With the introduction of Level 3 Autonomous Driving Systems, an ability to maintain the appropriate level of protection for reclined occupants will become highly relevant. Virtual tools, such as human body models offer an attractive tool to support the rapid shift in vehicle development and restraint system design. However, previous research has shown that, due to differences in lumbar spine and pelvis flesh formulations, the available human body models, while valid in upright scenarios, differ in their responses in recline postures. The goal of this study is to use an updated lumbar spine and different pelvis flesh formulations to evaluate how these changes affect the response of reclined occupants in frontal crashes. An updated simplified lumbar spine was developed based on recently released GHBMC update. The updated simplified lumbar spine model was imported into previously utilised GHBMC simplified and detailed models, and an alternative pelvis flesh attachment was developed creating a total of four modified human body models. These models were evaluated in the sled environment representative of recent post-mortem human subject recline test series. The pelvis-flesh attachment model had a substantial effect on the submarining outcome across all evaluated models. With the unified updated simplified lumbar spine model both human body models showed differences in kinematic response and recorded lumbar forces.

Accurate information about the body orientation is crucial when engineers and researchers try to describe the three-dimensional (3D) kinematics of that body in a precise manner. Various analytical methods were developed to calculate the body orientation from the body’s measured angular rate. All of those algorithms are based on the same underlying physics. Even though they solve the same governing motion equations, they each take a slightly different approach, both analytically and numerically. The objective of this study was to assess the accuracy of the various algorithms by comparing their predictions to reference kinematics data. For this study, the reference data comes from computer simulations as well as from dynamic crash-like experiments that incorporated 3D optical motion capture. Specifically, this study examines these algorithms to determine if they are actually different, which method produces results that are most similar to the reference data, and whether or not there are advantages or disadvantages to using one or the other for applications in crash testing analysis. Two methods, both utilizing an approach involving Euler parameters, were identified as the most accurate from the seven discussed. In addition, it was presented that characteristics of the angular velocity signal (its magnitude, period, etc) affect the magnitude of the error in the calculated orientation. Finally, it was shown that accuracy in the computed orientation is sensitive to the numerical integration algorithms used as part of the methods of obtaining body attitude.

While rollover crashes are rare, approximately one third of vehicle occupant fatalities occur in rollover crashes. Most severe-to-fatal injuries resulting from rollover crashes occur in the head or neck region, due to head and neck interaction with the roof during the crash. While many studies have used anthropomorphic test devices (ATDs) to predict head and neck injury, the biofidelity of ATDs in rollover has not been established. This study aims to build on previous research to compare the dynamic response and injuries sustained by four post mortem human surrogates (PMHS) to those predicted by six different ATDs in full-scale rollover crash tests. Additionally, this study evaluates injuries sustained by PMHS relative to possible contributing factors including occupant kinematics, occupant anthropometry, and vehicle roof deformation. While the vehicle kinematics and roof deformation were comparable for all tests, three out of the four PMHS sustained cervical spine injury, but only the tallest specimen sustained cervical spine fracture. Neck flexion at the time of head-to-roof contact appears to have affected cervical spine injury risk in these cases. Despite the injuries sustained in the PMHS, none of the six ATDs measured forces or accelerations that exceeded injury assessment reference values (IARVs), which adds to recent literature illustrating substantial differences between ATDs and PMHS in a rollover-like scenario.

