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Conventional viscous shock absorbers, in parallel with suspension springs, passively dissipate the excitation energy from road irregularity into heat waste, to reduce the transferred vibration which causes the discomfort of passengers. Energy-harvesting shock absorbers, which have the potential of conversion of kinetic energy into electric power, have been proposed as semi-active suspension to achieve better balance between the energy consumption and suspension performance. Because of the high energy density of the rotary shock absorber, a rotational energy-harvesting shock absorber with mechanical motion rectifier (MMR) is used in this paper. This paper presents the assessment of vehicle dynamic performance with the proposed energy-harvesting shock absorber in braking process. Moreover, a PI controller is proposed to attenuate the negative effect due to the pitch motion.

In recent years, structural adhesives have rapidly become the preferred alternative to resistance spot welding in fabricating stronger, lighter aluminum connections. Connections inevitably undergo and must withstand complex quasi-static and/or dynamic loads during their service life. Therefore, understanding how loading conditions affect the mechanical behavior of adhesive joints is vital to their design and the advancement of structural safety. Quasi-static and dynamic tests are performed to analyze both the strength and failure modes of aluminum 6062 substrates bonded by an adhesive (Darbond EP-1506) for an array of loading directions. An Arcan test device, which enables application of mixed-mode loads ranging from pure peel (mode I) to pure shear (mode II) to the adhesive layer, is employed in quasi-static testing. A self-designed medium-speed test machine is utilized to perform dynamic testing.

Failure of high voltage cables (HVCs) which sometimes occurs in electric vehicle collision is one of the fuses that leads to severe thermal runaway of the traction battery system, which has not gotten thorough investigations. This paper presents an experiment and simulation study on the failure behaviors of HVCs under indentation loadings. Tests were performed with different combinations of indenter (cylinder indenter with a diameter of 5 mm which was labeled as D5, cylinder indenter with a diameter of 15 mm which was labeled as D15 and wedge indenter with an angle of 60° which was labeled as V60) and loading speed (1.5 mm/min for quasi-static and 2m/s for dynamic). Experimental results indicated that the failure behavior of HVCs was both influenced by the indenter shape and loading speeds. Sharp indenter will led to a component failure sequence from outmost to innermost.

A novel fault tolerant brake strategy for In-wheel motor driven electric vehicles based on integral sliding mode control and optimal online allocation is proposed in this paper. The braking force distribution and redistribution, which is achieved in online control allocation segment, aim at maximizing energy efficiency of the vehicle and isolating faulty actuators simultaneously. The In-wheel motor can generate both driving torque and braking torque according to different vehicle dynamic demands. In braking procedure, In-wheel motors generate electric braking torque to achieve energy regeneration. The strategy is designed to make sure that the stability of vehicle can be guaranteed which means vehicle can follow desired trajectory even if one of the driven motor has functional failure.

Dieseline combustion as a concept combines the advantages of gasoline and diesel by offline or online blending the two fuels. Dieseline has become an attractive new compression ignition combustion concept in recent years and furthermore an approach to a full-boiling-range fuel. High speed imaging with near-parallel backlit light was used to investigate the spray characteristics of dieseline and pure fuels with a common rail diesel injection system in a constant volume vessel. The results were acquired at different blend ratios, and at different temperatures and back pressures at an injection pressure of 100MPa. The penetrations and the evaporation states were compared with those of gasoline and diesel. The spray profile was analyzed in both area and shape with statistical methods. The effect of gasoline percentage on the evaporation in the fuel spray was evaluated.

Hydraulic Engine Mount (HEM) is now widely used as a highly effective vibration isolator in automotive powertrain. A lumped parameter model is a traditional model for modeling the dynamic characteristics of HEM, in which the system parameters are usually obtained by experiments. In this paper, Computational Fluid Dynamics (CFD) method and nonlinear Finite Element Analysis (FEA) are used to determine the system parameters. A Fluid Structure Interaction (FSI) FEA technique is used to estimate the parameters of volumetric compliances, equivalent piston area, inertia and resistance of the fluid in the inertia track and decoupler of a HEM. A nonlinear FEA method is applied to determine the dynamic stiffness of rubber spring of the HEM. The system parameters predicated by FEA are compared favorably with experimental data and/or analytical solutions.

The issue of car-to-pedestrian impact safety has received more and more attention. For leg protection, a legform impactor with 2 degrees-of-freedom (DOF) proposed by EEVC is required in current regulations for injury assessment, and the Japan Automobile Manufacturers Association Inc. (JAMA) and Japan Automobile Research Institute (JARI) have developed a more biofidelic pedestrian legform since 2000. However, studies show that those existing legforms may not be able to cover some car-to-pedestrian impact situations. This paper documents the development of a new pedestrian legform with 4 DOFs at the knee-joint. It can better represent the kinematics characteristics of human knee-joint, especially under loading conditions in omni-direction impacts. The design challenge is to solve the packaging problem, including design of the knee-joint mechanisms and layout of all the sensors in a limited space of the legform.

