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Journal Article

A New Metamodeling Approach for Time-Dependent Reliability of Dynamic Systems with Random Parameters Excited by Input Random Processes

2014-04-01
2014-01-0717
We propose a new metamodeling method to characterize the output (response) random process of a dynamic system with random parameters, excited by input random processes. The metamodel can be then used to efficiently estimate the time-dependent reliability of a dynamic system using analytical or simulation-based methods. The metamodel is constructed by decomposing the input random processes using principal components or wavelets and then using a few simulations to estimate the distributions of the decomposition coefficients. A similar decomposition is also performed on the output random process. A kriging model is then established between the input and output decomposition coefficients and subsequently used to quantify the output random process corresponding to a realization of the input random parameters and random processes. What distinguishes our approach from others in metamodeling is that the system input is not deterministic but random.
Journal Article

A Nonparametric Bootstrap Approach to Variable-size Local-domain Design Optimization and Computer Model Validation

2012-04-16
2012-01-0226
Design optimization often relies on computational models, which are subjected to a validation process to ensure their accuracy. Because validation of computer models in the entire design space can be costly, a recent approach was proposed where design optimization and model validation were concurrently performed using a sequential approach with both fixed and variable-size local domains. The variable-size approach used parametric distributions such as Gaussian to quantify the variability in test data and model predictions, and a maximum likelihood estimation to calibrate the prediction model. Also, a parametric bootstrap method was used to size each local domain. In this article, we generalize the variable-size approach, by not assuming any distribution such as Gaussian. A nonparametric bootstrap methodology is instead used to size the local domains. We expect its generality to be useful in applications where distributional assumptions are difficult to verify, or not met at all.
Technical Paper

Analysis of Methods for Determining Sheared Edge Formability

2011-04-12
2011-01-1062
Imposing tensile stress on an edge of a sheet metal blank is a common condition in many sheet metal forming operations, making edge formability a very important factor to consider. Because edge formability varies greatly among different materials, cutting methods (and their control parameters), it is very important to have access to an experimental technique that would allow for quick and reliable evaluation of edge formability for a given case. In this paper, two existing techniques are compared: the hole expansion test and the tensile test. It is shown that the hole expansion test might not be adequate for many cases, and is prone to overestimating the limiting strain, because the burr on the sheared edge is typically smaller than what is observed in production. The tensile test represents an effective alternative to the hole expansion test. Advantages and disadvantages of each case are discussed.
Technical Paper

Assessment of Different Joining Techniques for Dissimilar Materials

2014-04-01
2014-01-0790
In this paper, experimental study and FEA simulation are performed to investigate the effect of three different methods for joining dissimilar metal coupons in terms of their strength and load transferring capacity. The joining techniques considered include adhesive bonding, bolting and hybrid bolting-and-bonding. Elastic-plastic material model with damage consideration is used for each of the joint components. Traction-separation rule and failure criterion is defined for adhesive. Load transfer capacity and the failure mode are assessed for each type of joining. Joint strength is examined in terms of the effects of adhesive property, bolt preload level, and friction coefficient. Results show that load transferred and failure mechanism vary significantly between samples with different joint methods; preload evolution in bolt changes with friction coefficient; hybrid joint generally has advantage over the other two methods, namely, bolting-only and bonding-only.
Book

Automotive Systems Engineering

2010-11-29
Automotive systems engineering addresses the system throughout its life cycle, including requirement, specification, design, implementation, verification and validation of systems, modeling, simulation, testing, manufacturing, operation and maintenance. This four-volume set features 49 papers, originally published from 1999 through 2010, that cover the latest research and developments on various aspects of automotive systems engineering. The four-volume set consists of these individual volumes: Automotive Systems Engineering – Overview Automotive Systems Engineering – Requirements and Testing Automotive Systems Engineering – Modeling Automotive Systems Engineering – Approach and Verification
Book

Automotive Systems Engineering - Approach and Verification

2010-11-29
Automotive systems engineering addresses the system throughout its life cycle, including requirement, specification, design, implementation, verification and validation of systems, modeling, simulation, testing, manufacturing, operation and maintenance. This book is the fourth in a series of four volumes on this subject and features 12 papers, published between 2002-2009, that address the challenges and importance of systems approach in system verification and validation, stressing the use of advanced tools and approaches. Topics covered include: Systems integration and verification Software engineering in future automotive systems development Configuration management of the model-based design process Buy the Set and Save! The four-volume set consists of these individual volumes: Automotive Systems Engineering – Overview Automotive Systems Engineering – Requirements and Testing Automotive Systems Engineering – Modeling Automotive Systems Engineering – Approach and Verification
Book

