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1

Numerical tests of the double spring with hangers

Krasoń W., Wysocki J., Zając K.

Journal of KONES

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2015

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Vol. 22, No. 4

163--170

EN

Subject of the work include selected numerical models of the test stand intended for testing a prototype double multi-leaf spring of bi-linear nature. Basic design assumptions of the stand were as follows: provide laboratory tests of multi-leaf (single and double) springs designed for dependent suspensions of passenger cars of permissible weight up to 3,5 tones. The stand should allow for testing basic spring and strength characteristics in the quasi-static conditions and dynamic conditions with the impact of the force impulse or a set variable load characterized by a particular force amplitude (displacement) and frequency of its variations. Considered stand models include the tested spring, base, support and the hanger. This paper presents two types of FEM models of the spring element (beam and 3D). In the first element, components of the spring-hanger system were mapped by means of beam elements, in the second one by means of definite solid elements. The spring was loaded with a vertical force from 0 to 10000 N. A non-linear analysis of the bi-linear spring was carried out including clearance as well as the elastic analysis of the stand. The results of the numerical tests are presented in a form of tabular specifications, diagrams of displacements, and reduced stresses of selected components of the stand.

2

Experimental investigations of double multi - leaf spring subjected to impact load

Bogusz P., Krasoń W., Wysocki J.

Journal of KONES

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2012

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Vol. 19, No. 2

45-51

EN

The article deals with experimental investigations of a prototype double multi-leaf spring, compound of a fourleaf main spring and a double-leaf supporting spring subjected to an impact test. In real conditions of car movement (e.g. curb, bump), dynamic oscillating loads, which generate dynamic stress in a car suspension affecting other elements of the car, occur. Consequently, effects of coupled oscillations having a great impact on comfort of a driver and passengers can be observed. The research was conducted in the Laboratory of Material and Construction Strength Department of Mechanics and Applied Computer Science (DMACS) in the Faculty of Mechanical Engineering of Military University of Technology. The experiment was carried out on an original construction of a spring impact hammer developed in DMACS. Energy of the impact was set up by changing mass of a beam with beater and beam dropping height. The results were presented in the form of table summaries, time-dependent load and displacement graphs. The methodology of the research presented in the paper and a set of measuring equipment can be utilized to evaluate load and vibrations of any multi-leaf spring under impact load with given energy. The experimental results obtained from the test are supposed to be used to verify and develop FEM model describing a spring under impact load and oscillations.

3

Analysis of vibrations of the simplified model of the suspension system with a double spring and a fluid damper

Krasoń W., Wysocki J.

Journal of KONES

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2011

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Vol. 18, No. 1

311-316

EN

The subject of the paper are forced vibrations of the rear suspension of the biaxial vehicle fitted with the double spring spatial shell model and the viscous damper, under the force pulse input with the given transient response. The play between the master and auxiliary spring is a specific feature of the double spring design [1, 6]. Numerical tests were taken for three variants of the viscous attenuation. The attenuation coefficient values for typical dependent suspensions and their range of changes were assumed on the basis of publication [14]. The problem of modelling and analysing, including contact issues, was solved with the use of the MSC Software programme package with the special use of MSC Patran pre-processor [12]. The numerical analysis of the suspension model with the geometrical nonlinearities, viscous attenuation, and time-varying load was taken with the use of the finite element method (FEM). The selected results of the model tests in the form of the suspension relative displacements (speeds) and deformations (stresses) for the selected points of the master and auxiliary spring against time are presented in the paper. The complete model of the suspension system makes possible to examine the influence of various inputs on the interoperation and the phenomena associated with the dynamic response of such a complex system.

4

Experimental verification of numerical test results for a double multi- leaf spring

Krasoń W., Wysocki J.

Journal of KONES

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2009

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Vol. 16, No. 3

185-193

EN

A double spring used in the vehicle suspension, as a combination of spring elements of characteristics close to linear ones, actually provides non-linear suspension characteristics. Due to requirements for the truck suspension being designed, the spring characteristics in the whole range of load changes should meet the vehicle motion smoothness related to keeping the frequency of own suspension vibrations within a range of l-2 Hz [8, l0]. A prototype double spring made of a four-leaf main spring and two- leaf auxiliary spring (Fig. 1) makes a subject of considerations. Characteristic features of that structural solution includes a clearance between the main spring and the auxiliary spring. This work presents the results of numerical tests for three models of MES double spring [23] that were compared with experimental test results. An evaluation of usability of individual numerical models was made for representation of a double spring characteristics, contact between individual leaves and regular stress in the main leaf (the so-called safety leaf). The smallest differences between the stress results obtained from numerical tests compared to the laboratory tests, for the beam and shell models, have been obtained only for one extreme main (longest) leaf.

5

A numerical analysis of a double multi-leaf spring model

Wysocki J., Krasoń W.

Journal of KONES

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2009

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Vol. 16, No. 1

541-550

EN

The use of a double spring in a vehicle suspension as a combination of elastic components of characteristics which are approximate to linear ones gives a nonlinear suspension nature, which should approximately meet the criterion of car motion smoothness connected with keeping the frequency of the free vibrations of the a motorcar body in the range of l - 2 Hz, in the whole range of load changes (cargo) [see references 8, 10]. The subject of considerations is a prototypical double spring that consists of a four-leaf main spring and a two-leaf auxiliary spring and is meant for the family of motor trucks (delivery trucks) of a total mass of about 3,51. The presence of a clearance between the main spring and the auxiliary spring is the specificity of the aforementioned structural solution. In the present study, there are presented different variants of FEM numericał models ofa double spring as well as selected aspects of their applications at the stage of the research on the displacements and deformations of selected structural components. The structures ofa two-dimensional beam model, a three-dimensional shell model and a solid model of a double spring are discussed. Moreover, the study discusses different approaches in the modelling of the effect of contact between particular leaves and their influence on analysis results. Selected model tests results were compared with experimental research results.