Vehicle Body Research Articles

Inertial mass modeling and compensation for an energy-harvesting vehicle suspension system with limited-DOF parallel mechanisms actuator

An energy-harvesting suspension can improve the energy efficiency of vehicle. By introducing a lower-mobility parallel mechanism as motion transfer in the energy-harvesting suspension, the stiffness of the system is significantly improved. However, the overlage equivalent of inertial mass make the system is difficult to control and imped the development of this kind of suspension. To solve the problem, an equivalent linearization model to calculate the nonlinear inertial mass of low-DOF (Degree Of Freedom) parallel mechanism actuator is studied firstly. Furthermore, a 2-DOF 1/4 suspension system dynamic model that includes inertial mass is proposed to analyze the vehicle acceleration, dynamic tire load, and dynamic stroke. On this basis, the linear-quadratic Gaussian (LQG) controller is adopted to compensate the inertial mass of the suspension to improve the system performance. Results show that the proposed model accurately reflects the characteristics of the suspension inertial mass, the root-mean-square (RMS) value of the vehicle body acceleration and suspension dynamic stroke through compensation controller is reduced by 33.4% and 30.89%, respectively. Moreover, the RMS of the dynamic tire load is reduced by 3.06%, and the system stability is improved significantly.

Lane change path planning using sweeping region for full-sized autonomous driving bus in urban environment

This paper presents a path planning method for the lane change maneuver of a full-sized autonomous driving bus in urban environment. A sampling method is incorporated for lane change path planning. Path candidates for lane changes are generated using the pattern of a quintic polynomial function. For optimal path selection among the candidates, a cost function and constraints are designed and applied, considering ride quality, lane change efficiency, and safety. Safety conditions account for lane departure and collision with obstacles. Considering large vehicles such as buses, the region swept by the vehicle body is derived by exploiting the geometrical relationship of the control point and corners, assuming that the control point follows the investigated path candidate. The sweeping region is utilized for accurate and efficient evaluation of the safety condition of the path candidate. Subsequently, longitudinal motion is planned based on Model Predictive Control (MPC) to maintain adequate clearance with surrounding vehicles and follow the desired speed. The proposed algorithm has been evaluated based on closed-loop simulations and vehicle-in-the-loop tests. The test results show that the proposed algorithm plans a safe lane change path, ensuring the vehicle body remains within the safe region. Additionally, the proposed algorithm is shown to enhance real-time performance.

Study on the Influence of Wind Load on the Safety of Magnetic Adsorption Wall-Climbing Inspection Robot for Gantry Crane

The maintenance of the surface of steel structures is crucial for ensuring the quality of shipbuilding cranes. Various types of wall-climbing robots have been proposed for inspecting diverse structures, including ships and offshore installations. Given that these robots often operate in outdoor environments, their performance is significantly influenced by wind conditions. Consequently, understanding the impact of wind loads on these robots is essential for developing structurally sound designs. In this study, SolidWorks software was utilized to model both the wall-climbing robot and crane, while numerical simulations were conducted to investigate the aerodynamic performance of the magnetic wall-climbing inspection robot under wind load. Subsequently, a MATLAB program was developed to simulate both the time history and spectrum of wind speed affecting the wall-climbing inspection robot. The resulting wind speed time-history curve was analyzed using a time-history analysis method to simulate wind pressure effects. Finally, modal analysis was performed to determine the natural frequency and vibration modes of the frame in order to ensure dynamic stability for the robot. The analysis revealed that wind pressure predominantly concentrates on the front section of the vehicle body, with significant eddy currents observed on its windward side, leeward side, and top surface. Following optimization efforts on the robot’s structure resulted in a reduction in vortex formation; consequently, compared to pre-optimization conditions during pulsating wind simulations, there was a 99.19% decrease in induced vibration displacement within the optimized inspection robot body. Modal analysis indicated substantial differences between the first six non-rigid natural frequencies of this vehicle body and those associated with its servo motor frequencies—indicating no risk of resonance occurring. This study employs finite element analysis techniques to assess stability under varying wind loads while verifying structural safety for this wall-climbing inspection robot.

