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Technical Paper

USE OF CFD SIMULATION TO PREDICT CAVITATION IN AUTOMOTIVE HEATER CORES

2005-11-22
2005-01-4027
Several heater cores failed due to erosion by cavitation. After analysis, most of failures were explained by the presence of impurities in the heater core. It was then decided with the customer to use CFD simulation in order to prove that the cavitation was not caused by design concept of the tank. In this paper, we present the results of heater core simulations done in 2D and in 3D with Fluent. The objective is to simulate the pressure and velocity distribution within the heater core and to verify if the zones of low pressure are below the saturation vapour pressure of the fluid causing cavitation. In these areas, the deterioration of the tubes might occur due to erosion by cavitation.
Technical Paper

US and UK Field Rollover Characteristics

2001-03-05
2001-01-0167
In this study, US and UK accident data were analyzed to identify parameters that may influence rollover propensity to analyze driver injury rate. The US data was obtained from the weighted National Automotive Sampling System (NASS-CDS), calendar years 1992 to 1996. The UK pre-roll data was obtained from the national STATS 19 database for 1996, while the injury information was collected from the Co-operative Crash Injury Study (CCIS) database. In the US and UK databases, rollovers accounted for about 10% of all crashes with known crash directions. In the US and UK databases, most rollovers occurred when the vehicle was either going straight ahead or turning. The propensity for a rollover was more than 3 times higher when going around a bend than a non-rollover. In the UK, 74% of rollovers occurred on clear days with no high winds and 14% on rainy days with no high winds. In the US, 83% of rollovers took place in non-adverse weather conditions and 10% with rain.
Technical Paper

US and UK Belted Driver Injuries with and without Airbag Deployments - A Field Data Analysis

1999-03-01
1999-01-0633
This study compares the effect of US and European airbag deployments on injury outcomes for belted drivers in frontal crashes. Driver weight, height and seat track position was also examined in relation to those outcomes. This information may help to prioritize and guide the logic for “Smart” airbags. For the study, only airbag-equipped cars were considered. Two accident databases were used: 1) the weighted and unweighted National Accident Sampling System (NASS-CDS) from the US, calendar years 1995 to 1996, and 2) the unweighted Co-operative Crash Injury Study (CCIS) from the UK, calendar years 1992 to 1998. The parameters investigated were Injury Severity Score (ISS), Equivalent Test Speed (ETS), occupant weight, occupant height and seat location. For US drivers, the injury rate and occurrence were calculated using weighted data, while for UK drivers, the rate and occurrence were obtained using unweighted data.
Technical Paper

Transient Simulation of DGI Engine Injector with Needle Movement

2002-10-21
2002-01-2663
Utilization of direct injection systems is one of the most promising technologies for fuel economy improvement for SI engine powered passenger cars. Engine performance is essentially influenced by the characteristics of the injection equipment. This paper will present CFD analyses of a swirl type GDI injector carried out with the Multiphase Module of AVL's FIRE/SWIFT CFD code. The simulations considered three phases (liquid fuel, fuel vapor, air) and mesh movement. Thus the transient behavior of the injector can be observed. The flow phenomena known from measurement and shown by previous simulation work [2, 7, 10, 11] were reproduced. In particular the simulations shown in this paper could explain the cause for the outstanding atomization characteristics of the swirl type injector, which are caused by cavitation in the nozzle hole.
Technical Paper

Thermal Electric Analysis of Bond Wires Used in Automotive Electronic Modules

2015-04-14
2015-01-0195
Bond wires are used in automotive electronic modules to carry current from external harness to components where flexibility under thermal cyclic loading is very essential between PCB (Printed Circuit Board) and connectors. They are very thin wires (few μm) made up of gold, aluminum or copper and have to undergo mechanical reliability to withstand extreme mechanical and thermal loads during different vehicle operation scenarios. Thermal reliability of bond wire is to make sure that it can withstand prescribed electric current under given boundary conditions without fusing thereby retaining electronic module's functionality. While carrying current, bond wire by virtue of its nature resists electric current flow and generates heat also called as joule heating. Joule heating is proportional to current flow and electrical resistance and if not handled properly can lead to thermal run away conditions.
Technical Paper

