Search Results

Far-side occupants are not addressed in current government regulations around the world even though they account for up to 40% of occupant HARM in side impact crashes. Consequently, there are very few crash tests with far-side dummies available to researchers. Sled tests are frequently used to replicate the dynamic conditions of a full-scale crash test in a controlled setting. However, in far-side crashes the complexity of the occupant kinematics is increased by the longer duration of the motion and by the increased rotation of the vehicle. The successful duplication of occupant motion in these crashes confirms that a sled test is an effective, cost-efficient means of testing and developing far-side occupant restraints or injury countermeasures.

The debate surrounding roof deformation and occupant injury potential has existed in the automotive community for over 30 years. In analysis of real-world rollovers, assessment of roof deformation and occupant compartment space starts with the post-accident roof position. Dynamic movement of the roof structure during a rollover sequence is generally acknowledged but quantification of the dynamic roof displacement has been limited. Previous assessment of dynamic roof deformation has been generally limited to review of the video footage from staged rollover events. Rollover testing for the evaluation of injury potential has typically been studied utilizing instrumented test dummies, on-board and off-board cameras, and measurements of residual crush. This study introduces an analysis of previously undocumented real-time data to be considered in the evaluation of the roof structure's dynamic behavior during a rollover event.

In some automotive electrical systems, it is advantageous to use power supplies and loads at two or more voltages. Often it is desirable to retain the single wire power architecture, with the car body providing the return circuit. A major difficulty in achieving this end is the matter of dealing with the possibility of a short circuit between feed wires at different voltages. It can be shown that source-side fuses cannot be relied upon to return the system to a safe state in all cases. Substantial effort was applied to this problem in the early years of the 21st century, but the results were less than completely satisfactory. Using entirely separate cable harnesses for each voltage, with physically separated routing, minimizes the risk of such a short occurring in the harness.

Micro-mobility is a fast-growing trend in the transportation industry with stand-up electric scooters (e-scooters) becoming increasingly popular in the United States. To date, there are over 350 ride-share e-scooter programs in the United States. As this popularity increases, so does the need to understand the performance capabilities of these vehicles and the associated operator kinematics. Scooter tip-over stability is characterized by the scooter geometry and controls and is maintained through operator inputs such as body position, interaction with the handlebars, and foot placement. In this study, testing was conducted using operators of varying sizes to document the capabilities and limitations of these e-scooters being introduced into the traffic ecosystem. A test course was designed to simulate an urban environment including sidewalk and on-road sections requiring common maneuvers (e.g., turning, stopping points, etc.) for repeatable, controlled data collection.

Obesity rates are increasing among the general population. This study investigates the effect of obesity on ejection and injury risk in rollover crashes through analysis of field accident data contained in the National Automotive Sampling System-Crashworthiness Data System (NASS-CDS) database. The study involved front outboard occupants of age 15+ years in 1994+ model year vehicle rollover crashes. Occupants were sorted into two BMI groups, normal (18.5 kg/m2 ≤ BMI < 25.0 kg/m2) and obese (BMI ≥30 kg/m2). Complete and partial ejection risks were first assessed by seating location relative to roll direction and belt use. The risk of serious-to-fatal injuries (MAIS 3+F) in non-ejected occupants were then evaluated. The overall risk for complete ejection was 2.10% ± 0.43% when near-sided and 2.65% ± 0.63% when far-sided, with a similar risk for both the normal and obese BMI groups.

Spine degeneration can lower injury tolerance and influence injury outcomes in vehicle crashes. To date, limited information exists on the effect of age and sex on thoracic spine 3-dimensional geometry. The purpose of this study is to quantify thoracic spinal column and canal geometry using selected geometrical measurement from a large sample of CT scans. More than 33,488 scans were obtained from the International Center for Automotive Medicine database at the University of Michigan under Institutional Review Board approval (HUM00041441). The sample consisted of CT scans obtained from 31,537 adult and 1,951 pediatric patients between the ages of 0 to 99 years old. Each scan was processed semi-automatically using custom algorithms written in MATLAB (The Math Works, Natick, MA). Five geometrical measurements were collected including: 1) maximum spinal curvature depth (D), 2) T1-to-T12 vertical height (H), 3) Kyphosis Index (KI), 4) kyphosis angle, and 5) spinal canal radius.

The energy dissipated by the fracture of wooden utility poles during vehicle impacts is not currently well documented, is dependent upon non-homogenous timber characteristics, and can therefore be difficult to quantify. While there is significant literature regarding the static and quasi-static properties of wood as a building material, there is a narrow body of literature regarding the viscoelastic properties of timber used for utility poles. Although some theoretical and small-scale testing research has been published, full-scale testing has not been conducted for the purpose of studying the vehicle-pole interaction during impacts. The parameters that define the severity of the impact include the acceleration profile, vehicle velocity change, and energy dissipation. Seven full-scale crash tests were conducted at Exponent's Arizona test facility utilizing both moving deformable and non-deformable barriers into new wooden utility poles.