Fatigue fracture mechanism and life prediction of steel-aluminium clinched joints under different stress ratios

Vehicle bodies are subject to complex random loads during travelling, making it imperative to investigate the effects of different stress ratios on the body joining structure. To investigate the fatigue performance of steel-aluminium clinched joints under different stress ratios, fatigue experiments were conducted on these joints subjected to different load levels at stress ratios of -0.4, 0.1, and 0.4. The fracture mechanism of steel-aluminium clinched joints under different stress ratios was investigated through analysis of the joint's fracture morphology and the composition of abrasive chips using Scanning Electron Microscope and Energy Dispersive Spectroscopy. A fatigue life prediction model for steel-aluminium clinched joints was developed by employing the modified Paris formulation of the Wallker equation. The results indicate that joint failure can be classified into three main forms: lower sheet fracture, upper sheet pull-off accompanied by lower sheet fracture and reaching infinite life (2 million times). The lower sheet of a fatigue failure specimen in a steel-aluminium clinched joint exhibited a novel form of fretting damage known as lower sheet inter-plate fretting wear. Furthermore, the application of Walker's improved Paris formula proved to be highly effective in accurately predicting the fatigue life of steel-aluminium clinched joints under different stress ratios, with the predicted results demonstrating excellent agreement with experimental findings.

Assessment of longitudinal load spectrum characteristics and structural fatigue damage of metro vehicle body in service

Aiming at the structural integrity requirements of service vehicles, there is an urgent need to construct a set of analytical methods based on service load characterization to realize the life assessment of the critical weak regions of the vehicle body. This study measured the longitudinal load spectrum of a metro vehicle body under a typical service line using a calibrated coupler and traction bar. Based on the signal characteristics of the longitudinal loads, a dynamic load feature decomposition method is proposed to decompose the longitudinal load features into trend and fluctuation signals to reflect the overall and local laws. The longitudinal load transfer characteristics of the vehicle body under traction, braking, linear, and curved conditions are innovatively analyzed, and a longitudinal load distribution ratio coefficient with generality is proposed as the input of effective service load. The service stress spectrum of the vital points of the vehicle body is constructed, which can more comprehensively and realistically respond to the service stress state of the vehicle body compared with the standard design loads, which further improves the accuracy of the structural integrity assessment.

CRUMPLE ZONE MODELLING OF PASSENGER VEHICLE USING MULTIPLE KELVIN MODEL AND OPTIMIZED WITH PARTICLE SWARM OPTIMIZATION

This paper presents the mathematical modelling of a vehicle crash system using a mass-spring-damper approach to simulate the behavior of a real vehicle during a frontal impact. A Multiple Kelvin model is developed to represent a real vehicle crash situation where the impact is introduced on the frontal vehicle body. The modelling process of Multiple Kelvin model is based on a single Kelvin model that developed into a set of seven mass-spring-damper systems representing the front crumple zone of a real vehicle. The model is then optimized for the parameters k and c using an optimization method namely Particle Swarm Optimization (PSO) algorithm in MATLAB-Simulink. The simulation results demonstrate deformation and acceleration responses closely follow the previous experimental results where the parameters namely Ni, Np, and iw are varied to enhance the model's precision through the calculation of error of 12.15 using parameters Ni = 80, Np = 40 and iw = 0.9.

A Dual-Layer Control System for Steering Stability of Distributed-Drive Electric Vehicle

In addressing the limitations of traditional steering stability control strategies applied to distributed-drive electric vehicles (DDEVs)—which primarily focus on measuring yaw rate and sideslip angle and may result in loss of control during steering maneuvers—this study conducts a more comprehensive analysis of DDEVs’ steering control stability. It specifically investigates the relationships among the lateral positions of both the front and rear wheels, the slip ratios, and the angular orientation of the vehicle’s body during steering processes. Furthermore, a dual-layer steering stability control system aimed at enhancing the steering stability performance of DDEVs is introduced. This control system consists of two components: a lateral controller and a longitudinal controller. The lateral controller aims to establish clear linkages among four key variables, the front and rear wheel sideslip angles, yaw rate, and sideslip angle, and then to compute the necessary active front wheel steering angle and corresponding yaw moment based on the current vehicle body attitude. The findings indicate that, in comparison to the conventional DDEV controller, the proposed two-layer controller achieves substantially closer alignment to the reference curve during steering, with the accuracy increased by a factor of approximately 5 to 20. These results unequivocally affirm the efficacy and viability of the proposed approach.

