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Technical Paper

Optimizing Valve Rotational Speed Using Taguchi Techniques

2010-04-12
2010-01-1096
As fuel economy regulations increase and customer preference shifts to smaller, higher power density engines it is more important to effectively cool certain areas of the cylinder head and valvetrain. In order to maximize valvetrain life and increase engine performance it is critical to maintain a near uniform valve seat temperature to enable proper sealing. As cylinder head bridges narrow, and the temperature increases, the water jacket may not be sufficient. An alternative method to ensuring equal temperature distribution across the valve is to promote low speed valve rotation. This will not only aid, cooling the valve seat, as well as cooling and cleaning the valves' seating surface. This paper describes the development and testing of a valve rotation study, utilizing the Taguchi approach in order to determine the most robust design. A test stand was utilized to examine the valve rotation in which the cam was driven directly using a DC motor.
Technical Paper

Standardization Proposal for “Automotive-Grade AVRCP” with Respect to In-Car use of Bluetooth Devices.

2010-04-12
2010-01-0689
With regard to the use of portable consumer electronic devices in an automobile, Bluetooth has become a widely accepted method for short range wireless communication between a vehicle and a portable device. One Bluetooth connectivity protocol for this use case is Audio/Visual Remote Control Profile (AVRCP). Currently, AVRCP specifies mandatory commands for both target devices (cellular phones and audio players), as well as for control devices like an audio head unit. However, there is no requirement that control devices and target devices implement the same commands, nor is there a requirement that supported commands utilize information that would be useful in improving the driver's experience (i.e. metadata). This paper will describe the impact of this reality from the perspective of the automotive consumer, and propose an “automotive grade” AVRCP that could provide a more consistent consumer experience in the automotive market.
Technical Paper

Evaluation of the Hybrid III 10-year-Old Dummy Chest Response in the Sled Test Environment

2010-04-12
2010-01-0137
Ten sled tests were conducted with a Hybrid III 10-year-old dummy under a 3-point belt only restraint condition to evaluate its performance. The results of the Hybrid III 10-year-old in these tests indicate that there are artifactural noise spikes observable in the transducer responses. A number of metal-to-metal contacts in the shoulder area were identified as one of the sources for the chest acceleration spikes. Noise spikes were also observed in the response from multiple body regions; however, the source of the spikes could not be determined. Compared to the other Hybrid III dummies, non-characteristic dummy chest deflection responses were also observed. This limited analysis indicates that the Hybrid III 10-year-old dummy requires additional development work to eliminate the metal-to-metal contacts in the shoulder area and to understand and correct the other sources of the noise spikes. More investigation is needed to determine if the chest deflection response is appropriate.
Technical Paper

Alternative to Hydrogen/Helium as Flame Ionization Detector Fuel

2013-04-08
2013-01-1045
Flame ionization detector (FID) analyzers used in emission testing to measure total hydrocarbon emissions have been operating for the last forty years on a fuel mixture of 40% H₂ and 60% helium. These mixtures were selected based on research studies reported in the literature indicating that this particular mixed fuel combination gave the best sensitivity and relative response of the different hydrocarbons present in vehicle exhaust with respect to propane, the calibration gas. During the past few years, it was announced that there is a worldwide shortage of helium which triggered the automotive industry to look for alternatives for helium to be used in FID fuels. Helium which is produced as a byproduct from natural gas fields is non-renewable, expensive, and extremely rare on the earth. Current supply cannot keep up with demand. There are only few natural gas fields producing helium and unless new natural gas fields are found, current helium amounts will continue to dwindle.
Technical Paper

Development of a Hybrid Powertrain Active Damping Control System via Sliding Mode Control Scheme

2013-04-08
2013-01-0486
This paper presents the design of a hybrid powertrain damping control algorithm using the sliding mode control (SMC) scheme. Motor control-based active damping control strategy is used to ensure smooth drive line operation and provide the driver with seamless driving experience. In the case of active damping control, motor and engine speeds are measured to monitor the driveline state, and corrective motor torques are generated to dampen out drive line vibrations. Drive lines are prone to internal vibration (engine, clutches and motors) as well as external disturbances caused by road inputs. As such, fast-response actuator-based damping control systems are desirable in a hybrid powertrain application, where a torque converter is generally not used. The most significant aspect of an active damping control algorithm is the error calculation, based on proper states information, and torque determination based on the adaptive control gain applied to the nonlinear system.
Technical Paper

Integrated Virtual Approach for Optimization of Vehicle Sensitivity to Brake Torque Variation