The Solution for Steady State Temperature Distribution in Monolithic Catalytic Converters

2001-03-05
2001-01-0941
This paper presents a simplified thermal model for round catalytic converters in steady state operation. Using this model, the analytic solution for the temperature distribution in the monolithic substrate is obtained. This analytic solution in the substrate is, then, combined with those in the intumescent mat [1] and the metal shell to obtain the temperature profile in the radial direction of the converter except for three unknown temperatures at the three material interfaces, which can be solved using an Excel application program. This analytical temperature solution facilitates the studies of the effects of various design parameters such as the exhaust gas temperature, exhaust gas flow rate, substrate cell geometry, converter dimensions, and ambient temperature and flow, etc.
Technical Paper

Suppression Technologies for Advanced Air Bags

2000-11-01
2000-01-C037
In May 2000 the National Highway Traffic Safety Administration (NHTSA) issued the final rule for the Advanced Air Bag regulations effective MY 2004 for vehicles to be sold in the United States. These regulations are in response to the air bag-induced injuries seen in the field, especially to children and short women. Advanced air bags require a vehicle manufacturer to design air bags for a broad array of occupants: 12-month-old, 3-year-old and 6-year-old children, and 5th percentile adult females, as well as 50th percentile adult males with new and more stringent injury criteria. Requirements for minimizing air bag risks include automatically turning off the air bag in the presence of young children or deploying the air bag in a manner much less likely to cause serious or fatal injury to out-of-position occupants. Technologies that disable the air bag in the presence of young children or adults in out-of-position are termed as "suppression technologies.'
Technical Paper

Rollover Stability Index Including Effects of Suspension Design

2002-03-04
2002-01-0965
In this paper a simple yet insightful model to predict vehicle propensity to rollover is proposed, which includes the effects of suspension and tire compliance. The model uses only a few parameters, usually known at the design stage. The lateral accelerations at the rollover threshold predicted by the model are compared to the results of simulations, in which vehicles with the same static stability factor, but different suspension characteristics and payloads are subjected to roll-inducing handling maneuvers. The results of simulations correlate well with the predictions based on the proposed model. Design recommendations for passive suspensions, which would increase rollover stability are discussed.
Technical Paper

Rheocasting of Semi-Solid A357 Aluminum

2000-03-06
2000-01-0059
The most popular aluminum alloys for semi-solid automotive components are A356 and A357. The density of rheocast semi-solid A357 is higher than die cast A357 and allows for both T5 and T6 heat treatment. The mechanical properties of rheocast semi-solid A357 was found to be more dependent upon the heat treat schedule and casting soundness than by the solid content of the semi-solid slurry or the globule shape.
Technical Paper

Reliability of Resonant Micromachined Sensors and Actuators

2001-03-05
2001-01-0618
There are an increasing number of applications for resonant micromachines. Accelerometers, angular rate sensors, voltage controlled oscillators, pressure and chemical sensors have been demonstrated using this technology. Several of these devices are employed in vehicles. Vibrating devices have been made from silicon, quartz, GaAs, nickel and aluminum. Resonant microsystems are in constant motion and so present new challenges in the area of reliability for vehicular applications. The impact of temperature extremes, cyclic fatigue, stiction, thermal and mechanical shock on resonant device performance is covered.
Technical Paper

