Performance Of Heavy Vehicles Research Articles

Methodology for analysis of heavy vehicle trafficability in deformable soils

Heavy vehicles have a wide range of applicability in our daily lives: buses, commercial trucks, and even defense vehicles are important to transport people and goods and provide protection. However, this field is not widely covered by the scientific literature in many aspects regarding their dynamic behavior, as most works tend to focus on personal vehicles (cars). This article elaborates on heavy vehicle trafficability on many different terrains or their capacity to operate in those soils, using an analysis based on the Wong–Reece method with deformable soil–rigid tire approximation. It also develops a dynamic model, using MATLAB SimulinkTM software, to show how heavy vehicle performance both kinematically and dynamically is influenced by the soil. To test both models, a numerical case study was conducted, using common parameters for wheeled heavy vehicles as inputs for the dynamic. Results indicate that heavy vehicles are often incapable of operating in highly deformable soils, sinking deeply into the ground; the soil also affects heavily the vehicle maximum velocity and gear from almost [Formula: see text] km/h in Greenville Loam soil to less than [Formula: see text] km/h in Upland Sandy Loam soil.

Structural Analysis and Prototyping of Truck Under-run Protection Device

In the present research work we are focusing on side under-run protection devices protect road users such as pedestrians and cyclists from slipping sideways under the wheels of trucks and trailers, and can also improve the aerodynamic performance of heavy vehicles. The basic objective is to improve the safety of the car and the occupants by designing the Rear Under-run Protection Device (RUPD) and car bumper. The choice of material and the structural design are major factors for impact energy absorption during a crash. This study concentrates on component functions, geometry, behavior of material and other parameters that influence the compatibility of the car bumper and rear under run protection device. The analysis was carried out using Finite Elements software SOLIDWORKS. This analysis is a partial work of a major project wherein the RUPD will be subjected to static testing with variable load distributions at different locations on RUPD. After the analysis, the pattern of the part is obtained using Rapid prototyping machine. This can be used for Machining/casting of the original part. Rapid Prototyping (RPT) can be defined as a group of techniques used to quickly fabricate a scale model of a part or assembly using three-dimensional computer aided design (CAD) data.

Practical Model for Real Structure and Performance of Heavy Vehicles

In this paper, a new practical model for real heavy vehicle structure is developed to investigate dynamic responses under steering/acceleration or braking maneuvers. The generalized six DoFs (degrees-of-freedom) nonlinear vehicle model M1 including longitudinal, lateral, yaw, vertical, roll and pitch dynamics is validated using the measured data reported in different studies. This model takes the CG (center of gravity) of sprung mass, unsprung mass and total vehicle mass into account. Based on this model, the effects of the inertia parameters on the vehicle dynamic responses are investigated for more comprehensive assessments of the model structure. Another nonlinear vehicle model M2 derived from M1 which assumes that the vehicle has a single CG as reported in literature is also developed. The dynamic responses of the vehicle model M1 are compared with those of the model M2 to demonstrate the performance potential of the proposed nonlinear model. The results of dynamic responses with the nonlinear vehicle model M1 suggest that the model could offer considerable potential in realizing enhanced ride and handling performance, as well as improved roll and pitch properties in a flexible manner.

Directional stability of tractor-semitrailers versus truck-full trailers

Recently the road transport in Egypt has been subjected to an intensive debate concerning the heavy vehicle’s safety predominantly due to the arising rates of their fatal accidents. Numerous aspects are involved such as the driver, the infrastructure of the national roads and the wide diversity of heavy vehicle configurations. This controversy has been given up recommending the deterrence of the truck full-trailer and stimulating the dependency of heavy transportation on tractor semi-trailer combinations. This paper presents a technical comparison of the dynamic performance of both combinations during different standard manoeuvres and loading scenarios. Furthermore, the international standards to measure and assess the heavy vehicle performance are outlined. The paper exemplifies a scientific algorithm to examine the heavy vehicle design against the requirements of the international standards by means of computer simulation modelling. The directional stability of such combinations has been numerically simulated using the validated yaw/roll model. The finding of the paper complies with the governmental trend to stop the use of full-trailers due to their poor directional stability.

