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Technical Paper

A 3D Simulation Methodology for Predicting the Effects of Blasts on a Vehicle Body

Triggered explosions are increasingly becoming common in the world today leading to the loss of precious lives under the most unexpected circumstances. In most scenarios, ordinary citizens are the targets of such attacks, making it essential to design countermeasures in open areas as well as in mobility systems to minimize the destructive effects of such explosive-induced blasts. It would be rather difficult and to an extent risky to carry out physical experiments mimicking blasts in real world scenarios. In terms of mechanics, the problem is essentially one of fluid-structure interaction in which pressure waves in the surrounding air are generated by detonating an explosive charge which then have the potential to cause severe damage to any obstacle on the path of these high-energy waves.
Journal Article

A 3D Semi-Empirical On-Road Transient Tire Model

To realistically predict the dynamics of a vehicle, the forces and moments in the contact patch must be accurately computed. A two-dimensional semi-empirical transient tire model was previously developed in the Advanced Vehicle Dynamics Lab (AVDL) at Virginia Tech, and extended the capabilities of the steady-state tire model also developed at AVDL. In this paper, a three-dimensional semi-empirical transient tire model is presented. The tire structure is modeled by an elastic ring supported on a spring and damper system. The elastic ring represents the belt ring and the spring and damper system represents the sidewall and the tread element. The analysis of the deformation of the tire structure with camber angle is performed on a flat surface to obtain the geometry of the contact patch and the normal pressure distribution. The forces and the moments are formulated using empirical data and based on theoretical mechanics.
Technical Paper

A 3D Linear Acoustic Network Representation of Mufflers with Perforated Elements and Sound Absorptive Material

The acoustics of automotive intake and exhaust systems is typically modeled using linear acoustics or gas-dynamics simulation. These approaches are preferred during basic sound design in the early development stages due to their computational efficiency compared to complex 3D CFD and FEM solutions. The linear acoustic method reduces the component being modelled to an equivalent acoustic two-port transfer matrix which describes the acoustic characteristic of the muffler. Recently this method was used to create more detailed and more accurate models based on a network of 3D cells. As the typical automotive muffler includes perforated elements and sound absorptive material, this paper demonstrates the extension of the 3D linear acoustic network description of a muffler to include the aforementioned elements. The proposed method was then validated against experimental results from muffler systems with perforated elements and sound absorptive material.
Technical Paper

A 3D Head Up Display with Simulated Collimation

A 3D Stereoscopic Head-Up Display (HUD) using direct projection on a transparent screen is presented. Symbol incrustation in conformity with the landscape is performed through the use of simulated collimation offering a large eye-box, in excess of conventional HUD. The use of spectral glasses for our transparent screen was decided as most commonly used polarizing or active glasses were not adapted. Furthermore it gave ususeful green laser attack protection.
Journal Article

A 3D Full Windshield Head Up Display

A new concept of Head Up Display is presented, using the windshield as a transparent screen. This breakthrough technology does not need the use of complex combiner, bulky optics and overhead projection unit. The novel system uses several holographic optical elements to perform a 3D stereoscopic display, with the ability to present floating graphical objects in a large field of view. Augmented Reality display will be possible, increasing considerably the User Experience and situational awareness, without the need of wearing a bulky and complex Head Mounted Display.
Technical Paper

A 3D Finite Element Model of Pelvis in Side Impact

A 50th percentile male pelvis finite element model was designed for impact simulation. Shell elements represented the pelvic bone, which geometry was taken into account. Non linear viscous springs accounted for soft tissues connecting skin to bone structure, and body segments inertia around the pelvis were represented using rigid bodies. Geometric and mechanical characteristics were taken either from litterature or by identification to in house experimental results. Three dimensional movements were reproduced by the model for static lateral loading and dynamic lateral impact simulation at two different velocities, 3.5 and 6.5 m/s, with a good agreement with experimental results. This model takes into account pelvic bone geometry, allowing an appreciation of its deformation and therefore injury risk.
Technical Paper

A 3D Eulerian Model to Improve the Primary Breakup of Atomizing Jet

A 3D Eulerian model has been developed to improve the primary break-up of an atomizing jet. The model is divided in three parts and is implemented in a modified version of KIVA II. The first part focuses mainly on the liquid dispersion, the second on the atomizing process itself, and the third on the adaptation of the model's mathematical formulation to the physics of the flow. Since the spray close to the injector is dense, an Eulerian formulation is thus chosen. However, when the spray is diluted, a Lagrangian formulation should then be applied. Different computations have been carried out using this new model and will be thoroughly discussed in this paper. The first calculation serves as a validation of the model. Those which follow demonstrate the importance of the internal liquid flow inside the injector on the spray development. They also manifest an influence of the air-co-flow, which assists the atomization of the spray.
Technical Paper

