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Development of a Hailstone Substitute for Representative Impact Tests

THIOT INGENIERIE-Paul Deconinck
Published 2019-06-10 by SAE International in United States
The present work started with the analysis of real hailstones collected during a storm in France. The microstructure of real hailstone was studied in order to highlight its composition and crystallographic orientations. It helped understanding the formation and the growing mechanisms of hail in the atmosphere. Its impact behaviour was then studied through two different impact experiments: ballistic impacts on rigid target and on deformable targets. It was then compared with the impact response of standard reference ices (manufactured following ASTM standard and with standard freezing) on the same impact setup. From these observations several ices (with different microstructures) were developed and also tested, in order to select the best candidate to simulated the real hailstone. The behaviour of these ices was also studied with quasi-static tension and compression test, and dynamic compression test on Split Hopkinson bar apparatus. A numerical model and an equation of state were developed in LS-Dyna finite element commercial code. At the end, this study that combines multidisciplinary and joint study between microstructure analysis, numerical modelling and experiments, helped to…
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Risk of Concussion in Low- to Moderate-Speed Frontal and Rear-End Motor Vehicle Collisions Evaluated Using Head Acceleration-Based Metrics

Exponent, Inc.-Stephanie A. Pasquesi, Alexander Bruno, Amy Courtney, Stacy M. Imler, Janine Smedley, Michael T. Prange
Published 2019-04-02 by SAE International in United States
Over the past decade, there has been an increase in awareness and concern about the occurrence and long-term effects of concussions. Traumatic brain injury (TBI)-related emergency department (ED) visits associated with motor vehicle collisions, including patients with a diagnosis of concussion or mild TBI (mTBI), have increased while deaths and hospital admissions related to TBI have decreased. The diagnostic criteria for concussion have evolved and broadened, and based on current assessments and diagnostic imaging techniques, there are often no objective findings, yet a diagnosis of concussion may still be rendered. Clinical assessment of concussion may be based only on patient-reported symptoms and history, making it difficult to objectively relate the reported increase in TBI-related ED visits due to motor vehicle collisions to specific collision parameters. This study aims to perform a scientific evaluation of concussion risk during motor vehicle collisions, strengthened by objective, quantitative data, specifically focusing on head acceleration-based metrics. Data from full-scale passenger vehicle crash tests are reported for frontal and rear-end collisions with delta-Vs ranging from 6.0 to 19.0 kph (3.7 to…
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Research on the Model of Safety Boundary Condition Based on Vehicle Intersection Conflict and Collision

Tongji University-Biao Wu, Xichan Zhu, Maozhu Liao, Rui Liu
Published 2019-04-02 by SAE International in United States
Because of the high frequency and serious consequences of traffic accidents in the intersection area, it is of great significance to study the vehicle conflict and collision scenarios of the intersection area. Due to few actual crash accidents occurring in naturalistic driving studies data or field operational tests data, the data of traffic accident database should be also used to analyze the intersection conflict and collision. According to the China Field Operation Test (China-FOT) database and the China in Depth Accident Study (CIDAS) database, the distribution feature of the respective intersection scenario type is obtained from the data analysis. Based on the intersection scenario type, two characters of intersection conflict and collision, the environmental character and the vehicle dynamic character, are used to analyze for the integration process of intersection conflict and collision. The environmental character contains several parameters, including environment type, weather and time, which has a strong influence on the collision accidents. Through the environmental parameters analyzing, the distribution model of environmental character is obtained. The vehicle dynamic character includes two vehicle dynamic…
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Evaluation of Occupant Kinematics in Low- to Moderate-Speed Frontal and Rear-End Motor Vehicle Collisions

