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Journal Article

A Copula-Based Approach for Model Bias Characterization

2014-04-01
2014-01-0735
Available methodologies for model bias identification are mainly regression-based approaches, such as Gaussian process, Bayesian inference-based models and so on. Accuracy and efficiency of these methodologies may degrade for characterizing the model bias when more system inputs are considered in the prediction model due to the curse of dimensionality for regression-based approaches. This paper proposes a copula-based approach for model bias identification without suffering the curse of dimensionality. The main idea is to build general statistical relationships between the model bias and the model prediction including all system inputs using copulas so that possible model bias distributions can be effectively identified at any new design configurations of the system. Two engineering case studies whose dimensionalities range from medium to high will be employed to demonstrate the effectiveness of the copula-based approach.
Technical Paper

A Cooperative Airline Program to Evaluate Engine Parts Aging Effects on a Current Turbofan Engine Model

1970-02-01
700329
The contribution that aged hardware makes to performance deterioration is of interest to operators of JT3D turbofan powered aircraft since a significant percentage of these engines have exceeded 20,000 hr of operation. Recent studies involving numerous engine disassemblies, rebuild, and test cell runs reveal the most significant effects of aged hardware are the loss in high and/or low compressor stall margin; and, that a large number of parts must be replaced to realize a significant improvement in fuel consumption, with the exception of the reduction that can be obtained by controlling turbine seal clearances.
Technical Paper

A Control and Fault Diagnosis Method for Pressure Sensor Based Brake Control System

2005-04-11
2005-01-1576
This paper proposes a control and fault diagnosis method for a pressure sensor based brake control system. The proposed wheel brake pressure control method consists of feedforward and feedback controller, respectively. The main purpose of the feedforward controller is to set the operating point of the feedback control, and the purpose of feedback controller is to improve the control response and the steady state error characteristic. Also, the proposed fault diagnosis method consists of three processes: a fault detection process, a fault isolation process and a fault identification process. In the fault detection process, a fault is detected by the difference between the estimated signal and the measured signal. Then, in the fault isolation process, the location of the fault is determined. Finally, in the identification process, the size and effect of the fault are evaluated.
Technical Paper

A Contribution for a Better Understanding of the Automotive Friction Material Characteristics Connected to Problems Deriving from Disc-Scoring Phenomena

2005-10-09
2005-01-3934
The aim of this work is to characterize the formation of metal pick-ups onto Automotive brake pads, that can lead to major wear problems for the friction material and for the rotors. The characterization of these metal pick-ups has been obtained by means of microscopy techniques (optical microscope and SEM analysis), by X-ray diffraction and thermal analysis, while it has been tried to evaluate the influence of morphological and compositional parameters (like amount of lubricants and of organic compounds) of the pad on the pick-ups formation by performing “true-scale” simulations following specific procedures.
Technical Paper

A Contract-Based Installation Methodology for Safety-Related Automotive Systems

2013-04-08
2013-01-0192
Today's automobiles contain a lot of electrical and electronic (E/E) systems with safety-related functionality. In a design-process compliant to the industrial standard ISO 26262 unknown dependencies between events and elements are risks that potentially violate safety requirements or safety goals. Therefore, the identification and analysis of dependent failures is important. Physical environment influences like temperature are one class of factors which can lead to coupling effects and cause dependent failures. In this paper we show a novel contract-based approach to deal with geometric installations of elements in an automobile. It avoids violations of safety requirements by identification and prevention of dependent failures resulting from coupling effects between elements. The influences of an element on environment factors and the failure effects of such environment factors on elements are explicitly specified as physical conditions.
Technical Paper

A Contact-Point Type Start of Injection Sensor for Diesel Engines

1985-09-01
851585
A simple contact-point based start of injection sensor has been developed for use in closed-loop injection timing control systems. The main element in this sensor is a highly durable thin film deposited by an advanced ion plating process. This sensor is expected to provide accurate detection of start of injection over all speed ranges. Sensor transient response in the feedback loop is also expected to be fast compared to other types of sensors. This detecting method can easily be applied to many kinds of injectors because of its simple structure. The durability has been confirmed by extensive testing.
Technical Paper

A Concise History of Thermoplastic Sealing Engine Cover Systems

1997-02-24
970079
The technology to manufacture thermoplastic rocker covers has evolved significantly since early applications in the US launched in 1980. New sealing methods and the widespread use of aluminum in cylinder heads make it easier to take advantage of the cost, weight and part integration opportunities that thermoplastics and the injection molding process have to offer. By understanding these developments, a functional, lightweight, low-cost, full-featured cover can be designed and manufactured.
Technical Paper

