Search Results (140)

Rear-end collisions represent a major concern in automotive safety, particularly due to the risk of whiplash injuries among vehicle occupants. The accurate simulation of occupant kinematics during such impacts is critical for the development of advanced safety systems. This paper presents an enhanced multibody simulation model specifically designed for rear-end crash scenarios, incorporating integrated active headrest mechanisms and sensor-based activation logic. The model combines detailed representations of vehicle structures, suspension systems, restraint systems, and occupant biomechanics, allowing for the precise prediction of crash dynamics and occupant responses. The system was developed using Simscape Multibody, with CAD-derived components interconnected through physical joints and validated using controlled experimental crash tests. Special attention was given to modelling contact forces, suspension behaviour, and actuator response times for the active headrest system. The model achieved a root mean square error (RMSE) of 4.19 m/s² and a mean absolute percentage error (MAPE) of 0.71% when comparing head acceleration in frontal collision tests, confirming its high accuracy. Validation results demonstrate that the model accurately reproduces occupant kinematics and head acceleration profiles, confirming its reliability and effectiveness as a predictive tool. This research highlights the critical role of integrated sensor-actuator systems in improving occupant safety and provides a flexible platform for future studies on intelligent vehicle safety technologies. Full article

This paper proposes a multibody model calibration method for vehicle misuse testing. During misuse tests conducted at high driving speeds, the vehicle’s responses can become highly nonlinear due to certain key model parameters. Direct calibration using a complex multibody model is time-consuming and unstable, as it may fail or diverge due to improper settings of the model parameters. Therefore, a modified quarter-vehicle model is proposed for the analytical calibration of these nonlinear parameters by introducing an additional constraint on the sprung mass to recover the restoring force. The new model features only two degrees of freedom and incorporates key nonlinear parameters, including the suspension’s stiffness and the wheel’s center mass. It is suitable for misuse tests involving tire detachment at high driving speeds. The detailed analytical calibration procedure for the nonlinear parameters is deduced and subsequently validated through numerical simulation using these parameters. When the parameters are sufficiently close to the actual ones or linearly related to the responses, an optimization method such as the least squares method can be applied, along with simulations using complex models in commercial software. Full article

Evaluating noise, vibration, and harshness (NVH) performance is crucial in vehicle development. However, NVH evaluation is often subjective and challenging to achieve through numerical simulation, and typically prototypes are required. Dynamic driving simulators are emerging as a viable solution for assessing NVH performance in the early development phase before physical prototypes are available. However, most current simulators can reproduce vibrations only in a single direction or within a limited frequency range. This paper presents a comprehensive design optimization approach to enhance the dynamic response of a full-spectrum driving simulator, addressing these limitations. Specifically, in complex driving simulators, vibration crosstalk is a critical and common issue, which usually leads to an inaccurate dynamic response of the system, compromising the realism of the driving experience. Vibration crosstalk manifests as undesired vibration components in directions other than the main excitation direction due to structural coupling. To limit the system crosstalk, a flexible multibody dynamics model of the driving simulator has been developed, validated, and employed for a global sensitivity analysis. From this analysis, it turns out that the bushings located below the seat play a crucial role in the crosstalk characteristics of the system and can be effectively optimized to obtain the desired performances. Bushings’ stiffness and locations have been used as design variables in a multiobjective optimization with the aims of increasing the direct transmissibility of the actuators’ excitation and, at the same time, reducing the crosstalk contributions. A surrogate model approach is employed for reducing the computational cost of the process. The results show substantial crosstalk reduction, up to 57%. The proposed method can be effectively applied to improve the dynamic response of driving simulators allowing for their extensive use in the assessment of vehicles’ NVH performances. Full article

Especially in real-world circumstances with uneven road surfaces and impulsive shocks, nonlinear dynamic effects in vehicle systems can greatly skew biometric data utilized to track passenger and driver physiological states. By creating a thorough multibody human–seat–chassis model, this work tackles the effect of vehicle-induced vibrations on the accuracy and dependability of biometric measures. The model includes external excitation from road-induced inputs, nonlinear damping between structural linkages, and vertical and angular degrees of freedom in the head–neck system. Motion equations are derived using a second-order Lagrangian method; simulations are run using representative values of a typical car and human body segments. Results show that higher vehicle speed generates more vibrational energy input, which especially in the head and torso enhances vertical and angular accelerations. Modal studies, on the other hand, show that while resonant frequencies stay constant, speed causes a considerable rise in amplitude and frequency dispersion. At speeds ≥ 50 km/h, RMS and VDV values exceed ISO 2631 comfort standards in the body and head. The results highlight the need to include vibration-optimized suspension systems and ergonomic design approaches to safeguard sensitive body areas and preserve biometric data integrity. This study helps to increase comfort and safety in both traditional and autonomous car uses. Full article

