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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

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.
Journal Article

Optimization of a Porous Ducted Air Induction System Using Taguchi's Parameter Design Method

2014-04-01
2014-01-0887
Taguchi method is a technology to prevent quality problems at early stages of product development and product design. Parameter design method is an important part in Taguchi method which selects the best control factor level combination for the optimization of the robustness of product function against noise factors. The air induction system (AIS) provides clean air to the engine for combustion. The noise radiated from the inlet of the AIS can be of significant importance in reducing vehicle interior noise and tuning the interior sound quality. The porous duct has been introduced into the AIS to reduce the snorkel noise. It helps with both the system layout and isolation by reducing transmitted vibration. A CAE simulation procedure has been developed and validated to predict the snorkel noise of the porous ducted AIS. In this paper, Taguchi's parameter design method was utilized to optimize a porous duct design in an AIS to achieve the best snorkel noise performance.
Technical Paper

Cause and Effect of Reversible Deactivation of Diesel Oxidation Catalysts

2014-04-01
2014-01-1518
To meet TierII/LEVII emissions standards, light duty diesel (LDD) vehicles require high conversion efficiencies from the Aftertreatment Systems (ATS) for the removal of both Hydrocarbon (HC) and Nitrogen Oxide (NOx) species. The most populous configuration for LDD ATS have the Selective Catalytic Reduction (SCR) catalyst positioned on the vehicle behind the close coupled Diesel Oxidation Catalyst (DOC) and Catalyzed Diesel Particulate Filter (CDPF). This SCR position may require active heating measures which rely on the DOC/CDPF to provide heat through the combustion of HC and CO in the exhaust. Although DOCs are always impacted by their aging conditions, some aging conditions are shown to be both reversible and irreversible.
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.
Technical Paper

2013 SRT Viper Carbon Fiber X-Brace

2013-04-08
2013-01-1775
The 2013 SRT Viper Carbon Fiber X-Brace, styled by Chrysler's Product Design Office (PDO), is as much of a work of art as it is an engineered structural component. Presented in this paper is the design evolution, development and performance refinement of the composite X-Brace (shown in Figure 1). The single-piece, all Carbon Fiber Reinforced Plastic (CFRP) X-Brace, an important structural component of the body system, was developed from lightweight carbon fiber material to maximize weight reduction and meet performance targets. The development process was driven extensively by virtual engineering, which applied CAE analysis and results to drive the design and improve the design efficiency. Topology optimization and section optimization were used to generate the initial design's shape, form and profile, while respecting the package requirements of the engine compartment.
Technical Paper

Die Wear Estimation in Automotive Sheet Metal Stamping

2013-04-08
2013-01-1171
Automotive industry's migration to usage of HSS (High Strength Steels), AHSS (Advance High Strength Steels) from conventional steels for their low weight and high strength properties has had its significant effects on die wear. The unpredictability of die wear can pose manufacturing issues, for example, undesirable tool life. Hence die wear has been gaining immense attention and lot of research work has been carried out to provide a die wear prediction method. This paper focuses on the method of estimating wear mathematically based on the mechanics behind die wear phenomenon. This is also an effort to study wear on die for an automotive component in critical areas for which the amount of wear are calculated. This study is further to be correlated with production data from die maintenance record, explicit measurement of die wear, etc., to validate the estimation.
Technical Paper

Smart Meshing Template Process with CAD/CAE Link

2013-04-08
2013-01-0637
The benefits of utilizing virtual engineering include not only shortened product development time and reduced reliance on expensive physical testing, but also the opportunities for greater standardization to support higher product quality. This paper describes a project for building a smart meshing template with a CAD/CAE link. The objective of the project is to optimize the utilization of CAD software and CAE preprocessing software capabilities. The deliverable of the project is a cylinder head mesh template which meets all the cylinder head durability simulation meshing requirements, and which links to CAD/CAE software. Special surface areas identified are built into the cylinder head CAD model design. By using one of the features in CAD software, all the special surfaces can be automatically updated throughout the design process.
Journal Article

Development of a Standard Spin Loss Test Procedure for FWD-Based Power Transfer Units

2013-04-08
2013-01-0361
As vehicle fuel economy continues to grow in importance, the ability to accurately measure the level of efficiency on all driveline components is required. A standardized test procedure enables manufacturers and suppliers to measure component losses consistently and provides data to make comparisons. In addition, the procedure offers a reliable process to assess enablers for efficiency improvements. Previous published studies have outlined the development of a comprehensive test procedure to measure transfer case speed-dependent parasitic losses at key speed, load, and environmental conditions. This paper will take the same basic approach for the Power Transfer Units (PTUs) used on Front Wheel Drive (FWD) based All Wheel Drive (AWD) vehicles. Factors included in the assessment include single and multi-stage PTUs, fluid levels, break-in process, and temperature effects.
Technical Paper