Analysis of the impact of misfiring on the throttle body in ayla vehicles using the fast fourier transform method

An essential component of an automobile's air intake system, the throttle body controls airflow during combustion by acting as an idle speed control mechanism. Making ensuring the throttle body is operating properly is crucial to keeping the engine running at its best. The Fast Fourier Transform vibration analysis is one technique used for this (FFT). A an LCGC Ayla 1000 cc vehicle's throttle body and engine underwent vibration testing with rotational rates set to 750 rpm, 1000 rpm, 1500 rpm, and 2000 rpm. Vibration responses were measured using an accelerometer sensor coupled to an FFT analyzer, and Matlab was used for analysis. The throttle body had anomalous frequency readings at 1977 Hz with an amplitude of 0.03171 m/s2, according to the test results. On the other hand, the frequency value at 1410 Hz with an amplitude of 0.03435 m/s2 was observed under normal circumstances. Similar to this, abnormal frequency values with an amplitude of 0.02378 m/s2 were found on the engine at 1493 Hz, whereas normal frequency values with the same amplitude were found at 1712 Hz. These results point to incomplete combustion as the cause of the increased vibration

Modal analysis and structural noise control of vehicle body frame

The structural noise inside the vehicle cabin is mainly low-frequency vibration, which is closely related to the modal characteristics of the vehicle frame. The finite element method was used to simulate and calculate the body frame under free modal conditions, and the first four effective modal shapes were obtained. The calculation error of the natural frequencies was verified through modal experiments. Taking structural stiffness into account, a sound-structure coupled model was established. The suspension connection point was selected as the excitation point, and a one-way dynamic load was applied to obtain the noise and vibration responses of the front and rear rows. Based on the modal analysis results, the top-roof reinforcement scheme was adopted to verify the noise suppression effect of the structure. The results show that the optimized structure can effectively suppress structural noise, which plays an important role in improving the NVH characteristics.

Investigation of the electrical quality and long-term stability of aluminum ground stud connections in automotive applications

The rapid advancement in the electrification of modern vehicles has led to a continuous increase in electrical consumers for various comfort and safety functions. Ground studs serve as the electrical interface between the conductive vehicle body and the onboard network. Drawn arc stud welding is an economical and established joining process for producing ground stud joints. The circuits in the onboard network are increasingly subject to greater demands regarding current-carrying capacity and long-term stability. Reliable signal and power transmission require minimal contact resistance at the electrical connection points of the ground stud system and must withstand various operating and environmental conditions over the entire service life. In this study, a ground stud made of AlMg5, with a ZnNi-coated steel cap nut was used on a 2.0 mm thick sheet of AlMg3. The electrical connection of the ground studs was made using tinned copper cable lugs and 35 mm² cables. To analyze the electrical resistance behavior in an accelerated test, the ground studs were subjected to a superimposed load with a cyclic current profile for 1008 h under changing climatic conditions. The results show that under the chosen operational and environmental conditions, accelerated aging and intermittent resistance behavior occur. A characteristic drop in resistance during the test indicates the failure point of the electrical connection. The cause of failure can be attributed to media penetration into the electrical contact zone. A failure of the electrical connection was observed after 512 h.

Friction Characteristics of Low and High Strength Steels with Galvanized and Galvannealed Zinc Coatings

As vehicle body structures become stronger and part designs more complex for lightweight, controlling frictional properties in automotive press forming has gained critical importance. Friction, a key factor in formability, is influenced by variables such as contact pressure, sliding velocity, sheet strength, and coatings. This study investigates the friction characteristics of steels with tensile strengths of 340 MPa and 980 MPa, under galvanized (GI) and galvannealed (GA) zinc coatings. Experimental results reveal that asperity flattening, a significant factor in determining friction, increases with contact pressure normalized by tensile strength, particularly for GI-coated steels. However, the relationship between friction and surface flattening deviates from conventional expectations, with the friction coefficient initially rising with increased flattening area up to ~20% before decreasing as flattening progresses. These findings suggest that traditional empirical formulas may not fully capture friction behavior under specific conditions. By understanding this inflection point, where friction reduces under high contact pressure, the study provides valuable insights for optimizing formability and improving sheet metal forming processes, especially in scenarios where precise friction control is critical for producing high-quality automotive parts.