OBJECTIVE:To provide an objective basis on which to evaluate the repeatability of vehicle crash test methods, a recently developed signal analysis method was used to evaluate correlation of sensor time history data between replicate vehicle crash tests. The goal of this study was to evaluate the repeatability of rollover crash tests performed with the Dynamic Rollover Test System (DRoTS) relative to other vehicle crash test methods.METHODS:Test data from DRoTS tests, deceleration rollover sled (DRS) tests, frontal crash tests, frontal offset crash tests, small overlap crash tests, small overlap impact (SOI) crash tests, and oblique crash tests were obtained from the literature and publicly available databases (the NHTSA vehicle database and the Insurance Institute for Highway Safety TechData) to examine crash test repeatability.RESULTS:Signal analysis of the DRoTS tests showed that force and deformation time histories had good to excellent repeatability, whereas vehicle kinematics showed only fair repeatability due to the vehicle mounting method for one pair of tests and slightly dissimilar mass properties (2.2%) in a second pair of tests. Relative to the DRS, the DRoTS tests showed very similar or higher levels of repeatability in nearly all vehicle kinematic data signals with the exception of global X' (road direction of travel) velocity and displacement due to the functionality of the DRoTS fixture. Based on the average overall scoring metric of the dominant acceleration, DRoTS was found to be as repeatable as all other crash tests analyzed. Vertical force measures showed good repeatability and were on par with frontal crash barrier forces. Dynamic deformation measures showed good to excellent repeatability as opposed to poor repeatability seen in SOI and oblique deformation measures.CONCLUSIONS:Using the signal analysis method as outlined in this article, the DRoTS was shown to have the same or better repeatability of crash test methods used in government regulatory and consumer evaluation test protocols.

Objective: The goal of this study was to characterize the rollover crash and to evaluate the repeatability of the Dynamic Rollover Test System (DRoTS) in terms of initial roof-to-ground contact conditions, vehicle kinematics, road reaction forces, and vehicle deformation.Methods: Four rollover crash tests were performed on 2 pairs of replicate vehicles (2 sedan tests and 2 compact multipurpose van [MPV] tests), instrumented with a custom inertial measurement unit to measure vehicle and global kinematics and string potentiometers to measure pillar deformation time histories. The road was instrumented with load cells to measure reaction loads and an optical encoder to measure road velocity. Laser scans of pre- and posttest vehicles were taken to provide detailed deformation maps.Results: Initial conditions were found to be repeatable, with the largest difference seen in drop height of 20 mm; roll rate, roll angle, pitch angle, road velocity, drop velocity, mass, and moment of inertia were all 7% different or less. Vehicle kinematics (roll rate, road speed, roll and pitch angle, global Z acceleration, and global Z velocity) were similar throughout the impact; however, differences were seen in the sedan tests because of a vehicle fixation problem and differences were seen in the MPV tests due to an increase in reaction forces during leading side impact likely caused by disparities in roll angle (3 degrees difference) and mass properties (2.2% in moment of inertia [MOI], 53.5mm difference in center of gravity [CG] location).Conclusions: Despite those issues, kinetic and deformation measures showed a high degree of repeatability, which is necessary for assessing injury risk in rollover because roof strength positively correlates with injury risk (Brumbelow 2009). Improvements of the test equipment and matching mass properties will ensure highly repeatable initial conditions, vehicle kinematics, kinetics, and deformations.

ABSTRACT The primary Kepler Mission provided nearly continuous monitoring of ∼200,000 objects with unprecedented photometric precision. We present the final catalog of eclipsing binary systems within the 105 deg2 Kepler field of view. This release incorporates the full extent of the data from the primary mission (Q0-Q17 Data Release). As a result, new systems have been added, additional false positives have been removed, ephemerides and principal parameters have been recomputed, classifications have been revised to rely on analytical models, and eclipse timing variations have been computed for each system. We identify several classes of systems including those that exhibit tertiary eclipse events, systems that show clear evidence of additional bodies, heartbeat systems, systems with changing eclipse depths, and systems exhibiting only one eclipse event over the duration of the mission. We have updated the period and galactic latitude distribution diagrams and included a catalog completeness evaluation. The total number of identified eclipsing and ellipsoidal binary systems in the Kepler field of view has increased to 2878, 1.3% of all observed Kepler targets. An online version of this catalog with downloadable content and visualization tools is maintained at http://keplerEBs.villanova.edu.

