Papers by Keyword: Shock Absorber

Abstract: In this article we seek to model a base valve of a twin tube shock absorber and study the behaviour of the valve under loaded conditions replacing a mono tube shock absorber. A top down approach was adopted for this work wherein a commercially available shock absorber was stripped down to obtain the individual valves inside. Product teardown was done for the various subassemblies and the base valve was isolated. Modelling was done in PTC Creo 2.0 and the FEA study for the stress and flow analysis was done using ANSYS 15.0. The materials as well as the hydraulic fluid selected for the design were validated and proved to give a better performance than a mono tube shock absorber currently being used in automobiles.

Abstract: This study reports on effects of tapered metering pins on a magnetorheological (MR) fluid subjected to shock loading. Using four types of tapered metering pins, we conducted drop impact tests and qualitative analysis of effects of tapered pins on an MR fluid with a magnetic field applied around an orifice area. We measured the displacement of a piston and calculated velocity and acceleration from the measured displacement. The four different tapered pins changed a piston stroke to bring the impacting mass to rest. The results indicated that the shape of the pins has an effect on the entire process of shock absorption, whereas magnetic field strength has an effect on the post-peak behavior only. These results show that a tapered metering pin has applicability to a shock absorber using an MR fluid.

Abstract: The paper presents a complex quarter car model obtained with ADAMS software, View module, useful in the first stage of suspension dimensioning and optimization.The model is equipped with compression and rebound stopper buffer and suspension trim corrector.The proposed quarter car model with two degrees of freedom (wheel and body) performs all these goals allowing changing:Geometrical elementsPosition of equilibrium, depending on vehicle load;Trim correction;Elastic and dissipative characteristics of the suspension and tire;Suspension stroke;Road profile, assessed either by simple or summation of harmonic functions or reproducing real roadsBuffers (for stroke limitation) position and characteristics;The models developed provide information on:Vertical stability assessed by vertical movements of the body and the longitudinal and transversal stability evaluated based on adherence characterized by wheel ground contact force and frequency of soil detachment wheel.Comfort assessed on the basis of body vertical acceleration and collision forces to the stroke ends.The body-road clearanceThe trim corrector efficiencyAll above performances evaluated function the road unevenness, acceleration, deceleration, turning regime.The damping characteristic is defined by damping forces at different speed for each strokes respectively one for rebound and other for compression.The contact force road-wheel is defined based tire rigidity law.The stopper buffer forces on rebound and compression are defined based each specific rigidity characteristics.The road excitation is realized with a function generator.The software allow the model evolution visualisation in real time, also generating the diagrams of displacements, forces, accelerations, speeds, for each elements or for relative evolution between diverse elements.The simulation was realized for unloaded and fully loaded car using a road generated by a sum of harmonic functions presented in equation (8).The excitation covers the specific frequencies area, being under the body frequencies up to the wheel proper frequencies.The realized ¼ car model, have reached the goal to evaluate the suspension trim correction advantages.The simulations confirm the trim corrector increases the suspension performances, thus for the analyzed case the trim corrector increase simultaneous:Body-ground clearance (evaluated by body higher increasing) between 18.5÷55.1 %Body stability (evaluated by maximal body displacement) between 9.8÷11.4 %Body comfort (evaluated by maximal body acceleration) between 3.4÷35.5 %Adherence (evaluated by maximal and RMS wheel-groundcontact force variation) between 7.0÷12.1 %Body and axles protection (evaluated by buffer strike force) between 10.8÷38.2 %

Abstract: The VZN shock absorber concept granted with European Patent EP 1 190 184 is characterized by damping coefficients self according with road and load conditions.The simulations made on vehicles equipped with new VZN shock absorbers concept relative to standard one, indicates better behavior concerning stability, comfort and reduced dissipated energy, with fuel consumption and pollution reducing effect.Starting on these remarks the paper evaluates the influence of the damping characteristic in suspension performances and dissipated energy, based a simulation on a Californian road realized with Matlab Simulink software.Since year 2006 simulations on model ¼ cars demonstrates the VZN damper concept give skyhook behavior, decrease squat, vertical acceleration, the number and intensity of stopper bumper collision, the adherence, increasing thus the vehicle stability, comfort and reliability.Tests on models ½ car, show the VZN concept increases stability at pitch and roll and confirm the previous results obtained on ¼ models.The current work completed previous research with one demonstrating other VZN qualities e.g. its capacity to manage damping coefficient, no more and no less, assuring high performances and thus reducing the dissipated energy, with favorable effect for reducing fuel consumption and pollution.The comparison between the behaviors of the VZN shock absorber relative to the standard shock absorber has been realized for body displacement, squat, acceleration and dissipated energy.The VZN progressive damper concept gives better behavior comparative to standard one, 6% at car body bounce, 37 % for RMS acceleration and 28.4 % for dissipated energy, these means it confer better body-ground clearance, comfort and fuel consumption and pollution.The VZN damping coefficients accorded with the vehicles load and with road unevenness confer a soft response at low excitation and strong reactions at high excitations, dissipating energy function of the needs, assuring thus comfort at small and medium excitation and protecting the axles and body at hard conditions.

