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Reduction of Steering Effort in the Event of EPAS Failure using Differential Braking Assisted Steering

SAE International Journal of Transportation Safety

University of Michigan-Duanxiang Zhang, Bo Lin, Ahmet Kirli, Chinedum Okwudire
  • Journal Article
  • 2017-01-1489
Published 2017-03-28 by SAE International in United States
Electric Power Assisted Steering (EPAS) is widely adopted in modern vehicles to reduce steering effort. It is probable that some EPAS systems will experience a shutdown due to reliability issues stemming from electrical and/or electronic components. In the event of EPAS failure, power assist becomes unavailable and the steering system reverts to a fully manual state, leading to excessive steering torque demands from the driver to maneuver the vehicle at lower speeds, i.e., under 30 mph. This situation has resulted in dozens of reported crashes and several OEM safety recalls in the past few years. Inspired by recent work which utilizes independent driving torque of in-wheel-motor vehicles to reduce steering torque, this paper proposes the use of Differential Braking Assisted Steering (DBAS) to alleviate steep increases in steering torque upon EPAS failure. DBAS requires software upgrades with minimal hardware modification to EPAS, which is preferable for a backup system. A preliminary evaluation of DBAS is carried out using simulations in CarSim. Results show that DBAS reduces steering torque to similar levels as EPAS in all…
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A New Data-Driven Design Method for Thin-Walled Vehicular Structures Under Crash Loading

SAE International Journal of Transportation Safety

Embry Riddle Aeronautical University-Xianping Du, Feng Zhu
Wayne State University-Clifford C. Chou
  • Journal Article
  • 2017-01-1463
Published 2017-03-28 by SAE International in United States
A new design methodology based on data mining theory has been proposed and used in the vehicle crashworthiness design. The method allows exploring the big dataset of crash simulations to discover the underlying complicated relationships between response and design variables, and derive design rules based on the structural response to make decisions towards the component design. An S-shaped beam is used as an example to demonstrate the performance of this method. A large amount of simulations are conducted and the results form a big dataset. The dataset is then mined to build a decision tree. Based on the decision tree, the interrelationship among the geometric design variables are revealed, and then the design rules are derived to produce the design cases with good energy absorbing capacity. The accuracy of this method is verified by comparing the data mining model prediction and simulation data. The result indicates that the data mining based methodology could overcome the weakness of traditional design method, i.e. lack of capability in information discovery from big datasets.
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Modeling of Rivets Using a Cohesive Approach for Crash Simulation of Vehicles in RADIOSS

SAE International Journal of Transportation Safety

Altair Engeneering GmbH-Marian Bulla
Ford Motor Company-Niels Pasligh, Robert Schilling
  • Journal Article
  • 2017-01-1472
Published 2017-03-28 by SAE International in United States
Rivets, especially self-piercing rivets (SPR), are a primary joining technology used in aluminum bodied vehicles. SPR are mechanical joining elements used to connect sheets to create a body in white (BiW) structure. To ensure the structural performance of a vehicle in crash load cases it is necessary to describe physical occurring failure modes under overloading conditions in simulations. One failure mode which needs to be predicted precisely by a crash simulation is joint separation. Within crash simulations a detailed analysis of a SPR joint would require a very high computational effort. The conflict between a detailed SPR joint and a macroscopic vehicle model needs to be solved by developing an approach that can handle an accurate macroscopic prediction of SPR behavior with a defined strength level with less computational effort. One approach is using a cohesive material model for a SPR connection. The paper describes cohesive element characteristics and calibration effort. Investigated element characteristics are an updated momentum calculation resulting from shear loads. It allows the adjustment of the width-height ratio for a constant meshing…
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External Biofidelity Evaluation of Pedestrian Leg-Form Impactors

SAE International Journal of Transportation Safety

Hyundai Kia R&D-Haeyoung Jeon
University of Virginia-Daniel Perez-Rapela, Jason Forman, Jeff Crandall
  • Journal Article
  • 2017-01-1450
Published 2017-03-28 by SAE International in United States
Current state-of-the-art vehicles implement pedestrian protection features that rely on pedestrian detection sensors and algorithms to trigger when impacting a pedestrian. During the development phase, the vehicle must “learn” to discriminate pedestrians from the rest of potential impacting objects. Part of the training data used in this process is often obtained in physical tests utilizing legform impactors whose external biofidelity is still to be evaluated. This study uses THUMS as a reference to assess the external biofidelity of the most commonly used impactors (Flex-PLI, PDI-1 and PDI-2). This biofidelity assessment was performed by finite element simulation measuring the bumper beam forces exerted by each surrogate on a sedan and a SUV. The bumper beam was divided in 50 mm sections to capture the force distribution in both vehicles. This study, unlike most of the pedestrian-related literature, examines different impact locations and velocities. The results show how the Flex-PLI and the PDI-1 exert greater forces on the bumper beam than the THUMS, while the PDI-2 produced bumper beam forces similar to the THUMS. The PDI-2 is…
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NHTSA’s Proposed Frontal Oblique Impact Test Protocol: Analyses and Evaluation

