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Technical Paper

Ride Quality Evaluation of a Bus Used in a City Public Transportation Service

2009-10-06
2009-01-2829
Ride quality is an important concern for users of road vehicles. Typically, vehicle comfort is qualified in a subjective manner to describe the users' perception, but mechanical vibration is utilized as a quantitative parameter. This work shows some results of mid-size bus' ride quality evaluation used in a typical city route for public transportation. The bus was instrumented and vertical acceleration was measured at the floor and on two seats, one at the middle of the bus and other in the most rear. Acceleration data was used to evaluate the vibration according to the ISO Standard 2631-1, considering only vertical direction for seated and standing passenger positions. The results showed that vibration levels in this bus can be high enough to negatively affect the passengers ride and comfort, increasing the risk of affecting human health.
Technical Paper

Vehicle's Dynamic Behavior Simulation as a Tool for Evaluating Geometrical Changes in Roads

2009-10-06
2009-01-2921
The relationship between road geometric design and vehicles moving along it should be in a harmonic way in order to reduce the risk of accident occurrence. As a safety issue, the accident black spot analysis can lead to improvements in traffic signaling and/or to changes to the conflictive roadway section. This paper shows the applicability of the vehicle's dynamic behavior simulation as a complementary tool for evaluating geometrical modifications of roadway sections. A simplified example is described using a typical heavy vehicle, which follows a roadway section under two scenarios, one with an unchanged path and other with some modifications in order to increase safety. Results showed that vehicle's dynamic simulation can offer a detailed perspective of the vehicle's behavior to identify the effectiveness of the proposed changes before they are applied in the practice.
Technical Paper

Effect of Road Irregularities in the Dynamic Behavior of a Heavy Vehicle

2014-09-30
2014-01-2302
Most of road accidents are caused by human factors. However, there are other factors involved in the occurrence of vehicular crashes, such as the physical condition of the road and vehicle itself. In order to increase road safety is essential to fully understand the interaction of those factors on vehicle's dynamic behavior, especially on heavy vehicles due to their greater mass, dimensions and potential damage that can provoke. This document presents information about the effect of some road surface irregularities on dynamic behavior of a three-axle heavy vehicle, based on a road with an ideally good condition (baseline). To do that, a numerical simulation model that includes both vehicle and road is used. It is able, at some degree, to simulate surface road conditions, such as potholes, friction coefficients at height levels of adjacent lanes.
Technical Paper

Experimental Evaluation of Baffles Geometry and Their Configuration in a Partially Filled Scaled Elliptical Tank

2005-11-01
2005-01-3581
The sloshing behavior of a liquid cargo is an issue that needs to be taken into account when evaluating the dynamic performance of tankers. In general, hazardous liquid materials require a free volume into the tank to absorb thermal expansion changes; therefore, tank has to be filled partially. Under that condition, sloshing is produced at the liquid surface which interacts with container walls generating forces that affect the vehicle’s behavior. In this work, results obtained from experimental tests carried out in a scaled elliptical-transversal-section tank for different filling levels, baffles’ geometries, and baffles’ arrays are presented. Tank is instrumented so that longitudinal forces due to sloshing can be measured when tank is suddenly stopped. The analysis of the results allows identifying the best baffle configuration to be applied in order to attenuate the longitudinal sloshing generated when the vehicle is moving on highways.
Technical Paper

Experimental Assessment of Baffles and Their Effect on the Longitudinal Sloshing Force in a Scaled Elliptical Tank

2005-11-01
2005-01-3577
The dynamic behavior of heavy vehicles moving on roads depends on load magnitude and its distribution, and a special concern may be directed to tankers. Liquid cargo at partial filled levels exhibits sloshing during vehicle longitudinal displacement, generating some forces which might alter vehicle's directional response and traction control. To attenuate the sloshing dynamic effect, transversal plates (baffles) are placed inside the container but increasing the structural container mass, arising vehicle's mass center and decreasing vehicle's useful load capacity. An experimental study on the effects of fill level and number of baffles on the sloshing attenuation is presented. For doing so, an instrumented scaled experimental tank of elliptical transversal section is used with water as liquid cargo, and longitudinal sloshing force is measured.
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