Search Results

With the increasing level of electrification of on-road, off-road and stationary applications, use of larger lithium-ion battery packs has become essential. These packs require large capital investments on the order of millions of dollars and pose a significant risk of self-annihilation without rigorous safety evaluation and management. Testing these larger battery packs to validate design changes can be cost prohibitive. A reliable numerical simulation tool to predict battery thermal runaway under various abuse scenarios is essential to engineer safety into the battery pack design stage. A comprehensive testing & simulation workflow has been established to calibrate and validate the numerical modeling approach with the test data for each of the individual sub model - electrochemical, internal short circuit and thermal abuse model. A four-equation thermal abuse model was built and validated for lithium-ion 21700 form factor cylindrical cells using NCA cathodes.

As advances in electrification continue within the vehicle industry, improving the front-end design process and managing the safety aspects of lithium-ion batteries is increasingly important. Structural damage to lithium-ion batteries can cause internal short circuit, leading to a large energy release that can lead to fire and thermal runaway that propagates throughout the battery pack. Southwest Research Institute has developed a mechanical model that can accurately predict mechanically-induced damage to lithium-ion battery cells and battery packs. This model also predicts whether the external damage will cause an internal short-circuit. This modeling process was illustrated using 21700 cylindrical cells with NCA cathode chemistry. High-speed impact tests were used to calibrate a single cell model, which was then scaled to a 12-cell battery module. This model was then used to accurately predict the outcome of an impact test on a 72-cell battery module.

The Department of Transportation (DOT) National Highway Traffic Safety Administration (NHTSA) awarded a contract to Southwest Research Institute (SwRI) to conduct research and testing in the interest of motorcoach fire safety. The goal of this program was to develop and validate procedures and metrics to evaluate current and future detection, suppression, and exterior fire-hardening technologies that prevent or delay fire penetration into the passenger compartment of a motorcoach - in order to increase passenger evacuation time. The program was initiated with a literature review and characterization of the thermal environment of motorcoach fires and survey of engine compartments, firewalls, and wheel wells of motorcoaches currently in North American service. These characterizations assisted in the development of test methods and identification of the metrics for analysis. Test fixtures were designed and fabricated to simulate a representative engine compartment and wheel well.

Despite drastic reduction of sulfur content in diesel fuel in the recent years, especially with the introduction of Ultra-Low Sulfur Diesel (ULSD), sulfur poisoning remains one of the most significant factors impacting performance of various catalysts in diesel aftertreatment systems. This is because even with ULSD, cumulative exposure of a catalyst over its lifetime in a heavy-duty diesel system may amount to kilograms of sulfur. In this study, we have found that the impact of sulfur poisoning on the performance of various diesel oxidation catalysts (DOC) strongly depends on the catalyst's operation history. For example, exposing a DOC to limited amounts of freshly deposited sulfur in bench reactor testing was shown to have a substantial detrimental effect. On the other hand, several samples which returned from vehicle or test-cell aging with high sulfur loading, have shown no signs of poisoning.

Various fire scenarios involving a hydrogen fuel system were simulated to evaluate their associated safety hazards. Scenarios included finite releases of hydrogen with delayed ignition as well as small hydrogen jet-fire releases. The scenarios tested resulted in minimal damage to the vehicle, minimal hazards to the vehicle's surroundings, and no observable damage or hazards within the passenger compartment.

Forty-eight materials from parts used inside and outside the passenger compartment of six motor vehicles were tested according to FMVSS 302. All samples passed the test although the FMVSS 302 test requirements do not apply to exterior materials. The same materials were also tested in the Cone Calorimeter (ASTM E 1354) at three heat fluxes. The FMVSS 302 performance diagram developed earlier on the basis of Cone Calorimeter data for 18 exterior materials from two vehicles appears to have more general validity for solid plastic parts, regardless whether they are taken from locations inside or outside of the passenger compartment. The previously-developed performance diagram is not applicable to plastic foams and fabrics. Additional criteria are proposed to predict whether a foam or fabric is likely to pass the FMVSS 302 test based on ignition time and peak heat release rate measured in the Cone Calorimeter at a heat flux of 35 kW/m2.