A nonlinear model predictive control for air suspension of hub motor electric vehicle based on hybrid H2/H∞ state estimation

To alleviate the vibration from the road irregularities and the unbalanced electromagnetic forces (UEFs), deteriorating the dynamic performance of hub motor electric vehicles (HM-EVs), a novel nonlinear model predictive control (NMPC) is proposed based on a hybrid H2/H ∞ filtering algorithm for the HM-EVs with air suspension (HM-AS). The dynamic HM-AS model involves the electric vehicle’s longitudinal, lateral, and vertical motion. The air suspension system between the body and the hub motor enhances ride quality and insulates the oscillation delivered to the vehicle body. Then, the dynamic HM-AS model is validated by the actual vehicle test, and the proposed filter is developed to obtain the vehicle states. Besides, the NMPC controller guarantees the dynamic performance of HM-AS by intervening in vehicle attitude, road-holding stability, motor safety, and ride comfort. Finally, compared with the application of PID and MPC, the efficiency of the proposed method is demonstrated based on several random road scenarios. The results indicate the proposed algorithm can alleviate the dynamic performance of HM-AS and reduce motor vibration.

Non-Destructive Testing of Joints Used in Refrigerated Vehicle Bodies

Non-Destructive Testing of Joints Used in Refrigerated Vehicle Bodies

Steering Mechanism and Capability of Forced Steering Device for Low-Floor Light Rail Train

For 70% low-floor trains on the light rail lines in Changchun, a multi-linkage forced steering device (FSD) is developed aiming at relieving the independently rotating wheelset (IRW) excessive flange wear and improving IRW bogie system running safety on curve line. This FSD employs guiding mode of steering four independently rotating wheels separately in a two-axle bogie, that is, four FSDs are employed to work together to realize the steering of a two-axle bogie. One side of an FSD is connected to the axle of an independently rotating wheel while the other side is attached to the front or rear vehicle body. When train passes through curve, the yaw angle between the IRW bogie and the front or rear carbody drives the linkage system to rotate to guide the independently rotating wheel towards its radial position. The coupled vehicle-track dynamics model for a 6-module single-type low-floor light rail train is developed and simulations of the train passing through tangent and curved tracks with and without FSD proposed are carried out. The results indicate that the FSD can improve the IRW restoring capability on tangent track and curve negotiation performance on whether sharp, medium, or large curved track. For example, passing through a curve with a radius of 200[Formula: see text]m, the IRW friction work has the biggest drop by 62.07% and the wheelset attack angle is second with a reduction rate of 55.02%. Adopting of larger steering stiffness, smaller steering clearance, and lever ratio greater than the ideal value can guarantee the higher steering ability of FSD. Besides, lower longitudinal stiffness of the trailer primary suspension is recommended because it can also enhance the steering ability of the FSD.

Research on adaptive hydraulic drive optimization control of concrete mixing tank truck for open-pit mine.

The non-axisymmetric problem caused by the fluid sloshing in the tank of a mining concrete mixing tank truck during driving is affected by the excitation of complex road surfaces. The fluid sloshing is coupled with the dynamics of the vehicle body due to the excitation of the complex road surface. The traditional hydraulic drive proportional integral differential (PID) control method is not effective in dealing with such problems, which can easily lead to accidents such as overturning. To improve the accuracy and stability of the hydraulic drive control system, this paper proposes an optimized particle filter PID adaptive control method based on the elastic firefly (FA) algorithm to accelerate the convergence speed of control parameter optimization, and then analyzes its hydraulic drive control characteristics and structural applications, and discusses step steering and double lane change modes are simulated under filling rates of 1.5 and 2.0, respectively. The experimental results show that compared with traditional PID control, the proposed adaptive control method can significantly reduce the average speed error of hydraulic drive control to 0.03km/h and the maximum speed error to 0.17km/h. It also improves the control tracking performance and stability. The practicality of the adaptive hydraulic drive is verified in the filling rate experiments under step steering and double-lane shifting conditions. It has important reference value for the practical application of hydraulic drive control optimization of mining concrete mixing transport tank trucks.

Mid-frequency propagation path analysis on vehicle body using structural intensity

With the penetration of electric vehicles, reduction of structure-borne road noise gets important issue to realize comfortable vehicles for customers.Sound generation mechanism of structure-borne road noise on vehicle body is analyzed basically by modal analysis in low-frequency range. On the other hand, as frequency increases, modal analysis cannot clarify vibration mechanism because vibration wavelength gets shorter, mode density gets high and mode shape gets complicated. Therefore, it is difficult to identify efficient countermeasure parts and inefficient damping materials are added to response panels in mid-frequency range. So alternative analytical methods in mid-frequency range are under research to understand vibration mechanism. In this paper, Structural intensity (SI) analysis is introduced to clarify sound propagation mechanism. This analysis method makes it possible to clarify the main energy propagation path from input point to vibrating panels on vehicle body. The results show that SI analysis unveils the main energy propagation path and gives the opportunity to reduce the panel vibration efficiently by controlling the energy propagation path in body frame structure without damping materials.

