Shock Absorber System Research Articles

Improved design of an active landing gear for a passenger aircraft using multi-objective optimization technique

One of the major subsystems of each airplane is the landing gear system which must be capable of tolerating extreme forces applied to structure during ground maneuver to improve vibration absorbing performance. The traditional landing gear system performs this function well under normal condition, whereas with varying condition of landing and situation of the runway for the airplane, performance of this system decreases noticeably. In this research, for overcoming this problem, the coefficients of controller, the parameters of hydraulic nonlinear actuator added to the traditional shock absorber system, and the vibration absorber are optimized simultaneously by the bee intelligent multi-objective algorithm. As well as, for proving adaptability of this algorithm, this paper presents the sensitivity analysis of three point landing due to the additional payload and the touchdown speed and the robustness analysis of one and two point landings due to the wind conditions as emergency situation on the runway as an innovated work. In order to evaluate the effectiveness and the efficiency of proposed method, the flight dynamic differential equations of an Airbus 320–200 vibrational model during the landing phase are derived and through the numeric technique are solved. The results of numerical analysis for this large-scale airplane model with six degrees of freedom demonstrate that the active shock absorber system in accordance with two types of the bee multi-objective algorithm has good performance in comparison with the passive approach to minimize the bounce displacement and momentum, the pitch displacement and momentum, the suspension travel and impact force in time-domain and frequency-domain by using signal processing, that results in improvement of passenger ride comfort importantly. As well as, enhancement of structure’s fatigue life is a likely case as a consequence of study applicable to the industry.

A novel indirect-drive regenerative shock absorber for energy harvesting and comparison with a conventional direct-drive regenerative shock absorber

Energy harvesting from the shock absorbers is now becoming an important technology in developing the electrical vehicles. Compared with other kinetic energy sources such as engine and brake systems which are continuous or periodic, the shock absorber is subjected to the fluctuated linear motion with relatively small displacement. This paper presents a novel indirect-drive regenerative shock absorber system that utilizes an arm-teeth mechanism to achieve linear to rotary motion conversion and to amplify its input speed for increasing energy harvesting output. The fluctuation of road randomness can be smoothed out through the flywheel. The proposed design has the advance of achieving all the targets with less number of components. Two prototypes of the direct-drive and indirect-drive regenerative shock absorbers have been built. The simulation models have been developed and validated by experimental results. The performance of this new indirect-drive system has been compared, through experimental testing and analytical modeling, with that of a conventional direct-drive system of the same generator configuration. The results show that this indirect-drive system can achieve greater peak power output and broader frequency bandwidth than the conventional direct-drive system. The indirect-drive system also presents a better ride comfort up to 13 Hz. Using Monte Carlo simulation, a parameter sensitivity analysis of both the indirect-drive and direct-drive systems has been carried out to compare their energy harvesting performances in terms of increasing the peak power output and broadening the energy harvesting frequency bandwidth. In both the systems, choosing the right tyre stiffness and electromechanical coupling constant is beneficial to increasing the peak power output ratio and the harvesting frequency bandwidth. The right choice of the gear ratio can further improve the peak power output ratio of the indirect-drive system. The variation of these parameters will allow for possibility of achieving higher power output when vehicle is driven on random road surfaces.

A Comprehensive Review of the Techniques on Regenerative Shock Absorber Systems

In this paper, the current technologies of the regenerative shock absorber systems have been categorized and evaluated. Three drive modes of the regenerative shock absorber systems, namely the direct drive mode, the indirect drive mode and hybrid drive mode are reviewed for their readiness to be implemented. The damping performances of the three different modes are listed and compared. Electrical circuit and control algorithms have also been evaluated to maximize the power output and to deliver the premium ride comfort and handling performance. Different types of parameterized road excitations have been applied to vehicle suspension systems to investigate the performance of the regenerative shock absorbers. The potential of incorporating nonlinearity into the regenerative shock absorber design analysis is discussed. The research gaps for the comparison of the different drive modes and the nonlinearity analysis of the regenerative shock absorbers are identified and, the corresponding research questions have been proposed for future work.

