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Grammatical Evolution Based Tool for Predicting Multivariable Response Surface for Laser Lap Welding

DaimlerChrysler Corporation-Mariana Forrest, Feng Lu
University of Toledo-Dominic Wilson, Devinder Kaur
Published 2008-04-14 by SAE International in United States
The problem of predicting the quality of weld is critical to manufacturing. A great deal of data is collected under multiple conditions to predict the quality. The data generated at Daimler Chrysler has been used to develop a model based on grammatical evolution. Grammatical Evolution Technique is based on Genetic Algorithms and generates rules from the data which fit the data. This paper describes the development of a software tool that enables the user to choose input variables such as the metal types of top and bottom layers and their thickness, intensity and speed of laser beam, to generate a three dimensional map showing weld quality. A 3D weld quality surface can be generated in response to any of the two input variables picked from the set of defining input parameters. This tool will enable the user to pick the right set of input conditions to get an optimal weld quality. The tool is developed in Matlab with Graphical User Interface for the ease of operation.
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Development of an Experimental FRF-Based Substructuring Model to Forward Predict the Effects of Beam Axle Design Modifications on Passenger Vehicle Axle Whine

DaimlerChrysler Corporation-Dan Ryberg, Hamid Mir
Published 2007-05-15 by SAE International in United States
This paper describes the process used to develop an experimental model with forward prediction capabilities for passenger vehicle axle whine performance, focusing initially on beam axle design modifications. This process explains how experimental Transfer Path Analysis (TPA), Running Modes Analysis (RMA) and Modal Analysis were used along with an experimental FRF-Based Substructuring (FBS) model. The objective of FBS techniques is to predict the dynamic behavior of complex structures based on the dynamic properties of each component of the structure. The FBS model was created with two substructures, the body/suspension and the empty rear beam axle housing. Each step in the creation of the baseline FBS model was correlated, and the forward predictive capability was verified utilizing an experimental modification to the beam axle structure.
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Improving Low Frequency Torsional Vibrations NVH Performance through Analysis and Test

DaimlerChrysler Corporation-Anthony Hage, Antoni Szatkowski
Altair Engineering Inc.-Zhe Li
Published 2007-05-15 by SAE International in United States
Low frequency torsional vibrations can be a significant source of objectionable vehicle vibrations and in-vehicle boom, especially with changes in engine operation required for improved fuel economy. These changes include lower torque converter lock-up speeds and cylinder deactivation.This paper has two objectives: 1)Examine the effect of increased torsional vibrations on vehicle NVH performance and ways to improve this performance early in the program using test and simulation techniques. The important design parameters affecting vehicle NVH performance will be identified, and the trade-offs required to produce an optimized design will be examined. Also, the relationship between torsional vibrations and mount excursions, will be examined.2)Investigate the ability of simulation techniques to predict and improve torsional vibration NVH performance. Evaluate the accuracy of the analytical models by comparison to test results. A simple model is presented which gives fairly accurate results and can be included in a full vehicle finite element model to calculate vehicle level NVH responses. A procedure to calculate the loads to be applied to the model is also presented.
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NVH Refinement of Diesel Powered Sedans with Special Emphasis on Diesel Clatter Noise and Powertrain Harshness

DaimlerChrysler Corporation-Phil Thomas
FEV Engine Technology, Inc.-Marcus Pollack, Kiran Govindswamy, Thomas Wellmann
Published 2007-05-15 by SAE International in United States
NVH refinement of passenger vehicles is crucial to customer acceptance of contemporary vehicles. This paper describes the vehicle NVH development process, with specific examples from a Diesel sedan application that was derived from gasoline engine-based vehicle architecture. Using an early prototype Diesel vehicle as a starting point, this paper examines the application of a Vehicle Interior Noise Simulation (VINS) technique in the development process. Accordingly, structureborne and airborne noise shares are analyzed in the time-domain under both steady-state and transient test conditions. The results are used to drive countermeasure development to address structureborne and airborne noise refinement. Examples are provided to highlight the refinement process for “Diesel knocking” under idle as well as transient test conditions.Specifically, the application of VINS to understanding the influence of high frequency dynamic stiffness of hydro-mounts on Diesel clatter noise is examined. In addition, examples are provided from studies aimed at reducing the perceived powertrain harshness under on-road operating conditions. Finally, the results from these studies are summarized and appropriate conclusions drawn with respect to the Diesel sedan NVH development…
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Application of the Modal Compliance Technique to a Vehicle Body in White

DaimlerChrysler Corporation-Kuang-Jen Liu
Roush Industries, Inc.-David Griffiths, Edward R. Green
Published 2007-05-15 by SAE International in United States
This paper describes the application of the modal compliance method to a complex structure such as a vehicle body in white, and the extension of the method from normal modes to the complex modes of a complete vehicle. In addition to the usual bending and torsion calculations, the paper also describes the application of the method to less usual tests such as second torsion, match-boxing and breathing. We also show how the method can be used to investigate the distribution of compliance throughout the structure.
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Validation of Vehicle NVH Performance using Experimental Modal Testing and In-Vehicle Dynamic Measurements

