) that can adjust damping characteristics for different road conditions while considering stability and comfort. However, the PSVD’s additional control system and valve-controlled components make it challenging to avoid time lag in the response of the damping force when the control current signal is switched. This time lag characteristic significantly impacts the performance of the control system, making it difficult to achieve optimal dynamic performance and potentially compromising the safety of drivers and passengers. As a result, understanding and representing the PSVD time lag characteristics and investigating their influence have become important research areas in the field of semi-active suspension. This article begins by explaining the mechanism behind the generation of PSVD time lag characteristics. It analyzes the structure and operating principle of the PSVD, identifying two main types of time lag: electromagnetic time lag and inertial time lag. To address the limitations of existing simulation models, the study combines parameterization and finite element simulation to create a multi-physics field time lag characteristics kinetic representation model of the PSVD, incorporating the electric, magnetic, mechanical, and fluid aspects. To validate the accuracy of the time lag characteristics simulation model, tests on the velocity and time lag characteristics of the PSVD are conducted. The simulation results are compared to the test results, demonstrating that the maximum error of the lag time meets the engineering confidence requirement. This confirms the feasibility of establishing a simulation model for the PSVD time lag characteristics. Finally, we analyze the PSVD total lag time under different working conditions using the simulation model. It explores the relationship between the PSVD total lag time and the lag time of each component, proposes a lag time decomposition relationship, and investigates the crucial influencing factors on the lag time.

Computational Fluid Dynamics Simulation and Optimization of Hydropneumatic Spring Damper Valves for Heavy Vehicle Applications

To satisfy the design requirements for a hydropneumatic spring damper valve, the inlet–outlet pressure drop (ΔP) and the axial force on the spool (FZ) of a valve were investigated using fluid–solid coupling simulations and multi-objective optimization, along with the effects of the diameters of three internal holes (DA, DB, and DC) in the valve on the ΔP and the FZ. First, a meshed computational fluid dynamics model of a damper valve was established based on its geometric structure. Next, the effects of the flow rate (Q) and the diameter of the damping hole in the internal structure on the ΔP and the FZ of the damper valve were investigated. The results showed that the ΔP and the FZ varied nonlinearly with Q. For a given Q, the ΔP decreased as DA, DB, and DC increased. For a given Q, the FZ was not related to DA and DC, but it decreased as DB increased. Finally, the structure of the damper valve was optimized by defining the ΔP and the FZ as the response variables and DA, DB, and DC as the explanatory variables. The results showed that the best configuration of the hole diameters was DA = 8.8 mm, DB = 5.55 mm, and DC = 6 mm. In this configuration, ΔP = 0.704 MPa and FZ = 110.005 N. The ΔP of the optimized valve was closer to the middle value of the target range than that of the initial valve design. The difference between the simulated and target values of the FZ decreased from 0.28% to 0.0045%, satisfying application requirements.

PERMODELAN INVERSI PEREDAM MAGNET-REOLOGI BERBASIS JARINGAN SARAF TIRUAN UNTUK SISTEM KENDALI

The application of artificial neural network (ANN) models in magnet-rheological damper modeling is of great interest in recently challenges. Therefore, this study aims to propose a solution to overcome this problem by conducting inverse modeling using an artificial neural network. This inverse model is applied to a meandering magnet-rheological valve damper to predict the current to produce the appropriate damping force. The simulation scheme is selected with current as output and damping force, velocity, and displacement as input. The best model is formulated by varying the architecture of the artificial neural network. The best artificial neural network architecture is obtained after doing these variations. The data is divided into 80% training data, 10% validation data, and 10% test data. The activation function used is a logsig function using three hidden layers with the number of neurons in each layer [30-20-30]. The algorithm used in the chosen architecture is Levenberg-Marquardt. The regression value of 0.991 and the MSE value of 0.001 were obtained from the modeling results. The required damping force is ensured that it can be predicted well using the selected artificial neural network. The test proves that the results of the regression constant are 0.999 and the MSE value is 0.0005 when the current output value is inverted to the damper artificial neural network.

Effects of the Damping Parameters on the Opening and Closing Characteristics of Vent Valves

The main function of the vent valve is to release part of the air at the outlet of the axial compressor to prevent engine surges. The damping parameters have an important effect on the opening and closing characteristics of the vent valve. The control characteristics of each component were obtained by finite element analysis and testing. The overall model of a two-stage partial pressure vent valve was established, and the reliability of the model was verified by testing. The opening and closing characteristics of the damper valve with different damping parameters were obtained by parametric simulation. The results show that there was a pressure mutation point in the middle support pressure and the pressure in the control chamber during operation of the vent valve, which made the valve open and close quickly. The damping hole of the middle shell and the middle nozzle of the support had the greatest influence on the open-close pressure ratio. The damping hole and nozzle of the middle shell had the greatest influence on the opening and closing stability. The results are used to guide the structural design, and the analytical method provides a theoretical basis for research of the same type of valve.

