Motor vehicle crashes can produce serious head or brain injuries due to contact with interior vehicle structures. It has been found through both field data analysis and experimental testing that many of these brain injuries occur in oblique crashes, even with the deployment of air bags. Research has determined that rotational head velocity is strongly correlated to the risk of brain injury through metrics such as Brain Rotational Injury Criteria (BrIC). The severity of rotational head motion could be related to the friction force developed during contact between the head and air bags. Although crash test dummy head skins are designed with appropriate mass properties and anthropometry as well as material type and thickness to emulate the proper impact response of the human head, it is not known whether they accurately represent the frictional properties of human skin during air bag interaction. This study experimentally characterized the friction coefficient between human skin and air bag fabrics using a pin-on-disc tribometer. Skin samples were harvested from different locations (forehead, cheeks, chin) from specimens of post-mortem human subjects (PMHS). Fabric samples were cut from six different air bags spanning various vehicle manufacturers and interior mounting locations. For comparison, four types of dummy head skin samples were also tested against the air bag samples. Friction was measured between different skinair bag material combinations at various linear velocities and normal forces. It was determined that the difference between human and dummy skin friction with the air bag samples varied significantly among different air bags; however, the effect of linear speed, normal force, and human skin sample harvesting location on friction coefficient is negligible. Except for one air bag fabric, the friction coefficients of the dummy skin are higher than those quantified for human skin.

Externalities of the road transportation are multidimensional in nature and involve the road-vehicle interaction under different environmental conditions. Estimating the pavement and vehicle damage potentials as a function of the conditions under which such interaction takes place, is important to avoid accelerated or catastrophic damages in these systems. Such an assessing is crucial from the perspective of pricing the effects of the vehicle on the infrastructure and vice versa. The existing models for pricing such interaction, critically depends on gross average statistical models. In this paper, it is proposed a deterministic approach to realize such an assessment, based upon validated approaches for the pavement damage. The simulation scheme considers different degrees-of-freedom vehicle models, and a discrete asphalt pavement, that make possible the simulation of massive traffic situations on realistic road lengths.

Vehicle aerodynamics is a prime domain of research and development. Multiple active and passive aerodynamic systems have been applied for its enhancement. The reduction of drag plays a pivotal role in the improvement of vehicle aerodynamic performance. The present paper studies the innovative design of a road vehicle for a fuel efficiency challenge, implemented for optimal drag reduction. Vortex generators are utilized as a passive aerodynamic feature for further minimization of the wake region size and reduction of pressure drag. High fidelity computational fluid dynamics simulations were applied for the evaluation of this design. Data was collated from simulations for both the cases, with and without the usage of vortex generators and compared objectively. The results of the study establish that the vehicle design has an exceptionally low drag coefficient. It also exhibits a strong reduction in drag when the vortex generators are fitted. These results reveal that the design can be deployed for production as a worthy competition vehicle.

Prior works showed that elderly females are a vulnerable segment of the population that needs special attention for their safety in traffic accidents. To study the injury performance of this vulnerable group in motor vehicle crashes (MVCs), a finite element model was developed to represent the full body of 70-year-old regular sized female. However, this model did not take the variations in size and shape among this group of people into account. In this study, an adaptive radial basis functions (RBF) methodology is developed to rapidly morph the baseline model to the target models defined by the statistical models of external body surface and the exterior ribcage. High speed frontal crash simulations are subsequently performed to investigate the effects of BMI on impact injuries. The results show that obese senior female occupants sustained higher risks of thorax, femur and head injuries than that of regular sized occupants. While BMI has no linear effect on head and thorax injury.

