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Viewing 211 to 240 of 15816
Technical Paper
2014-04-01
Shai Cohen, Dhafer Marzougui, Cing-Dao Kan, Fadi Tahan
Abstract Many dynamic test systems currently exist to assess rollover. This paper introduces a new test device that combines features from a multitude of different tests. It also covers the concept development, a scaled prototype design and test results from both physical and virtual tests. The Guided Rollover Test (GRT) device subjects vehicles to repeatable initial conditions by having a cart follow a guided maneuver similar to a forward J-turn with an increasing curvature sufficient to roll most vehicles. A test vehicle is carried on the cart at constant longitudinal velocity until it rolls. The cart is fitted with a tripping edge to eliminate slipping and remove the influence of tire properties and road-surface friction. Vehicles are subjected to a rollover based on their own performance characteristics which define the dynamics and consequently the roof to ground contact. Vehicle mechanical systems (suspension), passive safety systems (roof) and occupant containment systems (airbags, seat-belts, etc.) would be assessed under dynamic rollover loading.
Technical Paper
2014-04-01
Simon B. Albrodt, Fadi Tahan, Kennerly Digges
Abstract Different roof strength methods are applied on the 2003 Ford Explorer finite element (FE) model to achieve the current Federal Motor Vehicle Safety Standard (FMVSS) 216 requirements. Two different modification approaches are utilized. Additionally, the best design of each approach is tested dynamically, in rollover and side impact simulations. In the first approach, several roll cage designs are integrated in all pillars, roof cross-members, and in the side roof rails. A roll cage design with a strength-to-weight ratio (SWR) of 3.58 and 3.40 for driver and passenger sides, respectively, with a weight penalty of 18.54 kg is selected for dynamic test assessments. The second approach investigates different localized reinforcements to achieve a more reasonable weight penalty. A localized reinforcement of the B-pillar alone with a tube meets the new FMVSS 216 requirements with a weight penalty of 4.52 kg and is selected for dynamic analyses. The two selected reinforcement designs are tested in a dynamic unconstrained rollover crash under different pitch angles while using common rollover initial conditions.
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
Jan Vychytil, Jaroslav Manas, Hana Cechova, Stanislav Spirk, Ludek Hyncik, Ludek Kovar
Abstract The paper concerns the development of a new scalable virtual human body model. The model has been developed to assess safety risk during various complex crash scenarios including impacts from different directions. The novel approach described couples the basic multi-body structure with deformable segments, resulting in short calculation time. Each multi-body structure segment carries the particular surface parts that are linked to the segment with non-linear springs representing the behavior of related soft tissues. The response of particular body segments (head, thorax, pelvis, lower extremities) is validated in known impact scenarios and the response of the model is tuned to the experimental corridors obtained from literature. The tuning process involved the adjustment of both model material and numerical parameters in order to get the correct response for all the tests. Several energy level impacts from different directions are usually considered in order to generalize the model; to test its robustness and correct biofidelic performance.
Technical Paper
2014-04-01
Sheryl Janca, Kurt Shanks, Janet Brelin-Fornari, Ravi Tangirala, Massoud Tavakoli
Abstract A near-side, rear seat side impact component test, was conducted and validated utilizing a SIDIIs anthropomorphic test device (ATD). The test fixture consisted of the rear seat structure, side door, interior trim, and side airbag curtain module. Test parameters were determined from full scale tests including impact speed, angle of impact, and depth of door intrusion. A comparative assessment was conducted between the full scale test and the deceleration sled test including ATD contact with the vehicle interior, contact duration, sequential timing of ATD contact, and dummy injury measures. Validation was achieved so that the deceleration sled test procedure could be utilized for further evaluations.
Technical Paper
2014-04-01
Baeyoung Kim, Kangwook Lee, Jeong Keun Lee, June-Young Song
Abstract The role of CAB is protecting the passenger's head during rollover and side crash accidents. However, the performance of HIC and ejection mitigation has trade-off relation, so analytical method to satisfy the HIC and ejection mitigation performance are required. In this study, 3 types of CAB were used for ejection mitigation analysis, drop tower analysis and SINCAP MDB analysis. Impactor which has 18kg mass is impacting the CAB as 20KPH velocity at six impact positions for ejection mitigation analysis. In drop tower analysis, impactor which has 9kg mass is impacting the CAB as 17.7KPH velocity. Acceleration value was derived by drop tower analysis and the tendency of HIC was estimated. Motion data of a vehicle structure was inserted to substructure model and the SID-IIS 5%ile female dummy was used for SINCAP MDB analysis. As a result, HIC and acceleration values were derived by MDB analysis. As a result of ejection mitigation analysis, the impactor was ejected in type 1 of the CAB but the impactor was not ejected in type 2 and type 3.