While over 30% of US occupant fatalities occur in rollover crashes, no dummy has been developed for such a condition. Currently, an efficient, cost-effective methodology is being implemented to develop a biofidelic rollover dummy. Instead of designing a rollover dummy from scratch, this methodology identifies a baseline dummy and modifies it to improve its response in a rollover crash. Using computational models of the baseline dummy, including both multibody (MB) and finite element (FE) models, the dummy's structure is continually modified until its response is aligned (using BioRank/CORA metric) with biofidelity targets. A previous study (Part I) identified the THOR dummy as a suitable baseline dummy by comparing the kinematic responses of six existing dummies with PMHS response corridors through laboratory rollover testing. In this study (Part II), the whole-body kinematic responses of the THOR MB and FE models were validated with responses of the physical THOR dummy in experiments that simulated rollover conditions. This step is necessary to ensure accuracy of the computer-aidedengineering dummy design, thereafter improving confidence in the proposed rollover dummy design modifications. In addition, to ensure the robustness of the model validation, the sensitivities of the THOR dummy computational model responses to parameters with uncertainty in the experiment were assessed, including seatbelt pretension, friction, and dummy seating posture. In summary, both the THOR MB and FE model responses matched well with its physical counterpart. Future studies (Part III) will focus on using these validated dummy models for rollover dummy design modification and evaluation.

The study focused on the validation of the 50th percentile male model — a detailed FE model of the thoracic segment of the human body developed within project Development of a Finite Element Model of the Human Thorax and Upper Extremities (THOMO) co-funded by the European Commission (7th Framework Programme). The model response was tested in three impact scenarios: frontal, lateral and oblique. The resulting impactor contact force vs. time and chest deflection vs. time responses were compared with experimental results. The strain profile of the 5th rib was checked with lateral and oblique strain profiles from post-mortem human subject (PMHS) experiments. The influence of heart and lungs on the mechanical response of the model was assessed and the material data configuration, giving the most biofidelic thorax behaviour, was identified.

Effective passive countermeasure design for rollover injury prevention requires thorough understanding of the occupant response in rollover impact. Thus, the dummy biofidelity in rollover crashes is important. To evaluate the dummy biofidelity a test buck was developed for a variety of surrogate biofidelity analyses. The buck was designed to mimic the geometry and inertial properties of a modern strong-roof vehicle. It consisted of two major parts: a deformable, replaceable greenhouse and a rigid base. The goal of this study was to show that the greenhouse structure proposed in this paper, when loaded in a static roof crush test (similar to FMVSS 216) reaches the strength-to-weight ratio level of real vehicles and when loaded in a dynamic rollover test, the roof deformation matches deformation magnitude and shapes observed in the vehicles from the current United States (US) fleet. To achieve this goal a multi-step design approach was used, including a quasi-static roof crush test and a rollover test on fabricated prototypes of the buck roof structure. Based on the gathered data, modifications were introduced to the roof design to improve the greenhouse mechanical response, both dynamically and quasi-statically. Once the design was fixed, one additional static and twelve dynamic rollover tests were performed and roof structure deformation was compared to the measurements made on two late-model US-market vehicles (an SUV and a mini-van), tested in similar conditions. The roof exhibited a desired response under the quasi-static loading with the peak value (61.1 kN) within first 127 mm of platen motion, which resulted in the strength-to-weight ratio of 3.76. During the twelve rollover tests the magnitude and shape of the buck roof deformation were consistent with those measured on the two test vehicles. In the twelve tests the maximum resultant displacements of the trailing side A- and B-pillar (after excluding three outlier tests due to welding defects) were as follows: 189-223 mm and 183-222 mm, respectively. The component displacements of the B-pillar were: between 165-198 mm in SAE Y and between 84-106 mm in SAE Z. The results of this study showed that the designed roof structure can match the deformation magnitude and shapes, including the prevalence of greater lateral than vertical displacement, seen in the current US fleet vehicles. The roof developed in this study has a quasi-static response similar to that of real vehicles loaded in a FMVSS 216-like test. It mimics the stiffness of real vehicle roofs under static and dynamic roof crush loading, and thus it can be used with the test buck to simulate real vehicle rollover crashes to perform parametric analyses and evaluate dummy biofidelity.