Wheel Slip Regulation (WSR) is one of the Active Vehicle Safety Systems (AVSSs) for maintaining vehicle stability and maneuverability during emergency braking An approach for wheel slip prediction is proposed in this paper, which involves Auto-Regressive (AR) Time-Series modelling of longitudinal vehicle acceleration. This technique allows the usage of linear longitudinal vehicle dynamics for wheel slip estimation. A wheel slip prediction model was developed considering measurements from accelerometer and wheel speed sensor. This modified the Model Predictive Control (MPC) formulation to a univariate control input problem, involving braking torque. The objective function was devised for solving a least-squares reference tracking problem. An analytical solution for the MPC optimization problem was derived and implemented towards WSR. The proposed framework was programmed in MATLAB Simulink ® and co-simulated with IPG TruckMaker ® (a vehicle dynamic simulation software). The algorithm was tested in a Hardware-in-Loop (HiL) setup consisting of a pneumatic air brake system interfaced with IPG TruckMaker ® . Open loop studies from HiL led to the inclusion of Kalman filter for estimate tuning and PID inner loop control for brake pressure transients, which improved wheel slip regulation.

Wheel lock is an undesired phenomenon in Heavy Commercial Road Vehicles (HCRVs) and wheel slip control within a desired range is of crucial importance for stable and effective braking. This study proposes a framework to distribute brake force dynamically between the front and rear wheels, primarily to avoid instability by preventing wheel lock. Further, it ensures the maximum utilization of the available traction force at the tire-road interface that varies during the course of braking due to factors like load transfer. Wheel slip regulation provides an approach to maximize braking performance that subsumes the effects of varying road, load and braking conditions that occur during vehicle deceleration. The methodology proposed consists of a wheel slip controller that calculates the required brake force distribution parameters, which are then provided to the brake controller for control action. Sliding mode control was used because of the nonlinear nature of the longitudinal vehicle dynamic model considered and for robustness towards different parameter variations. The algorithm was implemented on a Hardware-in-Loop test setup consisting of a pneumatic air brake system, interfaced with IPG-TruckMaker ® (a vehicle dynamic simulation software), and co-simulated with MATLAB-Simulink ® . It was found that this algorithm improved the braking performance of a HCRV both in terms of stopping distance and vehicle stability.

The mesh morphing method is widely applied in building subject-specific human finite element models. However, there are many problems yet to be resolved when applying the mesh morphing method in subject-specific modeling, such as calculation difficulties and low morphing accuracy. To solve these problems above, an efficient peak-selection RBF mesh morphing method is proposed in the paper. Firstly, by comparing different types of radial basis functions, an optimal kernel function is selected to improve morphing accuracy. Secondly, the landmarks are reduced by selecting multiple peak nodes from the object surfaces, so as to reduce iteration steps and improve the mesh generation efficiency. The proposed peak-selection Radial Basis Function (RBF) mesh morphing method is further demonstrated through a subject-specific child finite element modeling problem. This mesh morphing method has important significance for analyzing the occupant injury of different body features in motor vehicle crashes.

Transient Scale Resolved Simulations, like the Detached Eddy Simulation, are currently seen to be the preferred modeling approach over the steady-state Reynolds Averaged Navier-Stokes (RANS) simulations for numerical investigations of external flow due to the former’s perceived capability of providing a more realistic flow field prediction. However, the latter approach is still a widely used methodology in road vehicle aerodynamic developments because of its faster turn-around time and cost-effectiveness. However, RANS models, like the SST k –ω, generally fail to produce well-correlated predictions. Studies reveal that good correlations with experiment cannot be achieved by simply refining the mesh when using the SST k –ω model. As such, this study explores the possibility of improving the prediction veracity by investigating the influence of a few selected model closure coefficients on the CFD prediction. This involves first identifying the effect of each individual model parameter on the prediction, and then formulating the best combination of the model closure coefficient values that yield the best correlation with the experiment. This procedure is applied to three different test objects: NACA 4412 airfoil at 12 degree angle of attack, the 25 degree slant angle Ahmed body, and a full-scale passenger road vehicle. Although some closure coefficients do not influence the CFD results much, the predictions are very sensitive to the choice of certain model constants, irrespective of the test object geometry. The study also shows that it is possible to formulate a combination of closure model coefficients that can produce very well correlated CFD predictions.

