Dynamic Load Coefficient of Tyre Forces from Truck Axles

Abstract

This study aims to predict the Dynamic Load Coefficient @LC) of tyre forces from truck axles. Dynamic Load Coefficient is frequently used to characterise the dynamic loads generated by axles. It is a simple measurement of the dynamic variation magnitude of the axle load, for a specific combination of road roughness and speed. Under normal operating conditions, the DLC's value is typically in the range of 0.05-0.3, and close to zero when the truck's wheels are moving over a perfectly smooth road. To achieve the objectives of this study, which is to determine the DLC's value for seven different types of axles, a simple validated quarter-truck model was excited by a random road surface profile, in order to simulate a vehicle-road interaction. Points are equally spaced along the simulated road to generate dynamic loadings over a broad range of truck speeds. Multiple trucks gross-weight conditions were used to present realistic traffic behaviour. The results showed that irregular road profiles, exciting the vehicle as it travelled, caused continually changing tyre forces. Also, dynamic loading was seen to be fundamentally influenced by the type of suspension (i.e., air and steel), loading condition, and vehicle speed. For example, the DLC value of the tyre forces of the quarter-truck fitted with a steel suspension was found to be more than twice that of the truck fitted with an air suspension. Tyre forces of the one-third laden truck were more aggressive than any other loading condition, due to the uncertain body-bounce generated by the tmck, which was strongly dependent on surface irregularities. At low speed, the DLC was greatly decreased if the load was increased. Furthermore, DLC value was always lower for trucks with air suspension over steel suspension, for the same load and vehicle speed. However, air suspension efficiency was clearly better for higher axle loads.

Predicting Vehicle Loads Variation with Road Profiles and Vehicle Characteristic

“…Even though it is much more simple than the half ore whole truck model that excluding the detailed suspension non-linearity and complexities of body mass motions that are typical for heavy vehicles, the frequency content of the dynamic loads is sufficiently realistic for the purpose of the study to uncover pavement response. Moreover, it was efficiently identified for use with personal computers to predict pavement loading [8][9][10][11][12][13].…”

Influence of semi-trailer truck operating conditions on road surface friendliness

“…Subsequently, other criteria were established in terms of AASHO, such as EC criteria in 1992 and Australia criteria in 1999 [9]. In this study, in order to analyze the influence of semi-trailer truck operating conditions on road surface, dynamic load coefficient (DLC) is chosen as objective function which is defined by a ratio of the root mean square of the vertical dynamic tire force over static load [7,8], as follows:…”

“…The DLC's value is in range of 0.05 to 0.3 under normal operating conditions. It may reach to the zero when the wheels are moving on a special smooth road or increase up to 0.4 when the tires of the axles spends a significant proportion of their time disconnecting the road surface [8].…”

Comparing the performance of suspension system of semi-trailer truck with two air suspension systems

“…In order to evaluate the dynamic wheel load performance of vehicle suspensions acting on the road surface, dynamic load coefficient ( ) is chosen as objective function which is defined by a ratio of the root mean square of the vertical dynamic wheel force over static load [10,11]:…”

“…It may reach to the zero when the wheels is moving on a special smooth road or increase up to 0.4 when the wheels of the axles spends a significant proportion of their time disconnecting the road surface [10][11][12].…”