Design of a Super Twisting Sliding Mode Controller for an MR Damper-Based Semi-Active Prosthetic Knee.

A large number of transfemoral amputees living in low-income countries could not access a much-needed prosthesis. Hence, affordable semi-active prosthetic knees have been designed in recent years. As the swing phase of the gait cycle is unstable as compared to the stance phase, these designs could not perfectly mimic this phase of a healthy human being. In contribution toward such a gap, this study proposes the modeling and design of a robust controller for magnetorheological (MR) damper-based semi-active prosthetic knee. A dynamic model representation for the swing phase of the single-axis knee is derived first. Subsequently, an MR damper valve model is developed. Then, a higher-order sliding mode controller is designed and evaluated for its stability and performance. The numerical simulation results show that the super twisting sliding mode controller improves the semi-active prosthetic knee’s tracking efficiency. The design exhibited the finest performance, providing a low normalized mean square error as compared to previous designs. The variable speed performance and robustness evaluation for this controller also showed its ability to continue providing excellent performance in the presence of disturbances.

Vibration suppression investigation and parametric design of tri-axle straight heavy truck with pitch-resistant hydraulically interconnected suspension

The vibration suppression of the proposed pitch-resistant hydraulically interconnected suspension system for the tri-axle straight truck is investigated, and the vibration isolation performances are parametrically designed to achieve smaller body vibration and tire dynamic load using increased pitch stiffness and optimized pressure loss coefficient. For the hydraulic subsystem, the transfer impedance matrix method is applied to derive the impedance matrix. These hydraulic forces are incorporated into the motion equations of mechanical subsystem as external forces according to relationships between boundary flow and mechanical state vectors. In terms of the additional mode stiffness/damping and suspension performance requirements, the cylinder surface area, accumulator pressure, and damper valve’s pressure loss coefficient are comprehensively tuned with parametric design technique and modal analysis method. It is found the isolation capacity is heavily dependent on installation scheme and fluid physical parameters. Especially, the surface area can be designed for the oppositional installation to separately raise pitch stiffness without increasing bounce stiffness. The pressure loss coefficients are tuned with design of experiment approach and evaluated using all conflict indexes with normalized dimensionless evaluation factors. The obtained numerical results indicate that the proposed pitch-resistant hydraulically interconnected suspension system can significantly inhibit both the body and tire vibrations with decreased suspension deformation, and the tire dynamic load distribution among wheel stations is also improved.

Damping Technology

Damper valve technology from RAPA optimises chassis damping characteristics

MODELLING THE SHOCK ABSORBER PISTON VALVE USING 2-WAY FLUID-STRUCTURE INTERACTION

The aim of this study is to examine the strongly coupled Fluid-Structure Interaction approach as a comprehensive method of predicting the performance of the shock absorber piston valve. For this purpose, numerical simulation sand experimental testing are carried out. The coupled CFD-FEA numerical model described in this article, contrary to the attempts made so far, takes into account the influence of contact between valve discs and the initial conditions of the disc stack preload. The model is based on the actual valve geometry used in the shock absorber design. As a result, the described approach is intended for use in industrial applications in development works, in particular, at the conceptual stage. To prove the reliability of the model, two valve compositions are chosen to be measured on a test bench and modelled in FSI simulations. For both of them, a satisfactory level of correlation is achieved, with the correlation error below 10% and well-predicted valve opening points. As a result, it is proved that the 2- way FSI approach has great potential to be successfully used to investigate the damper valve operation.

Increase in Tuning Ability of a Car Shock Absorber Valve using CFD

The purpose of the investigation was to improve the hydraulic damper valve to meet the automotive customer requirements. The original design was not good enough to achieve the damping forces in the range demanded. The main goal was to lower the minimum achievable forces at the compression stroke by reducing flow restrictions of piston valve. CFD analysis was used to verify proposed variants without the expense of prototyping and experimental testing. Design restrictions of present components were measured on the flow test bench and compared with previously done CFD analysis to ensure a proper correlation with a numerical model. The model was used to predict pressure drop over developed designs.

