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Journal Article

Assessment of Automatic Volume Leveling for Automotive Sound Systems

2013-04-08
2013-01-0162
This paper presents an assessment of competing algorithms for normalizing volume levels between tracks and/or sources in an automotive infotainment system. Portable media players such as smartphones and iPod® devices are extremely popular for listening to music collections or streaming content from the Internet. The lack of normalization is a source of dissatisfaction if the user experiences significant changes in audio level between tracks. Several commercially available algorithms exist to solve this problem. This research includes a double-blind listening test comparing an audio sample processed with the different leveling algorithms to an unprocessed reference. The listener preference rating is recorded and results indicate which algorithm is preferred.
Technical Paper

Statistical Modeling of Fatigue Crack Growth in Wing Skin Fastener Holes

2012-04-16
2012-01-0482
Estimation and prediction of residual life and reliability are serious concerns in life cycle management for aging structures. Laboratory testing replicating fatigue loading for a typical military aircraft wing skin was undertaken. Specimens were tested until their fatigue life expended reached 100% of the component fatigue life. Then, scanning electron microscopy was used to quantify the size and location of fatigue cracks within the high stress regions of simulated fastener holes. Distributions for crack size, nearest neighbor distances, and spatial location were characterized statistically in order to estimate residual life and to provide input for life cycle management. Insights into crack initiation and growth are also provided.
Journal Article

A New Automotive Air Conditioning System Simulation Tool Developed in MATLAB/Simulink

2013-04-08
2013-01-0850
Accurate evaluation of vehicles' transient total power requirement helps achieving further improvements in vehicle fuel efficiency. When operated, the air-conditioning (A/C) system is the largest auxiliary load on a vehicle, therefore accurate evaluation of the load it places on the vehicle's engine and/or energy storage system is especially important. Vehicle simulation models, such as "Autonomie," have been used by OEMs to evaluate vehicles' energy performance. However, the load from the A/C system on the engine or on the energy storage system has not always been modeled in sufficient detail. A transient A/C simulation tool incorporated into vehicle simulation models would also provide a tool for developing more efficient A/C systems through a thorough consideration of the transient A/C system performance. The dynamic system simulation software MATLAB/Simulink® is frequently used by vehicle controls engineers to develop new and more efficient vehicle energy system controls.
Technical Paper

An Efficient Alternative for Computing Algorithm Detection Thresholds

2006-04-03
2006-01-0009
Commonly, a significant event is detected when a normally stable engine parameter (ex. sensor voltage, sensor current, air flow, pedal position, fuel level, tire pressure, engine acceleration, etc.) transiently exceeds a calibrated detection threshold. Many implementations of detection thresholds rely on multi-input lookup tables or functions and are complex and difficult to calibrate. An approach is presented to minimize threshold calibration effort and complexity, while improving detection performance, by dynamically computing thresholds on-line based on current real-time data. Determining engine synchronization without a camshaft position sensor is presented as an illustrative application.
Technical Paper

Multivariate Statistical Methods for the Analysis of NVH Data

2005-05-16
2005-01-2518
The present work discusses the application of multivariate statistical methods for the analysis of NVH data. Unlike conventional statistical methods which generally consider single-value, or univariate data, multivariate methods enable the user to examine multiple response variables and their interactions simultaneously. This characteristic is particularly useful in the examination of NVH data, where multiple measurements are typically used to assess NVH performance. In this work, Principal Components Analysis (PCA) was used to examine the NVH data from a benchmarking study of hydraulic steering pumps. A total of twelve NVH measurements for each of 99 pump samples were taken. These measurements included steering pump orders and overall levels for vibration and sound pressure level at two microphone locations. Application of the PCA method made it possible to examine the entire set of data at once.
Technical Paper

Broadband Noise Source Models as Aeroacoustic Tools in Designing Low NVH HVAC Ducts

2006-04-03
2006-01-1192
Computational Fluid Dynamics (CFD) is an integral part of product development at Visteon Climate Systems with a validated set of CFD tools for airflow and thermal management processes. As we increasingly build CAE capabilities to design not only thermal comfort, but quiet systems, developing noise prediction capabilities becomes a high priority. Two Broadband Noise Source (BNS) models will be presented, namely Proudman's model for quadrupole source and Curle's boundary layer model for dipole source. Both models are derived from Lighthill's acoustic analogy which is based on the Navier-Stokes equations. BNS models provide aeroacoustic tools that are effective in screening air handling systems with higher noise levels and identifying components or surfaces that generate most of the noise, hence providing opportunities for early design changes. In this paper, BNS models were used as aeroacoustic design tools to redesign an automotive HVAC center duct with high levels of NVH.
Technical Paper

