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Frontal impacts with reclined occupants are rare but severe, and they are anticipated to become more common with the introduction of vehicles with automated driving capabilities. Computational and physical human surrogates are needed to design and evaluate injury countermeasures for reclined occupants, but the validity of such surrogates in a reclined posture is unknown. Experiments with post-mortem human subjects (PMHS) in a recline posture are needed both to define biofidelity targets for other surrogates and to describe the biomechanical response of reclined occupants in restrained frontal impacts. The goal of this study was to evaluate the kinematic and injury response of reclined PMHS in 30 g, 50 km/h frontal sled tests. Five midsize adult male PMHS were tested. A simplified semi-rigid seat with an anti-submarining pan and a non-production threepoint seatbelt (pre-tensioned, force-limited, seat-integrated) were used. Global motions and local accelerations of the head, pelvis, and multiple vertebrae were measured. Seat and seatbelt forces were also measured. Injuries were assessed via post-test dissection. The initial reclined posture aligned body regions (pelvis, lumbar spine, and ribcage) in a way that reduced the likelihood of effective restraint by the seat and seatbelt: the occupant's pelvis was initially rotated posteriorly, priming the occupant for submarining, and the lumbar spine was loaded in combined compression and bending due to the inertia of the upper torso during forward excursion. Coupled with the high restraining forces of the seat and seatbelt, the unfavorable kinematics resulted in injuries of the sacrum/coccyx (four of five PMHS injured), iliac wing (two of five PMHS injured), lumbar spine (three of five PMHS injured), and ribcage (all five PMHS suffered sternal fractures, and three of five PMHS suffered seven or more rib fractures). The kinematic and injury outcomes strongly motivate the development of injury criteria for the lumbar spine and pelvis, the inclusion of intrinsic variability (e.g., abdomen depth and pelvis shape) in computational simulations of frontal impacts with reclined occupants, and the adaptation of comprehensive restraint paradigms to predicted variability of occupant posture.

To serve as tools for assessing injury risk, the biofidelity of whole-body pedestrian impact dummies should be validated against reference data from full-scale pedestrian impact tests. To facilitate such evaluations, a simplified generic vehicle-buck has been recently developed that is designed to have characteristics representative of a generic small sedan. Three 40 km/h pedestrian-impact tests have been performed, wherein Post Mortem Human Surrogates (PMHS) were struck laterally in a mid-gait stance by the buck. Corridors for select trajectory measures derived from these tests have been published previously. The goal of this study is to act as a companion dataset to that study, describing the head velocities, body region accelerations (head, spine, pelvis, lower extremities), angular velocities, and buck interaction forces, and injuries observed during those tests. Scaled, transformed head accelerations exceeded 80 g prior to head contact with the windshield for two of the three tests. Head xaxis angular velocity exceeded 40 rad/s prior to head contact for all three tests. In all cases the peak resultant head velocity relative to the vehicle was greater than the initial impact speed of the vehicle. Corridors of resultant head velocity relative to the vehicle were also developed, bounded by the velocities observed in these tests combined with those predicted to occur if the PMHS necks were perfectly rigid. These results, along with the other kinematic and kinetic data presented, provide a resource for future pedestrian dummy development and evaluation.

The objective of the current study was to characterize the whole-body kinematic response of restrained PMHS in controlled laboratory rollover tests. A dynamic rollover test system (DRoTS) and a parametric vehicle buck were used to conduct 36 rollover tests on four adult male PMHS with varied test conditions to study occupant kinematics during the rollover event. The DRoTS was used to drop/catch and rotate the test buck, which replicated the occupant compartment of a typical mid-sized SUV, around its center of gravity without roof-to-ground contact. The studied test conditions included a quasi-static inversion (4 tests), an inverted drop and catch that produced a 3 g vertical deceleration (4 tests), a pure dynamic roll at 360 degrees/second (11 tests), and a roll with a superimposed drop and catch produced vertical deceleration (17 tests). Each PMHS was restrained with a three-point belt and was tested in both leading-side and trailing-side front-row seating positions. Whole-body kinematics were measured using a 3D motion capture system that quantified occupant displacement relative to the vehicle buck for the X-axis (longitudinal), Y-axis (lateral), and Z-axis (vertical) directions. Additionally the spine was divided into five segments to describe intrasegmental kinematics of the spine, including segment rotations as well as spinal extension and compression. The reported data represent the most complete set of kinematic response targets for a restrained occupant in a variety of dynamic rollover conditions, and are immediately useful for efforts to evaluate and improve existing ATDs and computational models for use in the rollover crash environment.

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.

The objective of this study is to compare the risk of injury to pedestrians involved in vehicle-pedestrian impacts as predicted by two different types of risk assessment tools: the pedestrian subsystem impactors recommended by the European Enhanced Vehicle-Safety Committee (EEVC) and post-mortem human surrogates (PMHS). Seven replicate full-scale vehicle-pedestrian impact tests were performed with PMHS and a mid-sized sedan travelling at 40 km/h. The PMHS were instrumented with six-degree-of-freedom sensor cubes and sensor data were transformed and translated to predict impact kinematics at the head center of gravity, proximal tibiae, and knee joints. Single EEVC WG 17/EuroNCAP adult headform, upper legform and lower legform impactor tests of the same vehicle were selected for comparison based on the proximity of their impact locations to that of the PMHS. The PMHS experienced higher HIC values (1830/2160) and lower impact velocities (8.5/7.5 m/s) than the impactor (1532 and 11.1 m/s) in impacts at the lower fourth of the windshield. The lower legform impactor (31 degrees) and PMHS (right: 25-40 degrees, and left: 24-39 degrees) predicted similar maximum knee bending angles. Some PMHS tibial accelerations (114-613 g) exceeded the proposed acceptance criteria (150-200 g) in both the absence and presence of distal tibial fracture, with the impactor predicting a similar result (335 g). The upper legform impactor test resulted in bending moments (361 Nm) and forces (6.3 kN) exceeding the acceptance criteria, while PMHS sustained pelvic injuries in 6 out of 7 tests.