The primary function of an airbag control module is to detect crashes, discriminate and predict if a deployment is necessary, then deploy the restraint systems including airbags and where applicable, pretensioners. At General Motors (GM), the internal term for airbag control module is Sensing and Diagnostic Module (SDM). In the 1994 model year, GM introduced its SDM on some of its North American airbag-equipped vehicles. A secondary function of that SDM and all subsequent SDMs is to record crash related data. This data can include data regarding impact severity from internal accelerometers and pre-crash vehicle data from various chassis and powertrain modules. Previous researchers have addressed the accuracy of both the velocity change data, recorded by the SDM, and the pre-crash data, but the assessment of the timing of the pre-crash data has been limited to a single family of modules (Delphi SDM-G).

A 3-2-2-2 array of linear accelerometers and a combination of a triaxial linear accelerometer and a triaxial angular rate sensor were mounted into a Hybrid III 50th percentile male ATD head-form and compared in a variety of short- and long-duration events. An appropriate low-pass filter cutoff frequency for differentiating the angular rate sensor data into angular accelerations was found by using a residual analysis to find individual cutoff frequencies for the three center of mass (COM) linear accelerometer channels and the three angular rate sensor channels and taking the arithmetic mean of the six cutoffs. The angular rate sensors provide more accurate rotational rates than integrated angular accelerations calculated from arrays of linear accelerometers and are less cumbersome, especially for events lasting longer than 200 ms.

Lane Departure Warning (LDW) systems, along with other types of Advanced Driver Assistance Systems (ADAS), are becoming more common in passenger vehicles, with the general aim of improving driver safety through automation of various aspects of the driving task. Drivers have generally reported satisfaction with ADAS with the exception of LDW systems, which are often rated poorly or even deactivated by drivers. One potential contributor to this negative response may be an increase in the cognitive load associated with lane-keeping when LDW is in use. The present study sought to examine the relationship between LDW, lane-keeping behavior, and concurrent cognitive load, as measured by performance on a secondary task. Participants drove a vehicle equipped with LDW in a demarcated lane on a closed-course test track with and without the LDW system in use over multiple sessions.

Low-speed collisions between tractor-semitrailers and passenger vehicles may result in large areas of visible damage to the passenger vehicle, but often produce limited damage to the tractor-semitrailer. Despite this, such accidents may lead to assertions of serious injury to the tractor driver and/or sleeper compartment occupant. Research regarding the impact environment and resulting injury potential of the occupants during these types of impacts is limited. This research investigated driver and sleeper compartment occupant responses to relatively low-speed and low-acceleration impact events. Five crash tests involving impact between a tractor-semitrailer and a passenger car were conducted. The test vehicles were a van semitrailer pulled by a tractor and three identical mid-sized sedans. The occupants of the tractor included a human driver and an un-instrumented Hybrid III 50th-percentile-male anthropomorphic test device (ATD).

Recently, side-by-side Recreational Off-Highway Vehicles (ROVs) have brought elements of the on-road vehicle occupant environment to the off-road trail-riding world. In general, ROV occupant protection during normal operation and in accident scenarios is provided predominately by a roll cage, seatbelts, contoured seats with seat backs, handholds, and other components. Typical occupant responses include both passive (inertial) and active (muscular) components. The objective of the current study was to evaluate and quantify these passive and active occupant responses during belted operation of an ROV on a closed course, as well as during 90-degree tip-over events. Passive occupant responses were evaluated using anthropomorphic test devices (ATDs) in 90-degree tip-overs simulated on a deceleration sled.

As the deployment of automated vehicles (AVs) on public roadways expands, there is growing interest in establishing metrics that can be used to evaluate vehicle operational safety. The set of Operational Safety Assessment (OSA) metrics, that include several safety envelope-type metrics, previously proposed by the Institute of Automated Mobility (IAM) are a step towards this goal. The safety envelope OSA metrics can be computed using kinematics derived from video data captured by infrastructure-based cameras and thus do not require on-board sensor data or vehicle-to-infrastructure (V2I) connectivity, though either of the latter data sources could enhance kinematic data accuracy. However, the calculation of some metrics includes certain vehicle-specific parameters that must be assumed or estimated if they are not known a priori or communicated directly by the vehicle.