A New Method of d'Alembert's Principle Finite Element Based Fatigue Calculation with Input of Loads and Accelerations

2013-04-08
2013-01-1003
The common practice in finite element based fatigue calculation with multiple channels of road load is to perform a set of unit load static stress analysis and conduct stress time history construction later during fatigue calculation. The main advantage of this so-called quasi-static finite element based fatigue calculation is to avoid time-consuming dynamic stress analysis and also reduce static stress analysis from millions of real load cases to a few dozens unit-load cases. The main disadvantage of this quasi-static finite element based fatigue calculation is the absence of vibration-induced stresses in stress time history construction and fatigue analysis. A decade ago, a modal transient finite element based fatigue calculation was proposed to introduce vibration-induced stresses into finite element based fatigue calculation. The idea is to add vibration-induced modal stresses to load-induced instant stresses in stress time history construction and fatigue calculation.
Technical Paper

CAE Simulation of Door Sag/Set Using Subsystem Level Approach

2013-04-08
2013-01-1199
The performance of door assembly is very significant for the vehicle design and door sag/set is one of the important attribute for design of door assembly. This paper provides an overview of conventional approach for door sag/set study based on door-hinge-BIW assembly (system level approach) and its limitation over new approach based on subassembly (subsystem level approach). The door sag/set simulation at system level is the most common approach adopted across auto industry. This approach evaluates only structural adequacy of door assembly system for sag load. To find key contributor for door sagging is always been time consuming task with conventional approach thus there is a delay in providing design enablers to meet the design target. New approach of door sag/set at “subsystem level” evaluates the structural stiffness contribution of individual subsystem. It support for setting up the target at subsystem level, which integrate and regulate the system level performance.
Technical Paper

Virtual Road Load Data Acquisition using Full Vehicle Simulations

2013-04-08
2013-01-1189
The concept of full vehicle simulation has been embraced by the automobile industry as it is an indispensable tool for analyzing vehicles. Vehicle loads traditionally obtained by road load data acquisition such as wheel forces are typically not invariant as they depend on the vehicle that was used for the measurement. Alternatively, virtual road load data acquisition approach has been adopted in industry to derive invariant loads. Analytical loads prior to building hardware prototypes can shorten development cycles and save costs associated with data acquisition. The approach described herein estimate realistic component load histories with sufficient accuracy and reasonable effort using full vehicle simulations. In this study, a multi-body dynamic model of the vehicle was built and simulated over digitized road using ADAMS software, and output responses were correlated to a physical vehicle that was driven on the same road.
Technical Paper

Charge Motion Analysis to Guide Engine Port Development and Enhance Combustion Stability for High Cooled Exhaust Gas Recirculation

2013-04-08
2013-01-1313
CAE tools are increasingly important in the automotive design process. In part, CAE tools can be useful in reducing the number of physical prototypes required during a product development effort. CFD tools can assess and predict cylinder charge motion for proposed designs, thereby limiting the need for prototype work. Though detailed combustion simulation results could help guide product development, the time required for such simulations limits their usefulness in the context of a production program. However equally valuable information can be obtained from gas exchange analyses which require less computation time and are run only from Intake Valve opening (IVO) to spark timing. Chemical kinetics is not included in this type of analysis. Using this approach, large numbers of configurations can be evaluated in a short period of time. Every passing year automotive engineers are challenged to attain higher fuel economy targets.
Technical Paper

Development of an Analytical Modeling Method and Testing Procedures to Aid in the Design of Cardan Joints for Front Steerable Beam Axles

2013-04-08
2013-01-0819
The Cardan joint of a steerable beam front axle is a complicated mechanical component. It is subjected to drive torque, speed fluctuations, and joint articulation due to powertrain inputs, steering, and suspension kinematics. This combination of high torque and speed fluctuations of the Cardan joint, due to high input drive torque and/or high steer angle maneuvers, can result in premature joint wear. Initially, some observations of premature wear were not well understood based on the existing laboratory and road test data. The present work summarizes a coordinated program of computer modeling, vehicle Rough Road data acquisition, and physical testing used to predict the joint dynamics and to develop advanced testing procedures. Results indicate analytical modeling can predict forces resulting from Cardan joint dynamics for high torque/high turn angle maneuvers, as represented by time history traces recorded in rough road data acquisition.
Technical Paper