A reduction of forces acting between the railway track and the vehicle is one of the key issues in the design of modern rolling stock. Because the capabilities of reducing wheel–rail contact forces in track curves by conventional methods are encountered at their limits, innovative approaches in the design of vehicle suspension and wheelset guidance occur. Among them, an active wheelset steering appears to be very promising. However, an active wheelset steering system is rather complicated and expensive and raises many safety issues. Therefore, a passive hydraulic system that links longitudinal motions of axle boxes is proposed. The system is relatively simple and, compared to the active wheelset steering, does not need any energy supply or sensor system for the detection of a track shape. Two arrangements of the hydraulic system had been proposed and implemented in a simulation model. The simulation model is based on a cosimulation of two separate models, a multibody model of an electric locomotive, and a model of the hydraulic system. The goal of this study is to evaluate the contribution of the hydraulic system to the natural radial alignment of wheelsets in curves and thus to reduce the wear of wheels and to determine the parameters of the hydraulic system to maximize the wear reduction benefits while minimizing a decrease in critical speed. Simulations of a vehicle running in various scenarios, including a run in a real track section of a length of 20 km, have been performed. As a criterion for the wear of wheels and rails, a T-gamma wear number was used, from which a sum of frictional work in wheel–rail contacts was calculated. The results of the simulations and the comparison of hydraulic axle box connection systems and a standard locomotive are presented and discussed in the paper. The results obtained confirmed a significant potential benefit of the proposed hydraulic system in reducing wheel wear on curved tracks. Full article

The current global context demands the development of new solutions that prioritize energy efficiency, time optimization, safety, and sustainability. Urban transportation is one of the sectors undergoing significant transformation. Pursuing new urban transportation solutions has become increasingly intense, involving research institutions and companies. Considering this context, this study focused on the optimization procedures for designing a new vehicle capable of vertical take-off for urban air mobility applications. This paper reports on the optimization process of a thruster deployment mechanism using statistical techniques. In particular, the authors tested the use of Design of Experiments (DOE) techniques for the optimal design of a structural component of a new vehicle for urban mobility purposes under development at the Applied Mechanics laboratory of the Department of Industrial Engineering of the University of Salerno. For this reason, it was decided that a parametric multibody model would be developed in the Simscape Multibody environment for structural optimization using designed experiment plans to “guide” the designer in the analysis phase and search for an optimal configuration using a minimum number of configurations. Finally, employing FEM analysis, the chosen configuration was validated. This study allowed us to test the use of DOE techniques to design new systems. It allowed us to evaluate different configurations, the static and dynamic behavior, the constraining reactions present in the joints, and the active forces and torques of the actuators, highlighting the correlation between factors that can guide the designer in identifying optimal solutions. Full article

Based on the Newton–Euler method, a multi-body coupling dynamics model of the separation process of underwater vehicles is established. The conditions of contact and detachment between the sub-vehicle and each group of elastic gaskets are analyzed in detail, and the elastic gasket constraint model is established to simulate the elastic contact and detachment process. Based on the Computational Fluid Dynamics (CFD) method, the hydrodynamic data of vehicles under different cases is calculated. In this context, a relatively accurate hydrodynamic database is established, where the hydrodynamic of the Unmanned Underwater Vehicle (UUV) is obtained through fitting, while those of the sub-vehicles are calculated using online interpolation. These provide conditions for realizing Fluid–Structure Interaction (FSI) calculation. Utilizing the FSI simulation method in the multi-body separation process, the separation dynamics of the multi-vehicle under the influence of elastic constraint parameters are analyzed. The simulation results show that the pitching attitude angles of the UUV and sub-vehicle in the separation process are negatively correlated with the change of elastic constraint stiffness, and the load is positively correlated with it, which are in opposite optimization directions. When the total stiffness of the elastic gaskets remains constant, changes in the number of elastic gaskets have a minimal impact on the UUV and sub-vehicle motion state during separation, but significantly affects the load fluctuations on the sub-vehicle, leading to structural vibration issues. The analysis method established in this paper is capable of quickly assessing the safety of underwater vehicle separation for different elastic gasket schemes, thereby facilitating the optimization of parameters. Full article