The windshield is one of the most critical vehicle components in terms of pedestrian safety; however, it has not been thoroughly and systematically investigated through combined experimental and theoretical analysis. Firstly, this paper carries out quasi-static experiments on Material Testing System (MTS) and dynamic experiments on Split Hopkinson Pressure Bar (SHPB) and new tests data are obtained. Results indicate that Polyvinyl butyral (PVB)-laminated glass behaves nonlinearly and rate-dependently under various strain rates, from 1x10-⁵s-₁~6x10₃ s-₁. Thus, a constitutive model covering all strain rates is proposed to describe the constitutive behavior of PVB-laminated glass and it fits well with the experimental data. Further, the constitutive relation is embedded into the 3D finite element model of windshield. With the definition of four governing factors and two evaluation indicators, the head protection characteristics of windshield are numerically studied.

In this paper, we focus on the active vehicular suspension controller design. A quarter-vehicle suspension system is employed in the system analysis and synthesis. Due to the difficulty and cost in the measuring of all the states, we only choose two variables to construct the feedback loop, that is, the control law is a static-output-feedback (SOF) control. However, the sensor reduction would induce challenges in the controller design. One of the main challenges is the NP-hard problem in the corresponding SOF controller design. In order to deal with this challenge, we propose a two-stage design method in which a state-feedback controller is firstly designed and then the state-feedback controller is used to decouple the nonlinear conditions. To better compensate for the varying vehicle load, a robust load-dependent control strategy is adopted. The proposed design methodology is applied to a suspension control example.

In vehicle accident, the bumper beam generally requires high stiffness for sufficient survival space for occupants while it may cause serious pedestrian lower extremity injuries. The aim of this study is to promote an aluminum-steel hybrid material double-hat bumper to meet the comprehensive requirements. The hybrid bumper is designed to improve the frontal crash and pedestrian protection performances in collision accidents. Finite element (FE) models of the hybrid bumper was built, validated, and integrated into an automotive model. The Fixed Deformable Barrier (FDB) and Transport Research Laboratory (TRL) legform model were used to obtain the vehicle crashworthiness and pedestrian lower leg injury indicators. Numerical results showed that the hybrid bumper had a great potential for crashworthiness performance and pedestrian protection characteristics. Based on this, a multi-objective optimization design (MOD) was performed to search the optimal geometric parameters.

The accuracy of road input identifiaction for autonomous vehicles (AVs) system, especially in state-based AVs control for improving road handling and ride comfort, is a challenging task for the intelligent transport system. Due to the high fatality rate caused by inaccurate state-based control algorithm, how to precisely and effectively acquire road rough information and chose the reasonable road-based control algorithm become a hot topic in both academia and industry. Uncertainty is unavoidable for AVs system, e.g., varying center of gravity (C.G.) of sprung mass, controllable suspension damping force or variable spring stiffness. To tackle the above mentioned, this paper develops a novel observer approach, which combines unscented Kalman filter (UKF) and Minimum Model Error (MME) theory, to optimize the estimation accuracy of the road rough for AVs system. A full-car nonlinear model and road profile model are first established.

This paper proposes a theoretical model to interpret the heat generation mechanism and thermal failure of shock absorber. For a common structure of double-tube shock absorber, all frictions between two contacting components of shock absorber are calculated particularly. The heat generation mechanism and heat distribution can be explained with the theoretical model. Thermal failure is a recurrent malfunction for traditional shock absorbers, which leads to shorten the service lives of vehicle components. Heat generation experiments are accomplished to validate the thermal degeneration of shock absorber. So this study is meaningful to develop a new system of vibration attenuation with satisfying reliability, which is essential to improve the riding comfort and handling stability of vehicles.

An identification method using recursive least-squares method with moving data window and reduced-order disturbance observer iteratively is proposed in this paper to identify fast time-varying braking force in the electronic mechanical braking system (EMB). For the type of EMB which generates braking force by balls screw and motor mounted beside wheel, the actuator will go rapidly to eliminate clearance at beginning of braking process by means of raising the braking response speed, and at the same time, increasing the motor output torque which might be far larger than required. The proposed identification method is able to identify the point of contact between the brake pads and the disk in time by identifying the change of break force, and the torque of motor will be changed in time to reduce the braking force overshoot so that brake locking is avoided.

