• Advances in Automotive Engineering
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• v.1 no.1
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• pp.1-20
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• 2018

The aim of this study is the optimization of the parameters of interconnected Hydro-Pneumatic (HP) suspension system of a three-axle vehicle for ride comfort and handling. For HP suspension systems of equivalent vertical stiffness and damping characteristics, interconnected HP suspension systems increase roll and pitch stiffness and damping characteristics of the vehicle as compared to unconnected HP suspension systems. Thus, they result in improved handling and braking/acceleration performances of the vehicle. However, increased roll and pitch stiffness and damping characteristics also increase roll and pitch accelerations, which in turn result in degraded ride comfort performance. Therefore, in order to improve both ride comfort and vehicle handling performances simultaneously, an optimum parameter set of an interconnected HP suspension system is obtained through an optimization procedure. The objective function is formed as the sum of the weighted vertical accelerations according to ISO 2631. The roll angle, one of the important measures of vehicle handling and driving safety, is imposed as a constraint in the optimization study. Upper and lower parameter bounds are used in the optimization in order to get a physically realizable parameter set. Optimization procedure is implemented for a three-axle vehicle with unconnected and interconnected suspension systems separately. Optimization results show that interconnected HP suspension system results in improvements in both ride comfort and vehicle handling performance, as compared to the unconnected suspension system. As a result, interconnected HP suspension systems present a solution to the conflict between ride comfort and vehicle handling which is present in unconnected suspension systems.

• Journal of the Korean Ceramic Society
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• v.32 no.1
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• pp.131-139
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• 1995

In order to improve transmittance and response properties, various compositions of light controllable films were prepared by phase separation method. The optical and response properties were measured with the variation of PMMA/suspension ratio and block copolymer/light polarizing particles. According to the increase of the PMMA/suspension ratio, the separated droplets of suspension were interconnected in the film. Decay time was 2.6 sec when PMMA/suspension ratio was 0.5 : 1 and ΔT(difference of the transmittance at OFF/ON states) was reduced with increasing of the ratio of PMMA/suspension. On block copolymer/light polarizing particles ratio variation, the highest transmittance of the film was 67.4% when its ratio was 0.6 : 1 and decay time was varied from 2.15 to 46.6 sec as block copolymer content increased 0.2 : 1 to 1 : 1.

• International Journal of Railway
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• v.2 no.3
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• pp.118-123
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• 2009

Railway track alignment Standards set a minimum lenght value for straight and circular alignments (art. 5.2.9.), in order to ensure passenger ride comfort in railway vehicles of which dynamic oscillations will thus have to be limited. The transitions between alignments can cause abrupt changes (usually called discontinuities or singular points of the alignment) of curvature, of rate of change of curvature or of rate of change of cant. A passenger is likely to experience effects due to the excitation of the elastic suspension of the vehicle which generates oscillations that are damped as the vehicle moves away from the singularity. The amplitude of these oscillations should be adequately attenuated by the damping of the suspension system within the interval between two successive singular points, especially to avoid resonances. Therefore minimum lengths between two successive singular points are stated in alignment standards. Nevertheless, these nonnative values can be overly conservative in some cases. As an alternative, track alignment designers could try to assess how much the excitation has been attenuated between two successive singular points and thus assess at which point a new singularity may be present without affecting ride comfort. Although such assessment can be made with commercial SW packages which simulate the dynamic behavior of a vehicle considered as a set of rigid bodies interconnected with elastic elements simulating the suspension systems (such as SIMPACK, ADAMS or VAMPIRE), a simplified and user-friendly computation method (based upon the analytical solution of differential equations governing the phenomenon) is made available in this paper to track design engineers, not always used to working with full dynamic models.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.226-232
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• 2000

This paper develops a finite element model for studying the crashworthiness analysis of a mid-size truck. A simulation for a truck frontal crash to a rigid barrier using the model is performed with PAM-CRASH installed in super computer SP2. Full vehicle model is composed of 86467 shell elements, 165 beam elements and 98 bar elements, and 86769 nodes. The model uses four material model such as elastic, elastic-plastic(steel), rigid and elastic-plastic(rubber) material model which are in PAM-CRASH. Frame and suspension system are modeled with 28774 shell elements and 31412 nodes. Cab is modeled with 34680 shell elements and 57 beam elements, and 36254 nodes. Bumper is modeled with 2262 shell elements, and 2508 nodes. Axle, steering shaft, etc are modeled using beam or bar elements. Mounting parts are modeled using rigid bodies. Bodies are interconnected using nodal constrains or joint options. To verify the developed model, frontal crash test with 30mph velocity to a rigid barrier is carried out. In the crash test, vehicle pulse at lower part of b-pillar is measured, and deformed shapes of frame and driver seat area are photographed. Those measured vehicle pulse and photographed pictures are compared those from the simulation to verify the developed finite element model.