Hydraulic Damper Research Articles

On the characteristics of natural hydraulic dampers: An image-based approach to study the fluid flow behaviour inside the human meniscal tissue

The meniscal tissue is a layered material with varying properties influenced by collagen content and arrangement. Understanding the relationship between structure and properties is crucial for disease management, treatment development, and biomaterial design. The internal layer of the meniscus is softer and more deformable than the outer layers, thanks to interconnected collagen channels that guide fluid flow. To investigate these relationships, we propose an integrated approach that combines Computational Fluid Dynamics (CFD) with Image Analysis (CFD-IA). We analyze fluid flow in the internal architecture of the human meniscus across a range of inlet velocities (0.1 mm/s to 1.6 m/s) using high-resolution 3D micro-computed tomography scans. Statistical correlations are observed between architectural parameters (tortuosity, connectivity, porosity, pore size) and fluid flow parameters (Re number distribution, permeability). Some channels exhibit Re values of 1400 at an inlet velocity of 1.6 m/s, and a transition from Darcy’s regime to a non-Darcian regime occurs around an inlet velocity of 0.02 m/s. Location-dependent permeability ranges from 20-32 Darcy. Regression modelling reveals a strong correlation between fluid velocity and tortuosity at high inlet velocities, as well as with channel diameter at low inlet velocities. At higher inlet velocities, flow paths deviate more from the preferential direction, resulting in a decrease in the concentration parameter by an average of 0.4. This research provides valuable insights into the fluid flow behaviour within the meniscus and its structural influences. 3D models and image stack are available to download at https://doi.org/10.5281/zenodo.10401592. Statement of significanceThe meniscus is a highly porous soft tissue with remarkable properties of load transfer and energy absorption. We give insight on the mechanism of energy absorption from high resolution uCT scans, never presented before, and a new method which combine CFD and image. The structure is similar to a sandwich structure with a stiff outside layer and a soft internal layer made of collagen channels oriented in a preferential direction guiding the fluid flow, enabling it to accommodate deformation and dissipate energy, making it a potentially optimized damping system. We investigate architectural/ fluid flow parameters- fluid regimes relationship, which is of interest of the readers working on designing suitable biomimetic systems that can be adopted for replacement.

Unveiling advanced modelling and analysis: the integrated system and formula for mass–spring–damper with hydraulic damper systems

Unveiling advanced modelling and analysis: the integrated system and formula for mass–spring–damper with hydraulic damper systems

Development of an Impact Energy Absorption Structure by an Arc Shape Stroke Origami Type Hydraulic Damper

Cylindrical hydraulic dampers used to reduce impacts and vibrations typically have linear strokes. In this study, a new arc-shaped stroke-type origami hydraulic damper with a nonlinear damping performance was proposed. By examining the damping effect of the origami hydraulic damper, the damping force was found to be proportional to the square of the motion velocity. A nonlinear dynamics governing equation was established using the derived formula for the damping force of the origami hydraulic damper, and a numerical analysis using the Runge–Kutta method was established. An impact test device with an arc-shaped stroke was developed, and the error between the numerical analysis value of the impact displacement and the measured experimental value was confirmed to be sufficiently small. An impact verification experiment confirmed that the damping effect of the origami hydraulic damper increases with the input energy of the impact. By varying the diameter of the orifice hole, which is an important design factor for an origami hydraulic damper, the damping effect of the origami hydraulic damper was found to increase as the diameter of the orifice hole decreased. To examine the effect of the type of hydraulic oil inside the origami hydraulic damper, water and edible oil were used to conduct impact verification experiments, and it was found that the effect on the impact damping effect was relatively small.

ИССЛЕДОВАНИЕ ОСНОВНЫХ ПАРАМЕТРОВ ГИДРОМЕХАНИЧЕСКОГО ДЕМПФЕРА ТРАНСПОРТНЫХ СРЕДСТВ, ИСПОЛЬЗУЕМЫХ В АГРОПРОМЫШЛЕННОМ КОМПЛЕКСЕ

The article presents materials related to the development of a promising design of a hydraulic damper in-stalled in the suspension of vehicles used in the agro-industrial complex. A special feature of the hydraulic damper design is the transition from vertical channels to horizontal channels in the piston and stem of the vi-bration damper. In this case, the vertical sections of the rod channels are mated with the horizontal sections of the piston channels. The presence of such calibrated holes in the piston and rod, as well as due to the ab-sence of bypass valves, can significantly reduce sudden pressure changes in the vibration damper during high-speed movements of both the rod and the piston. This significantly increases the smoothness of the ride, and, consequently, the comfort and safety of the vehicle and, thus, improves the working conditions of the personnel operating it. Analytical studies have been carried out, as well as hydrodynamic and strength calcu-lations of such determining parameters as the pressure of the working fluid and its flow rate. Recommenda-tions are given on the choice of rod and piston material for a promising design of a hydraulic damper for ve-hicles. A method of engineering calculations for determining the parameters of the throttling system is pro-posed, which allows to establish the criteria for the operability of the developed technical solution with a view to its possible application in industrial conditions.