Objective: The goal of this study was to evaluate how well an in-laboratory rollover crash test methodology that constrains vehicle motion can reproduce the dynamics of unconstrained full-scale steering-induced rollover crash tests in sand.Methods: Data from previously-published unconstrained steering-induced rollover crash tests using a full-size pickup and mid-sized sedan were analyzed to determine vehicle-to-ground impact conditions and kinematic response of the vehicles throughout the tests. Then, a pair of replicate vehicles were prepared to match the inertial properties of the steering-induced test vehicles and configured to record dynamic roof structure deformations and kinematic response.Results: Both vehicles experienced greater increases in roll-axis angular velocities in the unconstrained tests than in the constrained tests; however, the increases that occurred during the trailing side roof interaction were nearly identical between tests for both vehicles. Both vehicles experienced linear accelerations in the constrained tests that were similar to those in the unconstrained tests, but the pickup, in particular, had accelerations that were matched in magnitude, timing, and duration very closely between the two test types. Deformations in the truck test were higher in the constrained than the unconstrained, and deformations in the sedan were greater in the unconstrained than the constrained as a result of constraints of the test fixture, and differences in impact velocity for the trailing side.Conclusions: The results of the current study suggest that in-laboratory rollover tests can be used to simulate the injury-causing portions of unconstrained rollover crashes. To date, such a demonstration has not yet been published in the open literature. This study did, however, show that road surface can affect vehicle response in a way that may not be able to be mimicked in the laboratory. Lastly, this study showed that configuring the in-laboratory tests to match the leading-side touchdown conditions could result in differences in the trailing side impact conditions.

Rollover crashes are a serious public health problem in United States, with one third of traffic fatalities occurring in crashes where rollover occurred. While it has been shown that occupant kinematics affect the injury risk in rollover crashes, no anthropomorphic test device (ATD) has yet demonstrated kinematic biofidelity in rollover crashes. Therefore, the primary goal of this study was to assess the kinematic response biofidelity of six ATDs (Hybrid III, Hybrid III Pedestrian, Hybrid III with Pedestrian Pelvis, WorldSID, Polar II and THOR) by comparing them to post mortem human surrogate (PMHS) kinematic response targets published concurrently; and the secondary goal was to evaluate and compare the kinematic response differences among these ATDs. Trajectories (head, T1, T4, T10, L1 and sacrum), spinal segment (head-to-T1, T1-to-T4, T4-T10, T10-L1, and L1-to-sacrum) rotations relative to the rollover buck, and spinal segment extension/compression were calculated from the collected kinematics data from an optical motion tracking system. Response differences among the ATDs were observed mainly due to the different lateral bending stiffness of the spine from their varied architecture, while the additional thoracic joint in Polar II and THOR did not seem to provide more flexion/extension compliance than the other ATDs. In addition, the ATD response data were compared to PMHS response corridors developed from similar tests for assessing ATD biofidelity. All of the ATDs, generally, drifted outboard and upward during the tests similar to the PMHS. However, accompanied with this upward and outward motion, the ATD head and upper torso pitched forward (~10 degrees) while the PMHS' head and upper torso pitching rearward (~10 to ~15 degrees), due to the absence of flexion/extension compliance in the ATD spine. The differences in these pitch motions resulted in a difference of 130 mm to 160 mm in the longitudinal position of the head at 195 degrees of roll angle. Finally, substantially less lateral spinal bending was also observed in the ATDs compared to the PMHS. The results of the current study suggests there is greater upper spine flexion/extension, and lateral bending stiffness in all of the ATDs in comparison to the PMHS, and provided information for improvement of ATD biofidelity in future for rollover crashes.

