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Standard
2014-04-16
This SAE Recommended Practice covers the recommended testing techniques for the determination of electric field immunity of an automotive electronic device when the device and its wiring harness is exposed to a power line electric field. This technique uses a parallel plate field generator and a high voltage, low current voltage source to produce the field.
Technical Paper
2014-04-01
Jong Ho Lee
Abstract Since vehicle NVH reduction technology has improved dramatically, buzz, squeak and rattle (hereafter referred to as “BSR”) noise quantification from interior and exterior of the vehicle becomes an important factor to measure the quality of the vehicle. (The cost rate of BSR noise claims take around 10-15%, moreover BSR noise negatively affects customers to purchase vehicles.) Therefore, a research of BSR evaluation comes to the fore to make a premium car. In this paper, we would like to introduce the development of a vehicle excitation test mode, the full-vehicle BSR test system, and a sound acoustic camera to detect BSR noise. The test profiles were correlated with various road severities such as the domestic field test sites including 5,000km cross-country off road, 19 test tracks for BSR in R&D test center, and quality test tracks in domestic factories. These test modes were classified into 4 levels (Low-Normal-High-Crazy) by judging degrees of GRMS values. The full-vehicle test system can reproduce various field road profiles of the BSR for chassis parts, interior, and exterior for temperatures of −40∼60°C.
Technical Paper
2014-04-01
Qiang Yi, Stanley Chien, David Good, Yaobin Chen, Rini Sherony
Abstract According to pedestrian crash data from 2010-2011 the U.S. General Estimates System (GES) and the Fatality Analysis Report System (FARS), more than 39% of pedestrian crash cases occurred at night and poor lighting conditions. The percentage of pedestrian fatalities in night conditions is over 77%. Therefore, evaluating the performance of pedestrian pre-collision systems (PCS) at night is an essential part of the pedestrian PCS performance evaluation. The Transportation Active Safety Institute (TASI) of Indiana University-Purdue University Indianapolis (IUPUI) is conducting research for the establishment of PCS test scenarios and procedures in collaboration with Toyota's Collaborative Safety Research Center. The objective of this paper is to describe the design and implementation of a reconfigurable road lighting system to support the pedestrian PCS performance evaluation for night road lighting conditions. First, the test conditions of the road lighting (light intensity and uniformity) are generated by combining recommendations from road lighting design standards and the average measured lighting levels at various crash locations.
Technical Paper
2014-04-01
Sunil KV, Sunil Sheepri, Kiran Kandula, Amit Kumar
Abstract The durability evaluation of overhanging components of a vehicle (Ex: horn, radiator) is a challenge to durability engineers as resonance plays an important role in determining their fatigue life. As resonance cannot be avoided always, it is desirable to develop methods to evaluate life of the component in the presence of resonance. Though the existing vibration test standards suggest test profiles to evaluate resonance failures, there are cases in which, these methods do not yield the proving ground results. This may lead to unnecessary overdesign or unrealistic failures. In such cases it is suggested to generate a sweep endurance test procedure customized to the proving ground or actual roads. This paper studies a methodology for generating a sweep endurance test procedure for evaluation of resonating components. Responses like stress and accelerations were measured in test components in proving ground. Contribution of each frequency band towards overall damage is determined.
Technical Paper
2014-04-01
Songgang Li, Guobiao Yand, Weiming Zeng
Abstract The port structure consisting of spur pile, vertical pile and beam is subjected to impact loads, so its internal stress state of each point will rapidly change over time. Dynamic photoelastic method is used to study the dynamic stress and stress wave propagation. With epoxy resin and other materials, a photoelastic model of beam to column connection structure is processed and product. The dynamic response of the model under the impact load by the free fall is researched by the dynamic photoelastic method, and recorded by the new digital dynamic photoelastic system with a laser source and high-speed photography system. The internal dynamic stress propagation and distribution, the maximum shear stress and the dynamic stress concentration problems can be obtained by analyzing the dynamic response. Researching on the key part under impact load using dynamic photoelastic method can furnish the experimental evidence of transient stress phenomenon for theoretical research and engineering applications.
