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This paper presents the most recent advancement in the vehicle development process using the one-step or auto Transfer Path Analysis (TPA) in conjunction with the superelement, component mode synthesis, and automated multi-level substructuring techniques. The goal is to identify the possible ways of energy transfer from the various sources of excitation through numerous interfaces to given target locations. The full vehicle model, consists of superelements, has been validated with the detailed system model for all loadcases. The forces/loads can be from rotating components, powertrain, transfer case, chain drives, pumps, prop-shaft, differential, tire-wheel unbalance, road input, etc., and the receiver can be at driver/passenger ears, steering column/wheel, seats, etc. The traditional TPA involves two solver runs, and can be fairly complex to setup in order to ensure that the results from the two runs are consistent with subcases properly labeled as input to the TPA utility.

In the vehicle development process, one important step is to set a component performance target from the vehicle level performance. Conventional barrier-decoupler dash mats and floor trim underlayment systems typically provide sound transmission loss (STL) with minimal absorption. Thus the performance of such components can be relatively easily specified as either STL or Insertion Loss. Lightweight dissipative or multi-layered acoustic materials provide both STL and significant absorption. The net performance is a combination of two parameters instead of one. The target for such components needs to account for this combined effect, however different suppliers use unique formulations and manufacturing methods, so it is difficult and time consuming to judge one formulation against another. In this paper, a unique process is presented to set a component target as a combined effect of STL and absorption.

It is obvious at this point even to the most casual observer of the automotive industry that efforts to reduce mass throughout the vehicle are at a fervor. The industry is facing its most significant increase in fuel economy standards in its history, and light-weighting the vehicle is a major enabler. Despite the performance and quality of the brake system being intensely related to its mass, it too has not been spared scrutiny. However, like many modern automotive subsystems, it is very complex and mass reduction opportunities that do not sacrifice performance or quality are not always obvious. There are some interesting and sometimes even profound relationships between mass and other vehicle attributes built into brake system design, and making these more visible can enable a better balancing of brake system with the rest of the vehicle design objectives. Examples include - what is the cost, in terms of brake system mass, of added engine power? Of tire and wheel size?

With the ever increasing pressure to improve the fuel economy of vehicles, there has been a corresponding interest in reducing the mass and size of vehicles. While mass is easily quantifiable, vehicle size, particularly the notion of “interior space” as perceived by the customer, is not. This paper explores different ways in which vehicle spaciousness can be quantified and explores new metrics based on customer verbatims. A novel ‘spaciousness calculator’ combines individual metrics to provide a singular holistic rating for spaciousness, useful during vehicle development. Beyond spaciousness, the paper discusses techniques to quantify the ‘packaging efficiency’ of a vehicle; this allows engineers to maximize the interior space for a given exterior size.

An area of brake system design that has remained continually resistant to objective, computer model based predictive design and has instead continued to rely on empirical methods and prior history, is that of sizing the brake pads to insure satisfactory service life of the friction material. Despite advances in CAE tools and methods, the ever-intensifying pressures of shortened vehicle development cycles, and the loss of prototype vehicle properties, there is still considerable effort devoted to vehicle-level testing on public roads using “customer-based” driving cycles to validate brake pad service life. Furthermore, there does not appear to be a firm, objective means of designing the required pad volume into the calipers early on - there is still much reliance on prior experience.

The goal of this paper is to discuss the critical aspects of damper tuning for production vehicles. These aspects include ride and handling performance attributes, damper basics, conflicts in achieving desirable results, tuning philosophies, and the influence of the damper design. The marketplace has become increasingly competitive. Customer preference, cost, mass and regulatory pressures often conflict. Yet each year more vehicles are required to do all these things well. Damper tuning can play a significant role in resolving these conflicts. Although many papers have been written on the theory behind damper design and capabilities, there has been very little written about the techniques of tuning dampers for production vehicles. This paper attempts to discuss the critical aspects of damper tuning for production vehicles in four sections. The first section discusses the performance attributes of ride and handling. The second section provides a basic understanding of dampers.

The Sine with Dwell (SWD) maneuver is the basis for the NHTSA FMVSS-126 regulation. When put into effect, all vehicles under 10,000 lbs GVWR will need to pass this test. Understanding the variability in the yaw rate ratio and lateral displacement test metrics is important for vehicle design. Anything that influences vehicle handling can affect test metric variability. Vehicle handling performance depends largely on vertical tire patch loads, tire force and moment behavior, on slip angle, and camber angle. Tire patch loads are influenced, among other things, by weight distribution and (quasi-static and dynamic) roll-couple distribution. Tire force and moment relationships have a distinct shapes, but they all commonly rise to a peak value at a given slip angle value and then fall off with increasing slip angle. Severe handling maneuvers, like the SWD operate at slip angles that are at, or above, the peak lateral force.