Improving the Safety and Road Wear Performance of Heavy Vehicles in South Africa Using a Performance-Based Standards Approach

As a result of successful initiatives in Australia, New Zealand and Canada, the introduction of a Smart Truck or performance-based standards (PBS) approach in the heavy vehicle sector in South Africa was identified by the CSIR as a research area warranting funding because of the potential benefits in terms of transport efficiency, road/vehicle safety and the protection of road infrastructure. The PBS approach involves setting standards to specify the performance required from the operation of a vehicle on a network rather than prescribing how the specified level of performance is to be achieved. A need was identified to design, manufacture and operate a number of PBS demonstration projects in South Africa in order to gain practical experience in the PBS approach and to quantify and evaluate potential benefits. The Smart Truck demonstration projects have been designed and manufactured to comply with the safety standards of the Australian PBS system. These include directional and non-directional manoeuvres such as acceleration capability, slow speed swept path, static rollover threshold and rearward amplification. In order to evaluate the impact of the PBS vehicles on pavements, the South African Mechanistic-Empirical Design and Analysis Methodology was used to calculate the road wear characteristics of various baseline and PBS vehicle combinations. In most cases, the PBS vehicles were found to be significantly more road-friendly per ton of payload than the corresponding baseline vehicles. Modifications for reducing road wear were identified such as load redistribution in order to reduce the load on the steering axle, replacing wide-based single tyres with dual tyres and, where appropriate, replacing a single steer axle with a twin steer axle unit. The paper describes the results of road wear analyses of five PBS vehicles and the corresponding baseline vehicles.

Truck Equivalence Factors for Divided, Multilane Highways in Brazil

Trucks represent a high proportion of highway traffic in Brazil and are longer, heavier and have smaller engines than the trucks used in the development of HCM2000. Some users try to account for these differences by combining HCM2000 procedures with truck PCEs from prior versions. Generally, both this crude adaptation and use of the HCM2000 produce unsatisfactory results. This study focuses on estimating truck PCEs for divided multilane highways in Brazil. Truck characteristics (power, weight, etc.) were observed at several weigh stations on multilane highways. A sample of these trucks was tracked along road segments with multiple grades, using GPS units to collect vehicle performance data. Data on traffic composition and truck fleet mix were obtained from 17 toll plazas and a four-class truck classification scheme was created. Afterwards, CORSIM's heavy vehicle performance and car-following models were recalibrated using a genetic algorithm with truck performance data and traffic data collected on a divided multilane highway. The recalibrated CORSIM was then used to derive new PCEs using density as the measure of effectiveness, for scenarios in which grade magnitudes varied between 0% and 8%, with grade lengths between 0.5 and 2.0km and truck percents ranging from 0% to 50%. Equivalence factors ranged from 1.0 to 10.9 pc. PCE tables for specific grades and for extended segments were created to replace those used in the HCM2000. The results point to the need for development of a Brazilian HCM.

Logging Truck Vehicle Performance Prediction for Efficient Resource Transportation System Planning: Computer Modelling Approach

Transportation systems, characterized by extremely heavy logging trucks running on low standard roads, are critical to Canadian woodlands operations. Because predicting logging vehicle performance is essential to planning efficient forest road transportation systems, a Heavy Vehicle Performance Model (HVPM) was developed which takes into account the characteristics of forest road transportation system components in order to predict vehicle performance parameters such as speed and fuel consumption. Two independent field test data sets were used to verify the HVPM. Verification results showed that the average speed predicted by the HVPM was as much as 17 percent lower than the average observed speed, while predicted fuel consumption was as much as 20 percent higher than the field observations. Implementation of the HVPM is presented by showing how it is used to solve three forest road transportation problems: a practical application is given in a case study comparing the performance of two specified trucks on two proposed road alignments, the selection of truck components using vehicle performance predictions from the HVPM is illustrated, and the HVPM is used to predict truck performance on different classes of roads.

The Use of the Pendulum in Rubber Testing

Abstract During the past few years considerable interest has been shown in the use of pendulum methods for the study of resilience properties of rubber compounds. We feel therefore that an account of the development and use of the pendulum method in the Dunlop Rubber Co.'s laboratories will prove of general use. In this country the period from 1918 witnessed a rapid extension in road transport, carried at that time almost exclusively on solid tires. With this development the performance of heavy vehicles improved considerably and tires were operated under the increasingly severe conditions, both with respect to speed and load. It is well known, that if a solid tire is operated under sufficiently severe conditions it is no longer able to dissipate the heat developed within it, and its temperature rises until eventually an explosion or the familiar “blow-out” occurs. This phenomenon, of course, results from the fact that rubber is not perfectly elastic. When transmitting energy it does not release all the energy supplied to it. Some of the energy is always absorbed and appears in the rubber in the form of heat; the faster the energy is supplied, the greater is the increase in temperature.