Search results for "Shock absorber"
showing 10 items of 16 documents
A Mathematical Model for Vehicle-Occupant Frontal Crash Using Genetic Algorithm
2016
In this paper, a mathematical model for vehicle-occupant frontal crash is developed. The developed model is represented as a double-spring-mass-damper system, whereby the front mass and the rear mass represent the vehicle chassis and the occupant, respectively. The springs and dampers in the model are nonlinear piecewise functions of displacements and velocities respectively. More specifically, a genetic algorithm (GA) approach is proposed for estimating the parameters of vehicle front structure and restraint system. Finally, it is shown that the obtained model can accurately reproduce the real crash test data taken from the National Highway Traffic Safety Administration (NHTSA). The maximu…
Optimal Damping Constant Investigation on a Quarter-Car
2013
This paper shows an investigation on optimal damping constant performed in the frequency domain. The optimal damping constant is meant as that value that minimizes the acceleration of all connected bodies characterizing a two degree of freedom system sketching a quarter car. The connected bodies are sprung and unsprung mass respectively for quarter of chassis and tire, this last keeps the contact with the ground and it is connected with the sprung mass through a shock absorber characterized by spring and fluid damper. Optimal damping constant was determined by imposing analytical conditions on the expression of acceleration of two masses. Afterwards, the variation of acceleration and positi…
A mixed H<inf>2</inf>/H<inf>&#x221E;</inf>-based semiactive control for vibration mitigation in flexible structures
2009
In this paper, we address this problem through the design of a semiactive controller based on the mixed H 2 /H ∞ control theory. The vibrations caused by the seismic motions are mitigated by a semiactive damper installed in the bottom of the structure. It is meant by semiactive damper, a device that absorbs but cannot inject energy into the system. Sufficient conditions for the design of a desired control are given in terms of linear matrix inequalities (LMIs). A controller that guarantees asymptotic stability and a mixed H 2 /H ∞ performance is then developed. An algorithm is proposed to handle the semiactive nature of the actuator. The performance of the controller is experimentally evalu…
Mathematical modeling of vehicle frontal crash by a double spring-mass-damper model
2013
This paper presents development of a mathematical model to represent the real vehicle frontal crash scenario. The vehicle is modeled by a double spring-mass-damper system. The front mass m1 represents the chassi of the vehicle and rear mass m2 represents the passenger compartment. The physical parameters of the model (Stiffness and dampers) are estimated using Nonlinear least square method (Levenberg-Marquart algorithm) by curve fitting the response of a double spring-mass-damper system to the experimental displacement data from the real vehicle crash. The model is validated by comparing the results from the model with the experimental results from real crash tests available.
Extended fractional-order Jeffreys model of viscoelastic hydraulic cylinder
2020
A novel modeling approach for viscoelastic hydraulic cylinders, with negligible inertial forces, is proposed, based on the extended fractional-order Jeffreys model. Analysis and physical reasoning for the parameter constraints and order of the fractional derivatives are provided. Comparison between the measured and computed frequency response functions and time domain transient response argues in favor of the proposed four-parameter fractional-order model.
Firefly optimization used to identify hysteresis parameter on rotational MR-damper
2014
In his paper the physical properties and mathematical models of a semi-active magnetorheological (MR) damper is studied. The considered models are the Dahl model and Bouc-Wen model. The parameters for these models are found by using a firefly optimization algorithm that minimizes the difference between experimental and simulated data. The objective of his paper is to compare different mathematical MR-damper models with the experimental data. The simulation results illustrate he effectiveness of he proposed optimization algorithm.
Systemic analysis of the caulking assembly process
2017
The present paper highlights the importance of a caulking process which is nowadays less studied in comparison with the growing of its usage in the automotive industry. Due to the fact that the caulking operation is used in domains with high importance such as shock absorbers and brake systems there comes the demand of this paper to detail the parameters which characterize the process, viewed as input data and output data, and the requirements asked for the final product. The paper presents the actual measurement methods used for analysis the performance of the caulking assembly. All this parameters leads to an analysis algorithm of performance established for the caulking process which it …
Mathematical Modeling and Optimization of a Vehicle Crash Test based on a Single-Mass
2014
In this paper mathematical modelling of a vehicle crash test based on a single mass is studied. The models under consideration consist of a single mass, a spring and/or a damper. They are constructed according to the measured vehicle speed before the collision and measured vehicle accelerations in three directions at the centre of gravity. A new model of nonlinear spring-mass-damper is also proposed to describe the crash. Simulation results are provided to show the effectiveness and applicability of the proposed methods.
Study of a Semi Active Electromagnetic Regenerative Suspension
2016
The main objective of this work is the theoretical and numerical study of a device that allows recovering energy from an automobile suspension. In place of the viscous damper, which dissipates the kinetic energy of the vehicle due to rough roads or more marked obstacles, an electromagnetic damper performs the functions of the viscous shock absorber with a recovery of electric energy. The damper has permanent magnets and its working is based on the electromagnetic induction. The used ferromagnetic material is the Supermendur, which has very good ferromagnetic properties, but is expensive and difficult to found, so that the choice of different material is useful to reduce the costs. The mathe…
Design of an Electromagnetic Regenerative Damper and Energy Harvesting Assessment
2016
Design of an electromagnetic regenerative shock absorber is proposed in this paper. In order to increase the efficiency of land vehicles the sources of energy losses have to be eliminated, or reduced. For this reason, several systems, recovering kinetic energy and converting it into electrical power, were studied and designed in the last years. This energy, converted into heat in traditional systems, is recovered to increase the autonomy of the vehicle. The proposed device is constituted by a stator part which coils are placed in an innovative disposition. The moving part is constituted by a rod made in stainless steel with alternated permanent magnets and spacers, so that the relative moti…