Automotive Systems Engineering - Modeling

2010-11-29
Automotive systems engineering addresses the system throughout its life cycle, including requirement, specification, design, implementation, verification and validation of systems, modeling, simulation, testing, manufacturing, operation and maintenance. This book – the third in a series of four volumes on this subject – features 11 papers, published between 1999-2010, that address the challenges and importance of systems modeling, stressing the use of advanced tools and approaches. Topics covered include: Automotive systems modeling Model-based design culture Applications Buy the Set and Save! The four-volume set consists of these individual volumes: Automotive Systems Engineering – Overview Automotive Systems Engineering – Requirements and Testing Automotive Systems Engineering – Modeling Automotive Systems Engineering – Approach and Verification
Book

Automotive Systems Engineering - Overview

2010-11-29
Automotive systems engineering addresses the system throughout its life cycle, including requirement, specification, design, implementation, verification and validation of systems, modeling, simulation, testing, manufacturing, operation and maintenance. This book is the first in a series of four volumes on this subject and features 15 papers, published between 2004-2010, that emphasize the importance of systems concepts in the automotive area, and stress the use of advanced tools and approaches. Topics covered include: Technology transfer Six Sigma deployment Systems engineering capability in automotive systems In addition to 11 SAE technical papers, this volume also includes two invited papers: “Systems Engineering Definitions” by editor Subramaniam Ganesan and “Systems Engineering for Military Ground Vehicles” by M. Mazzara and R. Iyer. Buy the Set and Save!
Book

Automotive Systems Engineering - Requirements and Testing

2010-11-29
Automotive systems engineering addresses the system throughout its life cycle, including requirement, specification, design, implementation, verification and validation of systems, modeling, simulation, testing, manufacturing, operation and maintenance. This book - the second in a series of four volumes on this subject - features 11 papers, published between 2000-2010, that address the challenges and importance of requirements and testing in systems engineering, stressing the use of advanced tools and approaches. Topics covered include: Creating correct requirements Requirement analysis Document management Development Management Architecture for military vehicles Buy the Set and Save! Automotive Systems Engineering The four-volume set consists of these individual volumes: Automotive Systems Engineering - Overview Automotive Systems Engineering - Requirements and Testing Automotive Systems Engineering - Modeling Automotive Systems Engineering - Approach and Verification
Technical Paper

Decision-Based Universal Design - Using Copulas to Model Disability

2015-04-14
2015-01-0418
This paper develops a design paradigm for universal products. Universal design is term used for designing products and systems that are equally accessible to and usable by people with and without disabilities. Two common challenges for research in this area are that (1) There is a continuum of disabilities making it hard to optimize product features, and (2) There is no effective benchmark for evaluating such products. To exacerbate these issues, data regarding customer disabilities and their preferences is hard to come by. We propose a copula-based approach for modeling market coverage of a portfolio of universal products. The multiattribute preference of customers to purchase a product is modeled as Frank's Archimedean Copula. The inputs from various disparate sources can be collected and incorporated into a decision system.
Technical Paper

Experimental Study of Stretchability of Sheared Edge of Aluminum Sheet 6111-T4

2015-04-14
2015-01-0516
Experimental results on influence of trimming conditions on the shape of the sheared surface are combined with the results of stretching sheared samples after trimming. The objective of the research described in this paper is to study the mechanism of fracture initiation and cracks propagation during half-a-dog bone tensile test representing sheared edge stretching condition. One side of the sample had sheared surface obtained by the trimming process while the other side of the sample had a smooth surface. Significant attention was paid to understanding of fracture sources. An interrupted tensile test approach was employed to track fracture initiation and propagation during stretching of sheared surface. The results of the experimental study indicated that multiple sources of fracture were observed in the burr area for trimming with clearances exceeding 10% of the material thickness.
Journal Article

Flexible Design and Operation of a Smart Charging Microgrid

2014-04-01
2014-01-0716
The reliability theory of repairable systems is vastly different from that of non-repairable systems. The authors have recently proposed a ‘decision-based’ framework to design and maintain repairable systems for optimal performance and reliability using a set of metrics such as minimum failure free period, number of failures in planning horizon (lifecycle), and cost. The optimal solution includes the initial design, the system maintenance throughout the planning horizon, and the protocol to operate the system. In this work, we extend this idea by incorporating flexibility and demonstrate our approach using a smart charging electric microgrid architecture. The flexibility is realized by allowing the architecture to change with time. Our approach “learns” the working characteristics of the microgrid. We use actual load and supply data over a short time to quantify the load and supply random processes and also establish the correlation between them.
Technical Paper

Model-Based Embedded Controls Test and Verification

2010-04-12
2010-01-0487
Embedded systems continue to become more complex. As a result, more companies are utilizing model-based design (MBD) development methods and tools. The use of MBD methods and tools is helpful in increasing time to market and having instant feedback on the system design. One area that continues to mature is the testing and verification of the MBD systems. This paper introduces a hybrid approach to functional tests. The test system is composed of simulation software and real-time hardware. It is not always necessary to test a system in a real-time environment, but it is recommended if the goal is to deploy the system to a situation that requires real-time response. Vehicle drive cycles and powertrain control are utilized in this research as the example test case for this paper. In order to test the algorithms on a real-time system, it is necessary to understand the target controller's computing limitations and adjust the algorithms to meet these limitations.
Technical Paper