The use of Lithium-ion batteries in the transportation sector has its own unique set of requirements such as high-power demands, cooling challenges, and risk of mechanical failure due to crashes. Active and passive components of thermal management systems in battery-powered products are designed to mitigate the effects of thermal runaway events and prevent cell-to-cell propagation. Designing safe battery-powered systems requires an understanding of how the battery pack will behave while undergoing thermal runaway, including critical data such as total energy yielded, rate of energy generation, as well as venting patterns and directions. Details such as thermal runaway energy fractions associated with the cell casing as well as vent gas and ejecta can be used to inform and optimize battery pack designs and the product as a whole. The NASA Fractional Thermal Runaway Calorimeter (FTRC) was created to measure these values.

Electric vehicles (EVs) and the development around them has been rapid in recent years. As the battery is the most essential component of an electric vehicle, a lot of research and analysis has been focused on ensuring safe and reliable performance of batteries. Considering the location, size, and operating conditions for EV batteries, they must be designed with an in-built safety infrastructure keeping in mind certain realistic scenarios such as fire exposure, mechanical vibration, collisions, over-charging, single cell failures, and others. In this paper, we discuss an overview of various EV battery failure mechanisms, present current safety and abuse testing methods and standards associated with such mechanisms and discuss the need for the development and implementation of additional testing standards to better characterize the safety performance of EV battery packs.

Three years of data from the Large Truck Crash Causation Study (LTCCS) were analyzed to identify accidents involving heavy trucks (GVWR >10,000 lbs.). Risk of rollover and ejection was determined as well as belt usage rates. Risk of ejection was also analyzed based on rollover status and belt use. The Abbreviated Injury Scale (AIS) was used as an injury rating system for the involved vehicle occupants. These data were further analyzed to determine injury distribution based on factors such as crash type, ejection, and restraint system use. The maximum AIS score (MAIS) was analyzed and each body region (head, face, spine, thorax, abdomen, upper extremity, and lower extremity) was considered for an AIS score of three or greater (AIS 3+). The majority of heavy truck occupants in this study were belted (71%), only 2.5% of occupants were completely or partially ejected, and 28% experienced a rollover event.

During the course of a fire and subsequent exposure to the environment, iron and low-carbon steels oxidize by two mechanisms: high temperature oxidation and atmospheric corrosion. Of particular interest to fire investigators are oxide properties and distribution that could be of use to better understand important characteristics of the fire such as the location the fire originated, the direction the fire traveled or even temperature versus time characteristics. This could be particularly valuable in cases where burn damage to combustible material, which is known to be an important indicator of fire origin, is so extensive that little if any material remains after the fire. However, there is little data in the literature that specifically addresses the utility of oxide properties in the context of fire investigations.

Temperature measurements during a full-scale burn test of a 2001 full-size pickup truck showed that the fire progressed in distinct stages in both the engine and passenger compartments. Although the fire started in the engine compartment and had a relatively long growth period, when a localized area reached about 700°C, a distinct transition occurred where the rate of fire spread increased, leading to full involvement of all engine compartment combustibles. As the engine compartment became fully involved, a hot gas layer then accumulated at the ceiling of the passenger compartment, producing a strong vertical temperature gradient. When the temperature at the ceiling reached about 600°C, another distinct transition occurred where the rate of fire spread increased, leading to full involvement of the passenger compartment. The highest temperature during the test occurred within the engine compartment in an area that had the greatest fuel load, and not the area of origin.

Fires involving cars, trucks, and other highway vehicles are a common concern for emergency responders. In 2013 alone, there were approximately 188,000 highway vehicle fires. Fire Service personnel are accustomed to responding to conventional vehicle (i.e., internal combustion engine [ICE]) fires, and generally receive training on the hazards associated with those vehicles and their subsystems. However, in light of the recent proliferation of electric drive vehicles (EDVs), a key question for emergency responders is, “what is different with EDVs and what tactical adjustments are required when responding to EDV fires?” The overall goal of this research program was to develop the technical basis for best practices for emergency response procedures for EDV battery incidents, with consideration for suppression methods and agents, personal protective equipment (PPE), and clean-up/overhaul operations.

Interest in rear-seat occupant safety has increased in recent years. Information relevant to rear-seat occupant interior space and kinematics are needed to evaluate injury risks in real-world accidents. This study was conducted to first assess the effect of size and restraint conditions, including belt misuse, on second-row occupant kinematics and to then document key clearance measurements for an Anthropomorphic Test Device (ATD) seated in the second row in modern vehicles from model years 2015-2020. Twenty-two tests were performed with non-instrumented ATDs; three with a 5th percentile female Hybrid III, 10 tests with a 10-year-old Hybrid III, and 9 tests with a 6-year-old Hybrid III. Test conditions included two sled bucks (mid-size car and sport utility vehicle (SUV)), two test speeds (56 and 64 km/h), and various restraint configurations (properly restrained and improperly restrained configurations). Head and knee trajectories were assessed.