“Wheel balancing” is one of the common automotive repairs that the owners of an automobile usually experience. An unbalanced set of a tire and a rim or wheel on which the tire is mounted could cause vibration while driving. Such vibrations may be sensed by the driver at the steering wheel (known as smooth road shake). If left untreated for a long period of time, the vibration, induced by the imbalance, may propagate to chassis components such as bearing and bushing. This in turn causes excessive wear that eventually leads to a premature failure. Therefore, an early detection of wheel imbalances can not only significantly reduce the cost and time for diagnosis and repair of the wheel, but also prevent further damage to chassis components. This paper studies the feasibility of real-time detection of wheel imbalances in real world driving conditions, using recursive least square estimation method. The simulation study shows promising results for implementation in a real vehicle.

This paper describes the capabilities of a new two-motor plug-in hybrid-electric propulsion system developed for rear wheel drive. The PHEV system comprises a 2.0L turbocharged 4-cylinder direct-injected gasoline engine with the new hybrid transmission [1], a new traction power inverter module, a liquid-cooled lithium-ion battery pack, and on-board battery charger and 12V power converter module. The capability and features of the system components are described, and component performance and vehicle data are reported. The resulting propulsion system provides an excellent combination of electric-only driving, acceleration, and fuel economy.

SAE J2562 defines the background, apparatus and the directions for modifying the Scaled Base Load Sequence for a given a wheel rated load for a wheel design. This practice has been conducted on multiple wheel designs and over one hundred wheel specimens. All of the wheels were tested to fracture. Concurrently, some of the wheel designs were found to be unserviceable in prior or subsequent proving grounds on-vehicle testing. The remainder of the wheel designs have sufficient fatigue strength to sustain the intended service for the life of the vehicle. This is termed serviceable. Using the empirical data with industry accepted statistics a minimum requirement can be projected, below which a wheel design will likely have samples unserviceable in its intended service. The projections of serviceability result in a recommendation of a minimum cycle requirement for SAE J2562 Ballasted Passenger Vehicle Load Sequence.

AUTOSAR(AUTomotive Open System ARchitecture) establishes an industry standard for OEMs and the supply chain to manage growing complexity to the automotive electronics domain. Increased focus on software based features will prove to be a key differentiator between vehicle platforms. AUTOSAR serves to standardize automotive serial data communication protocols, interaction with respect to hardware peripherals within an ECU and allow ECU implementer to focus on development of unique customer focused features that distinguish product offerings. Adoption strategy and impact assessment associated with leveraging AUTOSAR for an E/E Architecture and the potential challenges that need to be considered will be described in this publication. This publication will also illustrate development strategies that need to be considered w.r.t deploying AUTOSAR like data exchange, consistency to BSW software implementation, MCAL drivers etc.

Mahalanobis Distance (MD) is gaining momentum in many fields where classification, statistical pattern recognition, and forecasting are primary focus. It is a multivariate method and considers correlation relationships among parameters for computing generalized distance measure to separate groups or populations. MD is a useful statistic in multivariate analysis to test that an observed random sample is from a multivariate normal distribution. This capability alone enables engineers to determine if an observed sample is an outlier (defect) that falls outside the constructed (good) multivariate normal distribution. In Mahalanobis-Taguchi System (MTS), MD is suitably scaled and used as a measure of severity in abnormality assessment. It is obvious that computed MD depends on values of parameters observed on a random sample. All parameters may not equally impact MD. MD could be highly sensitive with respect to some parameters and less sensitive to some other parameters.

In automotive noise control, the hood liner is an important acoustic part for mitigating engine noise. The random incidence absorption coefficient is used to quantify the component level acoustic performance. Generally, air gaps, type of substrate materials, density of the substrate materials and Air Flow Resistivity (AFR) of the cover scrim are the dominant control factors in the sound absorption performance. This paper describes a systematic experimental investigation of how these control factors affect flat sample performance. The first stage of this study is full factorial measurement based on current available solutions from sound absorber suppliers. The acoustic absorption of different hood liner constructions, with variations in materials, density, air gaps, and scrims was measured.