Technical Paper
2014-04-01
Ali Seyed Yaghoubi, Paul Begeman, Golam Newaz, Derek Board, Yijung Chen, Omar Faruque
Abstract The present investigation details an experimental procedure for frontal impact responses of a generic steel front bumper crush can (FBCC) assembly subjected to a rigid full and 40% offset impact. There is a paucity of studies focusing on component level tests with FBCCs, and of those, speeds carried out are of slower velocities. Predominant studies in literature pertain to full vehicle testing. Component level studies have importance as vehicles aim to decrease weight. As materials, such as carbon fiber or aluminum, are applied to vehicle structures, computer aided models are required to evaluate performance. A novel component level test procedure is valuable to aid in CAE correlation. All the tests were conducted using a sled-on-sled testing method. Several high-speed cameras, an IR (Infrared) thermal camera, and a number of accelerometers were utilized to study impact performance of the FBCC samples. A linear potentiometer was installed next to each crush-can to directly measure crush length of the can.
Technical Paper
2014-04-01
Gwansik Park, Taewung Kim, Jeff Crandall, Andy Svendsen, Nathaniel Saunders, Craig Markusic
Abstract The goal of this study was to evaluate the biofidelity of the three computational surrogates (GHBMC model, WorldSID model, and the FTSS ES-2re model) under the side impact rigid wall sled test condition. The responses of the three computational surrogates were compared to those of post mortem human surrogate (PMHS) and objectively evaluated using the correlation and analysis (CORA) rating method. Among the three computational surrogates, the GHBMC model showed the best biofidelity based on the CORA rating score (GHBMC =0.65, WorldSID =0.57, FTSS ES-2re =0.58). In general, the response of the pelvis of all the models showed a good correlation with the PMHS response, while the response of the shoulder and the lower extremity did not. In terms of fracture prediction, the GHBMC model overestimated bone fracture. The results of this study can be effectively utilized in a research that mainly relies on the response of computational surrogates without experimental tests, especially initial development stage of countermeasures for occupant protection from vehicular accidents.
Technical Paper
2014-04-01
Santosh Uttam Bhise, Meyyappan Valliappan
Abstract This paper highlights a simplified CAE model technique, which can simulate and predict door crush strength performance quickly. Such quick models can be used for DFSS and Design change studies. The proposed method suggests an equivalent sub model technique using only the door beam with tuned stiffness end springs to predict FMVSS214S full vehicle crush performance. Such models can be solved in minutes and hence very useful for DFSS studies during product design. The proposed method can be used to finalize door beam design for identical size of vehicle doors to meet required FMVSS214S crush performance. The paper highlights the door beam end springs tuning for identical size of cars and SUVs. Four vehicles were considered for the study. A single spring F-D (force -displacement) is tuned which correlated well for frond door of all the four vehicles. A separate unique spring F-D was needed which correlated well for rear door of all the 4 vehicles.
Technical Paper
2014-04-01
Sanjeev Kumar, Pinak Deb
Abstract The side impact accident is one of the very severe crash modes for the struck side occupants. According to NHTSA fatality reports, side impact accounts for over 25% of the fatalities in the US. Similar fatality estimates have been reported in the EU region. Side crash compliance of a compact car is more severe because of the less space available between the occupant and the vehicle structure, stringent fuel economy, weight and cost targets. The current work focuses on the development of Side body structure of a compact car through Computer Aided Tools (CAE), for meeting the Side crash requirements as per ECE R95 Regulation. A modified design philosophy has been adopted for controlling the intrusion of upper and lower portion of B-pillar in order to mitigate the injury to Euro SIDII dummy. At first, initial CAE evaluation of baseline vehicle was conducted. Further design iterations were carried out to optimize the stiffness of B-pillar for meeting the performance targets of B-pillar intrusion and velocity.