Experimental investigation of a dual-pontoon WEC-type breakwater with a hydraulic-pneumatic complementary power take-off system

Floating offshore multi-purpose structures have recently attracted much attention worldwide in terms of sharing costs, enhancing efficiencies and reducing environmental impacts. In this paper, hydrodynamic experiments are conducted to examine the accessibility of wave energy absorption by a dual-pontoon floating breakwater integrated with hybrid-type wave energy converters (WECs). The main structure and the air chamber between the two pontoons are designed as an Oscillating Buoy (OB) and an Oscillating Water Column (OWC), respectively. Two power take-off (PTO) systems, including a hydraulic system and a Wells turbine, are selected to extract wave energy from structural motion and chamber airflow. To investigate the hydraulic-pneumatic complementary effects, PTO damping coefficients of two systems are adjusted both individually and synchronously. Besides, the hydrodynamic comparison among different geometrical parameters, are further studied. The breakwater-integrated hybrid WEC system led to a larger optimal pneumatic damping for the OWC while the optimal hydraulic damping for the OB is not affected. Additionally, the internal air pressure is acting as a resistive force to pontoons, hence the pontoon motion is smaller, and part of the kinematic energy from pontoons is extracted by the OWC. Correspondingly, the wave attenuation capacity is enhanced by multiple harvesting manners, especially for long-period waves.

Influence of water hammer effect on low frequency oscillation of grid-connected hydropower station system

This paper aims to investigate the influence of the water hammer effect on low-frequency oscillations (LFO) in power systems, mainly quantifying and revealing the characteristics of hydraulic damping of LFO. The models of the grid-connected hydropower stations considering the water column elasticity (elastic model) and without considering it (rigid model) are respectively established and used as time domain validation models. The corresponding analytical formulas for the mechanical damping torque coefficients (MDTC) are derived to obtain the system's damping frequency characteristics. Finally, a method for quantifying the nonlinear system's damping is proposed. The results show that due to the effect of the water hammer wave, the system's damping frequency characteristics have changed, and damping peaks and valleys appear. The corresponding frequencies are determined by the frequency of the water hammer wave. The system has a critical oscillation frequency. When the frequency of LFO is below the critical frequency, water column elasticity must be considered. When the frequency of LFO is consistent with the frequency of the water hammer wave, the negative damping reaches its maximum. Finally, the proposed quantitative method was used to clarify the influence of the water hammer effect on the system's damping characteristics while considering nonlinear head loss.

Quasi-static shock absorber friction at low velocity reciprocating sliding conditions

The characteristics of vehicle shock absorbers have a major significance regarding vehicle dynamics, thus affecting vehicle ride comfort, handling and safety. Although much research focuses particularly on the hydraulic damping properties of this vital suspension component, friction properties are not considered in great detail. However, for driving scenarios of low excitation and velocity of the shock absorber due to moderate roughness of the road, the friction force generated by the shock absorbers and the remaining components is particularly important regarding the transfer of vibration from the road to the passenger. Hence, this study investigates the sensitivity of shock absorber friction to various parameters in the quasi-static domain. The effects of side force, temperature, excitation amplitude and waveform are determined for multiple shock absorbers. The results show no significant influence of the amplitude and waveform used in the conducted tests. Contrarily, the friction force strongly depends on the side force, which represents the variable load perpendicular to the shock absorber’s main axis arising during various driving events for MacPherson suspensions. An increased temperature reduces the side force effect.