Abstract: The paper purpose is to evaluate the efficiency of a new kind of suspension trim corrector based the tests on rigs an on the vehicle. The trim correction is realized by two pneumatic elements placed on the vehicle rear shock absorbers. The tests on rigs were realized on a hydropuls rig recording the force evolution with the stroke for some pneumatic pressure. Then the trim correctors were placed on the vehicle, being tested the trim evolution with the pneumatic pressure for some loaded states. Finally the tests were continued on road to evaluate their well behavior for some loaded vehicle states. All results confirmed the high efficiency of the new trim model and its well behavior on road. This reason the new trim corrector solution is in protection phase.

Abstract: Energy harvesting shock absorber is used for harvesting the kinetic energy in the vehicle suspension vibration. In this paper, we present design, modeling, and simulation of a novel energy harvesting shock absorber based on rack and pinion mechanism. The shock absorber consists of three main components: the mechanical vibration input, the transmission module, and the micro-generator module. The shock absorber is installed between the vehicle frame and chassis to obtain a relative linear motion acting as mechanical vibration input. The function of transmission mechanism module is to convert the relative linear motion to a unidirectional rotation for the input shaft of micro-generator. The micro-generator will produce electricity due to the input shaft rotating in one direction. This shock absorber was tested in simulation condition, and the last performance evaluation demonstrates the validity of the proposed energy harvesting shock absorber.

Abstract: A new type of shock absorber was designed. The shape memory alloy (SMA) bars were used as the kernel components for energy dissipation and restoration in the stress mode of pure tension. Their initial deformation was enlarged by the hydraulic system with two pistons of different sizes. In this way, high material utilization and high relative displacement were guaranteed together. The prototype device was fabricated, analyzed and experimental tested. The results show that the shape and amplitude of the force-displacement curve of the device could be easily changed by varying the hydraulic system, the number and/or the characteristics of the SMA bars. The new device can be separately or combined used as shock absorber and/or vibration isolation component for vehicles or other machines.

Abstract: It is the main decrease press type used in high speed train of semi suspension system, as the parameter can not be regulated freely of the semi suspension system, to design a kind of damping shock absorber which with the sensitive and soft system are very important, this system which using of the Electro hydraulic proportional valve to regulation the safety valve, the guide valve and the damping force of shock absorber, get the recycle method of the hydraulic system from inner to outside, and also using the suspension active control variable damping shock absorber to detect the road, this device, in fact, by vibration, which let the valve move relation, turn the mechanical energy into hot and release outside, thus decrease the vibration. To design this variable damping shock absorber ,compared with the semi suspension system ,for it has the connect system and Electro hydraulic proportional valve, and with the road detectors, and various variable parameters, Which let the high speed train more stable and safety, overcome the short of parameter regulation for the semi-automatic suspension system.

Abstract: It is still a difficult problem to solve for a suspension system simultaneously to hold the body of the car in comfort and to execute the requirements of other safety systems like ABS, ESP, steer-by-wire, etc systems. Passive suspension systems are unlikely to provide a solution, the introduction of semi-active suspensions in the practical use is necessary. A possible solution could be a permanent magnetic (PM) synchronous tube generator, which can operate as a controllable shock absorber parallel with energy recuperative operation. Designer software is realized, to calculate the geometrical and electrical parameters of permanent magnetic (PM) or high temperature superconductor (HTS) magnets for arbitrary vehicle suspension systems

Abstract: Due to the large and medium-sized cities in our country is more; the urban rail speed is low and the environmental protection high capacity requirements. Each city urban rail structures more or less differences. Especially fastener system is various, even in the same line also exist different deduction system; Because the subway in China fastener system is various and not a fixed is widely used fastener system; The paper gives a simple summary of subway common shock absorber fasteners in China. I hope it can give a reference to researchers on fasteners.