Technical Paper
2014-04-01
James Nelsen, Chang Su Seo
Abstract This paper outlines an improved methodology to perform calculations to verify the compliance of automotive door latch systems to minimum legal requirements as well as to perform additional due diligence calculations necessary to comprehend special cases such as roll over crashes and locally high inertial loadings. This methodology builds on the calculation method recommended by SAE J839 and provides a robust and clear approach for application of this method to cable release systems, which were not prevalent at the time J839 was originally drafted. This method is useful in and of itself but its utility is further increased by the application of the method to a Computer Aided Design (CAD) template (in this case for Catia V5), that allows some automation of the calculation process for a given latch type. This will result in a savings of time, fewer errors and allows for an iterative concurrent analysis during the design process.
Technical Paper
2014-04-01
Todd MacDonald, Moustafa EL-Gindy, Srikanth Ghantae, Sarathy Ramachandra, David Critchley
Abstract A performance investigation of Front Underride Protection Devices (FUPDs) with varying collision interface is presented by monitoring occupant compartment intrusion of Toyota Yaris and Ford Taurus FEA models in LS-DYNA. A newly proposed simplified dual-spring system is developed and validated for this investigation, offering improvements over previously employed fixed-rigid simplified test rigs. The results of three tested collision interface profiles were used to guide the development of two new underride protection devices. In addition, these devices were set to comply with Volvo VNL packaging limitations. Topology optimization is used to aid engineering intuition in establishing appropriate load support paths, while multi-objective optimization subject to simultaneous quasi-static loading ensures minimal mass and deformation of the FUPDs. While a new FUPD is developed and tested which highlights benefits of deflecting the passenger vehicle in small overlap cases, a dual stage FUPD is proposed revealing potential benefits in utilizing the radiator to absorb some collision energy.
Technical Paper
2014-04-01
Ishika Zonina Towfic, Jennifer Johrendt
Abstract The development of a collision severity model can serve as an important tool in understanding the requirements for devising countermeasures to improve occupant safety and traffic safety. Collision type, weather conditions, and driver intoxication are some of the factors that may influence motor vehicle collisions. The objective of this study is to use artificial neural networks (ANNs) to identify the major determinants or contributors to fatal collisions based on various driver, vehicle, and environment characteristics obtained from collision data from Transport Canada. The developed model will have the capability to predict similar collision outcomes based on the variables analyzed in this study. A multilayer perceptron (MLP) neural network model with feed-forward back-propagation architecture is used to develop a generalized model for predicting collision severity. The model output, collision severity, is divided into three categories - fatal, injury, and property damage only.
Technical Paper
2014-04-01
Michael Guerrero, Kapil Butala, Ravi Tangirala, Amy Klinkenberger
NHTSA has been investigating a new test mode in which a research moving deformable barrier (RMDB) impacts a stationary vehicle at 90.1 kph, a 15 degree angle, and a 35% vehicle overlap. The test utilizes the THOR NT with modification kit (THOR) dummy positioned in both the driver and passenger seats. This paper compares the behavior of the THOR and Hybrid III dummies during this oblique research test mode. A series of four full vehicle oblique impact crash tests were performed. Two tests were equipped with THOR dummies and two tests were equipped with Hybrid III dummies. All dummies represent 50th percentile males and were positioned in the vehicle according to the FMVSS208 procedure. The Hybrid III dummies were instrumented with the Nine Accelerometer Package (NAP) to calculate brain injury criteria (BrIC) as well as THOR-Lx lower legs. Injury responses were recorded for each dummy during the event. High speed cameras were used to capture vehicle and dummy kinematics. The vehicle restraint devices and their associated deployment times remained the same for each test.
Technical Paper
2014-04-01
Monica Majcher, Hongyi Xu, Yan Fu, Ching-Hung Chuang, Ren-Jye Yang
Vehicle restraint system design is a difficult optimization problem to solve because (1) the nature of the problem is highly nonlinear, non-convex, noisy, and discontinuous; (2) there are large numbers of discrete and continuous design variables; (3) a design has to meet safety performance requirements for multiple crash modes simultaneously, hence there are a large number of design constraints. Based on the above knowledge of the problem, it is understandable why design of experiment (DOE) does not produce a high-percentage of feasible solutions, and it is difficult for response surface methods (RSM) to capture the true landscape of the problem. Furthermore, in order to keep the restraint system more robust, the complexity of restraint system content needs to be minimized in addition to minimizing the relative risk score to achieve New Car Assessment Program (NCAP) 5-star rating. These call for identifying the most appropriate multi-objective optimization algorithm to solve this type of vehicle restraint system design problem.
