Refine Your Search

Topic

Author

Search Results

Technical Paper

“Taguchi Customer Loss Function” Based Functional Requirements

2018-04-03
2018-01-0586
Understanding customer expectations is critical to satisfying customers. Holding customer clinics is one approach to set winning targets for the engineering functional measures to drive customer satisfaction. In these clinics, customers are asked to operate and interact with vehicle systems or subsystems such as doors, lift gates, shifters, and seat adjusters, and then rate their experience. From this customer evaluation data, engineers can create customer loss or preference functions. These functions let engineers set appropriate targets by balancing risks and benefits. Statistical methods such as cumulative customer loss function are regularly applied for such analyses. In this paper, a new approach based on the Taguchi method is proposed and developed. It is referred to as Taguchi Customer Loss Function (TCLF).
Journal Article

Wheel Bearing Brinelling and a Vehicle Curb Impact DOE to Understand Factors Affecting Bearing Loads

2017-09-17
2017-01-2526
As material cleanliness and bearing lubrication have improved, wheel bearings are experiencing less raceway spalling failures from rotating fatigue. Warranty part reviews have shown that two of the larger failure modes for wheel bearings are contaminant ingress and Brinell damage from curb and pothole impacts. Warranty has also shown that larger wheels have higher rates of Brinell warranty. This paper discusses the Brinell failure mode for bearings. It reviews a vehicle test used to evaluate Brinell performance for wheel bearings. The paper also discusses a design of experiments to study the effects of factors such as wheel size, vehicle loading and vehicle position versus the bearing load from a vehicle side impact to the wheel. As the trend in vehicle styling is moving to larger wheels and low profile tires, understanding the impact load can help properly size wheel bearings.
Technical Paper

Virtual Powertrain Calibration at GM Becomes a Reality

2010-10-19
2010-01-2323
GM's R oad-to- L ab-to- M ath (RLM) initiative is a fundamental engineering strategy leading to higher quality design, reduced structural cost, and improved product development time. GM started the RLM initiative several years ago and the RLM initiative has already provided successful results. The purpose of this paper is to detail the specific RLM efforts at GM related to powertrain controls development and calibration. This paper will focus on the current state of the art but will also examine the history and the future of these related activities. This paper will present a controls development environment and methodology for providing powertrain controls developers with virtual (in the absence of ECU and vehicle hardware) calibration capabilities within their current desktop controls development environment.
Journal Article

Vehicle Integration Factors Affecting Brake Caliper Drag

2012-09-17
2012-01-1830
Disc brakes operate with very close proximity of the brake pads and the brake rotor, with as little as a tenth of a millimeter of movement of the pads required to bring them into full contact with the rotor to generate braking torque. It is usual for a disc brake to operate with some amount of residual drag in the fully released state, signifying constant contact between the pads and the rotor. With this contact, every miniscule movement of the rotor pushes against the brake pads and changes the forces between them. Sustained loads on the brake corner, and maneuvers such as cornering, can both produce rotor movement relative to the caliper, which can push it steadily against one or both of the brake pads. This can greatly increase the residual force in the caliper, and increase drag. This dependence of drag behavior on the movement of the brake rotor creates some vehicle-dependent behavior.
Technical Paper

Utilizing Finite Element Tools to Model Objective Seat Comfort Results

2012-04-16
2012-01-0074
The comfort assessment of seats in the automotive industry has historically been accomplished by subjective ratings. This approach is expensive and time consuming since it involves multiple prototype seats and numerous people in supporting processes. In order to create a more efficient and robust method, objective metrics must be developed and utilized to establish measurable boundaries for seat performance. Objective measurements already widely accepted, such as IFD (Indentation Force Deflection) or CFD (Compression Force Deflection) [1], have significant shortcomings in defining seat comfort. The most obvious deficiency of these component level tests is that they only deal with a seats' foam rather than the system response. Consequently, these tests fail to take into account significant factors that affect seat comfort such as trim, suspension, attachments and other components.
Journal Article