Comparative abuse tests were performed on commercially available 12 V and 36 V battery designs. Four methods were chosen from SAE J2464 standard, Electrical Vehicle Battery Abuse Testing, March 1999, and modified to apply them to typical-sized automotive batteries. The four tests included a Penetration Test, Crush Test, Radiant Heat Test, and Short Circuit Test. Both the 12 V and 36 V batteries showed minimal reactions to the tests, and there was no significant difference between results of the two designs with respect to the abuse tests performed. It should be stressed however, that this project was limited in scope and was not intended to be a thorough investigation in the batteries safety hazards.

This paper examines the role of inhalation toxicity of the products of combustion that are generated in post-collision motor vehicle fires by automotive materials used under the hood. Small-scale toxic gas measurements were performed at Southwest Research Institute® (SwRI®) on eighteen components of two of the vehicles that were tested previously at the Factory Mutual Test Center (FMTC). The small-scale toxic gas measurements were obtained under dynamic flow-through conditions in the Cone Calorimeter (ASTM E 1354) and under static conditions in two smoke chamber methods (ASTM E 662 and ASTM E 1995); all methods were supplemented with FTIR gas analysis. Average yields of toxic gases measured in the Cone Calorimeter are comparable to but consistently lower than values reported in the literature for the Fire Propagation Apparatus (ASTM E 2058).

The primary objective of this study was to compare the performance of “new” plastic fuel tanks vs. “aged” plastic fuel tanks when subjected to the standard fire exposure test described in ECE R34.01, Annex 5 Section 5.0 “Resistance to Fire.” The program also included a comparison of failure modes of plastic vs. metal fuel tanks when subjected to a simulated post-crash pool fire. The “new” tanks were purchased from the OEM suppliers (not weathered or pre-conditioned with fuel). The “aged” tanks were obtained from vehicles that were operated in a warm climate and considered to be weathered and fully conditioned with fuel. Three vehicle types, representing three fuel tank shapes and installations, were evaluated: 1.) “thin profile” tank, typical of front wheel drive cars with the tank mounted on the underbody near the rear seat area and in front of the rear axle; 2.) “square profile” tank, typical of SUV's with the tank mounted behind the rear axle; and 3.)

A fire exposure test was conducted on a 72.4 liter composite (Type HGV-4) hydrogen fuel tank at an initial hydrogen pressure of 34.3 MPa (ca 5000 psi). No Pressure Relief Device was installed on the tank to ensure catastrophic failure for analysis. The cylinder ruptured at 35.7 MPa after a 370 kW fire exposure for 6 min 27 seconds. Blast wave pressures measured along a line perpendicular to the cylinder axis were 18% to 25% less the values calculated from ideal blast wave correlations using a blast energy of 13.4 MJ, which is based on the ideal gas internal energy at the 35.7 MPa burst pressure. The resulting hydrogen fireball maximum diameter of 7.7 m is about 19% less than the value predicted from existing correlations using the 1.64 kg hydrogen mass in the tank.

Sulfur poisoning from engine fuel and lube is one of the most recognizable degradation mechanisms of a NOx adsorber catalyst system for diesel emission reduction. Even with the availability of 15 ppm sulfur diesel fuel, NOx adsorber will be deactivated without an effective sulfur management. Two general pathways are currently being explored for sulfur management: (1) the use of a disposable SOx trap that can be replaced or rejuvenated offline periodically, and (2) the use of diesel fuel injection in the exhaust and high temperature de-sulfation approach to remove the sulfur poisons to recover the NOx trapping efficiency. The major concern of the de-sulfation process is the many prolonged high temperature rich cycles that catalyst will encounter during its useful life. It is shown that NOx adsorber catalyst suffers some loss of its trapping capacity upon high temperature lean-rich exposure.