This study investigated the impact coefficient of a large-span steel truss arch railroad bridge under moving train loads, with the Nanning Three Banks Yongjiang Special Bridge serving as the case study. Field tests were conducted to measure the bridge’s self-vibration characteristics, dynamic deflection, and strain. A coupled vehicle–bridge vibration model was developed using the finite element software ABAQUS 2022 for the bridge and multi-body dynamics software SIMPACK 2022 for the CRH2 train. The two models were integrated to simulate the dynamic interaction between the train and bridge under different speeds and single-/double-track operations. The results demonstrate that the joint simulation of SIMPACK and ABAQUS was an effective method for the vehicle–bridge coupled vibration analysis. The key findings include the following: the deflection and stress impact coefficients increased with the train speed, where the main span exhibited larger deflection coefficients than the side span. The stress impact coefficients varied significantly across different bridge components, where the lower chord of the side span and the ties of the main span showed the highest values. While there was no substantial difference in the deflection impact coefficients between the single- and double-track operations, the stress impact coefficients showed deviations, particularly in the side span’s lower chord and ties, highlighting their sensitivity to vehicle-induced deflection. This study concluded that the bridge’s deflection impact coefficient met design specifications, but the stress impact coefficient exceeded the specified values, suggesting that stress amplification should be carefully considered in the design of similar bridges to ensure operational safety. Full article

The deep-sea landing vehicle (DSLV) swarm exploration system is a novel platform for the detection of marine mineral resources. A high-precision cooperative localization system with Ultra-Short Baseline (USBL), Doppler Velocity Log (DVL), and electronic compass (EC) plays a vital role in the DSLV swarm exploration system. However, DVL measurements can be seriously interrupted due to the complex operational underwater environment, leading to unstable localization performance. The accuracy of the cooperative localization system could be further degraded by the persistent rubber track slippage during the vehicle’s movement over the soft seabed. In this study, a data-driven cooperative localization algorithm with a velocity prediction model is proposed to improve the positioning accuracy of DSLV under track slippage. First, a velocity prediction model for DVL measurements is constructed using multi-output least squares support vector regression (MLSSVR), and a genetic algorithm (GA) is further employed to optimize the model’s hyperparameters in order to enhance the robustness of the framework. Furthermore, the outputs of MLSSVR are fed into a DSLV position estimation framework based on the Unscented Kalman Filter (UKF) to improve localization accuracy in the presence of DVL failures. To validate the proposed method, the RecurDyn multibody dynamics simulation platform is applied for data synthesis, accounting for both the impact of the soft seabed and real-world motion simulation. The experimental results indicate that during DVL failure, the proposed algorithm can effectively compensate for the cooperative localization errors caused by track slippage, thereby significantly improving the accuracy and reliability of the DSLV cooperative localization system. Full article

To address the vehicle-bridge coupling vibration issue of the Qingyuan Maglev Tourist Line, it is necessary to establish a maglev vehicle–bridge coupling dynamics simulation model that reflects the actual line conditions. Based on the vehicle and bridge structural parameters of the Qingyuan Maglev Tourist Line, this paper utilizes multi-body dynamics simulation software to create a medium–low-speed maglev vehicle dynamics model, and employs finite element software to construct a bridge model. Using the modal reduction method, the bridge finite element model is imported into the vehicle dynamics model through a rigid–flex coupling interface, establishing a medium–low-speed maglev vehicle suspension system–bridge coupling dynamics model. The accuracy of the established coupling simulation model was verified by comparing the simulation data from the coupling model with the dynamic response measured data from the Qingyuan Maglev Tourist Line. Finally, the impact of different control parameters on the vehicle–bridge coupling system was calculated, and the results indicate that selecting appropriate suspension control parameters can reduce the coupling vibration response between the maglev vehicle and the bridge. The main work of this paper is closely related to engineering, modeling based on the actual maglev line’s vehicle and bridge parameters, and validating the model through the dynamic test results of the line, laying the foundation for the suppression of maglev vehicle–bridge coupling vibration and system optimization. Full article

This paper concerns lightweight—up to 800 kg—UGVs (unmanned ground vehicles), where multi-tracked running gears are used to improve the obstacle negotiation performance. A comparison of four different multi-tracked systems and, for reference, classic tracked running gear is presented. Simulations in a multi-body dynamics program were performed, where running gear solutions overcame three typical obstacles and were assessed using a total of five effectiveness and functionality criteria. The simulation models took into account the variable track–ground contact surface. The ground parameters were validated by means of experimental tests for grassy terrain. In the results, the most advantageous solutions in each category are indicated, and design guidelines for increasing the obstacle-overcoming capabilities of multi-tracked UGVs are presented. Full article