Technical Paper
2014-04-01
Guobiao Yang, Jingyu Wang, Qirong Zhu, Ruhua Fang, Lianxiang Yang
Abstract With the rapid development of computing technology, high-speed photography system and image processing recently, in order to meet growing dynamic mechanical engineering problems demand, a brief description of advances in recent research which solved some key problems of dynamic photo-elastic method will be given, including:(1) New digital dynamic photo-elastic instrument was developed. Multi-spark discharge light source was replaced by laser light source which was a high intensity light source continuous and real-time. Multiple cameras shooting system was replaced by high-speed photography system. The whole system device was controlled by software. The image optimization collection was realized and a strong guarantee was provided for digital image processing. (2)The static and dynamic photo-elastic materials were explored. The new formula and process of the dynamic photo-elastic model materials will be introduced. The silicon rubber mold was used without the release agent. The epoxy resin sheet or block was solidified at room temperature and could be poured accurately once.
Technical Paper
2014-04-01
Andrea Matrisciano, Michal Pasternak, Xiaoxiao Wang, Oleksiy Antoshkiv, Fabian Mauss, Peter Berg
Abstract In this work are presented experimental and simulated data from a one-cylinder direct injected Diesel engine fuelled with Diesel, two different biodiesel blends and pure biodiesel at one engine operating point. The modeling approach focuses on testing and rating biodiesel surrogate fuel blends by means of combustion and emission behavior. Detailed kinetic mechanisms are adopted to evaluate the fuel-blends performances under both reactor and diesel engine conditions. In the first part of the paper, the experimental engine setup is presented. Thereafter the choice of the surrogate fuel blends, consisting of n-decane, α-methyl-naphtalene and methyl-decanoate, are verified by the help of experiments from the literature. The direct injection stochastic reactor model (DI-SRM) is employed to simulate combustion and engine exhaust emissions (NOx, HC, CO and CO2), which are compared to the experimental data. For this the mixing time is used as main modeled parameter, which is deduced from regular Diesel experiments.
Technical Paper
2014-04-01
Rama Subbu, Baskar Anthony Samy, Piyush mani Sharma
Abstract Fierce competition in India's motorcycle industry has led to constant product innovation among manufacturers. This has resulted in the reduction of the lifecycle of the vehicle and has driven the manufacturers to alter the product design philosophies and design tools. One of the performance factors that have continued to challenge motorcycle designers is ride comfort in vertical and longitudinal direction. An essential tool in the motorcycle development process is the ability to quantify and grade the ride comfort behavior. This is performed either through subjective or objective tests. Subjective tests have the disadvantage that numerous factors influence test drivers' opinion while objective measures have the advantage of repeatability. However, objective methods provide only an approximate grading of vehicles and it is difficult to get consistent results that we can rely upon It is proposed that consistent result could be achieved if the motorcycle is run over the pave track in similar repeated cycles.
Technical Paper
2014-04-01
Ben Wen, Gregory Rogerson, Alan Hartke
Abstract Tire rolling resistance is one of tire performance indicator that represents a force needed to maintain the constant rolling of a tire. There are quite few methods and standards to measure tire rolling resistance, such as ISO-28585, ISO-18164, SAE-J1269, SAE-J2452, …. These tests have been used by tire companies, vehicle manufactures, and government agencies to evaluate tire rolling resistance performance. SAE-J1269 and SAE-J2452 are two popularly used multi-condition rolling resistance tests for passenger and light truck tires. Examining the test conditions and procedures of these two test standards showed that some key procedures and conditions from both standards are similar although there are many difference as well. The study presented here is to analyze test results from both tests and their correlation under certain conditions. If the correlation exists, one test may provide test results for both test conditions, therefore, test efficiency can be improved.
Technical Paper
2014-04-01
Massimiliano Gobbi, Giampiero Mastinu, Giorgio Previati
A method for the measurement of the full mass properties of vehicles and subsystems is presented. The knowledge of the center of gravity location and of the inertia tensor of vehicles and subsystems is fundamental for performing accurate dynamic simulations, ranging from handling to durability. The accurate estimation of the inertia tensor can be achieved primarily via experimental tests. Given a rigid body and its mass, the proposed method allows to measure the center of mass location and the inertia tensor during a single test. The proposed technique is based on the analysis of the free motion of a multi-cable pendulum to which the vehicle or the subsystem is connected. The body under test is made rotating around three axes passing nearby the body center of mass with a highly non linear motion. The motion of the pendulum and the forces acting on the system are recorded and the mass properties are identified by means of a proper mathematical procedure based on a least square estimation.