Development of a High-Performance Low-Weight Hydraulic Damper for Active Vibration Control of the Main Rotor on Helicopters—Part 2: Preliminary Experimental Validation

Vibrations generated by the main rotor-gearbox assembly in a helicopter are the principal cause of damage to cockpit instruments and crew discomfort in terms of cabin noise. The principal path of vibration transmission to the fuselage is through the gearbox’s rigid support struts. This article is Part 2 of a two-part paper presenting an innovative solution involving the replacement of rigid struts with low-weight, high-performance active dampers for vibration control developed by Elettronica Aster S.p.A. Part 1 provided a comprehensive overview of the system layout obtained through a model-based design process and presented a thorough description of the adopted nonlinear mathematical model. Part 2 focuses on the physical realization of the damper and its dedicated experimental test bench. The mathematical model parameter fitting procedure is presented in detail, as it has been used to help in the definition and optimization of the control schemes and the verification of the expected performance. The experimental results obtained in Part 2 not only demonstrate the compliance of the active damper prototype with the acceptance tests outlined in the ATP but also provide compelling evidence reinforcing the promise of the presented solution for effective vibration reduction.

An Improved Model for Hysteretic Behavior Investigation on the Twin-tube Hydraulic Adjustable Damper

The damper, as an integral constituent of the automotive suspension system, assumes a critical function in determining the suspension’s overall performance. To enhance the ride comfort and stability of automobiles, further research on the performance of dampers is particularly important. In this paper, an improved mathematical model with a twin-tube hydraulic adjustable damper (THAD) was developed to analyze the hysteretic behavior. The cavitation process of THAD was studied by studying the compressibility of oil and the structure of the valve port. Mathematical model results and published data under compression stroke and rebound stroke are compared for different working situations. The simulation results consistently illustrate the correctness of the model.

Investigation of dynamic characteristics in the hydraulic shock absorber based on different FSI FEA methods

Two three-dimensional fluid-structure interaction (FSI) finite element analysis (FEA) models with different fluid cells and coupling solution methods of a gas-pressured hydraulic shock absorber is constructed, and the results are partially verified experimentally. Models with FCBI fluid cell and direct FSI solution method or FCBI-C fluid cell and iterative FSI solution method provide good simulation results of the FSI system of the hydraulic damper.

Standalone and Interconnected Analysis of an Independent Accumulator Pressure Compressibility Hydro-Pneumatic Suspension for the Four-Axle Heavy Truck

This paper has proposed a new hydro-pneumatic damper, allowing independent accumulator pressure compressibility from the chamber pressure which enhances isolation performances due its lower F-V hysteresis effect at moderate velocities. The system utilizes the generic hydraulic damper with two hydro-pneumatic accumulators and four check valves in its design. To evaluate the active suspension capability of proposed damper effectiveness, a 22-degrees-of-freedom (DOF), four-axle truck model is integrated with a hydraulic control valve, which is built in an LMS-AME sim environment. Then, the model is exported as an S-function into Matlab/Simulink co-simulation platform for the hydraulic servo-valve control input of a model predictive control (MPC) and proportional-integral-derivative (PID) output signal. Simulation results show that the MPC and an additional supply of fluid to the proposed damper provide better performances and an adaptive damping capability is established. This work also showcases the development and results of a roll interconnected suspension study to assess the proposed damper characteristics when it is interconnected. The various advantages of the proposed-HPIS system over the well-known hydraulic interconnected system (HIS) and hydro-pneumatic interconnected suspension (HPIS) system are studied.

Experiment and analysis of drop-weight damping control of MR semi-active impact resistance-based hydraulic actuator

The impact vibration caused by sudden changes in the external load of hydraulic actuators reduces the service life of hydraulic components and limits the high-precision applications of hydraulic actuators. Therefore, to improve the underdamped characteristics and impact resistance of valve-controlled cylinder systems, a semi-active impact resistance control of hydraulic actuator based on magnetorheological damper (MRD) is proposed. Firstly, based on the shear force characteristics of magnetorheological fluid, a multi-stage flow channel MRD is designed, which is connected in series with the hydraulic actuator to form a hydraulic damping actuator (HDA). Meanwhile, based on the mechanical experimental data, the parameters of MRD dynamic model are identified to ensure the accuracy of MRD output force. Secondly, a drop weight impact model is established, and a sliding mode controller which can track the command current in real time is designed, so as to realize the resistance force coupling between the MRD and the hydraulic actuator for improving the impact resistance control effect. Then the dynamic performance test and impact resistance simulation program are established to verify the excellent dynamic performance and impact resistance effect of the HDA with the sliding mode control. Finally, the drop weight impact experimental platform is built. The experimental results show that under the impact with a height of 200 mm, the dynamic offset of the HDA is only −1.25 mm, and the time to return to the original position is 0.08 s, which validate the excellent performance of the proposed scheme in improving the underdamped characteristics of the valve-controlled cylinder system and the dynamic response performance of the hydraulic actuator.