A study on the improvement of sound insulation performance of aluminum chassis

In recent years, the automobile industry has rapidly shifted towards electric vehicles, with an increasing number of vehicles using aluminum instead of steel for a significant portion or the entire or part of the vehicle body. Aluminum body panels reduce sound insulation performance compared to steel panels because they depend on surface density. This situation causes uncomfortable sound environment for vehicle passengers. To address the sound insulation issues associated with lightweight panels, it is necessary to research how to optimize the thickness and weight of interior and exterior car components in order to enhance sound insulation performance. In this study, the acoustic characteristics were initially confirmed by measuring indoor noise while driving a vehicle constructed from two different materials: steel and aluminum, under the same conditions as other parts. In addition, to select a sound absorbing material suitable for the characteristics of the vehicle body material, steel and aluminum panels were installed between the reverberation chamber and the anechoic chamber, respectively, and sound transmission loss was evaluated by combining the various thickness and weight. Based on these results, we decided on a proposed specification (aluminum panel with weight/thickness added) above the basic specification (steel panel with existing sound insulation parts).

Data-Driven Control Method Based on Koopman Operator for Suspension System of Maglev Train

The suspension system of the Electromagnetic Suspension (EMS) maglev train is crucial for ensuring safe operation. This article focuses on data-driven modeling and control optimization of the suspension system. By the Extended Dynamic Mode Decomposition (EDMD) method based on the Koopman theory, the state and input data of the suspension system are collected to construct a high-dimensional linearized model of the system without detailed parameters of the system, preserving the nonlinear characteristics. With the data-driven model, the LQR controller and Extended State Observer (ESO) are applied to optimize the suspension control. Compared with baseline feedback methods, the optimization control with data-driven modeling reduces the maximum system fluctuation by 75.0% in total. Furthermore, considering the high-speed operating environment and vertical dynamic response of the maglev train, a rolling-update modeling method is proposed to achieve online modeling optimization of the suspension system. The simulation results show that this method reduces the maximum fluctuation amplitude of the suspension system by 40.0% and the vibration acceleration of the vehicle body by 46.8%, achieving significant optimization of the suspension control.

Numerical study of vehicle motion during water exit under combined lifting force and wave action

During the retrieval process of the deep-sea mining vehicle (DSMV), the stability of the retrieval system is strongly influenced by the interaction between the vehicle body and the surrounding seawater due to the vehicle's complex shape and wave motion. Naturally, the negative side effects of significant changes in the vehicle's attitude and the water exit position can only increase retrieval's challenge. To investigate the characteristic of the flow field of the DSMV, this study employs the computational fluid dynamics method based on the Reynolds-averaged Navier–Stokes equations integrating the volume-of-fluid multiphase flow model with a fifth-order Stokes-wave model to explore the attitude and displacement changes of the vehicle during the water exit process in the ocean wave environment. The results indicate that the wave phase and lifting force are the major effect factors in the DSMV's water exit process. An appropriate lifting force under a specific wave phase can effectively reduce attitude changes and positional drift of the DSMV during water exit, thereby enhancing recovery efficiency and stability.

The Effect of Quenching Process on The Microstructure and Hardness of AISI 4140 Steel

Abstract Steel is a metal that has good strength widely used in industry, both in the construction and automotive fields as a protective material applied to the body of combat vehicles. Combat vehicle body materials must have high strength and hardness to withstand bullet penetration. Meanwhile, some types of steel do not have such strong point to endure impact and bullet penetration, so their strength and hardness need to be increased. One method that can be used to increase the qualities of steel is heat treatment, such as quenching process. In this research, the quenching process was carried out on commercial AISI 4140 steel to increase its hardness. The heat treatment process for AISI 4140 steel begins with an austenization process at a temperature of 850 °C with varying holding times, followed by a quenching stage using SAE 40 oil media. Afterward, the microstructure observation and hardness testing of the test material were carried out using the Optical microscope and Vickers method. The raw material has a hardness value of 215.58 VHN. After the heat treatment process in 30, 60, and 90 minutes was carried out, the hardness value of AISI 4140 steel reached 371.24, 474.48, and 545.5 VHN, respectively. The research results show that the longer the holding time in the quenching process lasts, the more increases the hardness value of the steel will be, which result in microstructure as a dominant martensite phase.