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Technical Paper

A Comparative Study of Automotive System Fatigue Models Processed in the Time and Frequency Domain

The objective of this paper is to demonstrate that frequency domain methods for calculating structural response and fatigue damage can be more widely applicable than previously thought. This will be demonstrated by comparing results of time domain vs. frequency domain approaches for a series of fatigue/durability problems with increasing complexity. These problems involve both static and dynamic behavior. Also, both single input and multiple correlated inputs are considered. And most important of all, a variety of non-stationary loading types have been used. All of the example problems investigated are typically found in the automotive industry, with measured loads from the field or from the proving ground.
Technical Paper

A Framework for Reliable and Durable Product Design

In this paper, a simplified and systematic approach to integrate reliability and durability aspects in design process is presented. A six step process is explained with the help of examples. Two alternatives for gathering means and standard deviations for key parameters are discussed. First a DOE approach based on orthogonal arrays is presented. Second approach is based on Taylor Series expansion. An example of beam design is solved with both of these approaches. The Second example also considers the degradation with time in service.
Technical Paper

A Functional View of Engineering

Many descriptions of product development are based on a timeline of activity. Timelines typically do not characterize the underlying strategy and flexibility embodied in the technical activity that actually takes place between activity nodes. Timelines alone will inhibit evolving to a more rational approach to product development. The view of engineering described in this paper is a functional view of engineering. It is what engineers do. It is aligned with the technical tools used by engineers. It applies to both product development and manufacturing. It's purpose is to enhance understanding of the function of engineering activities, including reliability.
Technical Paper

A Generic Teaching Case Study for Teaching Design for Six Sigma

There are several reasons why it can be daunting to apply Six Sigma to product creation. Foremost among them, the functional performance of new technologies is unknown prior to starting a project. Although, Design For Six Sigma (DFSS) was developed to overcome this difficulty, a lack of applicable in-class case studies makes it challenging to train the product creation community. The current paper describes an in-class project which illustrates how Six Sigma is applied to a simulated product creation environment. A toy construction set (TCS) project is used to instruct students how to meet customer expectations without violating cost, packaging volume and design-complexity constraints.
Technical Paper

A Method for Rapid Durability Test Development

Designing a durability test for an automatic transmission that appropriately reflects customer usage during the lifetime of the vehicle is a formidable task; while the transmission and its components must survive severe usage, overdesigning components leads to unnecessary weight, increased fuel consumption and increased emissions. Damage to transmission components is a function of many parameters including customer driving habits and vehicle and transmission characteristics such as weight, powertrain calibration, and gear ratios. Additionally, in some cases durability tests are required to verify only a subset of the total parameter space, for example, verifying only component modifications. Lastly, the ideal durability test is designed to impose the worst case loading conditions for the maximum number of internal components, be as short as practicable to reduce testing time, with minimal variability between tests in order to optimize test equipment and personnel resources.
Technical Paper

Accelerated Corrosion Testing of Automotive Evaporators and Condensers

There is an ongoing effort in the industry to develop an accelerated corrosion test for automotive heat exchangers. This has become even more important as automakers are focusing on corrosion durability of 15 years in the field versus current target of 10 years. To this end an acid immersion test was developed and reported in a previous paper for condensers (1). This paper extends those results to evaporators and establishes the efficacy of the test using these results and those reported in the literature. The paper also discusses variability in corrosion test results as observed in tests such as ASTM G85:A3 Acidified Synthetic Sea Water Test (SWAAT), and its relation to field durability.
Technical Paper

Acoustic Characteristics of Automotive Catalytic Converter Assemblies

An experimental study of the acoustic characteristics of automotive catalytic converters is presented. The investigation addresses the effects and relative importance of the elements comprising a production catalytic converter assembly including the housing, substrate, mat and seals. Attenuation characteristics are measured for one circular and one oval catalytic converter geometry, each having 400 cell per square inch substrates. For each geometry, experimental results are presented to address the effect of individual components in isolation, and in combination with other assembly components. Additional experiments investigate the significance of acoustic paths around the substrate and through the peripheral wall of the substrate. The experimental results are compared to address the significance of each component on the overall attenuation.
Technical Paper

Analytical Methods for Durability in the Automotive Industry - The Engineering Process, Past, Present and Future