Predicting rib fractures remains an important challenge for the automotive safety community. While current rib computational models can successfully be used to determine the load and deflection required to cause rib fracture, they fail to properly predict the fracture location. It is assumed that a better understanding of bone fracture mechanism will help to improve the biofidelity of rib computational model. The goal of this study was to perform tensile tests of rib bone coupons to determine the fracture characteristics of the rib cortical bone. Thirty seven bone coupons were machined and tested under dynamic tensile load. An optical system was used to measure the in-plane displacements and strains on the outermost surface of each coupon. The Young’s modulus, Poisson’s ratio and failure strain were calculated based on the gathered data. An in-depth analysis of the strain distribution on the coupon surface was performed with the view to identify the fracture mechanisms. This study suggests that tension is not the main phenomenon that explains the onset of fracture in the rib cortical bone, and that properly predict rib bone fracture may require to account for the bone anisotropy and heterogeneity.. INTRODUCTION redicting rib fractures created by a dynamic event remains an important challenge for the automotive safety community and injury biomechanics at large. It is clear that the mechanical response of the human thorax can be greatly influenced by the number of fractured ribs. To determine rib injury mechanisms under dynamic loading the behavior of the ribs and the entire rib cage have been extensively investigated (Kent et al., 2004; Song et al. 2009; Shigeta et al., 2009; Lessley et al., 2010; Hallman et al. 2010). The rib bone material properties for bovine (Ferreira et al., 2006; Adharapurapu et al., 2006) and human bone (Keller et al., 1990; Kemper et al., 2005; Hansen et al., 2008; Subit et al., 2011) have been reported by many researchers. The available data can be utilized to help to understand the rib mechanical behavior using modern engineering tools – e.g. finite element method (FEM) models. While current rib computational models can successfully determine the load and deflection required to cause the rib to fracture, they fail to properly predict the fracture location (Li et al., 2010). This indicates that further research is needed to P improve the knowledge of the fracture mechanisms in the rib, especially in its cortical bone. The cortical bone has voids and is a composite-like material that makes it non-homogenous. The bone material properties determined assuming homogeneity of the bone, are likely to inadequately describe the mechanical response of the rib. Therefore the goal of this study was to perform tensile tests of rib cortical bone coupons and analyze their deformation using a digital image correlation (DIC) method in order to determine the fracture characteristics of the rib cortical bone. A protocol was developed to machine and test rib bone coupons of constant thickness under dynamic loading. All the samples were imaged prior to testing using a microcomputed tomograph (microCT). METHODS The bilateral 6 and 7 ribs were harvested from three post mortem human subjects (PMHS; Table 1) in accordance with the ethical guidelines and research protocol approved by the Human Usage Review Panel and the University of Virginia institutional review board. Table 1. PMHS information Subject Age at time of death Couse of death Body mass (kg) Stature (cm) 510 69 Chronic obstructive pulmonary disease 93.4 168 511 49 Brain injury 98 175 518 70 Heart failure 67.6 165 Thirty seven bone coupons that were 25.4-mm long, 2.5-mm wide in the gage area, and 0.5 mm thick (fig. 1) were machined as it was described by Subit et al., 2013. Figure 1: Dimensions of the rib cortical bone coupon A hydraulic tensile machine (Model 8874, Instron Inc, Norwood, MA, USA), with a specially designed aluminum clamping system, was used to test the coupons under tensile loading (at constant velocity of 24 mm/s up to fracture). The clamping system consisted of two low-mass clamps (10.9 grams each, fig. 2). To prevent slippage of the coupon while avoiding bone crushing, a torque of 5 Nm was applied to the clamping screws prior to testing. The pins that go through the rod-end ball joints were utilized to connect the clamps to the base of the tensile machine and the end of the piston (fig. 3). After installing the clamps in the machine, all the samples were preloaded (between 1 N and 4 N) to ensure that there was no clearance between the pins and the clevises. Figure 2: Detailed view of the clamps Figure 3: Clamping system for the coupons The tensile load was measured by a three axis loadcell (model 6085, Denton Inc, Plymouth, MI, USA) located underneath the bottom clamp, connected to a standard data acquisition system (DEWE-2010, Dewton GmbH, Gratz, Austria). The displacement of the top clamp with reference to the tensile machine base was measured using a displacement potentiometer. The load and displacement were sampled at 100 kHz. An optical system was used to measure the in-plane displacements and strains of each coupon (Aramis, GOM, Germany). The bone coupons were stored in a saline solution until the black-and-white paint pattern (fig. 4a) was applied to the outermost surface of the coupon. The optical system was comprised of one high-speed imager (NAC GX-1, NAC Image Technology, Simi Valley, CA) with a 100 mm macro lens. The average strains (ε11 and ε12; fig. 4b) in the coupon gage area were calculated based from the Aramis results, and the tensile stress was estimated by dividing the tensile force by the cross-sectional area of the coupon gage area. The Young’s modulus, Poisson’s ratio and failure strain were also calculated. The (effective) Young’s modulus was defined as the slope of the stress-strain curve between 0 and 0.5%. The bone microstructure and porosity were analyzed based on the microCT images, with the use of the MATLAB software (The Mathworks, Natick, MA, USA), and an in-depth analysis of the strain distribution on the coupon surface was performed with the view to identifying the fracture mechanisms.