A Concept of Fully Recycling Automatic Transmissions

1998-11-30
982184
Used ATs (automatic transmissions) in the market were analyzed using a remanufacturing process, and causes of troubles/defects were investigated. By providing specific parts of an AT with sufficiently ample working-stress levels at the design stage, the remanufacturing cycle can be better controlled and managed, while still maintaining the quality of ATs at the highest levels. Scheduled part changes performed as part of this process successfully make an AT returnable to new-car assembly lines for reinstallation. This fully recycled AT enables reductions in steel and aluminum consumption, and thus contributes substantially to environmental protection efforts.
Technical Paper

A Concept for Catalyzed Ignition of Diesel Soot

1981-10-01
811236
This paper discusses the technology for disposal of diesel particulate by catalytic ignition and combustion. Using the trap-oxidizer concept, the collected soot was catalytically treated to make ignition and combustion more practical under diesel engine exhaust conditions. The catalyzed ignition was examined in a laboratory hot-tube reactor and the information thus obtained was used to design trials under engine exhaust conditions. Solutions of metal salts such as copper, manganese, or cobalt chlorides, or the corresponding nitrates, have been shown to be effective; most of this study was carried out using solutions of mixtures of copper chloride and sodium chloride. Suitable solvents included methanol, glycol-water mixtures, and distilled water. Soot-related parameters such as the soluble organic content, degree of compaction, graphitization, and surface area have been examined briefly during the course of the study.
Technical Paper

A Computational Study of Crystal Orientation Effects on High Strain Rate Performance of Single Crystal Copper

2019-04-02
2019-01-0714
This paper presents a computational study to investigate effects of crystal orientations on plasticity and damage of copper crystal at atomic scale. In the present study, a single crystal copper model was created as a target, which was struck and penetrated by a single crystal nickel. Three orientations, single slip system [1 0 1, 1 2 -1, -1 1 1], double slip system [1 1 2, 1 1 0, 1 1 -1], and octal slip system [1 0 0, 0 1 0, 0 0 1], were applied to the copper crystal. Their effects on plasticity and damage behavior of the single crystal copper were studied and compared using molecular dynamics simulations. Modified Embedded Atom Method potentials were applied to determine the pair interactions between the copper and nickel atoms.
Journal Article

A Computational Multiaxial Model for Stress-Strain Analysis of Ground Vehicle Notched Components

2017-03-28
2017-01-0329
Driveline and suspension notched components of off-road ground vehicles often experience multiaxial fatigue failures along notch locations. Large nominal load histories may induce local elasto-plastic stress and strain responses at the critical notch locations. Fatigue life prediction of such notched components requires detailed knowledge of local stresses and strains at notch regions. The notched components that are often subject to multiaxial loadings in services, experience complex stress and strain responses. Fatigue life assessment of the components utilizing non-linear Finite Element Analysis (FEA) require unfeasibly inefficient computation times and large data. The lack of more efficient and effective methods of elasto-plastic stress-strain calculation may lead to the overdesign or earlier failures of the components or costly experiments and inefficient non-linear FEA.
Technical Paper

A Computational Methodology for Fatigue Life Prediction Under Multiaxial Non-Proportional Loading

2001-03-05
2001-01-0837
A methodology for predicting the fatigue initiation life in metals experiencing multiaxial non-proportional loading is presented. The methodology utilizes nonlinear finite-element analysis to determine the stress distribution of the loaded component. This distribution is used in conjunction with a physically based damage law to determine the cycles to failure. The damage law is based on the fatigue prediction method introduced by Dang Van [1], and further developed by Papadopoulos [2] and Morel [3]. The fatigue damage initiation is treated as the persistent crystalline slip phenomenon taking place on the order of a grain or few grains. The damage variable is chosen to be the accumulated plastic strain at this scale. The initiation life is determined when the damage variable reaches a critical value. The developed methodology is applicable to both in-phase and out-of-phase loading, without any empirical adjustment parameter.
Technical Paper

A Comprehensive Study of Hole Punching Force for AHSS

2018-04-03
2018-01-0802
The elevated strength of advanced high strength steels (AHSS) leads to enormous challenges for the sheet metal processing, one of which is hole punching operation. The total tonnage must be estimated at each trimming stage to ensure successful cutting and protect the press machine. This paper presents the effects of hole punch configurations on the punching force with the consideration of punch shape, cutting clearance and material grade. The hole punching experiments were performed with DP590, DP980, DP1180 and one mild steel as a reference. The punching force coefficient is defined and presents a negative correlation with the material strength based on the experimental data. Surface quality was examined to analyze the damage accumulation during the punching process. The cutting mechanisms with various punch shapes were revealed through an extensive finite element simulation study.
Technical Paper

A Comprehensive Study of Door Slam

2004-03-08
2004-01-0161
As part of an ongoing technical collaboration between Ford and Rouge Steel Company, a comprehensive study of door slam event was undertaken. The experimental phase of the project involved measurements of accelerations at eight locations on the outer panel and strains on six locations of the inner panel. Although slam tests were conducted with window up and window down, results of only one test is presented in this paper. The CAE phase of the project involved the development of suitable “math” model of the door assembly and analysis methodology to capture the dynamics of the event. The predictability of the CAE method is examined through detailed comparison of accelerations and strains. While excellent agreement between CAE and test results of accelerations on the outer panel is obtained, the analysis predicts higher strains on the inner panel than the test. In addition, the tendency of outer panel to elastically buckle is examined.
Technical Paper