Improving the stability and handling of tractors when towing trailers and coupled units

BACKGROUND: Currently, almost all agricultural work is performed using tractors. As the transport speed of a tractor train increases, the amplitude of lateral and horizontal oscillations of its coupled units emerges and increases. At certain velocities, these oscillations become so large that they can lead to a rollover, in addition, shock loads occur in coupling devices, which make it difficult to handle a tractor train. The traditional method to prevent this is the velocity limit, which does not guarantee a positive result.
 AIMS: Development of methods to improve stability, handling and safety of wheeled tractor trains by reducing the galloping and yawing of a truck tractor when towing heavy loads.
 METHODS: The following options of the design of the system for countering the occurrence of self-oscillations in the design of a wheeled tractor train ensuring a reduction in the level of self-oscillations, increasing the stability, handling and safety of the tractor train have been proposed: the coupling device equipped with hydraulic damping devices operating at longitudinal and lateral folding; the control system for the individual traction electric drive of a truck tractor preventing the loss of wheel grip with the ground surface; the combined use of the control system for the individual traction electric drive of a truck tractor and the coupling device equipped with hydraulic damping devices; the combined use of the coupling device equipped with hydraulic damping devices and a steering correction system.
 RESULTS: With use of simulation modeling methods, it has been established that the coupling device equipped with hydraulic damping devices adjustable by the folding angle of the tractor train and by the yaw angle oscillations of a truck tractor body should be recognized as the most acceptable and effective system for reducing self-oscillations of a wheeled tractor train at the current state of the art.
 CONCLUSIONS: The practical value of the study lies in the possibility of using the proposed methods to eliminate the risk of self-oscillating processes in the design of promising types of agricultural machinery.

A compact adjustable hydraulic damper with symmetric high load behavior enabled by selective laser melting

This publication addresses the development of a compact, adjustable hydraulic damper that meets the requirements for vibration testing. Dampers from the literature do not meet all the requirements, such as compact design, vibration resistance, high strength, broadly adjustable and dominantly symmetrical damping, and modularity. Additive manufacturing (AM) enables the design of integral and compact systems that can compensate for several disadvantages of known damping systems. Three stages of development are presented, from a proof of concept to a prototype manufactured by Stereolithography (SLA) as Vat Photopolymerization (VPP-UVL/P) to a ready-to-use hydraulic damper manufactured by Selective Laser Melting (SLM) as Laser Powder Bed Fusion (PBF-LB/M). The final additively manufactured damper is much more compact due to its geometric freedom in the design phase and requires a much smaller number of components. The damper has been tested over a wide range of operating conditions and has proven its reliable damping performance even under high loads. This performance makes it suitable for many other systems subject to vibration.

A Meta-Heuristic Optimization Procedure for the Identification of the Nonlinear Model Parameters of Hydraulic Dampers Based on Experimental Dataset of Real Working Conditions

Abstract Hydralic dampers are widely implemented in railway vehicle suspension stages, especially in high-speed passenger trains. They are designed to be mounted in different positions to improve comfort, stability, and safety performances. Numerical simulations are often used to assist the design and optimization of these components. Unfortunately, hydraulic dampers are highly nonlinear due to the complex fluid dynamic phenomena taking place inside the chambers and through the by-pass orifices. This requires accurate damper models to be developed to estimate the influence of the nonlinearities of such components during the dynamic performances of the whole vehicle. This work aims at presenting a new parametric damper model based on a nonlinear lumped element approach. Moreover, a new model tuning procedure will be introduced. Differently from the typical sinusoidal characterization cycles, this routine is based on experimental tests of real working conditions. The set of optimal model parameters will be found through a metaheuristic iterative approach able to minimize the differences between numerical and experimental damper forces. The performances of the optimal model will be compared with the ones of the most common Maxwell model generally implemented in railway multibody software programs.

Numerical and experimental investigation on parameters determination of the suspension system for a high-speed train aiming at cross-line operation

Cross-line operation that can improve the utilization of railway equipment and transportation efficiency is expected to be the development of the future, and the key to realizing this is to guarantee the dynamics performance of high-speed trains operating on different railway lines. To this end, this study focuses on determining the parameters of a suspension system for a high-speed train equipped with semi-active dampers. Multi-body dynamics method is used to establish a mathematical model of a high-speed vehicle, and a numerical integration method is applied to calculate the system response. An improved genetic algorithm adopting the dynamic Hamming distance, dynamic crossover, and mutation coefficients is integrated into the numerical simulation process to determine the parameters. Based on the numerical analysis, the optimized damping values for various hydraulic dampers in their passive modes are obtained. Finally, an experimental validation based on roller-rig and field loop-line tests is performed, and the test results verify the effectiveness of the optimized parameters. Thus, the study findings can serve as a reference to enhance the realization of cross-line operation.