In the early days of the automotive industry, durability and reliability were hit or miss affairs, with end-users often being the first to know about any durability problems - and in many cases forming an essential part of the development process. More recently, automotive companies have developed proving ground and laboratory test procedures that aim to simulate typical or severe customer usage. These test procedures have been used to develop the products through a series of prototypes and to prove the durability of the product prior to release in the marketplace. Now, commercial pressures and legal requirements have led to increasing reliance on CAE methods, with fatigue life prediction having a central role in the durability engineering process.
Technical Paper

Application of Dual-Phase Steels for Automotive Closure Panels

With interest in improving vehicle quality and customer satisfaction, Ford Motor Company initiated an effort aimed at improving dent resistance of closure panels. An investigation of various means of product improvement led to the recognition of dual phase steels, due to their inherent formability and strain hardening attributes, as the most appropriate steel panel for outer panel applications. Ispat Inland's new Electro-galvanized dual phase steel DI-FORM 500 (henceforth referred to by the generic designation, DP500), which meets 500 MPa minimum tensile strength, was specifically designed to meet automotive exposed quality standards. This paper compares the dent resistance performance of automotive door assemblies manufactured with both Bake Hardenable 210 (BH210) and DP500 door outer panels. Results indicate the achievement of significantly improved outer panel dent resistance through the use of the DP500 product.
Technical Paper

Applying Six Sigma with the Theory of Inventive Problem Solving (TRIZ) to Reduce the Time to Solve Problems

This paper explores the interrelation of Six Sigma and TRIZ. The use of Six Sigma DMAIC and/or DCOV principles with merging of inventive principles of TRIZ is a suggestion of paths forward to reduce the time to solve problems. The search for solutions is paralyzed in some circumstances because of psychological inertia because of it is natural for people to rely on their own experience and not think outside their comfort spot. Six Sigma pollinated with TRIZ is an opportunity to find the ideal final result. A case study on a Truck Turn Signal is used to illustrate the idea.
Technical Paper

Attribute Analysis and Criteria for Automotive Exhaust Systems

This paper summarizes the attributes of automotive exhaust system and provides a guideline for exhaust system design, analysis and development. The exhaust system has various attributes including vibration, acoustics or noise, durability and thermal distribution, flow and power loss, emission, in addition to its interface with vehicle. This paper describes all these attributes and the corresponding performances, and develops criteria for each of the attributes. The paper also describes the interfaces between the exhaust system and powerplant with body structure.
Technical Paper

Authenticity of FE Modeling for Fatigue Assessment of Welds in Automotive Structures

MIG (Metal Inert Gas or Gas Metal Arc welding) and spot welding are the most common way of joining steel components in automotive body, and frame structures. The main design benefits of MIG welding are however the ability to join the parts with single side access and the reduction or elimination of flanges. Different finite element based methodologies exist for predicting the durability of welds. These methodologies are being used in the automotive industry to resolve potential and current durability issues in spot and MIG welded steel components and also to reduce expensive testing practices. However, the analysis results highly depend on the finite element modeling and the accuracy of weld data. This paper briefly describes some of the lessons learned while applying the weld life prediction technology for MIG and spot welds in automotive steel structural components.
Technical Paper

Automotive Audio System Development

Vehicle audio system performance is an important attribute for final costumers. In this sense, its evaluation is an important aspect for selecting the design and validation process for automobile manufacturers. Usually the vehicle audio system performance is evaluated only by subjective judgment. However the design requirements demands objective measurements to set targets establish benchmarking and apply refinements to the design. Thus, in order to evaluate and improve sound system performance, it has been established a subjective evaluation process on reproducing and analyzing customer perception in a more reliable way. To support this information, objective evaluations have been used based on total harmonic distortion (THD), normalized frequency response (NFR) methods and spectrogram, which have been shown as straight and fast objective tools. Reinforcing the objective evaluations, qualitative time-frequency spectrogram has been used.
Technical Paper

Automotive Stabilizer Bar System Design and Reliability

Stabilizer bar systems are present in almost every automobile sold today. They are used to tune ride, handling, and steering. This paper surveys the design alternatives for stabilizer bars, bushings, and links. It covers their function, performance, and basic design considerations. In addition, the paper provides an overview of stabilizer bar system reliability planning: ideal function, error states, noise factors, control factors, noise factor management, and validation testing are discussed.
Technical Paper

Brakes Standards Interface Analysis Considering Brazilian, European and North American Regulations Focusing on Technologies Introduction