This work proposes a method to simulate wheel lock of a Heavy Commercial Road Vehicle (HCRV) using pneumatic brake circuit on a brake dynamometer. The proposed methodology lumps the effects of wheel slip and load transfer during straight-line braking into ‘equivalent inertia’ on the wheels. This inertia profile could then be imported on a dynamometer interface and realized using suitable inertia discs and an electric motor. Equivalent inertia was computed from test datasets obtained from a Hardware-in-Loop (HiL) experimental system consisting of an air brake system and IPG TruckMaker ® , a vehicle dynamic simulation software. These datasets were obtained for various road, vehicle load and braking conditions. This framework would facilitate the evaluation of wheel slip regulation algorithms using a brake dynamometer by capturing necessary dynamics of HCRVs during braking. It is expected that such testing can be placed between HiL and on-road tests, and would provide greater confidence in Active Safety Systems (ASSs) before their deployment on vehicles.

Nearly 75% of energy produced by fuel is eventually rejected to the environment and ultimately goes unused in terms of waste heat in motor vehicles. A promising method of reclaiming energy waste is to use thermoelectric (TE) energy harvesters which are multi-material solid-state devices that convert a thermal gradient directly into electric potential. In current automotive applications, waste heat recovery systems using TE are only limited to integration on exhaust pipes to convert hot exhaust gases into electricity. In this study, we explored the use of TE materials in the shape of a car oil pan to utilize the temperature difference of hot engine oil and cool outside air and convert this temperature gradient into electricity. In this study, we performed finite element simulations to optimize the geometry and the quantity of thermoelectric modules. This optimization was performed to achieve maximum thermoelectric power under the constraints of manufacturability. Using these optimum design parameters, we determined that 2.3 kW output power can be recovered from the flat plate oil pan and 2.6 kW from the oil pan with a single step due to the enhanced surface area. These power amounts were found to be higher than those previously obtained from thermoelectric systems integrated to exhaust pipes.

This paper presents an energy-regenerative suspension device that is able to harvest some of the wasted energy that is generated in a suspension system. For a traditional road vehicle suspension system, shock absorbers are mainly dissipating energy to reduce vibration. The dissipated energy may be collected to improve the fuel economy of road vehicles. In this research, CarSim and Simulink are used to simulate and determine the harvestable energy in a conventional shock absorber under different operating conditions. A conceptual energy-regenerative absorber is designed and tested using a fabricated prototype. A variable speed motor is implemented to adapt the change of stroke length of a mechanism due to the various road roughness. Instruments, e.g., laser tachometer, pressure gauge, ammeter, voltmeter, and stopwatch, are used to collect data. The simulation and prototype testing results indicate that the proposed energy-regenerative suspension device could harvest dissipated energy to improve vehicle fuel economy.

The Linear Quadratic Gaussian (LQG) technique has been applied to the design of active vehicle suspensions (AVSs) for improving ride quality and handling performance. LQG-based AVSs have achieved good performance if an accurate vehicle model is available. However, these AVSs exhibit poor robustness when the vehicle model is not accurate and vehicle operating conditions vary. The H ∞ control theory, rooted in the LQG technique, specifically targets on robustness issues on models with parametric uncertainties and un-modelled dynamics. In this research, an AVS is designed using the H ∞ loop-shaping control, design optimization, and parallel computing techniques. The resulting AVS is compared against the baseline design through numerical simulations.

This paper focuses on the effects of aerodynamic aids on the lateral and longitudinal dynamics of high-speed road vehicles. Aerodynamic aids, such as spoilers, can reduce drag to improve vehicle’s fuel economy and acceleration performance. On the other hand, aerodynamic aids can be utilized to enhance the lateral stability of the vehicle at high speeds by generating downforce or negative lift. However, the co-existence of drag and lift creates a paradox, that is, the downforce generated to improve car’s high-speed stability acts as a parasitic force on the car-body and slows down the vehicle forward speed. This paper will illustrate the juxtaposed effects of the aerodynamic forces on the lateral stability of the vehicle. Airfoils in the role of external aerodynamic aids will be examined based on their shapes, geometrical configurations, and at varying relative positions using the CFD technique. Moreover, the effects of attack angles, change in Reynold’s numbers (air stream velocities), and varying ground clearance on the lateral dynamics of the vehicle will be analyzed using numerical simulations with ANSYS FLUENT software package. The results and reliability of CFD simulations has a high dependency on the size of the grid, thus the aim of this paper will be to ensure that the results are independent of the grid size. Selection of the optimum design will be based on performance parameters like drag and lift coefficients. The challenge posed here is to ensure the lateral stability of the vehicle while achieving high average speed. Therefore, the main goal of the study is to enhance handling capabilities of the road vehicles at high speeds while minimizing the drag.