Technical Paper
2014-04-01
Grant Hankins, Kenneth Krajnik, Bradley Galedrige, Shahab Sakha, Peter Hylton, Wendy Otoupal
Abstract A number of performance and safety related aspects of motorsports have begun to receive increased attention in recent years, using the types of engineering analysis common to other industries such as aerospace engineering. As these new engineering approaches have begun to play a larger role in the motorsports industry, there has been an increase in the use of engineering tools in motorsports design and an increase in the inclusion of motorsports in the engineering education process. The design, modeling, and analysis aspects of a recent project examining the design of roll cages for American short-track open-wheel racing cars will be discussed in this paper. Roll cage structures were initially integrated into cars of this type in the 1960s. Countless lives have been saved and serious injuries prevented since the introduction of cages into these types of cars. However, the general configuration of these cages has not seen significant change or improvement in the four decades since their introduction.
Technical Paper
2014-04-01
Kambiz Jahani, Sajjad Beigmoradi
Abstract Adequate visibility through the automobile windscreen is a critical aspect of driving, most often at very low temperatures when ice tends to be formed on the windscreen. The geometry of the existing defroster system needs to be improved in the vehicles, with the main aim of substantial increase in air mass flow reaching the windscreen through defroster nozzles and appropriate velocity distribution over the windscreen, while respecting all packaging constraints. The reason of this study is to investigate the windscreen deicing behavior of a vehicle by means of Computational Fluid Dynamics (CFD) with the main concern of improving deicing process by design an appropriate defroster. Two different defrosters with completely different geometry are considered for this purpose. A detailed full interior model of an existing vehicle is created via CAE tools. A transient simulation is performed and results are extracted to show how a proper design of the defroster will lead to considerable improve in deicing process.
Technical Paper
2014-04-01
Venkat Pisipati, Srikanth Krishnaraj, Edgar Quinto Campos
Abstract Motor vehicle safety standards are getting to be more demanding with time. For automotive interiors, instrument panel (IP) head impact protection is a key requirement of the Federal Motor Vehicle Safety Standard (FMVSS) 201. To ensure compliance of this requirement, head impact tests are conducted at 12 and 15 mph for performance verification. Computer simulation has become more prevalent as the primary development tool due to the significant reduction in time and cost that it offers. LS-DYNA is one of the most commonly used non-linear solvers in the automotive industry, particularly for safety related simulations such as the head impact of automotive interiors. LS-DYNA offers a wide variety of material models, and material type 024 (MAT 024, piecewise linear plasticity) is one of the most popular ones [1]. Although it was initially developed for metals, it is commonly used for polymers as well. LS-DYNA also offers several other material models specifically developed to simulate polymers, such as material types 019, 089, 123, to name a few.
Technical Paper
2014-04-01
Sanjeev Kumar, Deepak Katyal, Amit Singh
Abstract Recent advancement in numerical solutions and advanced computational power has given a new dimension to the design and development of new products. The current paper focuses on the details of work done in order to improve the vehicle performance in Offset deformable Barrier (ODB) crash as per ECER-94. A Hybrid approach involving the Structural Crash CAE as well as Multi-body Simulation in MADYMO has been adopted. In first phase of the development, CAE results of Structural deformation as well as Occupant injury of the baseline model were correlated with physical test data. The second phase includes the improvement in intrusion and crash energy absorption by structural countermeasures in the vehicle body. In third phase parametric study has been carried out via Madymo simulation in order to decide on the factors which can be controlled in order to mitigate the Occupant injury. Recommendations of Madymo simulation have been confirmed by conducting Physical sled tests. Finally a cost and weight effective countermeasure package which involves the modification in Body structure and Restraint system has been developed in order to comply with the ECE R-94 offset crash regulation.
Technical Paper
2014-04-01
Alan R. Wedgewood, Patrick Granowicz, Zhenyu Zhang
Abstract Materials used in automotive components play a key role in providing crash safety to passengers and pedestrians. DuPont's lightweight hybrid material technology, which combines injection molded fiber reinforced plastics with drape molded woven composite materials, provides safety engineers with stiff energy absorbing alternatives. In an effort to validate the hybrid material's crash performance while avoiding expensive crash testing, numerical tools and methodologies are applied in evaluation of a hybrid composite test beam. Multi-scale material models capturing nonlinear strain-rate dependency, anisotropic characteristics, and failure criteria, are calibrated on a fiber reinforced plastic and a woven fabric. The fiber orientation and warp/weft angles were extracted from injection and drape molding simulation. The material laws and orientation information are coupled in a single finite element analysis to predict the performance of the hybrid composite beam under a dynamic three point bending load.
