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Technical Paper

Multi Frequency Swept Sine Testing for Automotive Durability Testing of Engine Mounted Components

2011-05-17
2011-01-1658
Durability testing of engine mounted components is often performed using sine testing. To ensure that all resonance frequencies are excited, swept sine is used across the frequency range of excitation for the engine. This can be very costly and time consuming. A consortium of German automobile manufacturers recently approved the use of multiple simultaneous swept sine tones to reduce the time and cost of durability testing of engine mounted components. This paper describes a new multi frequency sine control technique that uses multiple swept sine control loops with independent digital tracking filters. The primary advantage of this technique is that it significantly reduces the required test duration. The result is a system capable of smooth continuous sine sweeps that excite all frequencies in the test range without sacrificing control performance.
Technical Paper

Investing Factors Affecting Door Slam Noise of SUV and Improved Performance by DFSS Approach

2011-05-17
2011-01-1595
Recent development in automobile industries has seen increased customer attention for good door slamming noise. One of the constituent which plays major role in building brand image of vehicle in terms of NVH performance is door slam noise quality. Hence it is very desirable to understand how different door elements radiate sound during a door-closing event and how to optimize a door structure to achieve specific sound target in order to ensure the door closing noise quality, NVH engineers needed to look at contributions from different door subsystems. The use of statistical tools like Six Sigma can further help them to ensure the consistency in results. This paper explains the systematic approach used to characterize different element of door which contributes to the overall door slam noise quality through QFD (Quality Function Deployment) and contribution analysis. The different mechanisms contributing to door slam noise were studied.
Journal Article

Full-Toroidal Traction Drive Variator Material and Fluid Durability

2011-04-12
2011-01-1424
Full-toroidal traction drives (IVT, TCVT & TVAD) have demonstrated a significant fuel economy, emissions and cost benefits across a diverse range of applications. However, increasing emphasis is being placed on power density and endurance limits, hence additional demands are being placed on the ability of the variator elements and traction fluid to withstand the heavily loaded rolling contact fatigue conditions within the variator. This paper describes the experimental work done to demonstrate the high temperature durability of traction fluid and variator disc and roller material. In addition, the latest fatigue endurance limit testing results are presented which provide further evidence of traction fluid ‘fill for life’
Technical Paper

CAE Methodology for Optimizing NVH, Functional Reliability, and Mass Reduction at Engine Concept Design Phase

2011-05-17
2011-01-1511
Due to the global economic downturn and higher environmental awareness, the social demands for low cost and fuel efficient vehicles are increasing. At the same time the engine power is increasing and customer expectations of reliability and NVH levels are increasing. To meet all the requirements, engineers are challenged to design light weight parts with higher performance. However, unconsidered mass reduction carries a risk of compromised NVH, Functional Reliability, and other functional demands. In order to resolve this contradiction, it is important to establish a basic structure with minimum necessary mass at the concept design phase, when there are still many degrees of freedom in the design space. Hence, a multi-objective optimization CAE methodology applicable for designing the basic structure of the Engine system was developed and is detailed below.
Technical Paper

A new Approach in AdBlue Dosing to Improve Performance and Durability of SCR Systems for the Use in Passenger Cars up to Heavy Duty Vehicles

2011-08-30
2011-01-2095
SCR technology is becoming more and more important for the segment of diesel-driven passenger cars. Due to space and functional demands the dependency of SCR performance on a uniform supply of ammonia into the catalytic substrates is highly increased. Both an even distribution of the AdBlue® spray and a completed evaporation and decomposition of the droplets are the key to achieve the desired ammonia spread. Evaluation of the influence of spray quality on the AdBlue® decomposition and catalyst performance are leading to a new approach in dosing, using a special nozzle and air-supply strategy. The resulting new technology is evaluated and compared to the state of the art.
Technical Paper

Failure Mode and Effects Analysis (FMEA): A Comparison Between VDA-Approach Versus QS-9000

2011-09-13
2011-01-2280
The Failure Mode and Effects Analysis is a quality method used by the automotive industry to ensure perfect quality of products before an introduction into mass production. Two industry standards are established on the market: on the one hand the approach by VDA (in German: Verband der Automobilindustrie) on the other hand the method according to QS-9000. If somebody is familiar with one method, working with the other one will result in misunderstanding and communication problems. Both standards do have the same principal ambition but the execution is totally different as common word definitions like “Function, Failure Modes, Effects and Causes” are interpreted differently. As a consequence information can be found in different columns of the chosen format sheet. For a better understanding of the two approaches the existing case study shown by VDA will be taken as an example to describe the equivalent steps according to QS-9000.
Technical Paper

Optimization of Gear Whine, Efficiency, and Durability of a Manual Transaxle

2009-05-19
2009-01-2064
Development of modern powertrains used in car and truck applications is more competitive than ever before. Powertrains and components previously considered to be advanced technology, such as hybrids and dual-clutch transmission technology, are now commonplace, being designed and manufactured in all worldwide markets. In order to stay competitive, powertrain OEMs must simultaneously optimize attributes such as performance, cost, weight, durability, fuel economy and NVH while producing new, desirable designs with reduced product development timelines. Oftentimes, the ideal solution for optimization of gear whine will result in an unexpected deterioration of durability, and vice versa. An advanced software tool was previously developed for the design of transmissions and transaxles, including analysis of the vibration, efficiency and durability performance under specified speeds and loads.
Technical Paper