Design of Laminated Seal for Triple Offset Butterfly Valve (350 °C) Used in Combined Cycle Power Plants

In combined cycle power plants (CCPPs), the bypass butterfly valve is a key component to facilitate regulation of exhaust gas energy available at the turbine and to not produce too much boost pressure. The conventional damper valve causes leakage, back flow into the turbine, and damage of the blade, and the existing dual-layered seal with polytetrafluoroethylene (PTFE) and metal should be frequently replaced owing to its low durability and deterioration of mechanical properties under a high temperature. This study devised a triple offset butterfly valve with a new type of seal by alternatively laminating stainless steel and graphite to improve valve performance at the high temperature (350 °C). The slope angles of the seal contact surface to prevent friction were calculated using the mathematical models of the triple offset. Thermal-structure coupled analyses by varying the number of graphite and thickness were conducted, and the seven-layer model with the graphite thickness of 0.8 mm, which shows airtightness and smooth operation, was chosen. The contact stresses behaviors of the graphite at 350 °C and at −196 °C were investigated, and it was found that the graphite is in charge of improving driving performance of the disc at the high temperature and sealing performance at the cryogenic temperature. The performance tests and the field tests of the suggested model verified its performance at the working temperature.

Research of the training methods and structure design of intelligent knee prosthesis based on physiological gait

The performance of intelligent prosthetic knee has an important effect on the realization of physiological gait of transfemoral amputees. A new type of single axis hydraulic damping knee prosthesis was designed based on the analysis of physiological gait. The training methods of the stance and swing phase were proposed. Knee prosthesis test was done through simulation and measurement device. The control target of peak flexion angle during swing of knee prosthesis is chosen to be 60-70°. When the damper valve closure was 0%, maximum swing-phase knee flexion angle of knee prosthesis were (86±2)°, (91±3)° and (97±3)° with the speed of 0.8 m/s, 1.2 m/s and 1.8 m/s, respectively. Once the valve closure was changed, maximum swing-phase knee flexion angle with different speeds could be adjusted between 60° and 70° and the required valve closure percentage were separately 25%, 40% and 70%. The damping adjustment law of intelligent knee prosthesis to achieve physiological gait was revealed.

A flexible control strategy for energy and comfort aware HVAC in large buildings

A data driven framework for the energy and comfort management in large buildings with multiple zones and dynamic occupancy patterns is presented in this paper. For such cases, precise heat conduction models derived using the classical thermal physics laws will be cumbersome. The approach uses the historical data to develop a multi-variable model through Structural Equation Modeling (SEM) so as to identify the relative dominance of the direct and indirect effects of thermal coupling among the neighboring zones, occupancy and the external climate variations on the thermal behavior of the building zones. Based on the information gathered from the SEM, we can predict the return temperatures more accurately, which in turn is employed to incorporate a flexible control strategy for the HVAC system. A controller fed with the temperature error and occupancy error, between the predicted and measured values, regulates the supply air fan speed via VFD motor and outside air damper valve openings. This has resulted in the energy savings while maintaining the occupant thermal comfort at the reasonable levels. The framework proposed has been evaluated using real data collected from an HVAC system of a big airport terminal building. The results show that the accuracy of prediction is relatively higher than with other regression techniques; and that the HVAC system is energy efficient and can ensure occupant comfort on real-time basis in large buildings.

Optimal design of an MR damper valve for prosthetic knee application

In this work, a magnetorheological (MR) damper valve is designed with the primary objective of controlling swing-phase damping in an above-knee prosthesis. Initially, a swing phase model of the desired single axis knee incorporating MR damper was modelled. The control parameters that govern damping force and displacement of the damper were identified and optimized to enable the prosthetic knee to produce near normal swing phase trajectory for ground walking as obtained from experimental data. Then, the MR damper valve is optimally designed by selecting typical performance indices of the damper for the intended application. A multi-objective optimization problem is formulated where the MR damper valve is constrained in a desired cylindrical volume defined by its radius and height. Effects of the geometrical design variables of the valve are analytically investigated by mapping finite element analysis (FEA) numerical responses with response surface method (RSM). The results show that the MR damper with designed damper valve enables the prosthetic knee to achieve near to normal swing phase trajectory, and compare to the existed MR damper, up to 71 % reduction by weight has been achieved.

Performance Evaluation of Magnetorheological Damper Valve Configurations Using Finite Element Method

The main purpose of this paper is to study various configurations of a magnetorheological (MR) damper valve and to evaluate their performance indices typically dynamic range, valve ratio, inductive time constant and pressure drop. It is known that these performance indices (PI) of the damper depend upon the magnetic circuit design of the valve. Hence, nine valve configurations are considered for which mathematical models are developed. A finite element model is built to analyze and investigate the PI of a 2-D axi-symmetric MR damper valve. All configurations of the damper valve are simulated within a given range of input current and number of turns of coil, and within this range, damping force, dynamic range, valve ratio, inductive time constant and achieved pressure drop have been evaluated. The simulation results show that the PI of the MR damper are highly dependent on the shapes of valves and hence the valve shape should be selected based on the intended application. The results obtained in this work provide an insight for designers to create application-specific MR dampers.