Technical Paper
2014-04-01
Haizhen Liu, Weiwen Deng, Changfu Zong, Jian Wu
Abstract This paper first presents an algorithm to detect tire blowout based on wheel speed sensor signals, which either reduces the cost for a TPMS or provides a backup in case it fails, and a tire blowout model considering different tire pressure is also built based on the UniTire model. The vehicle dynamic model uses commercial software CarSim. After detecting tire blowout, the active braking control, based on a 2DOF reference model, determines an optimal correcting yaw moment and the braking forces that slow down and stop the vehicle, based on a linear quadratic regulator. Then the braking force commands are further translated into target pressure command for each wheel cylinder to ensure the target braking forces are generated. Some simulations are conducted to verify the active control strategy. From the simulation results, it is shown that this active brake control strategy can not only ensure the flat tire vehicle stability, but also slow down the vehicle with a safe speed and for a shorter distance.
Technical Paper
2014-04-01
Erdem Uzunsoy, Emmanuel Bolarinwa, Oluremi Olatunbosun, Rui He
Abstract Sloped medians provide a run-off area for errant vehicles so that they can be safely stopped off-road with or without barriers placed in the sloped median. However, in order to optimize the design of sloped medians and the containment barriers, it is essential to accurately model the behavior of vehicles on such sloped terrain surfaces. In this study, models of a vehicle fleet comprising a small sedan and a pickup truck and sloped terrain surface are developed in CarSim™ to simulate errant vehicle behavior on sloped median. Full-scale crash tests were conducted using the vehicle fleet driven across a 9.754 meters wide median with a 6:1 slope at speeds ranging from 30 to 70 km/h. Measured data such as the lateral accelerations of the vehicle as well as chassis rotations (roll and pitch) were synchronized with the vehicle motion obtained from the video data. The measured responses were compared with responses obtained from simulation in CarSim™ to validate the vehicle and slope terrain models.
Technical Paper
2014-04-01
Shweta Rawat, Soumya Kanta Das
Abstract With the ever increasing emphasis on vehicle occupant safety, the safety of pedestrians is getting obscured behind the A-pillars that are expanding in order to meet the federal roof crush standards. The serious issue of pillar blind spots poses threats to the pedestrians who easily disappear from driver's field of view. To recognize this blinding danger and design the car around the driver's eye, this paper proposes the implementation of Aluminum Oxynitride marked under name AlON by Surmet Corporation for fabrication of A-pillars that can allow more than 80% visibility through them. AlON is a polycrystalline ceramic with cubic spinel crystal structure and is composed of aluminum, oxygen and nitrogen. With hardness more than 85% than sapphire, its applications range from aerospace to defense purposes which qualify it in terms of strength and thus imply that it can be conveniently used as A-pillars in vehicles. Furthermore, it possesses characteristics of being bonded to metals as well.
Technical Paper
2014-04-01
Jeong Keun Lee, Byung-Jae Ahn, Ye Ri Hong
Abstract In current inflatable curtain airbag development process, the curtain airbag performance is developed sequentially for the airbag coverage, FMVSS 226, FMVSS 214 and NCAP. Because the FMVSS 226 for the ejection mitigation and the NCAP side impact test require the opposite characteristics in terms of the dynamic stiffness of the inflatable curtain airbag, the sequential development process cannot avoid the iteration for dynamic stiffness optimization. Airbag internal pressure characteristics are can be used to evaluate the airbag performance in early stage of the development process, but they cannot predict dynamic energy absorption capability. In order to meet the opposite requirements for both FMVSS 226 and NCAP side impact test, a test and CAE simulation method for the inflatable curtain airbag was developed. The purpose of this study is to standardize the test setup for comparing the energy absorption capability of inflatable curtain airbag and to make criteria for meeting both FMVSS 226 and NCAP early in the program.