A Comprehensive Study of Chemical and Physical Properties of Metal Sulfides

2000-10-01
2000-01-2757
1 Natural and synthetic sulfides are important components in friction materials such as pads, linings and even clutch facings and are summarized under the term “Friction Stabilizers”. Their unique properties lead to a high and stable friction coefficient, low wear of pad and disk and decrease of vibrations. The tribological behaviour of friction stabilizers strongly depends on load and temperature. Analytical methods like DSC and TGA are used to investigate the chemical changes of these compounds during braking at high loads and temperatures. Tribological phenomena also strongly depend on the physical properties of the metal sulfides such as crystal structure, Mohs hardness and character of the chemical bonding. This discussion will cover the characteristics of classical natural sulfides like antimony, molybdenum and lead sulfide but also of synthetic complex sulfides. The obtained data are compared with practical measurements generated by dynamometer testing.
Journal Article

A Comprehensive Plasticity and Fracture Model for Metal Sheets under Multi-axial Stress and Non-Linear Strain Path

2017-03-28
2017-01-0315
A comprehensive plasticity and fracture model was built for metal sheets with application to metal sheet forming and vehicle crash simulations. The combined Bai-Wierzbicki (BW [1]) and CPB06ex2 [2] (or Yld2000-2D [3]) anisotropic plasticity model was further extended to consider elevated temperature effects in additional to the effect of multiaxial stress states. A fully modularized framework was established to combine isotropic, kinematic, and cross hardening behaviors under non-linear loading conditions. The all strain based modified Mohr-Coulomb (eMMC) fracture model was used to consider material anisotropy and nonlinear strain path. The model has been implemented into Abaqus/Explicit as a user material subroutine (VUMAT). Test results on advanced high strength steels, aluminum alloy sheets and magnesium alloy sheets are used to validate the modeling and testing methodologies. Very good correlation was observed between experimental and simulation results.
Technical Paper

A Composite Linear and Nonlinear Approach to Full-Vehicle Simulator Control

2005-04-11
2005-01-0937
This paper presents an approach to full-vehicle simulator control which accounts for nonlinearities in a vehicle/simulator system. The control scheme presented is based on the estimation of the system inverse dynamics. A composite linear/nonlinear approach to inverse system identification (SYS-ID) is presented. The linear portion of the SYS-ID uses time-domain methods to estimate the impulse response of the inverse system in a least squares sense. These results are then extended by using the regularized approach to least squares estimation. The nonlinear part uses the support vector machine to approximate the nonlinear deviations from the linear model. Two approaches to using this composite model are presented. Examples of the linear SYS-ID techniques are shown for a 2×2 system.
Technical Paper

A Composite Approach to Reducing Abrasive Wear

1983-09-12
831375
“Today, wearing parts are regularly subjected to abnormal loading conditions. They must be able to accept these conditions without failure. In continuous operations, unscheduled downtime greatly increases maintenance costs, not to mention the cost of lost production. White iron castings offer premium abrasion resistance for many of these applications, but are often not used due to the possibility of brittle failure and the difficulty of mechanical attachment. This paper discusses the properties and applications of a composite of martensitic white iron and mild steel. This laminate will accept medium to high impact without loss of service failure, and can be installed by mechanical means or with welded attachment.”
Technical Paper

A Complete Engine Diagnostic System for Military Application

1989-02-01
890397
The possibility of fast identification of defective components and the reduction of repair time of vehicles is a common requirement for military applications. In the development of a new power-pack for a tank application IVECO has included a complete diagnostic system that provides the following performances: at first level (i.e. on the field) the system provides indications on simple repair operations or the indication of a seriuos power-pack fault, such to require power-pack replacement. This level is fully supported on the tank itself and requires no external support. at second level (i.e. In a field workshop) the system identifies the defective sub-components, replaceable in such workshop, or indicates the need of a higher level workshop. This level requires an off-board, portable diagnostic unit.
Technical Paper

A Competitive Advantage Through Innovation

2001-03-05
2001-01-0976
The vast majority of products contain joints, therefore, joining technology is key to the strategic implementation of new materials. This paper considers three innovative solutions to industrial problems ClearWeld™ A recently developed technique for laser welding materials, creating a joint almost invisible to the human eye. AdhFAST™ This novel, three-in-one fastener, allows adhesive to be injected through the middle of the device whilst retaining the joint and controlling bondline thickness Vitresyn™ Transparent plastics such as polycarbonate and acrylic have the potential to replace glass in a number of applications, car headlamps and spectacle lenses for example. However, these plastics are relatively soft materials and need protection against abrasion and scuff damage. This recently developed system gives good protection at acceptable cost
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