Computational models of the human body are commonly used for injury prediction in automobile safety research. To create these models, the geometry of the human body is typically obtained from segmentation of medical images such as computed tomography (CT) images that have a resolution between 0.2 and 1mm/pixel. While the accuracy of the geometrical and structural information obtained from these images depend greatly on their resolution, the effect of image resolution on the estimation of the ribs geometrical properties has yet to be established. To do so, each of the thirty-four sections of ribs obtained from a Post Mortem Human Surrogate (PMHS) was imaged using three different CT modalities: standard clinical CT (clinCT), high resolution clinical CT (HRclinCT), and microCT. The images were processed to estimate the rib cross-section geometry and mechanical properties, and the results were compared to those obtained from the microCT images by computing the ‘deviation factor’, a metric that quantifies the relative difference between results obtained from clinCT and HRclinCT to those obtained from microCT. Overall, clinCT images gave a deviation greater than 100%, and were therefore deemed inadequate for the purpose of this study. HRclinCT overestimated the rib cross-sectional area by 7.6%, the moments of inertia by about 50%, and the cortical shell area by 40.2%, while underestimating the trabecular area by 14.7%. Next, a parametric analysis was performed to quantify how the variations in the estimate of the geometrical properties affected the rib predicted mechanical response under antero-posterior loading. A variation of up to 45% for the predicted peak force and up to 50% for the predicted stiffness was observed. These results provide a quantitative estimate of the sensitivity of the response of the FE model to the resolution of the images used to generate it. They also suggest that a correction factor could be derived from the comparison between microCT and HRclinCT images to improve the response of the model developed based on HRclinCT images.

Four whole-bodymale PMHS were subjected to inverted head-to-ground impacts that resulted in cervical compression in an attempt to compare the response of whole-body PMHS to component tests performed previously. Peak head forces in the current study (4495 N) were similar to those in previous studies, but differences in timing and magnitudes of second force peaks suggest that differences in constraints and/or boundary conditions affected the dynamics of the impact. While only moderate (AIS 2) injuries were produced in the current study, more serious and severe injuries have been produced previously, which suggests that constraint and/or boundary condition differences also affect injury type and tolerance.

This paper presents methods to investigate the dependence of the CT images resolution to the rib geometrical properties and the rib mechanical behavior during antero‐posterior bending. This study suggests that clinical‐CT images may be sufficient to create proper rib cage geometry. Post Mortem Human Surrogates (PMHS) ribs were harvested and tested under antero‐posterior bending. After the tests, 34 rib slices were cut from the posterior, lateral and anterior aspects. The sections were imaged with micro‐ and clinical‐CT, and their geometrical parameters were compared. The results showed that clinical‐CT overestimates the overall cross-sectional area by around 8%, cortical area by 40% and moments of inertia by 50%. A numerical scheme was developed to correct the measurements obtained from the clinical‐CT using the information gathered locally from micro‐CT. A parametric study was carried out: finite element models for the antero‐posterior bending tests were created based on the variations in geometrical parameters defined from the CT analysis. It was found that the FE model’s mechanical response was greatly sensitive to the image modality. The method presented in this study introduces a new approach that combines clinical‐CT images with the local measurements from micro‐CT. This combination was found to be effective in reducing the disparity between the experimental and numerical results.