Modeling Dependence and Assessing the Effect of Uncertainty in Dependence in Probabilistic Analysis and Decision Under Uncertainty

2010-04-12
2010-01-0697
A complete probabilistic model of uncertainty in probabilistic analysis and design problems is the joint probability distribution of the random variables. Often, it is impractical to estimate this joint probability distribution because the mechanism of the dependence of the variables is not completely understood. This paper proposes modeling dependence by using copulas and demonstrates their representational power. It also compares this representation with a Monte-Carlo simulation using dispersive sampling.
Journal Article

Multi-Objective Decision Making under Uncertainty and Incomplete Knowledge of Designer Preferences

2011-04-12
2011-01-1080
Multi-attribute decision making and multi-objective optimization complement each other. Often, while making design decisions involving multiple attributes, a Pareto front is generated using a multi-objective optimizer. The end user then chooses the optimal design from the Pareto front based on his/her preferences. This seemingly simple methodology requires sufficient modification if uncertainty is present. We explore two kinds of uncertainties in this paper: uncertainty in the decision variables which we call inherent design problem (IDP) uncertainty and that in knowledge of the preferences of the decision maker which we refer to as preference assessment (PA) uncertainty. From a purely utility theory perspective a rational decision maker maximizes his or her expected multi attribute utility.
Journal Article

Optimal Preventive Maintenance Schedule Based on Lifecycle Cost and Time-Dependent Reliability

2012-04-16
2012-01-0070
Reliability is an important engineering requirement for consistently delivering acceptable product performance through time. It also affects the scheduling for preventive maintenance. Reliability usually degrades with time increasing therefore, the lifecycle cost due to more frequent failures which result in increased warranty costs, costly repairs and loss of market share. In a lifecycle cost based design, we must account for product quality and preventive maintenance using time-dependent reliability. Quality is a measure of our confidence that the product conforms to specifications as it leaves the factory. For a repairable system, preventive maintenance is scheduled to avoid failures, unnecessary production loss and safety violations. This article proposes a methodology to obtain the optimal scheduling for preventive maintenance using time-dependent reliability principles.
Technical Paper

Precision Measurement of Deformation Using a Self-calibrated Digital Speckle Pattern Interferometry (DSPI)

2010-04-12
2010-01-0958
A self-calibrating phase-shifting technique using a Michelson Interferometer is presented to measure phase distribution more accurately in Digital Speckle Pattern Interferometry (DSPI). DSPI is a well-established technique for the determination of whole field deformation via quantitatively measuring the phase distribution of speckle interferograms that use the phase shifting technique. In the phase shifting technique, the phase distribution in a speckle interferogram is quantitatively determined by recording multiple intensity images (usually four images) in which a constant phase shift, e.g. 90 degrees, is introduced between each consecutive image. A precise phase determination is greatly dependent on the accuracy of the phase shift introduced. The popular methods to minimize the error resulting from inaccurate phase shift use various algorithms and need to record five or eight images (rather than four images).
Technical Paper

Prediction of Draw Bead Coefficient of Friction Using Surface Temperature

2002-03-04
2002-01-1059
Sheet metal stamping involves a system of complex tribological (friction, lubrication, and wear), heat transfer, and material strain interactions. Accurate coefficient of friction, strain, and lubrication regime data is required to allow proper modeling of the various sheet stamping processes. In addition, non-intrusive means of monitoring the coefficient of friction in production stamping operations would be of assistance for efficiently maintaining proper stamping quality and to indicate when adjustments to the various stamping parameters, including maintenance, would be advantageous. One of the key sub-systems of the sheet metal stamping process is the draw bead. This paper presents an investigation of the tribology of the draw bead using a Draw Bead Simulator (DBS) Machine and automotive zinc-coated sheet steels. The investigation and findings include: 1) A new, non-intrusive method of measuring the surface temperature of the sheet steel as it passes through the draw bead.
Technical Paper

Rapid Evaluation of Hermetic Seals in Automotive Microelectronic Packages Using Shearography

1996-02-01
960975
As the use of electronic devices in automobiles increases, the reliability of such devices is becoming increasingly important. One possible failure is due to leakage resulted from imperfect hermetical seal in mircochips and microelectronic packages. This paper presents an optical technique referred to as shearography for rapid evaluation of hermetics seals. The proposed process of leaking testing is very fast and practical.
Technical Paper

Rapid Measurement of Residual Stress by Computerized Shearography

1996-02-01
960974
This paper presents an optical method for evaluating residual stresses. The approach is based on measuring the deformation due to the relief of stress produced by a blind-hole drilling technique. The deformation is rapidly measured by shearography. Unlike the strain gage method, this method does not require mounting strain gages /transducers. A rapid process for detection of residual stress using a micro-indentation technique is also present. The method is practical for employment in a production/field environment.
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