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In this paper, the influence of lateral load transfers ( ) on the stability of heavy vehicles is analyzed. The coefficient has been analyzed by several researchers since different lateral load transfer in the vehicle axles, the stability of the vehicle is affected. This coefficient depends on the stiffness of the chassis and the fifth wheel, which is analyzed through a simulation made in the TruckSim®, a software specialized in vehicle dynamics.
International Journal of Mechanical Engineering and Technology (IJMET) Volume 10, Issue 12, December 2019, pp 451-459, Article ID: IJMET_10_12_045 Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJMET&VType=10&IType=12 ISSN Print: 0976-6340 and ISSN Online: 0976-6359 © IAEME Publication STABILITY AND LATERAL LOAD TRANSFER IN HEAVY VEHICLES Gonzalo G Moreno Contreras*, Juan Carlos Serrano, Cesar Peña Cortés Department of Mechanical, Mechatronic and Industrial Engineering, Faculty of Engineering, University of Pamplona, Pamplona, 543050, Colombia * Corresponding Author, Email : gmoren@unipamplona.edu.co ABSTRACT In this paper, the influence of lateral load transfers ( ) on the stability of heavy vehicles is analyzed The coefficient has been analyzed by several researchers since different lateral load transfer in the vehicle axles, the stability of the vehicle is affected This coefficient depends on the stiffness of the chassis and the fifth wheel, which is analyzed through a simulation made in the TruckSim®, a software specialized in vehicle dynamics Keywords: Heavy vehicles, Stability, Lateral Load Transfer, Safety road Cite this Article: Gonzalo G Moreno Contreras, Juan Carlos Serrano, Cesar Peña Cortés, Stability and Lateral Load Transfer in Heavy Vehicles International Journal of Mechanical Engineering and Technology 10(12), 2019, pp 451-459 http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=10&IType=12 INTRODUCTION The stability of heavy vehicles (HVs) has been the focus of research efforts in recent decades A variety of measurements has been defined to parameterize the stability of HVs or rollover limit The static rollover threshold ( ) is one of the most important parameters used to define the stability of vehicles This factor is highly dependent on the location of the vehicle’s center of gravity (CG) and represents the maximum lateral acceleration (expressed in terms of gravity acceleration - ) in a quasi-static situation immediately before one tire loses contact with the ground [1-4] According to the classic vehicle stability analysis (two-dimensional rigid model) when a vehicle is making a turn, the normal load is transferred from a side of the vehicle to the other side of the vehicle until the internal tire on the turn loses contact with the ground, which is known as the lateral load transfer coefficient ( ) [5] But, several researches reported that the factor is a three-dimensional phenomenon that is in turn influenced by different parameters of the vehicle and the road such as the chassis, suspension, tires, fifth-wheel, the banking angle, the longitudinal slope of the road, among other parameters [6-10] Considering these aspects, at the rollover limit Rill [5], Winkler [11], Kamnik [12], and Zhou and Zhang [13] reported that the chassis has a significant torsional compliance, which http://www.iaeme.com/IJMET/index.asp 451 editor@iaeme.com Gonzalo G Moreno Contreras, Juan Carlos Serrano, Cesar Peña Cortés would allow its front and rear parts to roll almost independently; therefore, the coefficient is different for each axle of the vehicle model, as shown in Fig and Eqs and 2: Figure Normal tire forces on the axles of the vehicle (1) (2) where is the lateral load transfer in the front axle of the vehicle, is the lateral load transfer in the rear axle of the vehicle, and is the normal tire force on the axle In this regard, at the rollover limit Kamnik [12] reported that the coefficient is different for the front and the rear axles of the trailer, therefore they detected that when an articulated vehicle makes a spiral maneuver, the coefficient on the front axle is approximately 70 % of the coefficient on the rear axle Taking into account these aspects, Moreno [10] reported that the three-dimensional factor is influenced by different parameters of the vehicle and the road, and the coefficient on the axles of the vehicle, as shown in Eq (3) ( ( ( ( ) ) ) ) (3) where is the three-dimensional static rollover threshold for a trailer model with trailer/trailer angle ( ), bank angle ( ) and grade angle ( ), is the instantaneous lateral distance between the zero-reference frame and the center of gravity, is the bank angle in percentage, is the instantaneous CG height, is the