A Filter Seal Model for Point Mobility Prediction of Air Induction Systems

2006-04-03
2006-01-1209
Virtual design validation of an air induction system (AIS) requires a proper finite element (FE) assembly model for various simulation based design tasks. The effect of the urethane air filter seal within an AIS assembly, however, still poses a technical challenge to the modeling of structural dynamic behaviors of the AIS product. In this paper, a filter seal model and its modeling approach for AIS assemblies are introduced, by utilizing the feature finite elements and empiric test data. A bushing element is used to model the unique nonlinear stiffness and damping properties of the urethane seal, as a function of seal orientation, preloading, temperature and excitation frequency, which are quantified based on the test data and empiric formula. Point mobility is used to character dynamic behaviors of an AIS structure under given loadings, as a transfer function in frequency domain.
Technical Paper

Automotive Axle Simulation and Correlation

2006-04-03
2006-01-1255
Up to date, computer aided engineering (CAE) has been used in improvement of design quality and reduction of cost and delivery time. Although it has been widely accepted as a standard product development tool by the engineering community, CAE still faces many challenges in improving simulation process efficiency through process integration and automation, and simulation accuracy by analytical model/physical testing correlation. CAE engineers are constantly improving the accuracy of their analytical models through test correlation to deliver higher confidence for their analysis result. Although laboratory testing has provided an effective way to accelerate product development, analytical simulation of the lab test has been used frequently to further reduce the development cost and time throughout many industries. This paper presents a case study of CAE correlation of a finite element (FE) model of an automotive beam axle assembly in a laboratory test environment.
Technical Paper

Control Method of Dual Motor-Based Steer-by-Wire System

2007-04-16
2007-01-1149
This paper describes a front road wheel steer-by-wire system with two actuator motors on the rack and pinion assembly to move the road wheels. Dual actuators are used to provide actuator redundancy and to enhance the fault tolerance capability. When one actuator faults or fails, the other actuator is designed to work independently and maintain full system performance. The paper emphasizes control method to implement the motion control for the front road wheel steer-by-wire system with two actuators on the common load. The proposed dual servo synchronization motion control implements the angle tracking for the road wheel reference input by controlling two actuators synchronously and cooperatively. It includes two servo feedback control loops to track the common reference input. The angular position error between two feedback loops is compensated using a synchronized compensator.
Technical Paper

Design Parameter Tradeoffs for LED Headlamp Applications

2007-04-16
2007-01-0871
High-power LEDs and LED headlamps have become a serious consideration for the automotive industry. White LEDs have achieved the required performance for initial automotive headlamp applications. However tradeoffs among several attributes such as efficiency, cost, weight and performance profoundly affect LED headlamp development and need to be addressed by vehicle manufacturers, lamp set makers and LED source suppliers in order for LED headlamps to be effective. The solutions to these tradeoffs relates to the behavior of the LED sources, the thermo-mechanical integration of LEDs in a headlamp environment and input from the vehicle manufacturer regarding styling and packaging for an LED headlamp on the respective targeted vehicles.
Technical Paper

High Efficient LED Headlamp Design-Styling versus Light Performance

2007-04-16
2007-01-0874
First LED headlamps will be released into the market in 2007. Special permissions allow this introduction although the official regulation is still under discussion in ECE. The LED technology for front lighting has entered into a new phase from theoretical, prototype status to real and practical applications. Additionally in Europe the legislation, which is under preparation, defines LED modules with one or more LED chips in a row which should be replaceable. With this boundary conditions headlamp suppliers needs to balance between an attractive and innovative styling, demanded by car manufacturers and the light performance to gurantee good visibility at night. The paper describes the methods how to design an LED headlamp with high efficiency by keeping in mind the parameters: packaging, weight, styling and light perfromance. Results with specific design proposals are shown.
Technical Paper

Radiated Noise Prediction of Air Induction Systems Using Filter Seal Modeling and Coupled Acoustic-Structural Simulation Techniques

2007-04-16
2007-01-0253
In this paper, an analytical procedure for prediction of shell radiated noise of air induction systems (AIS) due to engine acoustic excitation, without a prototype and physical measurement, is presented. A set of modeling and simulation techniques are introduced to address the challenges to the analytical radiated noise prediction of AIS products. A filter seal model is developed to simulate the unique nonlinear stiffness and damping properties of air cleaner boxes. A finite element model (FEM) of the AIS assembly is established by incorporating the AIS structure, the proposed filter seal model and its acoustic cavity model. The coupled acoustic-structural FEM of the AIS assembly is then employed to compute the velocity frequency response of the AIS structure with respect to the air-borne acoustic excitations.
Technical Paper

Multibody Dynamic Simulation of Steering Gear Systems With Three-Dimensional Surface Contacts

2006-02-14
2006-01-1960
In an effort to understand steering systems performance and properties at the microscopic level, we developed Multibody simulations that include multiple three-dimensional gear surfaces that are in a dynamic state of contact and separation. These validated simulations capture the dynamics of high-speed impact of gears traveling small distances of 50 microns in less than 10 milliseconds. We exploited newly developed analytic, numeric, and computer tools to gain insight into steering gear forces, specifically, the mechanism behind the inception of mechanical knock in steering gear. The results provided a three dimensional geometric view of the sequence of events, in terms of gear surfaces in motion, their sudden contact, and subsequent force generation that lead to steering gear mechanical knock. First we briefly present results that show the sequence of events that lead to knock.
Technical Paper