2013-04-08
2013-01-0596
Brake judder is a brake induced vibration that a vehicle driver experiences in the steering wheel or floor panel at highway speeds during vehicle deceleration. The primary cause of this disturbance phenomenon is the brake torque variation (BTV). Virtual CAE tools from both kinematics and compliance standpoints have been applied in analyzing sensitivities of the vehicle systems to BTV. This paper presents a recently developed analytical approach that identifies parameters of steering and suspension systems for achieving optimal settings that desensitize the vehicle response to BTV. The analytical steps of this integrated approach started with creating a lumped mass noise-vibration-harshness (NVH) control model and a separate multi-body dynamics (MBD) suspension model. Then, both models were linked to run in a sequence through optimization software so the results from the MBD model were used as quasi-static inputs to the lumped mass NVH model.
Technical Paper

Kinematic FCW System Modeling and Application for FCW Warning Strategy Evaluation

2011-04-12
2011-01-0590
One method of reducing the number and/or severity of vehicle crashes is to warn the driver of a potential crash. The theory is that there will be driving conditions in which the drivers are unaware of a potential crash and a warning system will allow them to, in some manner, avoid the accident or reduce the severity. In an attempt to develop an analytical understanding of Forward Collision Warning systems (FCW) for frontal impacts a 2-d mathematical/kinematic model representing a set of pre-crash vehicle dynamic maneuvers has been built. Different driving scenarios are studied to explore the potential improvement of warning algorithms in terms of headway reduction and minimization of false alarm rates. The results agree with the field data. NHTSA's new NCAP active safety criteria are evaluated using the model. The result from the analysis indicates that the NHTSA criteria may drive higher false alarm rates. Opportunities of minimizing false positive rates are discussed.
Technical Paper

A Technique to Predict Thermal Buckling in Automotive Body Panels by Coupling Heat Transfer and Structural Analysis

2014-04-01
2014-01-0943
This paper describes a comprehensive methodology for the simulation of vehicle body panel buckling in an electrophoretic coat (electro-coat or e-coat) and/or paint oven environment. The simulation couples computational heat transfer analysis and structural analysis. Heat transfer analysis is used to predict temperature distribution throughout a vehicle body in curing ovens. The vehicle body temperature profile from the heat transfer analysis is applied as an input for a structural analysis to predict buckling. This study is focused on the radiant section of the curing ovens. The radiant section of the oven has the largest temperature gradients within the body structure. This methodology couples a fully transient thermal analysis to simulate the structure through the electro-coat and paint curing environments with a structural, buckling analysis.
Technical Paper

Tonal Metrics in the Presence of Masking Noise and Correlation to Subjective Assessment

2014-04-01
2014-01-0892
As the demand for Sound Quality improvements in vehicles continues to grow, robust analysis methods must be established to clearly represent end-user perception. For vehicle sounds which are tonal by nature, such as transmission or axle whine, the common practice of many vehicle manufacturers and suppliers is to subjectively rate the performance of a given part for acceptance on a scale of one to ten. The polar opposite of this is to measure data and use the peak of the fundamental or harmonic orders as an objective assessment. Both of these quantifications are problematic in that the former is purely subjective and the latter does not account for the presence of masking noise which has a profound impact on a driver's assessment of such noises. This paper presents the methodology and results of a study in which tonal noises in the presence of various level of masking noise were presented to a group of jurors in a controlled environment.
Technical Paper

Optimization of HVAC Panel Aiming Studies using Parametric Modeling and Automated Simulation

2014-04-01
2014-01-0684
In an Automotive air conditioning system, the air flow distribution in the cabin from the HVAC (Heating, ventilation and air conditioning), ducts and outlets is evaluated by the velocity achieved at driver and passenger mannequin aim points. Multiple simulation iterations are being carried out before finalizing the design of HVAC panel duct and outlets until the target velocity is achieved. In this paper, a parametric modeling of the HVAC outlet is done which includes primary and secondary vane creation using CATIA. Java macro files are created for simulation runs in STAR CCM+. ISIGHT is used as an interface tool between CATIA and STARCCM+. The vane limits of outlet and the target velocity to be achieved at mannequin aim points are defined as the boundary conditions for the analysis. Based on the optimization technique and the number of iterations defined in ISIGHT, the vane angle model gets updated automatically in CATIA followed by the simulation runs in STARCCM+.
Technical Paper

Automotive Vehicle Body Temperature Prediction in a Paint Oven

2014-04-01
2014-01-0644
Automotive vehicle body electrophoretic (e-coat) and paint application has a high degree of complexity and expense in vehicle assembly. These steps involve coating and painting the vehicle body. Each step has multiple coatings and a curing process of the body in an oven. Two types of heating methods, radiation and convection, are used in the ovens to cure coatings and paints during the process. During heating stage in the oven, the vehicle body has large thermal stresses due to thermal expansion. These stresses may cause permanent deformation and weld/joint failure. Body panel deformation and joint failure can be predicted by using structural analysis with component surface temperature distribution. The prediction will avoid late and costly changes to the vehicle design. The temperature profiles on the vehicle components are the key boundary conditions used to perform structure analysis.
Journal Article