Development of a Procedure for Multi-Axial Road Load Reproductions on an Exhaust Test Rig

2009-05-19
2009-01-2030
OEM's increase the pressure on their suppliers to design, develop and test their products within a short time period. This requires design ‘first-time-right’ philosophy and advanced numerical and experimental methods. Four steps are required to experimentally asses the durability of exhaust systems. Environmental loads and strain references are acquired on the test track. This data is analyzed and damaging are sections retained. These sections are then reproduced on a test rig. During this reproduction, strain is measured at the reference locations and the damage is calculated and compared with the test track data.
Technical Paper

Braking Systems Creep Groan Noise: Detection and Evaluation

2009-05-19
2009-01-2103
“Creep groan” is a braking systems noise that is observed when a vehicle is starting to move from a stopped condition with brake pressure applied. Motion takes place when brake pressure is reduced while a motive force, such as an idling engine through an automatic transmission, or gravity due to the vehicle being on a slope, is present. The vibration causing the sound is commonly thought to result from friction force variation in stick-slip mode. Detection and evaluation of “creep groan” noise has been a challenge for NVH test groups. First, this sound typically is not purely tonal like the more common brake squeal, although ultimately it may produce a tonal subjective impression. In this work the authors study different methods that may be applied to “creep groan” detection and evaluation.
Technical Paper

Diesel Combustion Mode Switching - A Substantial NVH Challenge

2009-05-19
2009-01-2080
Tier 2, bin 5 diesel engines may use multiple combustion modes to achieve stringent emissions requirements. Unfortunately, switching between different combustion modes can cause step changes in noise that will be unacceptable to consumers. In this paper, several sound quality metrics are evaluated for their ability to quantify the NVH issues that arise during a rich pulse event. In addition, techniques are presented that allow an engine developer to reduce the NVH effects caused by changing combustion modes. Careful calibration tuning in close cooperation with performance and emissions development engineers is required to solve noise problems that arise from combustion mode switching events, since an NVH improvement may often come at the expense of a performance or emissions issue.
Technical Paper

A Study on the Optimization of Body Structure for Rattle Noise by Exciting Woofer Speakers

2009-05-19
2009-01-2110
With the recent development of technologies for interpreting vibration and noise of vehicles, it has become possible for carmakers to reduce idle vibration and driving noise in the phase of preceding development. Thus, the issue of noise generation is drawing keen attention from production of prototype car through mass-production development. J. D. Power has surveyed the levels of customer satisfaction with all vehicles sold in the U.S. market and released the Initial Quality Study (IQS) index. As a growing number of emotional quality-related items are added to the IQS evaluation index, it is necessary to secure a sufficiently high quality level of low-frequency speaker sound against rattle noise. It is required to make a preceding review on the package tray panel, which is located at the bottom of the rear glass where the woofer speakers of a passenger sedan are installed, the door module panel in which the door speakers are built.
Technical Paper

Simple Test Method for Squeak & Rattle Evaluation of Door Trim by Using Statically Repeated Loading Robot Arm

2009-05-19
2009-01-2112
Recently, major car maker is specified squeak and rattle test method for subsystems or components by objective method. Generally these test method is focused on vibration environmental conditions. Especially, door trim which is located close to occupant is required additional test for squeak and rattle which is produced by occupant's interaction with door trim. To evaluate this condition, generally it can be tested by subjective method such as striking or pushing and twisting several positions of door trim. Dosing so is very time consuming and including variation results as different decisions. So, this paper suggest a new approach for evaluating squeak and rattle which is relating occupant contacting conditions to interior part, especially interior door trim. Multi-axis robot arm is examined to push automatically several points of door trim.
Technical Paper

Reliability Engineering in Automotive Industry for the Local Market

2009-12-13
2009-28-0026
As complexity in automotive electronics is increasing, the need for robust and failure free electrical control units (ECUs) is increasing even more. This paper addresses the special requirements of automotive applications in the emerging market. A variety of international standards on reliability tests for automotive components exist. These standards mainly based on experiences from European, American or Japanese automotive applications. The differences will be pointed out for typical Engine ECU acting as the “brain” of the Engine (refer Figure 1). It will be shown that the approach “test fit the application” rather than the former procedure “test-to pass after standards” will be a knowledge-based solution.
Technical Paper

Measurement of Road Profile and Study it's Effect on Vehicle Durability and Ride

2009-01-21
2009-26-0070
Road roughness induces dynamic loads on vehicles, which cause fatigue damage as a result. Design of vehicle for durability is one of the key steps during vehicle development process. Vehicle durability is verified on test tracks, on test rigs, or, increasingly, by computer simulations. Does the test represent real-life vehicle usage? How many times should a vehicle travel over the test tracks to verify the durability? How should input signals to test rigs be generated? For doing this kind of analysis, it is always required to measure the vehicle response parameters such as wheel forces, axle and chassis acceleration etc. These measurement based approaches have high cost and are time consuming. As these are vehicle dependent parameters, exercises need to be repeated on each type/class of vehicle. Hence it is needed to identify and measure the parameter which is vehicle independent. It is commonly accepted that the road profile is the principle excitation to the vehicle.
Technical Paper