DaimlerChrysler Corporation-Jennifer M. Headley, Kuang-Jen J. Liu, Robert M. Shaver
Published 2007-05-15 by SAE International in United States
NVH targets for future vehicles are often defined by utilizing a competitive benchmarking vehicle in conjunction with an existing production and/or reference vehicle. Mode management of full vehicle modes is one of the most effective and significant NVH strategies to achieve such targets. NVH dynamic characteristics of a full vehicle can be assessed and quantified through experimental modal testing for determination of global body mode resonance frequency, damping property, and mode shape. Major body modes identified from full vehicle modal testing are primarily dominated by the vehicle's body-in-white structure. Therefore, an estimate of BIW modes from full vehicle modes becomes essential, when only full vehicle modes from experimental modal testing exist. Establishing BIW targets for future vehicles confines the fundamental NVH behavior of the full vehicle. In addition to vehicle body structure, the tire/wheel assembly, suspension, and chassis system affect overall on-road NVH performance of the vehicle. Understanding body acoustic and tactile sensitivity from various suspension and chassis attachment locations, and utilizing standardized NVH load cases under vehicle operating conditions, also benefit full vehicle NVH…
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Experimental Modal Methodologies for Quantification of Body/Chassis Response to Brake Torque Variation

DaimlerChrysler Corporation-Robert M. Shaver, Kuang-Jen J. Liu, Robert P. Uhlig
Published 2007-05-15 by SAE International in United States
Brake torque variation is a source of objectionable NVH body/chassis response. Such input commonly results from brake disk thickness variation. The NVH dynamic characteristics of a vehicle can be assessed and quantified through experimental modal testing for determination of mode resonance frequency, damping property, and shape. Standard full vehicle modal testing typically utilizes a random input excitation into the vehicle frame or underbody structure. An alternative methodology was sought to quantify and predict body/chassis sensitivity to brake torque variation. This paper presents a review of experimental modal test methodologies investigated for the reproduction of vehicle response to brake torque variation in a static laboratory environment. Brake caliper adapter random and sine sweep excitation input as well as body sine sweep excitation in tandem with an intentionally locked brake will be detailed. The associated body/chassis response of each methodology will be examined through modal parameter extraction. Results will be compared to the body/chassis response measured through standard experimental modal test input. Potential methods for quantifying and predicting body/chassis sensitivity to brake torque variation will be examined.
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Experimental Determination of an Engine's Inertial Properties

DaimlerChrysler Corporation-C. Q. Liu, Jeff Orzechowski
Published 2007-05-15 by SAE International in United States
Determination of an engine's inertial properties is critical during vehicle dynamic analysis and the early stages of engine mounting system design. Traditionally, the inertia tensor can be determined by torsional pendulum method with a reasonable precision, while the center of gravity can be determined by placing it in a stable position on three scales with less accuracy. Other common experimental approaches include the use of frequency response functions. The difficulty of this method is to align the directions of the transducers mounted on various positions on the engine. In this paper, an experimental method to estimate an engine's inertia tensor and center of gravity is presented. The method utilizes the traditional torsional pendulum method, but with additional measurement data. With this method, the inertia tensor and center of gravity are estimated in a least squares sense. To validate this method, a uniform rectangular box was used as a test sample, of which the inertial properties are known. The experimental results have a difference of less than 2% compared with the theoretical results. A through discussion…
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Axle Imbalance Measurement and Balancing Strategies

DaimlerChrysler Corporation-C. Q. Liu, Jeff Orzechowski
Published 2007-05-15 by SAE International in United States
This paper summarizes a study on axle balance measurement and balancing strategies. Seven types of axles were investigated. Test samples were randomly selected from products. Two significant development questions were set out to be answered: 1)What is the minimum rotational speed possible in order to yield measured imbalance readings which correlated to in-vehicle imbalance-related vibration. What is the relationship between the measured imbalance and rotational speed. To this end, the imbalance level of each axle was measured using a test rig with different speeds from 800 to 4000 rpm with 200 rpm increments.2)Is it feasible to balance axle sub-assemblies only and still result in a full-assembly that satisfies the assembled axle specification? To this end, the sub-assemblies were balanced on a balance machine to a specified level. Then with these balanced sub-assemblies, the full assemblies were completed and audited on the same balance test rig in the same way. Each sample was run through 5 install-test-remove cycles. A comparison of all of the measurements for repeatability and accuracy was done. Graphical presentation of histograms and…
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A New Method for Obtaining FRF of a Structure in Area Where Impact Hammer Cannot Reach

DaimlerChrysler Corporation-C. Q. Liu, Roger Pawlowski, Jeff Orzechowski
Published 2007-05-15 by SAE International in United States
The Frequency Response Function (FRF) is a fundamental component to identifying the dynamic characteristics of a system. FRF's have a significant impact on modal analysis and root cause analysis of NVH issues. In most cases the FRF can be easily measured, but there are instances when the measurement is unobtainable due to spatial constraints. This paper outlines a simple experimental method for obtaining a high quality input-output FRF of a structure in areas where an impact hammer can not reach during impact testing. Traditionally, the FRF in such an area is obtained by using a load cell extender with a hammer impact excitation. A common problem with this device is a double hit, that yields unacceptable results. The new method provided in this paper is shown to be superior to the traditional method for several reasons: (i) it is simple and requires no new equipment, (ii) a double hit issue is avoided, (iii) the desired FRF is calculated using a closed form equation, provided in this paper, which results in a more accurate solution.
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