Rollover accident of heavy vehicle during cornering is a serious road safety problem worldwide. In the past decade, based on the active intervention into the heavy vehicle roll dynamics method, researches have proposed effective anti-roll control schemes to guarantee roll stability during cornering. Among those studies, however, roll stability control strategies are generally derived independent of front steering control inputs, the interactive control characteristic between steering and anti-roll system have not been thoroughly investigated. In this paper, a novel roll stability control structure that considers the interaction between steering and anti-roll system, is presented and discussed.

The ability of actively adjusting attitude provides a great advantage for those vehicles used in special environments such as off-road environment with extreme terrains and obstacles. It can improve vehicles’ stability and performance. This paper proposes an attitude control system for realizing the active attitude adjustment and vehicle motion control in the same time. The study is based on a vehicle with six wheel independent drive and six independent suspensions (6WIDIS), which is a kind of unmanned vehicle with six in-wheel drives and six independent hydro pneumatic suspensions. With the hydro- pneumatic suspensions, the vehicle’s attitude can be actively adjusted. This paper develops a centralized- distributed control strategy with attitude information obtained by multi-sensor fusion, which can coordinate the complex relationship among the six wheels and suspensions. The attitude control system consists of three parts.

This paper conducts simulation research on engine torque ripple suppression based on the engine torque observer by using a flywheel-ISG (integrated starter generator). Usually, engine torque can be suppressed by using a passive method such as by installing a flywheel or torsional damper. However, failure problems arise in hybrid system because of different mechanical characters of the engine and its co-axial ISG motor. On the prototype test bench, the flywheel of the engine has been removed and replaced by an ISG rotor, namely FISG (flywheel ISG). Besides, the crank and FISG rotor are directly connected, which means no dampers or clutches are installed. If the engine torque ripples can be suppressed by the same level as the flywheel and damper by FISG active torque compensation, the new system can be more compact and economical. Simulation efforts are made to verify its feasibility. Firstly, based on the experimental test bench, which is currently under construction.

In a monotube magnetorheological fluid damper (MRFD), there usually exists a compensation chamber with designated initial gas pressure. This enclosed compensation chamber works as an air spring to some degree to provide force to the working piston. In this work, in order to extend the external damping force range and improve the controlling efficiency, a structure of MRFD with three additional accumulators is proposed. These additional accumulators are connected to the atmosphere through an air pump and the compensation chamber with a barometric valve. The external damping force range thus can be rapidly adjusted through mode shifting with this configuration. A mathematical model of this damper with coupled effects between the air and the magnetorheological fluid (MRF) is developed. Comparing the bench tests results with some simulation outcomes, the simulation model of this MRFD is validated.

Small lightweight electric vehicle (SLEV) is an approach for compensating low energy density of the current battery. However, small lightweight vehicle presents technical challenges to crash safety design. One issue is that mass of battery pack and occupants is a significant portion of vehicle's total weight, and therefore, the mass distribution has great influence on crash response. This paper presents a parametric analysis using finite element modeling. We first build LS-DYNA model of a two-seater SLEV with curb weight of 600 kg. The model has no complex components and can provide reasonable crash pulses under full frontal rigid barrier crash loading and offset deformable barrier (ODB) crash loading. For given mass of battery pack and one occupant (the driver), different battery layouts, representing different combinations of center of gravity and moment of inertia of the whole vehicle, are analyzed for their influences on the crash responses under the two frontal crash loadings.

The electromagnetic regenerative suspension has attracted much attention recently due to its potential to improve ride comfort and handling stability, at the same time recover kinetic energy which is typically dissipated in traditional shock absorbers. The key components of a ball-screw regenerative suspension system are a motor, a ball screw and a nut. For this kind of regenerative suspension, its damping character is determined by the motor's torque-speed capacity, which is different from the damping character of the traditional shock absorber. Therefore, it is necessary to establish a systematic approach for the parameter matching of ball-screw regenerative suspension, so that the damping character provided by it can ensure ride comfort and handling stability. In this paper, a 2-DOF quarter vehicle simulation model with regenerative suspension is constructed. The effects of the inertia force on ride comfort and handling stability are analyzed.

In order to obtain a good understanding of mechanical behaviors of lithium-ion battery modules in electric vehicles, comprehensive experimental and numerical investigations were performed in the study. Mechanical indentation tests with different indentation heads, different loading directions and different impact speeds were performed on battery modules with prismatic cells. To mitigate thermal runaway, only fully discharged battery modules were used. The force-displacement responses and open circuit voltage were recorded and compared. It was found that the battery modules experienced different failure modes when subjected to mechanical abuse. Besides internal short circuit of cells, external short circuit from bus bar and vapor leakage of electrolyte were also found to deteriorate the mechanical and electrical integrity of the tested modules. Mechanical anisotropy and dynamic effect were found on the battery module.