In this paper, a collision avoidance algorithm (CAA) has been proposed using variable time headway considering heterogeneous traffic. The time headway used in the proposed CAA was tuned based on the traffic scenarios, the host vehicle’s load conditions and the type of the lead vehicle that the host vehicle encounters in the traffic. The proposed variable time headway would help to avoid the intervention of the collision avoidance system during normal driving and gain driver’s acceptance. The CAA was evaluated using a hardware-in-the-loop (HiL) experimental set-up integrated with the vehicle dynamic simulation software IPG/TruckMaker ® for different categories of lead vehicles such as 2/3 wheelers, passenger cars, light commercial road vehicles (LCVs) and heavy commercial road vehicles (HCVs). From the results, it was observed that while following a HCV, a smaller time headway was sufficient to prevent a collision compared to following a passenger car, LCV and 2/3 wheeler.

Modern methods for analyzing motor vehicle deformation rely upon a force-deflection analysis to determine deformation work energy. Current methods provide acceptable accuracy when calculating the velocity change of vehicles involved in a collision but require significant modification to accommodate oblique and low-velocity collision events. The existing algorythms require vehicle-specific structural stiffness coefficients for each colliding vehicle, determined from full-scale impact testing. The current database of vehicle structural stiffness values is generated mainly through government safety standard compliance testing and is quite extensive for frontal impacts involving passenger cars and many light trucks and SUVs. However, the database is devoid of specific crash testing necessary for deformation analysis of rear and side structures of many vehicles. Additionally, there remains a dearth of structural stiffness coefficients for heavy commercial vehicles, buses, recreational vehicles, heavy equipment and motorcycles, rendering the application of the current force-deflection analysis approach useless for many impacts involving such vehicles. The research presented, known as the Generalized Deformation and Total Velocity Change System of Equations , or G-DaTA ΔV ™, develops an accurate, reliable and broadly-applicable system of equations requiring knowledge of the structural stiffness coefficients for only one vehicle, rather than both vehicles involved in a collision event, regardless of the impacted surfaces of the vehicle. The developed methodology is inclusive of non-passenger vehicles such as commercial vehicles and even motorcycles, and it also accommodates impacts with objects and surfaces not supported by the current structural stiffness coefficient database. The G-DaTA ΔV ™ system of equations incorporates the linear and rotational collision contributions resulting from conservative forces acting during the impact event. The contributions of the G-DaTA ΔV ™ system of equations are as follows: 1. Consideration of non-conservative contributions from tire-ground forces and inter-vehicular frictional energy dissipation commonly present during non-central collision configurations. 2. Ability to solve for collision energy of a two-vehicle system using a single structural stiffness for only one of the colliding vehicles using work/energy principles. 3. Determination of the total velocity change for a vehicle resulting from a given impact event, which results from conservative and non-conservative force contributions. 4. The ability to predict the time period to reach maximum force application during an impact event, allowing for the determination of the peak acceleration levels acting on each vehicle during an impact. The results of applying the G-DaTA ΔV ™ to full-scale impact tests conducted as part of the RICSAC collision research will be presented. Additionally, analysis of real-world collision data obtained through the National Automotive Sampling System demonstrates a close correlation with the collision values recorded by the vehicle event data recorders (EDRs) as part of the supplemental restraint system airbag control moducles (ACM). Compared to other analysis methods currently used, determining the total velocity change of a vehicle due to a collision event is achieved with a higher level of both accuracy and precision when using the G-DaTA ΔV ™. The generalized approach of the G-DaTA ΔV ™ applies to collisions ranging from the simple collinear impact configuration to the most rigorous conditions of offset and oblique impacts. The comprehensive formulation provides greater utility to the researcher or forensic analyst in determining the contributions of the vehicle-roadway-driver environment as it relates to real-world collision events and their effects on vehicle and highway safety.