Physicochemical Characteristics of Soot Deposits in EGR Coolers

2010-04-12
2010-01-0730
Physicochemical characteristics of the soot deposits in a fouled EGR cooler are studied in this paper. It is found that a three-layer model for the soot deposited in the EGR cooler may well describe the behavior of the depositing process: a dense base layer with micro pores (≺ 5 nm), a randomly packed intermediate layer with meso pores (5-50 nm) and a loose surface layer with macro pores (≻ 50 nm). The surface layer is thick and highly porous, formed by mechanical interlocking of the agglomerated primary soot particles or soot clusters. The soot particles in the surface layer may be removed by a high shear EGR flow. Condensates in the deposit, especially water, can have a significant influence on the structure of the deposit. Capillary forces on the wetted soot particles could be comparable to the contact forces holding the particles together. It is found that the hydroscopicity of the soot particles vary with their content of soluble organic fraction (SOF).
Technical Paper

Performance Evaluation of Door & Seat Side-Impact Airbags for Passenger Van and Sport-Utility Vehicles

1998-02-23
980912
Side impact accounts for a significant source of societal harm, injury and death. To address this issue, Europe and US have introduced legislation to be met for the new vehicle certification. In an effort to meet these regulations and the market demand for safety, Automotive manufacturers have significantly improved vehicle side structure integrity and introduced side impact airbags are for added protection. Today, passenger vans, light truck and sport-utility type vehicles are all popular consumer choices in the US. These vehicles differ significantly from passenger cars in many respects and as such need special design considerations for side airbags. Here, MADYMO-3D model of a generic passenger van / Sport-Utility type vehicle is created and correlated to FMVSS-214 side impact crash test. This model is used to evaluate both door and seat mounted side airbag designs in different orientations at standard test impact condition and at a higher speed.
Journal Article

Particulate Fouling in EGR Coolers

2009-10-06
2009-01-2877
The physical process of particulate fouling in EGR coolers is analyzed in this paper. Various particulate-deposition mechanisms are discussed and an order of magnitude comparison suggests that thermophoresis is the dominant mechanism for the EGR cooler fouling. The EGR temperature at the cooler inlet, the soot particle concentration in EGR, and the EGR mass flow rate are found to be the parameters governing the EGR cooler fouling. The structure for the soot deposit buildup on the cooler wall is also discussed. It is found that the surface layer of the deposit governs the fouling factor. A comprehensive model for soot particle depositions is developed employing heat, mass, and momentum transfer theories for the particle-gas system. The fouling model developed in this study can predict the process of deterioration in the effectiveness. The predictions of EGR cooler fouling are compared with experimental data and good agreement is observed.
Technical Paper

Optimization of Oxygen Sensor

2000-03-06
2000-01-1364
Optimization of the mechanical aspects of a heated conical oxygen sensor for desired performances, such as low heater power, good poison resistance, fast light-off, and broad temperature range, etc. was achieved with computer modeling. CFD analysis was used to model the flow field in and around a sensor in an exhaust pipe to predict the convection coefficients, poisoning, and switching time. Heat transfer analysis coupled with electrical heating was applied to predict temperature and light-off time. Results of the optimization are illustrated, with good agreements between modeling and testing.
Technical Paper

Numerical Prediction of Brake Fluid Temperature Rise During Braking and Heat Soaking

1999-03-01
1999-01-0483
Long repetitive braking, such as one which occurs during a mountain descent, will result in a brake fluid temperature rise and may cause brake fluid vaporization. This may be a concern particularly for passenger cars equipped with aluminum calipers and with a limited air flow to the wheel brake systems. This paper describes the computer modeling techniques to predict the brake fluid temperature rise as well as other brake component temperatures during braking and heat soaking. Numerical results are compared to the measured vehicle data and the effects of relevant brake system parameters on the fluid temperature are investigated. The techniques developed in this study will help brake engineers to build a safer brake system and reduce the extensive vehicle tests currently required.
Technical Paper