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
Hang Yin, Weiming Zeng, Guobiao Yang, Songgang Li
Abstract When an object was subjected an impact loading, stress wave was produced in the object. Studying the regularity of stress-wave propagation was significant to the study of objects subjected to impact loading. When stress wave travelled in the object, principal stress on free boundary was useful to theoretical analysis and calculation. In this article, a new kind of dynamic photoelastic apparatus was used. Isochromatic and isoclinic of the object subjected to impact loading could be obtained combining dynamic photoelastic experiment and related test equipment. By analyzing the isoclinic, there would be a conclusion that the angle between the isoclinic and the free boundary was not 0°or 90°. So the values of the two principal stress on the boundary were all not 0. The result obtained from the electrometric method came to the same conclusion. Analysis showed the result of dynamic photoelastic method was compatible with the result of electrometric method. So the method in this article was feasible and accurate.
Technical Paper
2014-04-01
Horst Lanzerath, Niels Pasligh
Abstract Structural adhesives are widely used across the automotive industry for several reasons like scale-up of structural performance and enabling multi-material and lightweight designs. Development engineers know in general about the effects of adding adhesive to a spot-welded structure, but they want to quantify the benefit of adding adhesives on weight reduction or structural performance. A very efficient way is to do that by applying analytical tools. But, in most of the relevant non-linear load cases the classical lightweight theory can only help to get a basic understanding of the mechanics. For more complex load cases like full car crash simulations, the Finite Element Method (FEM) with explicit time integration is being applied to the vehicle development process. In order to understand the benefit of adding adhesives to a body structure upfront, new FEM simulation tools need to be established, which must be predictive and efficient. Therefore new FEM crash methods for structural adhesives have been investigated and validated with the help of test results.
Technical Paper
2014-04-01
Mathias Poklitar, Lothar Seybold
As part of the launch of the refrigerant R-1234yf there were a number of studies done regarding the ignition behavior of this new refrigerant in passenger cars. These tests were conducted by a number of automobile manufacturers, component suppliers, and the refrigerant supplier under laboratory conditions at the component and vehicle level. In November 2009 the international automotive industry concluded that the R-1234yf can be used safely in automotive air conditioning systems. Further tests were conducted by different automobile manufacturers, suppliers, and the refrigerant supplier under various laboratory and vehicle operation conditions means hot surfaces in the engine compartment. A number of vehicle manufactures have conducted full vehicle crash tests. In this paper, real world accidents are analyzed using the German In-Depth Accident Study (GIDAS) database as well as the thermal parameters for ignition of R-1234yf, i.e. concentration and surface temperature to create a worst-case scenario.
Technical Paper
2014-04-01
Bryan Styles, Jeffrey Santrock, Curtis Vincent, Michael Leffert, Narasimha Putcha
An evaluation methodology has been developed for assessing the suitability of R-1234yf in vehicles. This relates primarily to evaluating the flammability of R-1234yf in the engine compartment during a frontal collision. This paper will discuss the process followed in the methodology, the technical rationale for this process, and the results of the analysis. The specific types of analysis included in the methodology are: exhaust-system thermal characterization, computer simulated crash tests, actual crash tests, teardown and examination of crashed parts, and releases of refrigerant onto hot exhaust manifolds. Each type of analysis was logically ordered and combined to produce a comprehensive evaluation methodology. This methodology has been applied and demonstrates that R-1234yf is difficult to ignite when factors that occur in frontal crashes are simultaneously considered. Factors considered in this analysis include: crush and deformation of the vehicle structure, airflow in the engine compartment, exhaust system temperatures during different driving scenarios, and coolant release due to damage of the engine coolant system.
Technical Paper
2014-04-01
Lothar Seybold, Bryan Styles, Ioannis Lazaridis, Hans-Joerg Kneusels
The European Commission (EC) as well as the United States Environmental Protection Agency (EPA) published legislations to regulate or encourage the use of low Global Warming Potential (GWP) refrigerants applied to Mobile Air Conditioning (MAC) systems. Europe mandates a GWP less than 150 of MAC refrigerants for new vehicle types. The thermodynamic refrigerant properties of R-1234yf are slightly different from the properties of R-134a, currently used in MAC systems. Although the basic material data show that R-1234yf is flammable, ignition tests performed for an automotive engine under-hood environment reveal design and packaging influences of its ignition behavior. After extensive collaborative research in 2009, the Society of Automotive Engineers Cooperative Research Team (SAE CRP1234) concluded that R-1234yf is suitable for use in automotive applications. Further ignition risk assessment regarding R-1234yf usage in MAC systems was done by SAE CRP1234-4 in 2013. They concluded that “risks are still very small compared to the risks of a vehicle fire from all causes and well below risks that are commonly viewed as acceptable by the general public.”
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