A 3D DNS Investigation on the Flame-Wall Interactions and Heat Loss in a Constant Volume Vessel

A direct numerical simulation of turbulent premixed flames in a constant volume vessel is conducted to understand flame-wall interactions and heat loss characteristics under the pressure rising condition. The contribution of the burnt region to the total heat flux is more significant compared to the reaction region. The velocity profiles indicate inward and outward motions. The profile of the turbulent kinetic energy is damped by the wall, and no distinct turbulence production is observed. Since the turbulence is weakened in the burnt region, the effect of near wall turbulence to the total wall heat flux is considered to be limited.
Journal Article

A 3D CFD Simulation of GDI Sprays Accounting for Heat Transfer Effects on Wallfilm Formation

During gasoline direct injection (GDI) in spark ignition engines, droplets may hit piston or liner surfaces and be rebounded or deposit in the liquid phase as wallfilm. This may determine slower secondary atomization and local enrichments of the mixture, hence be the reason of increased unburned hydrocarbons and particulate matter emissions at the exhaust. Complex phenomena indeed characterize the in-cylinder turbulent multi-phase system, where heat transfer involves the gaseous mixture (made of air and gasoline vapor), the liquid phase (droplets not yet evaporated and wallfilm) and the solid walls. A reliable 3D CFD modelling of the in-cylinder processes, therefore, necessarily requires also the correct simulation of the cooling effect due to the subtraction of the latent heat of vaporization of gasoline needed for secondary evaporation in the zone where droplets hit the wall. The related conductive heat transfer within the solid is to be taken into account.
Technical Paper

A 3D CFD Simulation for Optimization of Metal Fiber DPF System

Metal fiber DPF system is cheaper and more endurable than ceramic filter; however, the regeneration near the wall (outer layer) is difficult because of the heat loss and the less gas flow rate near the wall. In this study, a 3D CFD simulation is performed to find the flow control method for the more uniform mass flux for all filter layer. The major control factors are filter porosity, distribution plate and swirler. By placing the distribution plate in front of the filter the flow near the wall can be increased. The optimum place and size was chosen. The swirler can increase the flow more near the wall.
Technical Paper

A 360×226 Pixel CMOS Imager Chip Optimized for Automotive Vision Applications

Multiple automotive systems are now being developed which require an imager or vision chip to provide information regarding vehicle surroundings, vehicle performance, and vehicle passenger compartment status. Applications include lane departure, lane tracking, collision avoidance, as well as occupant position, impaired driver, and occupant identification. These applications share many requirements, including robust design, tolerance for the automotive environment, built in self-test, wide dynamic range, and low cost. In addition, each application has unique requirements for resolution, sensitivity, imager aspect ratio, and output format. In many cases, output will go directly to vehicle systems for processing, without ever being displayed to the driver. Commercial imager chips do not address this wide spectrum of requirements. A CMOS imager chip has been designed to address these unique automotive requirements.
Technical Paper

A 322,000 kilometer (200,000 mile) Over the Road Test with HySEE Biodiesel in a Heavy Duty Truck

In July 1997, the Pacific Northwest and Alaska Regional Bioenergy Program, in cooperation with several industrial and institutional partners initiated a long-haul 322,000 km (200,000 mile) operational demonstration using a biodiesel and diesel fuel blend in a 324 kW (435 HP), Caterpillar 3406E Engine, and a Kenworth Class 8 heavy duty truck. This project was designed to: develop definitive biodiesel performance information, collect emissions data for both regulated and non-regulated compounds including mutagenic activity, and collect heavy-duty operational engine performance and durability information. To assess long-term engine durability and wear; including injector, valve and port deposit formations; the engine was dismantled for inspection and evaluation at the conclusion of the demonstration. The fuel used was a 50% blend of biodiesel produced from used cooking oil (hydrogenated soy ethyl ester) and 50% 2-D petroleum diesel.
Technical Paper

A 30 mph Front/Rear Crash with Human Test Persons

A great deal of data is available concerning accident simulation tests with test dummies or cadavers but in comparison there is very little material on tests involving living volunteers. This paper describes crash tests and sled tests with human test persons and Hybrid II dummies. To obtain a realistic accident simulation the tests were run with standard Audi 80 vehicles fitted with the standard seat belt systems. The results clearly demonstrate that none of the test persons sustain any kind of physical injury at a precisely defined level of accident severity (vehicle-to-vehicle crash at a collision speed of approx. 30 mph). In some cases considerable differences are revealed between the loadings imposed on the dummies and the human test persons.
Technical Paper