Mining dump trucks play an important role in engineering construction and resource extraction. Current research mainly focuses on the dynamic modeling and reliability analysis of the vehicle frame, suspension and overall model. However, with the development of electric drive, the wheel hub system has become an important component in mining truck equipment. This paper investigates the multi-body modeling of a mining truck’s hub drive reduction system in order to analyze its output characteristics including the stability of the angular velocity of its planetary carriers and the fluctuations in its meshing forces. A bench experiment was also conducted to verify the accuracy and stability of the proposed modeling. And the simulation results revealed that the fluctuations in the angular velocity of the planetary carriers were primarily influenced by the excitation from the hub motor’s input and the meshing forces between the gears of the reducers, which were mainly determined by the contact stiffness, damping, and clearance value during gear contact. Full article

This study introduces an innovative vehicle-modeling framework based on the Reduced Multibody System Transfer Matrix Method, incorporating wheel–ground contact and friction to analyze dynamic performance metrics, including vertical acceleration, suspension deflection, and angular acceleration. The model is applied to simulate vehicle behavior at 40 km/h on Class D road conditions. To enhance dynamic characteristics, suspension parameters were optimized using the NSGA-II algorithm. The optimization process achieved significant reductions in vertical acceleration (24.12%), suspension deflection (25.98%), and angular acceleration (4.93%). The Pareto frontier facilitated the selection of a representative solution that balances smoothness, stability, and suspension performance. Frequency, PSD, and RMS analyses were performed under different road conditions and speeds to verify the robustness of the optimization results. The application of the transfer matrix method is extended to vehicle suspension modeling and optimization, offering valuable insights into improving ride comfort and stability. Additionally, it highlights the effectiveness of advanced multi-objective optimization techniques in improving vehicle dynamics and provides a robust methodology for practical applications. Full article

Compared to wheeled vehicles, tracked robotic vehicles have less ground pressure, greater traction adhesion, and stronger climbing and obstacle crossing capabilities, making them suitable for agricultural production in hilly areas. Good steering performance directly relates to the mobility performance and operating efficiency of tracked robotic vehicles. Affected by the ground slope, the ground pressure distribution of the vehicle’s two tracks is uneven, leading to changes in its steering performance. Therefore, analyzing and researching the steering performance of a tracked robotic vehicle under sloped conditions is of great significance. This study establishes a slope steering model for tracked robotic vehicles based on a ground pressure model of the multi-peak varying amplitude cosine distribution and the shearing displacement relationship between the track and the ground, and analyzes the impact of vehicle structural parameters, road surface parameters, and steering parameters on steering performance. To verify the proposed theoretical model, multi-body dynamics software is utilized for simulation modeling and analysis. Turning tests on different slopes are conducted on a “soil–machine–crop” integrated experimental platform. The relative error between the numerical analysis results and the virtual simulation software’s results is less than 12%, and the relative error between the numerical analysis results and the experimental results is less than 10.3%; the good consistency between the theoretical results and the simulation’s results and the experimental results indicates that the model is, indeed, correct and effective. The established steering model can provide a theoretical basis for the design and control of new steering mechanisms for agricultural tracked robotic vehicles. Full article

Track irregularity is one of the principal excitations that induces coupled vibrations in vehicle–bridge systems. Understanding the sensitive wavelength of track irregularities is critical for the evaluation and management of track conditions. Notably, existing studies generally focus on railway systems, but the characteristics of sensitive wavelengths in monorail systems are insufficiently understood. This study aims to investigate the influence of longitudinal level irregularity (LLI) on the dynamic response of the monorail tour transit system (MTTS), as well as the sensitive wavelength of LLI. First, a joint model was developed by integrating multi-body dynamics with the finite element method. The LLI utilized in the numerical mode was simulated by trigonometric functions with various frequencies (i.e., wavelengths) and amplitudes. The dynamic responses of monorail vehicles, including the wheel load reduction rate and vertical acceleration, were obtained and then used to evaluate track conditions. Results indicate that the dynamic responses of MTTS are mainly affected by the LLI with a wavelength of less than 5 m. In addition, it was found that, in the studied ranges, the sensitivity wavelength grows as the vehicle speed increases. Finally, the recommended value of LLI control under various track conditions was evaluated. Full article