Technical Paper
2014-04-01
Omar Ramadan, Gary Webster, Luc Menard, Aaron Wilcox, Martin Kellen, Edgar Matida
Abstract This paper draws from several recent activities conducted at Advanced Engine Technology Ltd. (AET) which were aimed at improving the capability, precision, and durability of the Ignition Quality Tester (IQT™). The paper includes descriptions of the current Totally Automated Lab Model IQT™-TALM technology, recent experimental results such as updates to the IQT™ measurement capabilities and a summary of a Micro Intra-Laboratory Study (μILS) results. The results show that the standard deviation of Derived Cetane Number for most of the fuel samples tested was considerably lower than that obtained when those fuel samples were tested in the ASTM National Exchange Group and Energy Institute diesel fuel exchange programs.
Technical Paper
2014-04-01
Amey Zare, Advaita Datar, Mitsuhiko Kikuchi, Satoshi Ichikawa, Miwako Hasegawa, Shigenori Tsunekado
A flag is a global boolean variable used to achieve synchronization between various tasks of an embedded system. An application implementing flags performs actions or events based on the value of the flags. If flag variables are not implemented properly, certain synchronization related issues can arise which can lead to unexpected behavior or failure of the underlying system. In this paper, we present an automated verification technique to identify and verify flag usage patterns at an early stage of code development. We propose a two-step approach which consists of: a. identification of all potential flag variables and b. verification of flag usage patterns against predefined set of rules. The results of our experiment demonstrate that the proposed approach reduces the cost and complexity of the flag review process by almost 70%.
Technical Paper
2014-04-01
Lijiao Yu, Hongyu Zheng, Changfu Zong
Abstract Nowadays, electric control steering system has been a main tendency. It consists of Electric Power Steering (EPS) system, Steer by Wire (SBW) system and Active Front Steering (AFS) system. EPS is more widely applied and its technology is more developed. By 2010, the cars equipped with EPS have reached almost 30%. This paper describes one integrated test bench which can test and verify electric control steering system. The main target of the paper is to design and set up a resistance loading system for the test bench referred. The paper takes EPS as a prototype to verify the designed resistance loading system. If the resistance loading system provides a precise simulated torque for the bench, the results of tests will be more approximate with vehicle tests and the acquired data will be reliable for electric control steering system's design and improvement. The linear electric cylinder applied in the loading system is used to provide simulated torque for the bench. The linear electric cylinder is combined with a kind of software independently designed.
Technical Paper
2014-04-01
Juwan Kim, Munsung Kim, Sang-Gun Joo, Sung Pil Heo, Youngdug Yoo
Numerical durability analysis is the only approach that can be used to assess the durability of vehicles in early stages of development. In these stages, where there are no physical prototypes available, the road wheel forces (or spindle forces) for durability testing on Belgian PG (Proving Ground) must be predicted by VPG (Virtual Proving Ground) or derived from the measured forces of predecessor vehicles. In addition, the tuning parts and geometry are not fixed at these stages. This results in the variation of spindle forces during the development stages. Therefore, it is not reasonable to choose the forces predicted at a specific tuning condition as standard forces. It is more reasonable to determine the standard forces stochastically using the DB of the measured forces of predecessor vehicles. The spindle forces measured or predicted on Belgian PG are typically stationary random. To treat the force signals stochastically, it is necessary that the forces are expressed in analytic formulation.
Technical Paper
2014-04-01
Mindy Heading, Douglas Stein, Jeff Dix
Abstract Ejection Mitigation testing is now required by the U.S. government through FMVSS 226 [1]. FMVSS 226 contains the requirement of using a linear guided headform in a horizontal impact test into the inflated curtain, or other ejection mitigation countermeasure that deploys in the event of a rollover. The specification provides dimensions for a featureless headform [2] but there are limited specifications for the headform skin surface condition. In the “Response to Petitions” of the 2011 Final Rule for FMVSS 226 [3], the NHTSA declined the option to include a headform cleaning procedure. This research presents a case study to quantify the effect of changes in the friction between the headform and curtain on the measured excursion. The study presented here shows that a change in friction between the headform and curtain can affect excursion values by up to 135 millimeters (mm).