A recent study of engine sensitivity revealed that spark plugs used in conventional spark-ignited gasoline-fueled engines do not always fire in the intended fashion. Rather than firing to the ground strap during each ignition event, the arc frequently travels to the “rim” or “shell” of the spark plug. This behavior is termed rim-fire and although observed by other researchers in industry, its effects on engine performance are not widely reported. This paper addresses some of the quantitative effects of rim-fire on engine performance. Combustion data were recorded for various repeat conditions on a Ford 1.8L Zetec engine. The first set of engine tests used four, new, conventional, automotive spark plugs. The second set of engine tests used four modified spark plugs that induced 100% rim-fire when the ground strap was permanently removed. The study focused on part- and full-load engine performance, EGR tolerance, and step-transient characteristics.

Radioactive tracer technology (RAT) is an important tool in measuring component wear in an operating engine on a real-time basis. This paper will discuss the use of RAT to study and evaluate boundary lubricant and surfactant chemistries aimed at providing benefits in wear control. In particular, RAT was employed to study ring and bearing wear as a function of engine operating condition (speed, load, and temperature) and lubricant characteristics. Prior to testing, the engine's compression rings and connecting rod bearings were subjected to bulk thermal neutron bombardment in a nuclear reactor to produce artificial radioisotopes that were separately characteristic of the ring and bearing wear surfaces. The irradiated parts were installed in the test engine, after which testing to a specific test matrix was accomplished.

This paper describes a study to determine the influence of preimpact vehicle braking on the positions and postures of unrestrained, children in the front seat at the time of collision. Anesthetized baboons were used as child surrogates. The unrestrained animals were placed in various initial sitting, kneeling, and standing positions typically assumed by children while traveling in automobiles. Tests were conducted with various front seat positions and seat covering materials. Measurements were made of pertinent vehicle dynamics and surrogate kinematics during the hard braking event. For each initial condition evaluated, a photosequence is given showing typical positions and postures of the surrogate during the braking event.

This paper summarizes the results of tests conducted with anesthetized animals that were exposed to a wide range of passenger inflatable restraint cushion forces for a variety of impact sled - simulated accident conditions. The test configurations and inflatable restraint system concepts were selected to produce a broad spectrum of injury types and severities to the major organs of the head, neck and torso of the animals. These data were needed to interpret the significance of the responses of an instrumented child dummy that was being used to evaluate child injury potential of the passenger inflatable restraint system being developed by General Motors Corporation. Injuries ranging from no injury to fatal were observed for the head, neck and abdomen regions. Thoracic injuries ranged from no injury to critical, survival uncertain.

Injuries produced by standard three point restraint systems with retractors will be compared between cadavers in laboratory simulated collisions at 30 mph barrier equivalent speed and lap and shoulder belted front seat occupants in real world frontal collisions of '73-'75 full sized cars. Tests conducted at SwRI with belted, unembalmed, fresh cadavers have resulted in extremely severe thoracic and cervical injuries, including multiple rib fractures, fractures of the sternum, clavicle and cervical vertebrae. On the other hand, injury data from a national accident investigation study to evaluate the effectiveness of restraints in late model passenger cars indicates that such injuries in real world crashes of equivalent severity are not always observed. The reasons possible for these differences are discussed. Both programs at SwRI are funded by the National Highway Traffic Safety Administration.

General agreement exists that the ultimate goals of traffic accident research are to reduce fatality, mitigate injury and decrease economic loss to society. Although massive quantities of data have been collected in local, national and international programs, attempts by analysts to use these data to explore ideas or support hypotheses have been met by a variety of problems. Specifically, the coded variables in the different files are not consistent and little information on accident etiology is collected. Examples of the inadequacies of present data in terms of the collected and coded variables are shown. The vehicular, environmental and human (consisting of human factors and injury factors) variables are disproportionately represented in most existing data files in terms of recognized statistical evidence of accident causation. A systems approach is needed to identify critical, currently neglected variables and develop units of measurement and data collection procedures.

RADIATION can produce almost instantaneous failure of modern aircraft lubricants, tests at Southwest Research Institute show. Two types of failures demonstrated are rapid viscosity rise and loss of heat conductivity. Furthermore, it was found that lubricants can become excessively corrosive under high-level radiation. Generally speaking, the better lubricants appeared to improve in performance while marginal ones deteriorated to a greater extent under radiation. When the better lubricants were subjected to static irradiation prior to the deposition test, there was a minor increase in deposition number as the total dose was increased.