A 3.4 kW, 42 V High Efficiency Automotive Power Generation System

A 3.4 kW, 42 V permanent magnet alternator based high power generation system was built and tested in the Delphi R&D laboratory. It is belt driven system with 3.37: 1 pulley ratio. The size of the alternator is slightly less than the production CS-144 Lundell machine with 1/3 less inertia. For cost reasons, the controller uses a single SCR bridge rectifier. The prototype, which is capable of producing 34A/80A at idle/cruising speed, has been tested in the laboratory yielding 84.5%/70.7% efficiencies. Up to cruising speed, the system shows an improvement in full load efficiencies of 5-6 percentile points over a similar 14 V permanent magnet machine with dual SCR bridge. This efficiency improvement is due to the reduction in the converter losses as the current is reduced to one third of its 14 V values even with the same copper losses in both machines.
Technical Paper

A 3-Shaft versus a 2-Shaft Cycle in Automotive Gas Turbines

A 3-shaft cycle turbine with a twin-spool compressor system is compared to a 2-shaft cycle with a variable geometry power turbine. Operating in a heavy commercial vehicle, the following engine parameters are considered: specific output power, fuel consumption, engine response, torque characteristics, and engine braking capability. The 3-shaft cycle showed an average improvement of 5% in sfc, a stall torque ratioof 3.8 versus 2.65 for the 2-shaft cycle, a potential increase in engine braking capability, and engine response consistent with the 2-shaft cycle.
Technical Paper

A 3-Dimensional Application of SAE Standards for Driver's Eye Range and the Interior Environment Section of the Field of View Standard

A 3-dimensional procedure has been developed to apply the Driver's Eye Range standard and the interior environment section of the Field of View standards. The procedure uses line-of-sight as a more accurate method of locating and creating the information required. This method produces a truer representation of what is seen and allows for expansion into other obstructions. The procedure can be enhanced with computer macros to shorten the time required to produce these studies.
Technical Paper

A 3-D Surface Topography Measurement System and Its Applications

A 3-D surface topography measurement system was constructed for the surface characterization of an area. This system consists of a personal computer, a microdisplacement stage and a surface profilometer. The microdisplacement system moves the samples laterally for successive traces and ensures the parallelism of each surface profile. The personal computer coordinates the stage movement and surface profile measurements, provides large data storage, and allows rapid data manipulation. This system provides an easy, effective way to characterize a surface, together with versatile displays to observe and record surface topography. It has been used for wear-scar characterization and paint-defect detection. A relocation fixture was incorporated with the 3-D surface-measurement system to provide a powerful tool to observe progressive changes in the surface topography during tribological tests.
Technical Paper

A 3-D Joint Model for Automotive Structures

A simple, design-oriented model of joints in vehicles structures is developed. This model accounts for the flexibility, the offsets of rotation centers of joint branches from geometric center, and the coupling between rotations of a joint branch in different planes. A family of joint models with different levels of complexity is also defined. A probabilistic system identification is used to estimate the joint model parameters by using the measured displacements. Statistical tools which identify important parameters are also presented. The identification methodology is applied to the estimation of parameters of a B-pillar to rocker joint.
Technical Paper

A 2D Vehicle-to-Vehicle Crash Model for Fleet Analysis (Part-I)

This paper presents a 2D model for frontal vehicle-to-vehicle crashes that can be used for fleet modeling. It presents the derivational details and a preliminary assessment of the model. The model is based on rigid-body collision principles, enhanced adequately to represent energy dissipation and lateral engagement that plays a significant role in oblique frontal vehicle-to-vehicle crashes. The model employs the restitution and the apparent friction in order to represent dissipation and engagement respectively. It employs the impulse ellipse to identify the physical character of the crash, based on the principal directions of impulse. The enhancement of the rigid body collision model with restitution and apparent friction is based on collision simulations that use very simple finite element vehicle representations. The dependence of the restitution and the apparent friction on the incidence angle, the frontal offset, and the mass ratio, as predicted by the 2D model, has been presented.
Technical Paper

A 2D Model for Tractor Tire-Soil Interaction: Evaluation of the Maximum Traction Force and Comparison with Experimental Results

The paper investigates the interaction between soil and tractor tires through a 2D numerical model. The tire is schematized as a rigid ring presenting a series of rigid tread bars on the external circumference. The outer profile of the tire is divided into a series of elements, each one able to exchange a normal and a tangential contact force with the ground. A 2D soil model was developed to compute the forces at the ground-tire interface: the normal force is determined on the basis of the compression of the soil generated by the sinking of the tire. The soil is modeled through a layer of springs characterized by two different stiffness for the loading (lower stiffness) and unloading (higher stiffness) condition. This scheme allows to introduce a memory effect on the soil which results stiffer and keeps a residual sinking after the passage of the tire. The normal contact force determines the maximum value of tangential force provided before the soil fails.