EGR Systems Evaluation in Turbocharged Engines

2013-04-08
2013-01-0936
EGR systems are widely applied in modern turbocharged diesel engines to reduce engine-out emissions and will, or are being used to mitigate engine knock in SI engines for improved SI engine efficiency and power. In this paper, different EGR systems are detailed and evaluated theoretically based on the thermodynamics of a turbocharged system featuring an EGR sub-system. Turbine expansion ratio is utilized as a metric to estimate engine efficiency, i.e., pumping losses during the gas exchange process. Approaches such as compressor and turbine bypassing are evaluated as well. Based on above analysis, a new approach is put forward to expand the turbocharger work zone, particularly in the high efficiency regions by correctly utilizing EGR systems at all engine speed range: low-pressure loop EGR system at lower engine speed range and high-pressure loop EGR system at high engine speed range.
Technical Paper

1D Modeling of AC Refrigerant Loop and Vehicle Cabin to Simulate Soak and Cool Down

2013-04-08
2013-01-1502
Simulation has become an integral part in the design and development of an automotive air-conditioning (AC) system. Simulation is widely used for both system level and component level analyses and are carried out with one-dimensional (1D) and Computational Fluid Dynamics (CFD) tools. This paper describes a 1D approach to model refrigerant loop and vehicle cabin to simulate the soak and cool down analysis. Soak and cool down is one of the important tests that is carried out to test the performance of a heating, ventilation and air-conditioning (HVAC) system of a vehicle. Ability to simulate this cool down cycle is thus very useful. 1D modeling is done for the two-phase flow through the refrigerant loop and air flow across the heat exchangers and cabin with the commercial software AMESim. The model is able to predict refrigerant pressure and temperature inside the loop at different points in the cycle.
Technical Paper

Studies on AC Suction Line Pressure Drop using 1D Modeling

2013-04-08
2013-01-1503
In an automotive air-conditioning (AC) system, the amount of work done by the compressor is also influenced by the suction line which meters the refrigerant flow. Optimizing the AC suction line routing has thus become an important challenge and the plumbing designers are required to come up with innovative packaging solutions. These solutions are required in the early design stages when prototypes are not yet appropriate. In such scenarios, one-dimensional (1D) simulations shall be employed to compute the pressure drop for faster and economical solution. In this paper, an approach of creating a modeling tool for suction line pressure drop prediction is discussed. Using DFSS approach L12 design iterations are created and simulations are carried out using 1D AMESim software. Prototypes are manufactured and tested on HVAC bench calorimeter. AC suction line pressure drop predicted using the 1D modeling co-related well with the test data and the error is less than 5%.
Technical Paper

Developing the AC17 Efficiency Test for Mobile Air Conditioners

2013-04-08
2013-01-0569
Chrysler, Ford, General Motors, the U.S. Environmental Protection Agency (EPA) and the California Air Resources Board (CARB) have collaborated over the past two years to develop an efficiency test for mobile air conditioner (MAC) systems. Because the effect of efficiency differences between different MAC systems and different technologies is relatively small compared to overall vehicle fuel consumption, quantifying these differences has been challenging. The objective of this program was to develop a single dynamic test procedure that is capable of discerning small efficiency differences, and is generally representative of mobile air conditioner usage in the United States. The test was designed to be conducted in existing test facilities, using existing equipment, and within a sufficiently short time to fit standard test facility scheduling. Representative ambient climate conditions for the U.S. were chosen, as well as other test parameters, and a solar load was included.
Technical Paper

Impact of Functional Safety on EMC: ISO 26262

2013-04-08
2013-01-0178
The complexity of both hardware and software has increased significantly in automotive over the past decade. This is apparent even in the compact passenger car market segment where the presence of electronic control units (ECU) has nearly tripled. In today's luxury vehicles, software can reach 100 million lines of code and are only projected to increase. Without preventive measures, the risk of safety-related system malfunction becomes unacceptably too high. The functional safety standard ISO 26262, released as first edition in 2011, provides crucial safety-related requirements for passenger vehicles. Although the standard defines the proper development for safety-related systems to ensure the avoidance of a hazard, it's implication for electromagnetic compatibility (EMC) is not clearly defined. This paper outlines the impact of ISO 26262 for EMC related issues, and discusses the standard's implications for EMC requirements on the present EMC practices for production vehicles.
Journal Article

Random Vibration Testing Development for Engine Mounted Products Considering Customer Usage

2013-04-08
2013-01-1007
In this paper, the development of random vibration testing schedules for durability design verification of engine mounted products is presented, based on the equivalent fatigue damage concept and the 95th-percentile customer engine usage data for 150,000 miles. Development of the 95th-percentile customer usage profile is first discussed. Following that, the field engine excitation and engine duty cycle definition is introduced. By using a simplified transfer function of a single degree-of-freedom (SDOF) system subjected to a base excitation, the response acceleration and stress PSDs are related to the input excitation in PSD, which is the equivalent fatigue damage concept. Also, the narrow-band fatigue damage spectrum (FDS) is calculated in terms of the input excitation PSD based on the Miner linear damage rule, the Rayleigh statistical distribution for stress amplitude, a material's S-N curve, and the Miles approximate solution.
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