It is very important and unquestionable that we need to have a clear technical requirement for Air Brake Systems and its components, since it is one of most important regarding safety. Looking to heavy commercial vehicles and possible air brake system failures, everything becomes clearly to pay total attention for these normative and regulatory requirements. Historically, the development of Brakes technology has started on EUA and Europe and consequently two strong and distinct requirements were structured: FMVSS 121 and ECE-R13. From decades people are trying to harmonize these requirements and for passenger cars, the evolution was faster. However, for commercial vehicles there are more peculiarities considering regional applications and some of them cultural and implementation time. As globally market is growing so fast as well new markets around the world, become fundamental the clearly understanding of these similarities, variants, peculiarities and correlated requirements.
Technical Paper

Bumper Fatigue Cracks

One thing that is very important in a carmaker company is its know-how built during all its life. Such an experience allows, for instance, to correlate the customer expected product life with accelerated tests procedures. When it comes to cars, it is usual to have correlated proving routes in such way that if a prototype can take a number of passing in the proving ground without failure, it is unlikely the car is going to fail during a regular life. In the other hand, if a failure at determined percentage of the test happens, it is predictable that the same failure shows up at the same percentage of the product design life. This paper proposes a methodology based on the SxN fatigue theory to solve durability issues observed in correlated durability tests.
Technical Paper

CAE Approach for Light Truck Frame Durability Evaluation Due to Payload Increase

The growing competition of the automotive market makes more and more necessary the reduction of development time and consequently, the increase of the capacity to quickly respond to the launching of the competitors. One of the most costly phases on the vehicle development process is the field durability test, both in function of the number of prototypes employed and the time needed to its execution. More and more diffused, the fatigue life prediction methods have played an important part in the durability analysis via CAE. Nevertheless, in order they can be reliable and really being able to reduce the development time and cost, they need to be provided with load cases that can accurately represent the field durability tests. This work presents a CAE approach used for light trucks in order to get a reasonable understanding of component durability behavior due to payload increase. In general, road load data is not available for a new payload condition.
Technical Paper

Calculating System Failure Rates Using Field Return Data. Application of SAE-J3083 for Functional Safety and Beyond

In early design activities (typically before the hardware is built), a reliability prediction is often required for the electronic components and systems in order to assess their future reliability and in many cases to meet customer specifications. These specifications may include the allocated reliability for a particular electronic unit and in the cases of functional safety products to meet the ASIL (Automotive Safety and Integrity Level) requirement specified by the functional safety standard ISO 26262. The standard allows for the use of “statistics based on field returns or tests” as a valid alternative to the handbook-based reliability prediction. This paper presents a newly developed SAE-J3083 standard “Reliability Prediction for Automotive Electronics Based on Field Return Data”, which covers the types of the required data, ways to collect it, and the methodology of how to process this data to calculate the failure rates and meet the expected safety goals.
Technical Paper

Challenges and Approaches to Design for Six Sigma in the Automotive Industry

Design for Six Sigma has been applied successfully in many industries, but industry differences present challenges that influence implementation. Implementers in the automotive industry face the challenge of integrating DFSS into mature and complex product development systems. This requires a clear definition of the DFSS role in an organization and clear guidelines for project scope. But effective definitions and guidelines will vary depending on an organization's place in the supply chain. In addition, varying levels of project scope present challenges in determining effective metrics. Organizations are best served by a flexible set of metrics that drive the right behavior at all organizational levels. Once roles and metrics are established, balancing DFSS with other ongoing programs becomes a challenge. Over time, the elements of DFSS should be integrated into a holistic system that produces high quality, market-winning products.
Technical Paper

Closures weatherstrips with variable cross sections

Closures systems performance is a trade-off between NVH (Noise, Vibration and Harshness) and DCE (Door Closing Efforts) requirements. Dynamic sealing performance and sheet metal rigidity are the key contributors for a stable system. The seals actuate like a spring on the system. Higher seal load is good for NVH performance, adding more dumping to the system, but it will negatively affect DCE, as it will demand additional energy to close the system. Nominal seal load must be defined to achieve a balance between these attributes. This study is about dynamic sealing profiles with variable seal load, which provides tunable solutions to address the trade-off between NVH and DCE on the side doors or rear closures. Dynamic sealing weatherstrips are made of sponge EPDM extruded profiles with a specified load, defined by its CLD (Compression Load Deflection), which is given by the cross section design.