Modeling and calculation of hydromechanical systems dynamics based on the volume rigidity theory

A method for modeling hydraulic systems of hydromechanical devices based on the application of the volume rigidity theory - the property of the hydraulic system to keep its volume unchanged when the pressure of the working medium changes is proposed. The main analytical dependencies intended for modeling the hydraulic system are presented. An example of simulation and calculation of a hydromechanical shock absorber system which confirms the correctness and convenience of using the volume rigidity theory in modeling hydromechanical drive systems of complex machines is presented. The results of the numerical experiment make it possible to evaluate the functioning quality of the drive system under investigation to reveal the effect of the main design and system functional parameters on its operation. The graphs of the change in the main functional parameters of the shock absorber under investigation in real time are given, which make it possible to visually evaluate the results of a numerical experiment and draw conclusions about the need for modernization.

Parameters Synthesis of the Shock Absorber System for an Elastic Object with Incomplete Data on Stochastic External Loads

The elastic object and the deprecation system are described by a system of nonlinear ordinary differential equations. Probabilistic characteristics of external influence are not define. According the guaranteed result method it can be any of a finite set of deterministic realizations. Optimizing the parameters of the passive depreciation system reduces to solving a minimax multicriteria problem. The depreciation parameters can vary in a given class without introducing additional restrictions. To calculate the extremum of the objective function, the search algorithm of the Nelder-Mead deformable polyhedron is used. The results are illustrated by an example.

Study on coupled shock absorber system using four electromagnetic dampers

Recently, the electromagnetic damper, which is composed of an electric motor, a ball screw, and a nut, was proposed. The electromagnetic damper has high responsiveness, controllability, and energy saving performance. It has been reported that it improved ride comfort and drivability. In addition, the authors have proposed a coupling method of two electromagnetic dampers. The method enables the characteristics of bouncing and rolling or pitching motion of a vehicle to be tuned independently. In this study, the authors increase the number of coupling of electromagnetic dampers from two to four, and propose a method to couple four electromagnetic dampers. The proposed method enables the characteristics of bouncing, rolling and pitching motion of a vehicle to be tuned independently. Basic experiments using proposed circuit and motors and numerical simulations of an automobile equipped with the proposed coupling electromagnetic damper are carried out. The results indicate the proposed method is effective.

Multi-physics based Simulations of a Shock Absorber Sub-system for PHM

The multi-physics involve Mechanical, Thermal, Hydraulic, and Pneumatic based modeling and simulation of an oleo-pneumatic shock absorber with fault capabilities presented in this paper. The fault simulated in this model is leakage due to eccentricity. The one-dimensional shock absorber system models render loads at different sink velocities. These load values, used in the structural model to do static stress analysis. By using these loads directly from the system model eliminates the error in load computation from the loads group, thereby eliminating the time and cost involved in this activity. The models and static stress analyses are done with both 1-D and 3-D elements. The 3-D landing gear model meshed with using both auto and manual mesh generation options. The consequences of both 1-D, and 3-D models mesh generation are discussed in this paper. The static stress analysis, compared with the experimental results and it is found that the results are within 5% deviation. Based on the static stress analysis computed the life of a landing gear.

Modelling, Testing and Analysis of a Regenerative Hydraulic Shock Absorber System

To improve vehicle fuel economy whilst enhancing road handling and ride comfort, power generating suspension systems have recently attracted increased attention in automotive engineering. This paper presents our study of a regenerative hydraulic shock absorber system which converts the oscillatory motion of a vehicle suspension into unidirectional rotary motion of a generator. Firstly a model which takes into account the influences of the dynamics of hydraulic flow, rotational motion and power regeneration is developed. Thereafter the model parameters of fluid bulk modulus, motor efficiencies, viscous friction torque, and voltage and torque constant coefficients are determined based on modelling and experimental studies of a prototype system. The model is then validated under different input excitations and load resistances, obtaining results which show good agreement between prediction and measurement. In particular, the system using piston-rod dimensions of 50–30 mm achieves recoverable power of 260 W with an efficiency of around 40% under sinusoidal excitation of 1 Hz frequency and 25 mm amplitude when the accumulator capacity is set to 0.32 L with the load resistance 20 Ω. It is then shown that the appropriate damping characteristics required from a shock absorber in a heavy-haulage vehicle can be met by using variable load resistances and accumulator capacities in a device akin to the prototype. The validated model paves the way for further system optimisation towards maximising the performance of regeneration, ride comfort and handling.