Technical Paper
2014-04-01
Ram Kiran Tholeti, Shyamsundar Kumbhar, Nainish Kumar B, R Govindarajan
Abstract Scooter segment growth is tremendously increasing in India. The increased competition challenges automotive manufacturers to deliver the high quality and high reliable product to the market. Higher reliability involves increased durability testing which involves time and cost. Stress testing a part of durability is initially conducted on prototype vehicles for structural design validation and then later on production units to ensure its structural integrity. The obtained data from the tests can be used for future structural design improvements. Scooters with small tires, suspension limitations transfers more loads to structure, challenges engineers to design robust structure without compromising on weight much. It is necessary to look at Real World Usage Pattern (RWUP) and to create a stress life cycle block for simulation of accelerated testing, thereby optimizing the testing time and the development costs. The aim of this paper is to provide a procedure for deriving an accelerated stress test cycle for evaluation of chassis based on Road Load Data Acquisition (RLDA).
Technical Paper
2014-04-01
Claudine Miraval, Pierre-Olivier Santacreu, Saghi Saedlou, Antoine Acher
Abstract The evolution of emission control standards on particulate matter and NOx has led to a significant increase of complexity of the diesel exhaust line which includes catalytic converter, particulate filter and selective catalytic reduction systems. The exhaust line is no longer a component that customers can change easily; its durability has to be studied for longer lifespan and if possible to be predicted. From a corrosion point of view, emission control systems have led to more and more severe conditions for stainless steel material used in the exhaust line. In particular, mufflers are exposed to higher temperature during the regeneration of the particle filter and also to acidification of gas condensates due to high sulphur content that can be found in diesel. To assess material performance in these severe conditions, a test method was developed to simulate the environment of the inner part of a muffler through corrosion cycles composed of oxidation steps in a furnace and dipping steps in a synthetic condensate.
Technical Paper
2014-04-01
Sunil Kumar Chippa, Bhavani Srinivasaiah, Samraj Jabez Dhinagar
Abstract Automated testing of manufactured products reduces the lead time to considerable extent in the process of production to delivery. Products like automobiles demand automated testing, for which robots and vision systems are widely employed. The basic functionality of a vision system in automation is to detect an object and then recognize it. In current automotive industry such systems are being used for robotic guidance, component tracking, dimensional gauging etc. There is a need to test the proper functionality of a speedometer fitted on a motorbike in the production line itself. Focused work on detection and recognition of Analog type and Digital type speedometer console reading of a motorbike is described in this paper. A vision based system is proposed which recognizes the speedometer reading instantaneously at the desired time. Image binarization, connected component analysis combined with character recognition algorithms are used to achieve the desired recognition, which resulted in reduced lead time hence contributing to lean manufacturing
Technical Paper
2014-04-01
Kun Diao, Lijun Zhang, Dejian Meng
Abstract Brake squeal shows a significant uncertainty characteristic. In this paper, a series of bench tests were carried out to study the uncertainty of brake squeal on a multi-function brake inertia dynamometer test bench. Then based on time-frequency analysis results, a creative squeal confirmation and determination method was presented, which can show the squeal variations in the domains of time, frequency and amplitude together. An uncertainty analysis method was also established, in which the statistical parameters of squeal frequency and sound pressure level (SPL), and probability density evaluation of frequency based on Quantile-Quantile Plot (QQ plot) were given. And a judgment method of the frequency doubling was devised based on numerical multiple and occurrence concurrence, as well as the uncertainty statistical analysis method considering frequency doubling. All the methods established were applied to the uncertainty analysis of brake squeal. It was found that, both the squeal frequency and SPL are dispersed, and each squeal has its own statistical results.
Technical Paper
2014-04-01
Valerie Earlene Bumbaca
Abstract Virtually every major automaker has announced intentions of producing an electric vehicle (EV). Hyundai Motor Group has also announced plans to sell an electric vehicle in the next several years. There is strong and increasing support for electric vehicles in the USA due to an interest in protecting the environment, limiting dependence on oil, and reducing the associated cost of petroleum-based transportation. From a durability perspective, battery performance and longevity are significant concerns. In order to better prepare for upcoming electric vehicles, Hyundai-Kia America Technical Center, Inc (HATCI) Vehicle Evaluation group is developing an EV durability test and battery lifecycle laboratory test based on real world EV customer usage. Since there is limited availability of real world customer information for electric vehicles, a program has been started to collect EV customer usage data. This will be correlated with test inputs for both road and lab testing. An outside vendor has been contracted to collect data on customer usage from existing Nissan Leaf and Chevrolet Volt customers.