Effects of Vehicle Mass and Other Parameters on Driver Relative Fatality Risk in Vehicle-Vehicle Crashes

2013-04-08
2013-01-0466
Regression models are used to understand the relative fatality risk for drivers in front-front and front-left crashes. The field accident data used for the regressions were extracted by NHTSA from the FARS database for model years 2000-2007 vehicles in calendar years 2002-2008. Multiple logistic regressions are structured and carried out to model a log-linear relationship between risk ratio and the independent vehicle and driver parameters. For front-front crashes, the regression identifies mass ratio, belt use, and driver age as statistically significant parameters (p-values less than 1%) associated with the risk ratio. The vehicle type and presence of the ESC are found to be related with less statistical significance (p-values between 1% and 5%). For front-left crashes the driver risk ratio is also found to have a log-log linear relationship with vehicle mass ratio.
Journal Article

Forward Collision Warning Timing in Near Term Applications

2013-04-08
2013-01-0727
Forward Collision Warning (FCW) is a system intended to warn the driver in order to reduce the number of rear end collisions or reduce the severity of collisions. However, it has the potential to generate driver annoyances and unintended consequences due to high ineffectual (false or unnecessary) alarms with a corresponding reduction in the total system effectiveness. The ineffectual alarm rate is known to be closely associated with the “time to issue warning.” This results in a conflicting set of requirements. The earlier the time the warning is issued, the greater probability of reducing the severity of the impact or eliminating it. However, with an earlier warning time there is a greater chance of ineffectual warning, which could result in significant annoyance, frequent complaints and the driver's disengagement of the FCW. Disengaging the FCW eliminates its potential benefits.
Journal Article

Statistical Considerations for Evaluating Biofidelity, Repeatability, and Reproducibility of ATDs

2013-04-08
2013-01-1249
Reliable testing of a mechanical system requires the procedures used for the evaluation to be repeatable and reproducible. However, it is never possible to exactly repeat or reproduce the tests that are used for evaluation. To overcome this limitation, a statistical evaluation procedure can generally be used. However, most of the statistical procedures use scalar values as input without the ability to handle vectors or time-histories. To overcome these limitations, two numerical/statistical methods for determining if the impact time-history response of a mechanical system is repeatable or reproducible are evaluated and elaborated upon. Such a system could be a vehicle, a biological human surrogate, an Anthropometric Test Device (ATD or dummy), etc. The responses could be sets of time-histories of accelerations, forces, moments, etc., of a component or of the system. The example system evaluated is the BioRID II rear impact dummy.
Journal Article

Hybrid III Head/Neck Analysis Highlighting Nij in NCAP

2012-04-16
2012-01-0102
Nij, a function of upper neck forces and moment, plays a dominant role in the vehicle's star rating under the new NHTSA NCAP front impact program. This is mainly due to an artifact in the mapping of the Nij into the “risk” value used in the star rating, and the fact that the neck region is not weighted appropriately to reflect its real world significance relative to the other body regions in the NCAP rating. New test data also show that compared with the 50th male driver Nij, the 5th female passenger Nij is significantly more challenging to contain and therefore it is more dominant in the star rating. This paper describes the Hybrid III dummy head and neck impact response and provides a method to determine the external force acting on the head. The force and its acting point on the head are determined from head acceleration, angular acceleration, and the upper neck forces.
Journal Article

System Security and System Safety Engineering: Differences and Similarities and a System Security Engineering Process Based on the ISO 26262 Process Framework

2013-04-08
2013-01-1419
Today's vehicles contain a number of safety-critical systems designed to help improve overall vehicle safety. Such systems may control vital vehicle functions such as steering, braking and/or propulsion independently of the driver. In today's vehicles, much emphasis has been placed on helping ensure that these safety-critical vehicle systems operate as intended. Applying rigorous system safety engineering principles in developing these safety-critical automotive systems helps ensure that they operate as desired and expected. Less emphasis has been placed to-date on helping ensure cybersecurity of cyber-physical automotive systems. However, this is changing as both the world and the automotive industry become more aware of the potential ramifications of cyber-attacks on vehicles.
Journal Article

What's Speed Got To Do With It?

2010-04-12
2010-01-0526
The statistical analysis of vehicle crash accident data is generally problematic. Data from commonly used sources is almost never without error and complete. Consequently, many analyses are contaminated with modeling and system identification errors. In some cases the effect of influential factors such as crash severity (the most significant component being speed) driver behavior prior to the crash, etc. on vehicle and occupant outcome is not adequately addressed. The speed that the vehicle is traveling at the initiation of a crash is a significant contributor to occupant risk. Not incorporating it may make an accident analysis irrelevant; however, despite its importance this information is not included in many of the commonly used crash data bases, such as the Fatality Analysis Reporting System (FARS). Missing speed information can result in potential errors propagating throughout the analysis, unless a method is developed to account for the missing information.
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