Vehicle Dynamics Modeling And Handling Simulation Of Heavy-duty Truck Based On ADAMS

In recent years, heavy-duty trucks as the important vehicles have vigorously developed with efforts to increase national control of overloading and the development of road transport industry. In order to enhance the capacity of independent development and international competitiveness for heavy-duty trucks, "11th Five-Year" National 863 Project has integrated the development of heavy-duty trucks as an important issue, and CAE methods play an important role. As one of original suspension components, leaf springs are widely applicable to heavy-duty trucks in the light of the advantages of both guiding and damping. The development of leaf springs not only has a direct influence on accurately obtaining leaf springs'characteristics parameters, but also makes a key role in analyzing and evaluating heavy-duty trucks performance. Therefore, the research of heavy-duty trucks with leaf springs is very important.Compared with the traditional methods, the research indicates that CAE methods are greatly helpful to improve the accuracy of leaf springs. First of all, a variety of leaf spring models based on CAE methods were analyzed and studied in detail. Based on this, a new equivalent method was deeply studied and the leaf spring equivalent model was constructed. According to the original vehicle data the enterprise provided, model parameters required for modeling the subsystem models of the vehicle in ADAMS/Car were obtained and summarized, then a dynamics model of heavy-duty truck was completed. Finally, based on handling national standards, combined with real vehicle handling test procedures, the handling performance of the vehicle model was simulated and validated. The main contents are described as follows: (1) Research of leaf spring equivalent method and construction of the equivalent modelIn order to solve the heavy workload and more degrees of freedom in leaf spring modeling process, a new equivalent method of leaf spring was put forward. Combined with beam analysis method in Material Mechanics, leaf springs were simplified as freely supported beam of constant section, then symmetrical leaf springs and unsymmetrical leaf springs were theoretically analyzed. Based on the principle that vertical stiffness and maximum stress keep unchanged, conversion formulas of elasticity modulus and thickness of leaf springs were deduced. Combined with actual data the enterprise provided, leaf spring equivalent model was constructed by Beam method, parameters of discrete rigid parts and flexible beam were obtained, and the detailed construction procedure of leaf spring equivalent model was introduced. Constraints and forces were imposed on leaf spring equivalent model, and the model was validated by comparing with vertical stiffness of real leaf springs. (2) Acquisition of dynamics parameters for heavy-duty truckAccording to the original data of heavy-duty truck the enterprise provided, geometry parameters, quality parameters, mechanical characteristics parameters and the like for vehicle subsystems in ADAMS/Car was systematically summarized. Acquisition method of modeling parameters was studied. Quality, moment of inertia and mass center coordinates of vehicle subsystems were obtained. Transmission principle of powertrain subsystem in ADAMS/Car was analyzed, the equivalent method that reflecting drum braking performance on the basis of disc brake template was studied, and the distribution of steering ratio and the acquisition method of power-assist steering characteristics were introduced.(3) Construction of dynamics model for heavy-duty truckThe construction procedure of cab subsystem, frame subsystem, crate subsystem, axle subsystem, leaf spring subsystem, powertrain subsystem, braking subsystem and steering subsystem was described in detail. Combined with modeling parameters obtained, subsystem models were constructed. Applying the leaf spring equivalent model constructed, the dynamics model for heavy-duty truck was constructed. The quality and moment of inertia for the full vehicle model were checked so as to meet the requirements of real vehicle.(4) Handling simulation and validation for heavy-duty truck dynamics modelApplicable to dynamics model for heavy-duty truck completed, based on handling national standards, combined with real vehicle handling test procedures, parameters setting methods for handling simulation conditions in ADAMS/Car were specifically described. Steering wheel angle step input test, steering wheel angle pulse input test, returnability test, steering efforts test, pylon course slalom test, and steady static circular test were simulated to validate the dynamics model for heavy-duty truck by comparing with test curves of real vehicle.By studying the equivalent method of leaf spring, the multi-leaf widely used in heavy-duty trucks can be simplified the less-leaf, which provides a new way for the design and development of leaf springs. It not only reduces heavy workload because of more leaf springs and low efficiency, but also makes a foundation for constructing dynamics model for heavy-duty truck, even analyzing the overall vehicle performance. The detailed construction method of heavy-duty truck dynamics model provides technical support for improving the development of heavy-duty trucks in the enterprise. Engineers can quickly collect data of different subsystems, which improves work efficiency, further makes a basis on optimization of vehicle performance.