Frequency-dependent automotive suspension damping systems: State of the art review

Configuration of a passive suspension of a passenger vehicle most often requires a compromise between its handling, road-holding, and ride (passenger) comfort. Nowadays, car manufacturers (automotive OEMs) are forced to develop ways for enhancing the functionality of shock absorbers and yet keeping their costs low. The use of so-called frequency-dependent (FD) valves in hydraulic passive suspension dampers, which allow the damping force to vary with the frequency of the excitation (or its change rate), is a satisfactory solution to the problem by means of adaptive passive valves. In this study, the effectiveness of the FD technology in passenger vehicles is demonstrated on the basis of a quarter-car simulation model. This is followed by a comprehensive review of several FD type valve structures currently offered by various automotive damper suppliers. Their advantages as well as potential drawbacks are shown and hydraulic circuits are formulated for each of the considered designs. Exemplary characteristics of a FD shock absorber obtained from own measurements are shown, too. The results of subjective qualitative evaluation of analyzed cases are presented and appropriate directions for further development steps are proposed. Finally, simulation results of functional model of FD shock absorber are presented.

An Evaluation Study of a New Designed Oscillating Hydraulic Trainer of Neck.

In view of the importance of neck strength training and the lack of adequate training equipment, this study designed a new oscillating hydraulic trainer (OHT) of neck based on oscillating hydraulic damper. We used surface electromyography (sEMG) and subjective ratings to evaluate the neck OHT and compared the results with a simple hat trainer (HATT) and traditional weight trainer (TWT) to verify the feasibility and validity of the OHT. Under similar exercise conditions, 12 subjects performed a set of neck flexion and extension exercise with these 3 trainers. The sEMG signals of targeted muscles were collected in real time, and subjects were asked to complete subjective evaluations of product usability after exercise. The results showed that the root mean square (RMS%) of sEMG indicated that the OHT could provide two-way resistance and train the flexors and extensors simultaneously. The overall degree of muscle activation with OHT was higher than that with the other two trainers in one movement cycle. In terms of resistance characteristics exhibited by the sEMG waveform, duration (D) with OHT was significantly longer than HATT and TWT when exercising at a high speed, while Peak Timing (PT) was later. The ratings of product usability and performing usability of OHT were remarkably higher than that of HATT and TWT. Based on the above results, the OHT was proved to be more suitable for strength training, such as neck muscles, which were getting more attention gradually, but lacked mature and special training equipment.

Response power of floating three-body wave energy converter with different shapes

A study on the hydrodynamic characteristics of buoys in a floating three-body WEC (wave energy converter) has been conducted in this paper using STAR-CCM+, based on the linear wave conditions, by numerically analyzing the impacts of buoy geometry (cuboid, cylindroid, boat-like, and capsule) on the floating motions and capture energy. Hinge constraints and hydraulic damping are considered in the numerical model, and the effects of wave parameters on the captured power of WECs are analyzed. Numerical results show that with the increase of wave period, the capture power of each WEC first increases and then decreases, and the capsule-shaped WEC has the largest power capture capability with a capture width of 0.469λ. While the boat-like also has a considerable capture width (0.459λ), with a lower wave resistance (6657.5 N) and 16% less mass, so this novel WEC has more potential for practical applications.

Development of a High-Performance Low-Weight Hydraulic Damper for Active Vibration Control of the Main Rotor on Helicopters—Part 1: Design and Mathematical Model

The helicopter vibrations generated by the main rotor/gearbox assembly are the principal cause of damage to cockpit instruments and discomfort of the crew in terms of cabin noise. The principal path of vibration transmission to the fuselage is through the gearbox rigid support struts. With the aim of reducing these vibrations, this paper presents the design of a low-weight high-performance active damper for vibration control developed by Elettronica Aster S.p.A. The system is intended to replace the conventional struts and is composed of an electro-hydraulic actuator hosted within a compliant structure. This parallel nested structure allows the system to reach a high-power density. A physics-based mathematical model was used as a design digital twin to optimize the performance to meet the strict requirements. The active damper was designed for a reference application of a 15-seat medium-sized twin-engine helicopter. The model was used to perform the tests specified in the acceptance and testing procedure document, showing the compliance with the requirements of the current design. The damper physical realization, test bench design, experimental campaign, and model validation will be presented in Part 2.