Technical Paper
2014-04-01
Derek R. Braden, David M. Harvey
Abstract There is a continual growth of test and validation in high reliability product applications such as automotive, military and avionics. Principally this is driven by the increased use and complexity of electronic systems deployed in vehicles, in addition to end user reliability expectations. Higher reliability expectations consequently driving increased test durations. Furthermore product development cycles continue to reduce, resulting in less available time to perform accelerated life tests. The challenge for automotive electronic suppliers is performing life tests in a shorter period of time whilst reducing the overall associated costs of validation testing. In this paper, the application of prognostic and health monitoring techniques are examined and a novel approach to the validation and testing of automotive electronics proposed which it is suggested may be more cost effective and efficient than traditional testing. The holistic method explored in this paper fuses real time test data obtained during the monitoring of products throughout an environmental exposure with key factors from manufacturing and product design.
Technical Paper
2014-04-01
Prashant Khapane, Uday Ganeshwade
Abstract Vehicle water wading capability refers to vehicle functional part integrity (e.g. engine under-tray, bumper cover, plastic sill cover etc.) when travelling through water. Wade testing involves vehicles being driven through different depths of water at various speeds. The test is repeated and under-body functional parts are inspected afterwards for damage. Lack of CAE capability for wading equates to late detection of failure modes which inevitably leads to expensive design change, and potentially affects program timing. It is thus of paramount importance to have a CAE capability in this area to give design loads to start with. Computational fluid dynamics (CFD) software is used to model a vehicle travelling through water at various speeds. A non-classical CFD approach was deemed necessary to model this. To validate the method, experimental testing with a simplified block was done and then verified with CFD modelling. The simple rectangular block at two different speeds and three immersion depths in water was utilized for the purpose.
Technical Paper
2014-04-01
Pawel Skruch, Gabriel Buchala
The paper presents a model-based approach to testing embedded automotive software systems in a real-time. Model-based testing approach relates to a process of creating test artifacts using various kinds of models. Real-time testing involves the use of a real-time environment to implement test application. Engineers shall use real-time testing techniques to achieve greater reliability and/or determinism in a test system. The paper contains an instruction how to achieve these objectives by proper definition, implementation, execution, and evaluation of test cases. The test cases are defined and implemented in a modeling environment. The execution and evaluation of test results is made in a real-time machine. The paper is concluded with results obtained from the initial deployment of the approach on a large scale in production stream projects.
Technical Paper
2014-04-01
James G. McLeish, Russell Haeberle
Quality, Reliability, Durability (QRD) and Safety of vehicular Electrical/Electronics (E/E) systems traditionally have resulted from arduous rounds of Design-Built-Test-Fix (DBTF) Reliability and Durability Growth Testing. Such tests have historically required 12-16 or more weeks of Accelerated Life Testing (ALT), for each round of validation in a new product development program. Challenges have arisen from: The increasing number of E/E modules in today's vehicle places a high burden on supplier's test labs and budgets. The large size and mass of electric vehicle power modules results in a lower test acceleration factors which can extend each round of ALT to 5-6 months. Durability failures tend to occur late in life testing, resulting in the need to: perform a root cause investigation, fix the problem, build new prototype parts and then repeat the test to verify problem resolutions, which severely stress program budgets and schedules. To resolve these challenges, automakers and E/E suppliers are moving to Physics of Failure (PoF) based durability simulations and reliability assessment solutions performed in a Computer Aided Engineering (CAE) Environment.
Technical Paper
2014-04-01
Louis Chretien, Adrien Laurino
Abstract The effect of cold-working, i.e. wire drawing, on the corrosion behavior of a 6101 and a 1370 aluminum alloy was investigated in NaCl solutions. For the both alloys, a “grain size - corrosion resistance” was highlighted. The preliminary works performed on Al-Cu welds showed two scales of heterogeneity and two scales of heterogeneity of media which are not considered by the current automotive specifications. Consequently, it seems to be necessary to establish new pertinent specifications to evaluate the new Al solutions.