For the conventional 6 speed automatic transmission with engine stop-start powertrain, an electrically-driven auxiliary pump is implemented to maintain the transmission line pressure as required to lock-up the CB1234 clutch during engine auto-stop conditions. Upon releasing the brake pedal, the transmission engages into first gear with the objective to accelerate the vehicle in a responsive manner. In this study, a novel normally-engaged dual-piston clutch concept is designed to keep the CB1234 clutch locked-up during engine auto-stop conditions with the intention to eliminate the auxiliary pump without compromising vehicle performance. This dual piston clutch concept requires a relatively low line pressure to release the normally-engaged clutch when needed, thus, minimizing the hydraulic pumping work. To explore the functionality of this concept under a wide-open-throttle (WOT) auto-start transition, modeling and simulation of the normally-engaged dual-piston clutch is completed.

Rapidly increasing customer, financial, and regulatory pressures are creating clear changes in the calculus of vehicle design for modern automotive OEM's (Original Equipment Manufacturers). Customers continue to demand shorter product lifecycles; the increasingly competitive global market exerts pressure to reduce costs in all stages of development; and environmental regulations drive a continuous need to reduce mass and energy consumption. OEM's must confront these challenges while continuing to satisfy the customer. The foundation to meeting these challenges includes: (1) Continued development of objective metrics to quantify performance; (2) Frontloading vehicle design content and performance synthesis; (3) A precise understanding of the customer and their performance preferences under diverse usage conditions. These combined elements will enable products better optimized amongst competing (and often contradictory) imperatives.

Today's sophisticated state-of-the-art powertrains with various intelligent control units (xCU) need to be calibrated and tested stand-alone as well as in interaction. Today the majority of this work is still carried out with prototype vehicles on test tracks. Moving prototype vehicle tests from the road into the lab is key in achieving shorter development times and saving development cost. This kind of frontloading requires a modular and powerful simulation of all vehicle components, test track, and driver in steady state and dynamic operation. The described HIL (Hardware In the Loop) high performance driveline dyno test bed uses driveline components and models from the engine all the way to the wheel ends. The test cell was built to do real time vehicle maneuvers and NVH testing. This test setup can emulate any road surface and grade and vehicle inertia including wheels and engine as close to reality as possible.

Refinements were made to a post-processing technique, termed the Thermal Stratification Analysis (TSA), that couples the mass fraction burned data to ignition timing predictions from the autoignition integral to calculate an apparent temperature distribution from an experimental HCCI data point. Specifically, the analysis is expanded to include all of the mass in the cylinder by fitting the unburned mass with an exponential function, characteristic of the wall-affected region. The analysis-derived temperature distributions are then validated in two ways. First, the output data from CFD simulations are processed with the Thermal Stratification Analysis and the calculated temperature distributions are compared to the known CFD distributions.

For a CAE model of the park pawl dynamic system, the engagement speed calculation is done by controlling the input rotational velocity of the vehicle. Usually, it requires multiple adjustment of the input rotational velocity to get the engagement speed and that demands time, effort and file management skill of an analyst. The current objective of this paper is to demonstrate how software Isight, working with ABAQUS Explicit as the solver, can be used to automate the engagement speed calculation procedure and thus reduce the time and effort required of a CAE analyst. The automated system is developed in a way such that the accuracy of the results can be controlled by the end user. It is observed that the automated system significantly saves an analyst's effort. The system design can be optimized easily for modifiable design features such as the torsional spring and the actuator spring stiffness values using the proposed procedure.

Emission compliance at the production level has been a challenge for vehicle manufacturers. Diesel oxidation catalyst (DOC) plays a very important role in controlling the emissions for the diesel vehicles. Vehicle manufacturers tend to ‘over design’ the diesel oxidation catalyst to ‘absorb’ the production variations which seems an easier and faster solution. However this approach increases the DOC cost phenomenally which impacts the overall vehicle cost. The main objective of this paper is to address the high variation in CO tail pipe emissions which were observed on a diesel passenger car during development. This variation was posing a challenge in consistently meeting the internal product requirement/specification.

The automotive industry is one of the most competitive enterprises in the world. Customers face an ever-expanding number of entries in each market segment vying for their business. Sales price, brand image, marketing, etc. all play a role in purchase decisions, but the factor distinguishing products that consistently perform in the market place is the ability to satisfy the customer. Steering character plays a critical role in the customer driving experience and can be one of the most heavily debated topics during a new vehicle program. The proliferation of EPS steering systems now allows engineers to calibrate steering feel to almost any desired specification. This raises a key question: What subjective & objective characteristics satisfy customers in a particular market segment?