Near and Far-Side Adult Front Passenger Kinematics in a Vehicle Rollover

2001-03-05
2001-01-0176
In this study, U.S. accident data was analyzed to determine interior contacts and injuries for front-seated occupants in rollovers. The injury distribution for belted and unbelted, non-ejected drivers and right front passengers (RFP) was assessed for single-event accidents where the leading side of the vehicle rollover was either on the driver or passenger door. Drivers in a roll-left and RFP in roll-right rollovers were defined as near-side occupants, while drivers in roll-right and RFP in roll-left rollovers were defined as far-side occupants. Serious injuries (AIS 3+) were most common to the head and thorax for both the near and far-side occupants. However, serious spinal injuries were more frequent for the far-side occupants, where the source was most often coded as roof, windshield and interior.
Technical Paper

Laser Welding: An Exploratory Study towards Continuous Improvement on Stainless Steel Welding Joints

2009-10-06
2009-36-0330
The utilization of Laser welding process has increased during last years in several areas of industry, due to many benefits that can be achieved with this technology, such as: flexibility, productivity and quality. Thus, the optimization of Laser welding processes has been considered as a “green field” to be explored by Laser manufacturers, automation companies and process/project engineers. Nowadays there are few researches that provide a roadmap for Laser welding processes improvement that approaches both the aspects and characteristics applied to evaluate the Laser weld application performance. Therefore, this paper has per its main purpose through an exploratory study to provide parameters toward continuous improvement of Laser welding process considering both types of Lasers: Laser spot weld and Laser seam weld of stainless steel joints, thus this work may be considered as theoretical and practical reference to be applied by people involved with Laser welding applications.
Technical Paper

LIN Bus and its Potential for Use in Distributed Multiplex Applications

2001-03-05
2001-01-0072
The increasing features and complexity of today's automotive architectures are becoming increasingly difficult to manage. Each new innovation typically requires additional mechanical actuators and associated electrical controllers. The sheer number of black boxes and wiring are being limited not by features or cost but by the inability to physically assemble them into a vehicle. A new architecture is required which will support the ability to add new features but also enable the Vehicle Assembly Plants to easily assemble and test each subsystem. One such architecture is a distributed multiplex arrangement that reduces the number of wires while enabling flexibility and expandability. Previous versions have had to deal with issues such as noise immunity at high switching currents. The LIN Bus with its low cost and rail-to-rail capability may be the key enabling technology to make the multiplexed architecture a reality.
Technical Paper

Instrument Panel Skin Manufactured with 100% Recycled TPO Material

2002-03-04
2002-01-1262
Desiring to push thermoplastic poly-olefin (TPO) technology to its fullest limits and to confirm our position as the leader in the manufacturing of environmentally friendly TPO instrument panels, we have designed a process to manufacture 100% recycled instrument panel skins. This closed-loop process begins with extruding 100% recycled TPO flake into sheet stock to be painted and vacuum formed. The painted sheet is vacuum formed and the offal is ground into regrind flake, ready to be extruded again, thus completing the closed-loop process. This paper will describe a 100% closed loop recycling process for TPO instrument panels, discuss the intense validation process for recycled material and prove the robustness and durability of this interior solution.
Technical Paper

Influence of Active Chassis Systems on Vehicle Propensity to Maneuver-Induced Rollovers

2002-03-04
2002-01-0967
The purpose of this paper is to evaluate through simulations the effects of active chassis systems on vehicle propensity to rollover caused by aggressive handling maneuvers. A 16 degree-of-freedom computer model of a full vehicle is used for this purpose. It includes models of active chassis systems and the associated control algorithms, and allows for simulation of vehicle dynamic behavior under large roll angles. The controllable chassis systems considered in this investigation are active rear steer, brake based vehicle stability enhancement system and active anti-roll bar. The maneuvers used in simulation are the double lane change and the fishhook maneuvers with increasing steering amplitudes. The vehicle represents a midsize SUV with a marginal static stability factor of 1.09 and aggressive tires. The results of simulations demonstrate that the uncontrolled vehicle rolls over in both maneuvers when the steering angle is sufficiently large.
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