This paper investigates the combined effects of specific impact direction and impact location on the serious-to-maximum (AIS3–6) thoracic injuries of drivers in frontal impacts based on the 1995–2009 data from the United States Department of Transportation (US DOT) National Automotive Sampling System/Crashworthiness Data System (NASS/CDS). The selected sample is limited to three impact locations near the driver side (distributed, offset and corner) and two impact directions (pure frontal and oblique) treated as the frontal direction, resulting in a total of six crash configurations. The risks of thoracic injury for drivers in all frontal crash configurations are evaluated. The relative risks with 95% confidence intervals are calculated. Binary logistic regressions are fitted to the datasets for further examination of the effects of impact direction and impact location on the serious-to-maximum thoracic injuries. Occupant characteristics and crash severity are also included as explanatory variables. Overall, impact location and impact direction have considerable influences on thoracic injury pattern and severity for drivers. For distributed and corner deformation, oblique loading is approximately 3 times more likely to lead to thoracic injures than pure frontal loading. Conversely, the relative risk is 3.44 for offset deformation, which indicates that, for this impact location, frontal impact is more associated thoracic injuries compared to oblique impact. The effects of impact location and impact direction on serious-to-maximum injuries for three types of anatomical structures (organ, skeletal and vessel) are assessed as well. In addition to crash related variables (impact location and impact direction), results of the binary logistic regressions also indicate that crash severity (OR, 7.67–81.35) and occupant characteristics, including age (OR, 4.80–20.83), gender (OR, 1.16) and BMI (OR, 1.81), significantly affect the risks of thoracic injuries in frontal motor vehicle collisions.

The use of transportation residual energy can represent an alternative energy source to reduce the consumption of fossil fuels. In specific economic environments, in which the road conditions are not good, the vibration of the vehicles’ masses, represent a potential enormous source for such alternative energy source. In this paper, the conceptual design of an energy-harvesting accessory to be installed in existing suspensions of vehicles, is presented. The principles of operation include an electromagnetic generator, a rectifier and a battery. Validation of the proposed accessory is made through simulation that indicates the feasibility of this device.

In today’s society, those who do not take advantage of public transportation services typically drive personal vehicles to school, work, and other locations of interest. Due to the required amount of physical exertion, walking or riding a bike is often avoided. This is concerning given that a large percentage of carbon and hazardous emissions emanate from motor vehicles. This creates a need for an alternative means of travel for shorter commutes with electric bikes (e-bikes) one potential solution. They have zero tailpipe emissions and significantly lower overall emissions relative to motorized vehicles; however, their cost often prevents them from being readily marketable. In order to address this issue, two undergraduate capstone design teams have constructed e-bikes using recycled and donated parts over the past two years. In the first year, the runner from a pickup truck was scavenged from a junkyard and employed as the frame to provide for the greatest environmental benefit. However, this resulted in an odd bicycle shape because of limited material availability. As a result, the second years team decided to use a donated chrome moly tube as the frame while focusing on ergonomics and aesthetics. This second bike was designed so that a male rider of average height (5′10″ – 1.78 m) could complete commutes of several miles in relative comfort. Both e-bikes employ a direct drive motor (first year – front wheel; second year – back wheel) to provide assistance when needed, leaving the rider less fatigued. To promote further development in electric bike design, each team has made a considerable effort to record the design process with highlights presented in this effort. Furthermore, e-bike testing results are presented including center of mass calculations, braking distances, turning radii, and overall efficiencies quantified by the miles traveled using the same battery pack. This information will be used to compare the bikes against each other in order to illustrate bike attributes that are desired when an electric motor is employed. The result is an appealing, cost-effective, and efficient electrical bike that will greatly reduce traffic related emissions should it become widely implemented. Given the issues related to transportation at a university (e.g., available parking) including the reticence of students to traverse long distances across campus to attend classes, it is believed that this effort can serve as a model example to other universities who might see e-bikes as a potential solution to reducing congestion and improving student attendance.