Energy Regeneration From Suspension Dynamic Modes and Self-Powered Actuation

This paper concerns energy harvesting from vehicle suspension systems. The generated power associated with bounce, pitch, and roll modes of vehicle dynamics is determined through analysis. The potential values of power generation from these three modes are calculated. Next, experiments are carried out using a vehicle with a four jack shaker rig to validate the analytical values of potential power harvest. For the considered vehicle, maximum theoretical power values of 1.1, 0.88, and 0.97 kW are associated with the bounce, pitch, and roll modes, respectively, at 20 Hz excitation frequency and peak-to-peak displacement amplitude of 5 mm at each wheel, as applied by the shaker. The corresponding experimental power values are 0.98, 0.74, and 0.78 kW. An experimental rig is also developed to study the behavior of regenerative actuators in generating electrical power from kinetic energy. This rig represents a quarter-vehicle suspension model where the viscous damper in the shock absorber system is replaced by a regenerative system. The rig is able to demonstrate the actual electrical power that can be harvested using a regenerative system. The concept of self-powered actuation using the harvested energy from suspension is discussed with regard to applications of self-powered vibration control. The effect of suspension energy regeneration on ride comfort and road handling is presented in conjunction with energy harvesting associated with random road excitations.

Modelling and Testing of a Hydraulic Regenerative Shock Absorber System

Modelling and Testing of a Hydraulic Regenerative Shock Absorber System

Investigation of Annular Gap Size for Optimizing the Dynamic Range of MR Damper Using Comsol Multiphysics Software

Magneto-rheological (MR) fluid technology has made it possible to develop reliable, revolutionary vibration control systems for a variety of commercial, medical and military applications. MR fluid shock absorber systems are enabled by remarkably versatile MR fluid technology, which allows the system to respond instantly and controllably to varying levels of vibration or shock with simple, robust designs. This paper presents a parametric study of the MR dampers for semi-active vibration control. The influence of gap size of the damper on the viscous stress of the MR fluid is examined. It is inferred from the study that the viscous stress of the MR fluid for different parameters such as gap size influences the dynamic range of MR fluid dampers.The simulated results depict a maximum viscous stress of 1765.441 N/m2for a gap size of 1.85 mm. The developed dynamic range would allow for smaller size of the device, higher dynamic yield stress and low power consumption. The simulated results using COMSOL multiphysics for the verification of the parametric strategy have been presented. Results of this study shall enhance the design of MR dampers for different control applications.

Electrorheological Semiactive Shock Isolation Platform for Naval Applications

This paper presents a semiactive shock absorber system, which utilizes the special properties of electrorheological (ER) valves and which is intended to protect sensitive equipment on ships or submarines. It consists of a platform and a base plate, which are connected via an ER damper and an air spring. The resulting acceleration of the platform upon an external shock of the base plate should be significantly reduced while assuring fast and accurate repositioning of the platform after the shock. A control strategy is discussed, which fulfills these requirements using only one acceleration sensor. Simulation studies and measurement results on a prototype prove the feasibility of the proposed system.

Design of a Piezoelectric Energy-Harvesting Shock Absorber System for a Vehicle

Only ∼20% of a vehicle's fuel consumption is used for overcoming air drag force and friction with the road. Vibration energy produced during driving is dissipated by shock absorbers in the vehicle suspension. A new Piezoelectric Energy-Harvesting Shock Absorber (PEHSA) system for vehicles has been developed to act as an energy harvester that converts vibration energy to electrical energy. Cylindrical piezoelectric transducers are combined with the cylinder of the shock absorber to generate electricity from changes in fluid pressure produced by piston vibrations. A multiphysics simulation was performed using COMSOL Multiphysics to determine the characteristics of the PEHSA system.