front track width of the trailer model, is the weight of the trailer, is the normal force on the front inner tire, is the normal force on the rear outer tire, is a system variable ( ( ( ) ), is the distance between the fifth-wheel and the front axle, and is the front axle width For the validation of these aspects, a model of a semi-trailer was analyzed using the software TruckSim® [14], which is specialized software of mechanical simulation used in a wide variety of driving simulations This software allows evaluating and analyzing the performance of a vehicle when making certain maneuvers on a selected road The paper is organized as follows: in Section two studies of lateral load transfer made with TruckSim® [14] are analyzed, and the conclusions are drawn in Section http://www.iaeme.com/IJMET/index.asp 452 editor@iaeme.com Stability and Lateral Load Transfer in Heavy Vehicles CASE STUDY In this analysis, a three-dimensional vehicle model of a semi-trailer is used, the model is composed by the truck with one axle on the front and one axle on the rear, and a trailer with three axles, as shown in Fig Figure Semi-trailer – TruckSim® [14] Table and Fig show the parameters of the heavy vehicle and the road used in this analysis Table Parameters of the trailer Parameter Vehicle weightInitial vehicle track width ( ) Vertical spring stiffness per axle ( ) Number of axles at the front (trailer) (4 tires per axle) Number of axles at the rear (trailer) (4 tires per axle) Vertical stiffness per tire ( ) CG height Wheelbase of the trailer ( ) Distance between the front axle and vehicle CG ( ) Radius of the circular road ( ) Bank angle ( ) Speed of the test ( ) Value 364.147 1.815 2500 980 2.1 4.26 60 10 50:1 to 60 Units kN m kN.m-1 kN.m-1 m m m m % km/h Figure Circular road – TruckSim® [14] http://www.iaeme.com/IJMET/index.asp 453 editor@iaeme.com Gonzalo G Moreno Contreras, Juan Carlos Serrano, Cesar Peña Cortés For the factor calculation, the steady-state circular tests [15] were conducted on two path references: Test 1: 60 m radius circle with 10 % of bank angle ( ), and Test 2: 100 m radius circle (flat paved surface) To calculate the factor, the tests were made at constant tangential speed ( ), therefore a constant inertial force was applied until the lateral load transfer in the rear axles of the trailer become complete ( , , and axles) 2.1 Test Using the 60 m radius circle with 10 % of bank angle ( ), the first test was made with a vehicle speed of 50 km/h, and showed that the lateral load transfer ( ) in the axle of the semi-trailer was not complete Figure shows the normal forces on tires of the axle Figure Normal force on tires of axle - = 50 km/h The second test was made with a vehicle speed of 55 km/h, and showed that the coefficient was completed in the axle, but it was not in the and axles Figures to show the normal forces on tires of , , and the axles Figure Normal force on tires of http://www.iaeme.com/IJMET/index.asp 454 axle - = 55 km/h editor@iaeme.com Stability and Lateral Load Transfer in Heavy Vehicles Figure Normal force on tires of axle - = 55 km/h Figure Normal force on tires of axle - = 55 km/h The third test was made with a vehicle speed of 58 km/h, and showed that the coefficient in the , , and axles were complete Figures to 10 show the normal forces on tires of , , and the axles Figure Normal force on tires of http://www.iaeme.com/IJMET/index.asp 455 axle - = 58 km/h editor@iaeme.com Gonzalo G Moreno Contreras, Juan Carlos Serrano, Cesar Peña Cortés Figure Normal force on tires of axle - = 58 km/h Figure 10 Normal force on tires of axle - = 58 km/h In this specific case, Fig 11 shows that the coefficient in the axle was not complete This fact is important since it corroborated the proposed theory by Rill [5], Winkler [11], Kamnik [12], and Zhou and Zhang [13] Figure 11 Normal force on tires of Making an analysis of the normal forces on the front axle is about 57 % (Eq (1)) http://www.iaeme.com/IJMET/index.asp 456 axle - = 58 km/h axle, the lateral load transfer on the editor@iaeme.com Stability and Lateral Load Transfer in Heavy Vehicles Taking into account that the factor can be expressed in terms of the lateral acceleration and the gravity acceleration – (Eq (3)), rearranging the equation (Eq (4)) and replacing the speed of the vehicle ( ) and the radius of curvature ( ), the factor for the TruckSim model (Test 1) is 0.4409 (4) 2.2 Test Following the same methodology of the previous example, and using the 100 m radius circle (flat paved surface), the test made with a vehicle speed of 64 km/h shows that the lateral load transfer ( ) in the , , and the axles were complete, but in the axle was not Figures 12 to 15 show the normal forces on tires of the , , , and the