The Effect of Outer Ring Distortion on Wheel Bearing Friction Torque

2017-09-17
2017-01-2521
Wheel bearing friction torque (“drag”) directly contributes to vehicle fuel economy and CO2 emissions. At the same time, one of the most important factors for long-term durability of wheel bearings is effective seal performance. Since these two factors are often in conflict, it is important to balance the desire for low friction with the need for optimal sealing. One factor that affects wheel bearing sealing performance is the distortion of the outer ring that occurs when the bearing is mounted to the steering knuckle with fasteners. Minimizing this distortion is not just important for sealing, however. This paper explores the relationship between the outer ring distortion and the resulting friction torque. A design of experiments (DOE) approach was used in order to study the effects of the fastening bolt torque, constant velocity joint (CVJ) fastening torque, and outer ring distortion on component-level drag.
Video

Test Method for Seat Wrinkling and Bagginess

2012-05-22
This study evaluates utilizing an accelerated test method that correlates customer interaction with a vehicle seat where bagginess and wrinkling is produced. The evaluation includes correlation from warranty returns as well as test vehicle results for test verification. Consumer metrics will be discussed within this paper with respect to potential application of this test method, including but not limited to JD Power ratings. The intent of the test method is to aid in establishing appropriate design parameters of the seat trim covers and to incorporate appropriate design measures such as tie downs and lamination. This test procedure was utilized in a Design for Six Sigma (DFSS) project as an aid in optimizing seat parameters influencing trim cover performance using a Design of Experiment approach. Presenter Lisa Fallon, General Motors LLC
Technical Paper

Tensile Material Properties of Fabrics for Vehicle Interiors from Digital Image Correlation

2013-04-08
2013-01-1422
Fabric materials have diverse applications in the automotive industry which include upholstery, carpeting, safety devices, and interior trim components. The textile industry has invested substantial effort toward development of standard testing techniques for characterizing mechanical properties of different fabric types (e.g. woven and knitted). However, there are presently no standards for determination of Young's modulus, Poisson's ratio and tensile stress-strain properties required for the detailed modeling of fabric materials in vehicle structural simulations. This paper presents results from uniaxial tensile tests of different automotive seat cover fabric materials. Digital image correlation, a full field optical method for measuring surface deformation, was used to determine tensile properties in both the warp/wale and the weft/course directions. The fabrics were tested with and without the foam backing.
Journal Article

Sizing Next Generation High Performance Brake Systems with Copper Free Linings

2017-09-17
2017-01-2532
The high performance brake systems of today are usually in a delicate balance - walking the fine line between being overpowered by some of the most potent powertrains, some of the grippiest tires, and some of the most demanding race tracks that the automotive world has ever seen - and saddling the vehicle with excess kilograms of unsprung mass with oversized brakes, forcing significant compromises in drivability with oversized tires and wheels. Brake system design for high performance vehicles has often relied on a very deep understanding of friction material performance (friction, wear, and compressibility) in race track conditions, with sufficient knowledge to enable this razor’s edge design.
Technical Paper

Modified Experimental Approach to Investigate Coefficient of Friction and Wear under Lubricated Fretting Condition by Utilizing SRV Test Machine

2018-04-03
2018-01-0835
Fretting is an important phenomenon that happens in many mechanical parts. It is the main reason in deadly failures in automobiles, airliners, and turbine engines. The damage is noticed between two surfaces clamped together by bolts or rivets that are nominally at rest, but have a small amplitude oscillation because of vibration or local cyclic loading. Fretting damage can be divided into two types. The first type is the fretting fatigue damage where a crack would initiate and propagate at specific location at the interface of the mating surfaces. Cracks usually initiate in the material with lower strength because of the local cyclic loading conditions which eventually lead to full failure. The second type is the fretting wear damage because of external vibration. Researchers have investigated this phenomenon by theoretical modeling and experimental approaches. Although a lot of research has been done on fretting damage, some of the parameters have not been well studied.
Technical Paper