Technical Paper
2014-04-01
Bjoern Lumpp, Mouham Tanimou, Martin McMackin, Eva Bouillon, Erica Trapel, Micha Muenzenmay, Klaus Zimmermann
Abstract Current exhaust gas emission regulations can only be well adhered to through optimal interplay of combustion engine and exhaust gas after-treatment systems. Combining a modern diesel engine with several exhaust gas after-treatment components (DPF, catalytic converters) leads to extremely complex drive systems, with very complex and technically demanding control systems. Current engine ECUs (Electronic Control Unit) have hundreds of functions with thousands of parameters that can be adapted to keep the exhaust gas emissions within the given limits. Each of these functions has to be calibrated and tested in accordance with the rest of the ECU software. To date this task has been performed mostly on engine test benches or in Hardware-in-the-Loop (HiL) setups. In this paper, a Software-in-the-Loop (SiL) approach, consisting of an engine model and an exhaust gas treatment (EGT) model, coupled with software from a real diesel engine ECU, will be described in detail. A virtual (SiL) test bench is realized with which the diesel engine software functions can be calibrated without any special hardware, using industry- standard calibration tools like INCA from ETAS.
Technical Paper
2014-04-01
Lawrence Banasky
Abstract In an effort to reduce the cost and time associated with bench level automotive electrical and electromagnetic compatibility (EMC) validation tests, a survey was created to request advice from the test labs that perform this testing. The survey focuses particularly on the development of the test plan document and the preparation of the test setup. The survey was sent to a targeted group of individuals with experience in performing this type of testing. The invitees work at laboratories that represent the majority of labs in the world that are authorized to perform component electrical / EMC validation testing for automotive original equipment manufacturers (OEMs). There were a significant number of responses; it is possible that representatives from all of the invited laboratories responded. The survey results provide demographic information about the test labs and their participants. The participants possess a tremendous amount of test experience and are therefore qualified to provide recommendations on the subject.
Technical Paper
2014-04-01
Karsten Schmidt, Jens Harnisch, Denny Marx, Albrecht Mayer, Andre Kohn, Reinhard Deml
Abstract Integration scenarios for ECU software become more complicated, as more constraints with regards to timing, safety and security need to be considered. Multi-core microcontrollers offer even more hardware potential for integration scenarios. To tackle the complexity, more and more model based approaches are used. Understanding the interaction between the different software components, not only from a functional but also from a timing view, is a key success factor for high integration scenarios. In particular for multi-core systems, an amazing amount of timing data can be generated. Usually a multi-core system handles more software functionality than a single-core system. Furthermore, there may be timing interference on the multicore systems, due to the shared usage of buses, memory banks or other hardware resources. The current approach for timing analysis, often based on execution times and sequences of executions in Gantt charts, will not scale arbitrarily for high integration scenarios on multi-core systems.
Technical Paper
2014-04-01
Guobiao Yang, Yingbin Chi, Qirong Zhu, Lianxiang Yang
Abstract In this paper, Digital Image Correlation Method (DICM) is employed to measure the shear mechanical property of the new style automotive structural adhesive specimens and traditional spot welded specimens under quasi static uniaxial shear tensile test. This experiment adopts a non-contact measuring method to measure the strain of specimens. A CCD and a computer image processing system are used to capture and record the real-time surface images of the specimens before and after deformation. Digital correlation software is used to process the imagines before and after deformation to obtain the specimen's strain of the moment. And then both the force-displacement curve and the stress-strain curve during the tensile process could be obtained. The test and analysis results show that the new style structural adhesive specimens have a great advantage with the spot welded specimens. It provides experimental evidence for further improvement of this structural adhesive. And the digital image correlation method is a non-contact measuring method.
Technical Paper
2014-04-01
Pierre-Olivier Santacreu, Laurent Faivre, Antoine Acher
Thermal fatigue of austenitic and ferritic stainless steel grades has been experimentally and numerically investigated. A special test has been developed to determine the thermal fatigue resistance of clamped V-shaped specimens. This test permits to impose thermal cycle by alternating resistance heating and air cooling. The thermal fatigue life of a specimen is expressed as the number of cycles to failure. For a given grade, the fatigue life depends on the maximal and minimal temperature of the cycle, holding time at the maximal temperature and specimen thickness. The advantage of this V-shape test is that it is a simple procedure quite representative of the thermal fatigue process occurring in an exhaust manifold. This test is well suited to perform a study of damage mechanisms and to compare stainless steel grades. Examination of the failed specimens indicated that cracks could be mainly attributed to out-of-phase (OP) thermal fatigue process especially in case of ferritic grades. For austenitic steels (AISI304 EN1.4301, AISI321 EN1.4541 or AISI308 EN1.4828) at a critical temperature or above, an in-phase (IP) thermal fatigue mechanism is coupled with oxidation and creep, which are further significantly reducing the lifetime.
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