SAE International Journal of Transportation Safety

Ford Motor Company-Saeed Barbat, Xiaowei Li
  • Journal Article
  • 2017-01-1475
Published 2017-03-28 by SAE International in United States
On December 2015, The National Highway Traffic Safety Administration (NHTSA) published its proposal to implement U.S New Car Assessment Program (NCAP) changes covering three categories of crashworthiness, crash avoidance and pedestrian protection, beginning with the 2019 model year. The crashworthiness category included a new frontal oblique impact (OI) test protocol. The test compromises of a new Oblique Moving Deformable Barrier (OMDB), new THOR 50th percentile male (THOR-50M) anthropomorphic test device (ATD), and a new test configuration. An OMDB of 2,486 kg (5,480 lb) impacts a stationary target vehicle at a speed of 90 kph (56 mph) at an angle of 15 degrees with a 35% barrier overlap with the front end of the target vehicle. In vehicle-to-vehicle collisions, the lighter weight vehicle experience higher velocity change and higher acceleration levels, thereby, occupants in the lighter vehicle experience higher injury risk. This paper describes the analyses of a series of 31 OI tests conducted by NHTSA, in which the target vehicles used were of different sizes and weight distribution ranging between 1034 Kg (SMART)-2624 Kg (Silverado).Deformation…
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Six-Degree-of-Freedom Accelerations: Linear Arrays Compared with Angular Rate Sensors in Impact Events

SAE International Journal of Transportation Safety

Exponent Inc-Joseph Olberding, Michael Prange
JP Research Inc.-William R. Bussone
  • Journal Article
  • 2017-01-1465
Published 2017-03-28 by SAE International in United States
SAE J211 provides no definitive specification as to the appropriate procedures for filtering angular rate sensor data prior to differentiation into angular acceleration data, especially for impact data. Accordingly, a 3-2-2-2 array (nine-accelerometer-package or NAP) of linear accelerometers and a triaxial angular rate sensor were mounted into a Hybrid III 50th-percentile-male ATD headform and compared in a variety of impact events and multibody simulations. Appropriate low-pass digital filter cutoff frequencies for differentiating the angular rate sensor data into angular accelerations were sought via residual analysis in accordance with current SAE J211 guidelines. It was found that there was no specific cutoff frequency that consistently matched the angular accelerations determined by the 3-2-2-2 array, and the combination of a triaxial linear accelerometer and a triaxial rate sensor could not simultaneously match the 3-2-2-2 summed square and peak angular accelerations regardless of cutoff frequency. The differentiation step to convert angular velocity data into angular acceleration data was found to insert frequency-dependent noise which low-pass filtering could not adequately eliminate. This may be overcome in the future if…
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An Assessment of Inflatable Seatbelt Interaction and Compatibility with Rear-Facing-Only Child Restraint Systems

SAE International Journal of Transportation Safety

Ford Motor Company-Kevin Pline, Derek Board, Nirmal Muralidharan, Srinivasan Sundararajan, Eric Eiswerth, Katie Salciccioli, Noelle Baker
  • Journal Article
  • 2017-01-1445
Published 2017-03-28 by SAE International in United States
Ford Motor Company introduced the inflatable seatbelt system in 2011 and the system is now available in the second row of several Ford and Lincoln models. An important consideration is the interaction of the inflatable seatbelt system with child restraint systems (CRS). A comprehensive series of frontal impact sled tests, using a standardized test method, was conducted to compare the performance of rear-facing-only CRS installed using an inflatable seatbelt to the same CRS installed using a standard seatbelt. CRS models from several manufacturers in the North American market were tested both with and without their bases. CRABI 12 month old or Hybrid III 3 year old anthropomorphic test devices (ATD) were restrained in the CRS. The assessment included the ability to achieve a satisfactory installation with the inflatable seatbelt, comparisons of ATD and CRS kinematics, CRS system integrity, and comparisons of ATD responses. In all cases, acceptable installations of the CRS were achieved with the inflatable seatbelt system. When installed with the base, there was a statistically significant reduction in HIC36 for the ATDs restrained…
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Validating Google Earth Pro as a Scientific Utility for Use in Accident Reconstruction

SAE International Journal of Transportation Safety

ARCCA Inc.-Shawn Harrington, Joseph Teitelman, Erica Rummel, Brendan Morse, Peter Chen, Donald Eisentraut, Daniel McDonough
  • Journal Article
  • 2017-01-9750
Published 2017-03-14 by SAE International in United States
With the prevalence of satellite imagery in the analysis of collision events growing in the field of accident reconstruction, this research aims to quantify, refine, and compare the accuracies of measurements obtained utilizing conventional instruments to the measurements obtained using Google Earth Pro software. Researchers documented and obtained 1305 unique measurements from 68 locations in 25 states and provinces in the United States, Canada, and Australia using measuring wheels and tape measures. Measurements of relevant features at each location (crosswalks, curved roadways, off-road features, etc.) were documented and subdivided into three groups: On-Road, Off-Road, and Curved Path measurements. These measurements were compared to the measurements obtained of the same features from current and historical satellite imagery within Google Earth Pro. The accuracy of the relative measurements was divided into distance-based subsets within the three groups; for example, the error of measurements ranging from 0 - 12 feet to over 1000 feet both On- and Off-road were quantified and compared. These comparisons established the rate of error for each distance-based subset for the On-Road, Off-Road, and…
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