Modeling the Stiffness and Damping Properties of Styrene-Butadiene Rubber

2011-05-17
2011-01-1628
Styrene-Butadiene Rubber (SBR), a copolymer of butadiene and styrene, is widely used in the automotive industry due to its high durability and resistance to abrasion, oils and oxidation. Some of the common applications include tires, vibration isolators, and gaskets, among others. This paper characterizes the dynamic behavior of SBR and discusses the suitability of a visco-elastic model of elastomers, known as the Kelvin model, from a mathematical and physical point of view. An optimization algorithm is used to estimate the parameters of the Kelvin model. The resulting model was shown to produce reasonable approximations of measured dynamic stiffness. The model was also used to calculate the self heating of the elastomer due to energy dissipation by the viscous damping components in the model. Developing such a predictive capability is essential in understanding the dynamic behavior of elastomers considering that their dynamic stiffness can in general depend on temperature.
Technical Paper

Model-Based Systems Engineering and Control System Development via Virtual Hardware-in-the-Loop Simulation

2010-10-19
2010-01-2325
Model-based control system design improves quality, shortens development time, lowers engineering cost, and reduces rework. Evaluating a control system's performance, functionality, and robustness in a simulation environment avoids the time and expense of developing hardware and software for each design iteration. Simulating the performance of a design can be straightforward (though sometimes tedious, depending on the complexity of the system being developed) with mathematical models for the hardware components of the system (plant models) and control algorithms for embedded controllers. This paper describes a software tool and a methodology that not only allows a complete system simulation to be performed early in the product design cycle, but also greatly facilitates the construction of the model by automatically connecting the components and subsystems that comprise it.
Journal Article

Lockheed Martin Low-Speed Wind Tunnel Acoustic Upgrade

2018-04-03
2018-01-0749
The Lockheed Martin Low-Speed Wind Tunnel (LSWT) is a closed-return wind tunnel with two solid-wall test sections. This facility originally entered into service in 1967 for aerodynamic research of aircraft in low-speed and vertical/short take-off and landing (V/STOL) flight. Since this time, the client base has evolved to include a significant level of automotive aerodynamic testing, and the needs of the automotive clientele have progressed to include acoustic testing capability. The LSWT was therefore acoustically upgraded in 2016 to reduce background noise levels and to minimize acoustic reflections within the low-speed test section (LSTS). The acoustic upgrade involved detailed analysis, design, specification, and installation of acoustically treated wall surfaces and turning vanes in the circuit as well as low self-noise acoustic wall and ceiling treatment in the solid-wall LSTS.
Technical Paper

Learning Gasoline Direct Injector Dynamics Using Artificial Neural Networks

2018-04-03
2018-01-0863
In today’s race for improved fuel economy and lower emissions from gasoline engines, precise metering of delivered fuel is essential. Gasoline Direct Injection fuel systems provide the means for improved combustion efficiency through mixture preparation and better atomization. These improvements can be achieved from both increasing fuel pressure and using multiple injection events, which significantly reduce the required energizing time per injection, and in a number of cases, force the injector to operate at less than full stroke. When the injector operates in this condition, the influence of variation in injector dynamics account for a large percentage of the delivered fuel and require compensation to ensure accurate fuel delivery. Injector dynamics such as opening delay and closing time are influenced by operating conditions such as fuel pressure, energizing time, and temperature.
Journal Article

Iterative Learning Algorithm Design for Variable Admittance Control Tuning of A Robotic Lift Assistant System

2017-03-28
2017-01-0288
The human-robot interaction (HRI) is involved in a lift assistant system of manufacturing assembly line. The admittance model is applied to control the end effector motion by sensing intention from force of applied by a human operator. The variable admittance including virtual damping and virtual mass can improve the performance of the systems. But the tuning process of variable admittance is un-convenient and challenging part during the real test for designers, while the offline simulation is lack of learning process and interaction with human operator. In this paper, the Iterative learning algorithm is proposed to emulate the human learning process and facilitate the variable admittance control design. The relationship between manipulate force and object moving speed is demonstrated from simulation data. The effectiveness of the approach is verified by comparing the simulation results between two admittance control strategies.
Technical Paper

Initial Comparisons of Friction Stir Spot Welding and Self Piercing Riveting of Ultra-Thin Steel Sheet