Exponent Inc.-Alexander Bruno, Megan Toney-Bolger, Juff George, Jeffrey Koller, Anton Filatov, Joseph Olberding
Published 2019-04-02 by SAE International in United States
Low- to moderate-speed motor vehicle collisions are a common crash type and are sometimes associated with injury complaints. Understanding occupant motion (kinematics) in response to low- and moderate-speed motor vehicle collisions is important for evaluating occupant interactions with interior vehicle structures, including the restraint systems, with the ultimate goal of assessing injury potential. Furthermore, quantitative occupant kinematic data from full-scale crash testing of late-model passenger vehicles is limited for collisions at low- to moderate-speeds. The current study reports kinematic data from full-scale frontal and rear-end crash tests of late-model, mid-size sedans with delta-Vs ranging from 6.0 to 19.0 kph (3.7 to 11.8 mph) and 5.6 to 19.5 kph (3.5 to 12.1 mph), respectively. For each test vehicle, the motion of a Hybrid III 50th-percentile male anthropomorphic test device (ATD) restrained in the driver seat was recorded using high-speed onboard video. Motion tracking of the video was used to evaluate the excursion and velocity of each ATD’s head, shoulder, elbow, and knee with respect to the vehicle interior. Restraint loads were recorded via load cells placed…
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Evaluation of Harness Tightening Procedures for Child Restraint System (CRS) Sled Testing

Ohio State University-Julie Mansfield, Gretchen Baker, John Bolte
Published 2019-04-02 by SAE International in United States
Sled testing procedures should reflect a rigorous level of repeatability across trials and reproducibility across testing facilities. Currently, different testing facilities use various methods to set the harness tension for child restraint system (CRS) sled tests. The objective of this study is to identify which harness tightening procedure(s) produce tensions within a reasonable target range while showing adequate reproducibility, repeatability, and ease-of-use. Five harness tightening procedures were selected: A) FMVSS 213 procedure, B) a 3-prong tension gauge, C) ECE R44/R129 procedure, D) two finger method, and E) pinch test. Two CRS models were instrumented with a tension load cell in the harness system. Seven sled room operators were recruited to perform each of the five harness tightening procedures for ten repetitions apiece on both instrumented CRS using a Hybrid III 3-year-old. The static harness tension measured by the load cell was recorded after each procedure was completed. Data were analyzed for mean, variance, reproducibility, and repeatability. Operator feedback surveys were used to quantify ease-of-use.The ECE R44/R129 procedure produced harness tensions which were quite low. The…
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Innovative Knee Airbag (KAB) Concept for Small Overlap and Oblique Frontal Impacts

Detroit Engineered Products (DEP) Inc.-Rahul Makwana
Ford Motor Co., Ltd.-Pardeep Jindal
Published 2019-04-02 by SAE International in United States
Considerable research has been conducted in terms of attempting to reduce lower leg injury risk in full frontal impacts, in some cases by the use of a knee airbag (KAB). However, there has been limited research into the performance of KAB systems during a crash test with increased oblique loading, such as the IIHS small overlap frontal test, an oblique moving deformable barrier test (OI) being researched by NHTSA, and a mobile progressive deformable barrier test (MPDB) that is expected to be implemented by Euro NCAP in the next few years. The objective of the current numerical study was concentrated on the evaluation of an innovative KAB concept design intended to reduce ATD right inboard lower leg/foot responses under small overlap and oblique loading conditions. A novel appendage KAB concept design was developed with the help of morphing and computational studies which were performed with different ATD sizes. In the study, one of the lower leg/foot responses was monitored and compared over a conventional KAB design. Cases investigated in the study showed that the novel…
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Using Adjusted Force-Displacement Data to Predict the EBS of Car into Barrier Impacts