Simulative Analysis of Dynamic Characteristics of Automobile Shock Absorbers Based on Fluid-structure Interaction

The fluid-structure interaction(FSI) modeling and solving techniques of shock absorbers are studied.The fluid field grid model of damper valve and the finite element contact model of superposition throttle-slices with higher accuracy are established based on FSI method with multi-solvers.The FSI model of shock absorbers is solved and analyzed combined by finite volume method(FVM) and finite element method(FEM).The speed characteristic and indicator diagram of shock absorbers are obtained.The internal pressure field and velocity field of damper valve are analyzed.The nonlinear dynamic characteristics of superposition throttle-slices are analyzed.The simulation results show that the pressure field of core region of damper valve changes rapidly because of the impact of high speed oil.The velocity of throttle-slices steps when the valve opens and closes.It makes the throttle channel change suddenly,and makes the indicator diagram bend down at the valve-opening point.The fluid field grid model of core region of damper valve and the finite element contact model of superposition throttle-slices have great influence to the accuracy of simulation.The FSI model is closed to the physical reality because of the consideration of turbulent flow of oil and the contact slip and large deflection of throttle-slices.The simulation results are in good agreement with the experimental results.

Prediction of the pressure–flow characteristic of a Belleville washer-based damper valve

Flow control valves used in automotive suspension dampers are almost universally based upon the restriction of flow using Belleville washers. These washers can best be described as a non-flat washer of conical shape and uniform thickness. They are also known as disc springs and are commonly used for load bearing in which their compactness and ability to produce a wide range of load–deflection characteristics provide an alternative to conventional coil springs. Due to the non-linear behaviour of Belleville washers, and the complex flow paths in an automotive damper valve, it is difficult to predict the resulting pressure–flow characteristic. As a result, damper valve design is often considered to be a ‘black art’ best carried out by an experienced engineer using an experimental-based trial-and-error approach. Clearly, without the aid of an analytical tool to predict the behaviour of prototype systems it is difficult for the designer to fully exploit the functionality of a particular design. The current paper describes theoretical and experimental studies undertaken to investigate the pressure–flow characteristic of a Belleville washer-based damper valve. Existing load–deflection theory was extended to account for the hydraulic pressure acting on the surfaces of the washer. However, poor agreement was obtained between the measured pressure–flow data using a uniform pressure distribution across the washer diameter. For this reason the model was developed further to include the effect of a non-uniform pressure distribution within the valve. Computational fluid dynamics software was used to predict the pressure regime within the valve and this, in turn, was used to calculate the forces acting on the surface of the Belleville washer. The improved model was found to match the experimental behaviour with good accuracy, both for a range of spring pre-load conditions and for applications where several washers are stacked up in parallel. However further work would be required to develop a reliable simulation tool as an element of trial and error was necessary to estimate some simulation parameters.

Modular High-Force Seismic Magneto-Rheological Fluid Damper

In this work, a large-scale magneto-rheological fluid (MRF) bypass valve damper for seismic mitigation applications is designed, constructed, and tested. The damper utilizes a simple design, with a modular bypass MRF valve, connected to a passive commercial seismic damper. The modular feature of the new MRF valve provides the flexibility of adding as much force as needed to the damper with minimal modification to an existing passive viscous damper. The performance of the MRF valve and the combined semiactive bypass MRF damper are examined through quasi-static and dynamic tests. It is demonstrated that the proposed modular MRF bypass damper can provide a maximum damping force over 200 kN which meets the high-force requirements of a semiactive seismic damper for large-scale structure vibration control.

Hydraulically interconnected vehicle suspension: theoretical and experimental ride analysis

In this paper, a previously derived model for the frequency-domain analysis of vehicles with hydraulically interconnected suspension (HIS) systems is applied to the ride analysis of a four-degrees of freedom roll-plane, half-car under a rough road input. The entire road surface is assumed to be a realisation of a two-dimensional Gaussian homogenous and isotropic random process. The frequency responses of the half-car, in terms of bounce and roll acceleration, suspension deflection and dynamic tyre forces, are obtained under the road input of a single profile represented by its power spectral density function. Simulation results obtained for the roll-plane half-car fitted with an HIS and those with conventional suspensions are compared in detail. In addition, sensitivity analysis of key parameters of the HIS to the ride performance is carried out through simulations. The paper also presents the experimental validation of the analytical results of the free and forced vibrations of the roll-plane half-car. The hydraulic and mechanical system layouts, data acquisition system and the external force actuation mechanism of the test set-up are described in detail. The methodology for free and forced vibration tests and the application of mathematical models to account for the effective damper valve pressure loss are explained. Results are provided for the free and forced vibration testing of the half-car with different mean operating pressures. Comparisons are also given between the test results and those obtained from the system model with estimated damper valve loss coefficients. Furthermore, discussions on the deficiencies and practical implications of the proposed model and suggestions for future investigation are provided. Finally, the key findings of the investigation on the ride performance of the roll-plane half-car are summarised.