2018-04-03
2018-01-1236
Due to the limitations on resistance spot welding of ultra-thin steel sheet (thicknesses below 0.5 mm) in high-volume automotive manufacturing, a comparison of friction stir spot welding and self-piercing riveting was performed to determine which process may be more amenable to enabling assembly of ultra-thin steel sheet. Statistical comparisons between mechanical properties of lap-shear tensile and T-peel were made in sheet thickness below 0.5 mm and for dissimilar thickness combinations. An evaluation of energy to fracture, fracture mechanisms, and joint consistency is presented.
Technical Paper

Identification of Organic Acids in Used Engine Oil Residues by Pyrolysis-Comprehensive 2D Gas Chromatography-Time of Flight Mass Spectrometry

2016-10-17
2016-01-2274
The amount of acidic material in used engine oil is considered an indicator of the remaining useful life of the oil. Total acid number, determined by titration, is the most widely accepted method for determining acidic content but the method is not capable of speciation of individual acids. In this work, high molecular weight residue was isolated from used engine oil by dialysis in heptane. This residue was then analyzed using pyrolysis-comprehensive two dimensional gas chromatography with time-of-flight mass spectrometry. Carboxylic acids from C2-C18 were identified in the samples with acetic acid found to be the most abundant. This identification provides new information that may be used to improve the current acid detection methodologies for used engine oils.
Technical Paper

Hydraulically Damped Rubber Body Mounts with High Lateral Rate for Improved Vehicle Noise, Vibration and Ride Qualities

2013-05-13
2013-01-1906
In today's competitive market, noise and vibration are among the most important parameters that impact the success of a vehicle. In body-on-frame construction vehicles, elastomeric body mounts play a major role in isolating the passenger compartment from road noise, harshness, shake, and other vibrations in the chassis as well as improving ride quality across a wide frequency range. This paper describes the work carried out to design a fluid filled mount with high lateral stiffness that can alter the perceived Noise, Vibration and Harshness (NVH) performance of current production body-on-frame trucks. It was found that the quietness and ride qualities can be significantly improved by positioning the glycol-filled mounts at the anti-node of the frame first vertical bending mode; under the C-pillar intersection with the frame. The performance of mounts in this area is known to be critical to ride quality.
Journal Article

General Motors’ New Reduced Scale Wind Tunnel Center

2017-03-28
2017-01-1534
The General Motors Reduced Scale Wind Tunnel Facility, which came into operation in the fall of 2015, is a new state-of-the-art scale model aerodynamic test facility that expands GM’s test capabilities. The new facility also increases GM’s aerodynamic testing through-put and provides the resources needed to achieve the growing demand for higher fuel economy requirements for next generation of vehicles. The wind tunnel was designed for a nominal model scale of 40%. The nozzle and test section were sized to keep wind tunnel interference effects to a minimum. Flow quality and other wind tunnel performance parameters are on par with or better than the latest industry standards. A 5-belt system with a long center belt and boundary layer suction and blowing system are used to model underbody flow conditions. An overhead probe traverse system is installed in the test section along with a model positioning robot used to move the model in an out of the test section.
Technical Paper

General Motors Hydra-Matic 9T50 Automatic Transaxle

2018-04-03
2018-01-0391
General Motors Global Propulsion Systems’ first nine-speed automatic transmission makes its debut in the 2017 Chevrolet Malibu, advancing a legacy of multispeed transmissions designed to optimize efficiency, performance and refinement. The Hydra-Matic 9T50 nine-speed is paired with a Ecotech 2.0L Turbo engine in the Malibu, contributing to an EPA estimated 33 mpg highway, a three-percent increase over the 2016 Malibu with an eight-speed automatic paired to the same engine. The 9T50 has a wider 7.6:1 overall ratio, which is the ratio between the first gear ratio and the top gear ratio, - compared to the six-speed’s 6.0:1 ratio. The 9T50 is fitted with a “deep” 4.69 first gear ratio for excellent off-the-line acceleration and a “tall” 0.62 top gear ratio for low-rpm highway cruising. That balance optimizes acceleration and fuel economy while reducing engine noise during cruising.
X