axles Figure 12 Normal force on tires of axle - = 64 km/h Figure 13 Normal force on tires of axle - = 64 km/h http://www.iaeme.com/IJMET/index.asp 457 editor@iaeme.com Gonzalo G Moreno Contreras, Juan Carlos Serrano, Cesar Peña Cortés Figure 14 Normal force on tires of axle - = 64 km/h Figure 15 Normal force on tires of axle - = 64 km/h Making an analysis of the normal forces on the front axle is about 56% (Eq (1)), of the Eq (4) the 2) is 0.3221 axle, the lateral load transfer on the factor for the TruckSim model (Test CONCLUSIONS In the present study, it is evident that the last trailer of a heavy vehicle is the critical unit Additionally, it is evident that in the heavy vehicles the stiffness of the chassis and the fifth wheel allow that the lateral load transfer in the axles to be different, which consequently affects the stability of the vehicle In this sense, it can be concluded that the lateral transfer of load on the front axle depends on the flexibility of the chassis and the fifth wheel, and can vary between 56% according to the present research and 70% according to Kamnik [12] This fact is important since it guides for researchers and mechanical designers to concentrate their research on these devices It can also be observed that the banking angle of the road increases the stability factor, which in turn decreases the level of risk due to rollover accidents of heavy vehicles REFERENCES [1] C Winkler, “Experimental Determination of the Rollover Threshold of Four TractorSemitrailer Combination Vehicles” UMTRI Research Review, The University of Michigan Transportation Research Institute 1987 http://www.iaeme.com/IJMET/index.asp 458 editor@iaeme.com Stability and Lateral Load Transfer in Heavy Vehicles [2] T D Gillespie, “Fundamentals of Vehicle Dynamics” SAE International, 7th ed., Warrendale, PA, ISBN 1560911999 1992- [3] A Hac, “Rollover Stability Index Including Effects of Suspension Design” SAE International - SAE 2002 World Congress, Detroit, March 4–7 2002 [4] G Moreno, E Flórez, C Pa, “Stability study of heavy vehicles” Revista Colombiana de Tecnologías de Avanzada ISSN: 1692-7257 – Universidad de Pamplona v.2 No 30 p 2017 [5] DOI: https://doi.org/10.24054/16927257.v30.n30.2017.2756 [6] G Rill, “Road Vehicle Dynamics: Fundamentals and Modeling” CRC Press, ISBN 9781-4398-3898-3 2011 [7] T Chang, “Effect of Vehicles Suspension on Highway Horizontal Curve Design” Journal of Transportation Engineering, Vol 127, No 1, pp 89–91 2001 [8] NYSDOT, D Q A B “Recommendations for AASHTO Super-Elevation Design” Design Quality Assurance Bureau, NYSDOT, Washington, D.C 2003 [9] J Woodrooffe, P Sweatman, A Arbor, D Middleton, R James, J R Billing, “National Cooperative Highway Research Program – NCHRP Report 671” Review of Canadian Experience with the Regulation of Large Commercial Motor Vehicles Ed National Academy of Sciences, Washington, D.C., ISBN 978-0-309-15518-2 2010 [10] G Moreno, L Nicolazzi, R S Vieira, D Martins “Suspension and tyres: the stability of heavy vehicles”, International Journal of Heavy Vehicle Systems, v 24 (No 4) pp 305326 2017 doi:10.1504/IJHVS.2017.10007635 [11] G Moreno, L Nicolazzi, R S Vieira, D Martins, “Stability of Long Combination Vehicles”, International Journal of Heavy Vehicle Systems, v 25 (No 1) pp 113-131 2018 DOI: 10.1504/IJHVS.2018.10011111 [12] C Winkler, “Rollover of Heavy Commercial Vehicles” UMTRI Research Review, The University of Michigan Transportation Research Institute, Vol 31, No 4, pp 1–20 2000 [13] R Kamnik, F Boettiger, H Hunt, “Roll dynamics and lateral load transfer estimation in articulated heavy freight vehicles” Proceedings of the Institution of Mechanical Engineers: Journal Automobile Engineering 2003 [14] S Zhou, S Zhang, “Assessing the effect of chassis torsional stiffness on tractor semitrailer rollover” Appl Math, v 7, n 2, p 633–637, 2013 [15] TruckSim® Mechanicla Simulation Virtual CAE, São Caetano Sul-SP, Brazil 2017 [16] ISO-14792 “Heavy commercial vehicles and buses – Steady-state circular tests” International Organization for Starndardization Geneva, Switzerland 2011 http://www.iaeme.com/IJMET/index.asp 459 editor@iaeme.com ... lateral load transfer on the editor@iaeme.com Stability and Lateral Load Transfer in Heavy Vehicles Taking into account that the factor can be expressed in terms of the lateral acceleration and. .. and the conclusions are drawn in Section http://www.iaeme.com/IJMET/index.asp 452 editor@iaeme.com Stability and Lateral Load Transfer in Heavy Vehicles CASE STUDY In this analysis, a three-dimensional... (2) where is the lateral load transfer in the front axle of the vehicle, is the lateral load transfer in the rear axle of the vehicle, and is the normal tire force on the axle In this regard,