Composite materials have emerged as promising materials in applications where low weight and high strengths are desired. Aerospace industry has been using composite materials for past several decades exploiting their characteristics of high strength to weight ratio over conventional homogenous materials. To provide a wider selection of materials for design optimization, and to develop lighter and stronger vehicles, automobile industries have been exploring the use of composites for a variety of components, assemblies, and structures. Composite materials offer an attractive alternate to traditional metals as designers have greater flexibility to optimize material and structural shapes according to functional requirements. However, any automotive structure or part constructed from composite materials must meet or exceed crashworthiness standards such as Federal Motor Vehicle Safety Standard (FMVSS) 208. Therefore, for a composite structure designed to support the integrity of the automotive structure and provide impact protection, it is imperative to understand the energy absorption characteristics of the candidate composite structures. In the present study, a detailed finite element analysis is presented to evaluate the energy absorbing characteristics of a carbon fiber reinforced polymer composite lower rail, a critical impact mitigation component in automotive chassis. For purposes of comparison, the analysis is repeated with equivalent aluminum and steel lower rails. The study was conducted using ABAQUS CZone module, finite element analysis software. The rail had a cross-sectional dimension of 62 mm (for each side), length of 457.2 mm, and a wall thickness of 3.016 mm. These values were extracted from automobile chassis manufacturer’s catalog. The rail was impacted by a rigid plate of mass 1 tonne (to mimic a vehicle of 1000 Kg gross weight) with an impact velocity of 35 mph (15646.4 mm/s), which is 5 mph over the FMVSS 208 standard, along its axis. The simulation results show that the composite rail crushes in a continuous manner under impact load (in contrast to a folding collapse deformation mode in aluminum and steel rails) which generates force-displacement curve with invariable crushing reactive force for the most part of the crushing stroke. The energy curves obtained from reactive force-displacement graphs show that the composite rail absorbs 240% and 231% more energy per unit mass as compared to aluminum and steel rails. This shows a significant performance enhancement over equivalent traditional metal (aluminum and steel) structures and suggests that composite materials in conjunction with cellular materials/configurations have a tremendous potential to improve crashworthiness of automobiles while offering opportunities of substantial weight reductions.

Lower neck injuries inferior to C4 level, such as fractures and dislocations, occur in motor vehicle crashes, sports, and military events. The recently developed interaction criterion, termed N ij , has been used in automotive safety standards and is applicable to the upper neck. Such criterion does not exist for the lower neck. This study was designed to conduct an analysis of data of lower neck injury metrics toward the development of a mechanistically appropriate injury criterion. Axial loads were applied to the crown of the head of post mortem human subject (PMHS) head-neck complexes at different loading rates. The generalized force histories at the inferior end of the head-neck complex were recorded using a load cell and were transformed to the cervical-thoracic joint. Peak force and peak moment (flexion or extension) were quantified for each test from corresponding time histories. Initially, a survival analysis approach was used to derive injury probability curves based on peak force and peak moment alone. Both force and moment were considered as primary variables and age a covariate in the survival analysis. Age was found to be a significant (p<0.05) covariate for the compressive force and flexion moment but insignificant for extension moment (p>0.05). A lower neck N ij formulation was done to derive a combined interactive metric. To derive cadaver-based metrics, critical intercepts were obtained from the 90% injury probability point on peak force and peak moment curves. The PMHS-based critical intercepts derived from this study for compressive force, flexion, and extension moment were 4471 N, 218 Nm, and 120 Nm respectively. The lower cervical spine injury criterion, Lower N ij (LN ij ), was evaluated in two different formulations: peak LN ij and mechanistic peak LN ij . Peak LN ij was obtained from the LN ij time history regardless of when it occurred. Mechanistic peak LN ij was obtained from the LN ij time history only during the time when the resulting injury mechanism occurred. Injury mechanism categorization included compression-flexion, compression-extension, and those best represented by a more pure compression-related classification. Mechanistic peak LN ij was identified based on the peak timing of the injury mechanism. Peak LN ij and mechanistic peak LN ij were found to be significant (p<0.05) predictors of injury with age as a covariate. The 50% injury probability was 1.38 and 1.13 for peak LN ij and mechanistic peak LN ij , respectively. These results provide preliminary data based on PMHS tests for establishing lower neck injury criteria that may be used in automotive applications, sports and military research to advance safety systems.