Simple Application of DOE Methods to Reduce Whistle Noise in a HPAS Pump Relief Valve

2005-05-16
2005-01-2468
The present work demonstrates the application of Design of Experiments (DOE) statistical methods to the design and the improvement of a hydraulic steering pump noise, vibration, and harshness (NVH) performance in relief. DOE methods were applied to subjective ratings to examine the effect of several different factors, as well as the interactions between these factors on pump relief NVH. Specifically, the DOE was applied to the geometry of the cross ports on a hydraulic relief valve to improve “whistle” noise in the pump. Statistical methods were applied to determine which factors and interactions had a significant effect on pump whistle. These factors were used to produce a more robust cross port configuration reducing whistle noise. Lastly, the final configuration was experimentally verified on the test apparatus and subjectively confirmed in vehicle-level testing.
Technical Paper

Analytical Calculation of the Critical Speed of a Driveshaft

2005-05-16
2005-01-2310
Determination of the critical speed of a driveshaft is critical for development and validation of its design for use in a vehicle because of its destructive effects. Typical calculations to determine critical speed are either over simplistic and not very accurate or very complicated requiring CAE software and capabilities. An analytical five-section non-prismatic beam model was developed to fill in this gap. The model was developed to compute the critical speed in a worksheet and proven to be as or more accurate as utilizing FEA methods. The model worksheet calculates the critical speed for one-piece conventional driveshafts and adapted for Visteon's Slip-In-Tube (SIT) driveshafts.
Technical Paper

Designing a Tuned Torsional Damper for Automotive Applications Using FEA and Optimization

2005-05-16
2005-01-2293
Tuned mass dampers are frequently used in vehicles to resolve vibration issues arising from problematic torsional modes. The design of a tuned damper is straightforward, but evaluating its effect on other system modes is time consuming. An upfront design tool will accelerate the process of designing and evaluating the damper's affect on system level dynamic characteristics. Computer aided engineering tools have been developed to design a tuned torsional damper using two different approaches. In the first approach, a two-degree of freedom torsional system model is utilized. In the second approach, a detailed finite element model of a driveline system is considered. In the second approach, the effect of the damper to the vehicle driveline system response at the hypoid pinion nose and other desired locations is studied to assess the effectiveness of the damper design. In both approaches, the damper rotational inertia is considered as a design variable.
Technical Paper

A Real Time Statistical Method for Engine Knock Detection

2007-04-16
2007-01-1507
The traditional method of engine knock detection is to compare the knock intensity with a predetermined threshold. The calibration of this threshold is complex and difficult. A statistical knock detection method is proposed in this paper to reduce the effort of calibration. This method dynamically calculates the knock threshold to determine the knock event. Theoretically, this method will not only adapt to different fuels but also cope with engine aging and engine-to-engine variation without re-calibration. This method is demonstrated by modeling and evaluation using real-time engine dynamometer test data.
Technical Paper

Model Reference Adaptive Control of a Pneumatic Valve Actuator for Infinitely Variable Valve Timing and Lift

2007-04-16
2007-01-1297
Electro-pneumatic valve actuators are used to eliminate the cam shaft of a traditional internal combustion engine. They are used to control the opening timing, duration, and lift of both intake and exhaust valves. A physics based nonlinear mathematical model called the level one model was built using Newton's law, mass conservation and thermodynamic principles. A control oriented model, the level two model, was created by partially linearizing the level one model for model reference parameter identification. This model reduces computational throughput and enables real-time implementation. A model reference adaptive control system was used to identify the nonlinear parameters that were needed for generating a feedforward control signal. The closed-loop valve lift tracking, valve opening and closing timing control strategies were proposed.
Technical Paper

Heat Simulation in Lighting

2007-04-16
2007-01-1388
During last 10-15 years we could have seen quite big changes in automotive lighting. The most important changes are: a) plastic materials mostly removed metal and glass material from lighting products raised heat issue of plastics materials b) escalation of competition between lighting suppliers (globalization, merging, …) decrease of time and cost for development of the new product as much as possible
Technical Paper

Quantitative Characterization of Near-Field Fuel Sprays by Multi-Orifice Direct Injection Using Ultrafast X-Tomography Technique

2006-04-03
2006-01-1041
A low-pressure direct injection fuel system for spark ignition direct injection engines has been developed, in which a high-turbulence nozzle technology was employed to achieve fine fuel droplet size at a low injection pressure around 2 MPa. It is particularly important to study spray characteristics in the near-nozzle region due to the immediate liquid breakup at the nozzle exit. By using an ultrafast x-ray area detector and intense synchrotron x-ray beams, the interior structure and dynamics of the direct injection gasoline sprays from a multi-orifice turbulence-assisted nozzle were elucidated for the first time in a highly quantitative manner with μs-temporal resolution. Revealed by a newly developed, ultrafast computed x-microtomography technique, many detailed features associated with the transient liquid flows are readily observable in the reconstructed spray.
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