MEA Forensic Engineers & Scientists-Russell Gish, Ross Hunter, Ryan Fix, Kodiak Brush
Published 2019-04-02 by SAE International in United States
Our goal was to evaluate whether modifications to the force-displacement curves derived from a high-speed NHTSA frontal barrier test could be used to improve predictions of the equivalent barrier speed of a low-speed crash involving the same vehicle. Using an earlier iteration of the technique described here, Hunter et al. [2] showed that the F-D curves from higher-speed tests over-predicted the EBS of lower-speed tests by 21±17%. After modifying the earlier technique to account for powertrain stack-up and barrier force attenuation prior to reaching peak dynamic crush, the technique evaluated here reduced this error to 1% with a standard deviation that varied between ±9% and ±13% depending on which engine accelerometers were chosen for the adjustment. These findings suggest that the method and modifications proposed here can be used to reconstruct car crashes provided that there is a relationship between dynamic crush and residual crush. Of the 158 NHTSA tests used in this study, only seven of the crash tests reported residual crush measured to the bumper beam. These seven data points indicate the average…
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Performance of Event Data Recorders Found in Toyota Airbag Control Modules in High Severity Frontal Oblique Offset Crash Tests

Kineticorp, LLC.-William Bortles
University of Tulsa-Ryan Hostetler
Published 2019-04-02 by SAE International in United States
This paper presents an in-depth analysis of the performance of Event Data Recorders (EDRs) found in the Airbag Control Modules (ACMs), as tested in support of the National Highway Traffic Safety Administration’s Frontal Oblique Offset Program. Previous studies have examined EDR performance in high severity full-frontal barrier crash tests and moving deformable barrier side impact tests. This paper presents data from a high severity oblique frontal impact test in which the vehicle was struck by a moving deformable barrier. This paper examines the results of EDR data downloaded from two 2015 model year Toyota Highlanders, and the results of EDR reported change in velocity (delta-v), to vehicle mounted accelerometers and reference instrumentation. This paper will analyze EDR performance in reporting: Seatbelt buckle status,Occupant Size Classification, Front Passenger,Airbag and seatbelt pretensioner deployment time(s),Longitudinal delta-v, andLateral acceleration/crash pulse.
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Influence of DISH, Ankylosis, Spondylosis and Osteophytes on Serious-to-Fatal Spinal Fractures and Cord Injury in Rear Impacts

Collision Research & Analysis Inc.-Samuel White
ProBiomechanics LLC-David Viano, Chantal Parenteau
Published 2019-04-02 by SAE International in United States
Seats have become stronger over the past two decades and remain more upright in rear impacts. While head restraints are higher and more forward providing support for the head and neck, serious-to-fatal injuries to the thoracic and cervical spine have been seen in occupants with spinal disorders, such as DISH (diffuse idiopathic skeletal hyperostosis), ankylosis, spondylosis and/or osteophytes that ossify the joints in the spine. This case study addresses the influence of spinal disorders on fracture-dislocation and spinal cord injury in rear impacts with relatively upright seats. Nineteen field accidents were investigated where serious-to-fatal injuries of the thoracic and cervical spine occurred with the seat remaining upright or slightly reclined. The occupants were lap-shoulder belted, some with belt pretensioning and cinching latch plate. The occupants were older and had pre-existing disorders of the spine, including DISH, ankylosis, spondylosis and/or osteophytes that ossify the spinal joints. The crashes were summarized and the mechanism for injury was analyzed. The 19 cases involved fracture-dislocation and spinal cord injury at areas of the spine where DISH, ankylosis, spondylosis and/or…
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FRED II Quasistatic Seat Testing Rearward: An Improved Method Based on the SAE H-point Manikin

Collision Research & Analysis Inc.-Samuel White
Ford Motor Company-Roger Burnett
Published 2019-04-02 by SAE International in United States
Various methods have been used to load a seat in the rear direction, including FMVSS 207, assorted body blocks and QST (quasistatic seat test). However, each method lacks some critical aspect of occupant loading of the seat or is too complex for routine development work. A new method is presented to determine the strength and energy transfer of a seat to an occupant in rear impacts that reflects how an occupant interacts with the seat in a rear impact. A metal-cast H-point manikin, called FRED II, was modified to support a loading bar and was pulled rearward into the seatback by a hydraulic ram. The force and displacement of the loading and the inboard and outboard seatback angle were measured. The response of the seat was recorded by video. The moment about the recliner pivot at peak force was determined by aligning the center of the recliner in side views of the seat position initially and at peak load. The height of the cable above the center of the recliner was determined giving the moment…
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