Study on Variable Universe Fuzzy PID Control for Landing Gear Based on MRF (Magneto-Rheological Fluid) Damper

Aircraft landing gear shock system model was established, The system vibration differential equation and state-space equation were deserved。Based on the general fuzzy PID controller, the idea of fuzzy PID controller and its application in shock absorber system were studied. Based on MATLAB, the system simulation model was established, and the fuzzy PID control of semi-active suspension is analyzed compared to variable universe fuzzy PID control. The results show that the variable universe fuzzy PID control had better control effect.

The Technique of Seismic Isolation in Story-Adding Buildings Using Light-Weight Steel Structure and its Application

Light-weight steel structure story-adding is a widely used technology in house reconstruction. In this paper, it introduces an technique that using seismic isolation theory in story-adding buildings using light-weight steel structure. On the basis of mechanism analysis, a number of lead rubber bearings（LRB）are set between the top storey of existing building and the newly light steel structure, and the upgraded building is developed as a TMD shock absorber system. Combined a project instance, the relevant technical measures and detail constitutions are given. It should be reference to storey-adding engineering designs.

Self-tuning Control on Integrated System of EPS and SAS Based on Pole Placement

Entire vehicle multi-degree of freedom dynamic model of Semi-Active Suspension(SAS) and Electric Power Steering(EPS) integrated system including yaw, roll and pitching motion is established. Self-tuning integrated control strategy of SAS and EPS integrated system based on pole placement is designed, and approach of on-line identification which combines the pole placement method with least square parameter estimation method is constructed. To carry out the real-time control on system, based on the simulation calculation, the developed adjustable shock absorber and integrated system controller are installed in a certain mini car. Real vehicle road test is carried on, and the simulation results are in good agreement with the test ones. Moreover, under self-tuning integrated control based on pole placement, the peak value and standard deviation of vertical acceleration of centroid, roll angle of vehicle body, pitching angle, yaw angular velocity, side angle of centroid are then reduced, vehicle ride comfort, handling stability and attitude change of vehicle body are improved, entire vehicle overall performance is enhanced.

Dynamics of controlled pneumatic shock-absorber systems for large objects

The damping properties of pneumatic shock absorbers may be improved by controlling the restoring force. The dynamics of a building with a pendulum-type shock-absorber system under an external perturbation is compared with its motion in the case of pneumatic shock absorbers, with and without hydraulic damping.

Study on an Improved Shock Absorber Used in the Oil Test Pipe Under Impact Load

ABSTRACTPerformance of an improved shock absorber designed for absorbing and isolating the oil test pipe vibration is researched in this paper. 3D finite element model is established for the analysis of the shock absorber system accurately by the FEA software ANSYS/LS-DYNA. Numerical simulations show that the effect of the shock absorber can be greatly improved by optimizing the plastic material parameter. In the practice petroleum well test, the new designed shock absorber showed good shock absorption effect and no damage on the detecting instruments was observed even after ten times loading.

Design on a new oil well test shock absorber under impact load

Continuous operation of test and measurement is a new operating technique in the petroleum exploitation, which combines perforation with test and measurement effectively. In order to measure the original pressure of stratum layer exactly and prevent testing instrument from being impaired or damaged, a suitable shock absorber is urgently necessary to research. Based on the attempt on the FEM analysis and experiment research, a new shock absorber is designed and discussed in this paper. 3D finite element model is established and simulated accurately by LS-DYNA, the effect and the dynamic character of the shock absorber impact by half sinusoidal pulse force under the main lobe frequency are discussed both on theoretics and experiment. It is shown that the new designed shock absorber system has good capability of shock absorption for the impact load.

4043 小型ロケット打上げにおけるパラシュート開傘衝撃(S60-2 小型宇宙システム(2),21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

In recent years, small hybrid rocket experiments are actively carried out by students in Japanese universities. In the experiments, rockets are usually retrieved by a mounted parachute. In the inflation process, however, the rocket structures experience considerable opening shock load, and in some cases, result in destruction of the primary structure. In this paper, we describe the opening shock load with the acceleration data acquired by sensor mounted on two hybrid rockets. We also discuss the design and the performance of the shock absorber system.