A Systematic and Disciplined Process for Developing Drive Files for Squeak and Rattle and Durability Tests in the Lab

2009-01-21
2009-26-0048
The pressure to shorten vehicle product development time-to-launch means more in-lab tests must be performed earlier, and before vehicle prototypes are available for road or test track evaluations. Squeak and Rattle (S&R) evaluations of subsystems/modules and components must be performed using realistic road excitation conditions. How S&R performance degrades as the vehicle, module or component accumulates customer miles or kilometers must be assessed before the design is frozen. Durability tests must be performed earlier in the design/development timeline as well. All these pressures point to having a systematic, disciplined and streamlined methodology or protocol for acquiring and processing road vibration data useful for S&R and durability tests.
Technical Paper

Component Load Predication from Wheel Force Transducer Measurements

2011-04-12
2011-01-0737
The correlation of the component load time history with customer usage is becoming a most challenging task for vehicle durability performance development. Modern vehicle design process needs to obtain accurate component load as early as possible. Therefore, several load prediction methods based on vehicle multi-body dynamics model have been developed, such as fully-analytical method, semi-analytical method, etc. Component load prediction process using semi-analytical method is presented in this paper. An instrumented mule car with four wheel force transducers and several data acquisition channels is driven through the proving ground according to test procedure. The road load data obtained from the spindle is used as input signals for multi-body dynamics model which has been correlated with test. The relevant component loads are then obtained. The results in the vertical direction agree with the test data very well for the whole proving ground test procedure.
Technical Paper

Modeling and Simulation of Peak Load Events Using Adams - Driving Over a Curb and Skid Against a Curb

2011-04-12
2011-01-0733
The durability peak load events Driving over a curb and Skid against a curb have been simulated in Adams for a Volvo S80. Simulated responses in the front wheel suspension have been validated by comparison with measurements. Due to the extreme nature of the peak load events, the component modeling is absolutely critical for the accuracy of the simulations. All components have to be described within their full range of excitation. Key components and behaviors to model have been identified as tire with wheel strike-through, contacts between curb and tire and between curb and rim, flexibility of structural components, bump stops, bushings, shock absorbers, and camber stiffness of the suspension. Highly non-linear component responses are captured in Adams. However, since Adams only allows linear material response for flexible bodies, the proposed methods to simulate impact loads are only valid up to small, plastic strains.
Journal Article

An Improved Finite Element-Based Model for Reliability Assessment of a Profile-Type Automotive Body Experiencing Uncertain Loading Conditions and Material Properties

2011-04-12
2011-01-0731
Beam-type structural elements are generally utilized in construction of majority of the automotive structures, e.g. the buses, trailers, and solid axles. These components are usually subjected to spatially-random or uncertain load conditions during their service lives. Moreover, material properties of the beams-type structural elements may vary from a sample to another in a random manner. The situation will be more complex when both material properties and load conditions exhibit random natures in the spatial domain. In the present paper, an algorithm is presented to assess the probabilistic behavior of the beam-type vehicle's components in relation with the strength and deflection requirements. A consistent finite element reliability model that may be employed for beams with arbitrary inclinations under simultaneous spatially-random loading conditions and random material properties is introduced.
Journal Article

A Simulation and Optimization Methodology for Reliability of Vehicle Fleets

2011-04-12
2011-01-0725
Understanding reliability is critical in design, maintenance and durability analysis of engineering systems. A reliability simulation methodology is presented in this paper for vehicle fleets using limited data. The method can be used to estimate the reliability of non-repairable as well as repairable systems. It can optimally allocate, based on a target system reliability, individual component reliabilities using a multi-objective optimization algorithm. The algorithm establishes a Pareto front that can be used for optimal tradeoff between reliability and the associated cost. The method uses Monte Carlo simulation to estimate the system failure rate and reliability as a function of time. The probability density functions (PDF) of the time between failures for all components of the system are estimated using either limited data or a user-supplied MTBF (mean time between failures) and its coefficient of variation.
Journal Article

Reliability Prediction for the HMMWV Suspension System

2011-04-12
2011-01-0726
This research paper addresses the ground vehicle reliability prediction process based on a new integrated reliability prediction framework. The integrated stochastic framework combines the computational physics-based predictions with experimental testing information for assessing vehicle reliability. The integrated reliability prediction approach incorporates the following computational steps: i) simulation of stochastic operational environment, ii) vehicle multi-body dynamics analysis, iii) stress prediction in subsystems and components, iv) stochastic progressive damage analysis, and v) component life prediction, including the effects of maintenance and, finally, iv) reliability prediction at component and system level. To solve efficiently and accurately the challenges coming from large-size computational mechanics models and high-dimensional stochastic spaces, a HPC simulation-based approach to the reliability problem was implemented.
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