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The knee is one of the regions of interest for pedestrian safety assessment. Past testing to study knee ligament injuries for pedestrian impact only included knees in full extension and mostly focused on global responses. As the knee flexion angle and the initial ligament laxity may affect the elongation at which ligaments fail, the objectives of this study were (1) to design an experimental protocol to assess the laxity of knee ligaments before measuring their elongation at failure, (2) to apply it in paired knee tests at two flexion angles (10 and 45 degrees). The laxity tests combined strain gauges to measure bone strains near insertions that would result from ligament forces and a custom machine to exercise the knee in all directions. Failure was assessed using a four-point bending setup with additional degrees of freedom on the axial rotation and displacement of the femur. A template was designed to ensure that the two setups used the exact same starting position.

Obese vehicle occupants sustain specific injury patterns in case of accidents in which the interaction between the seat belt and the abdomen may play a role. This study aimed to collect geometrical characteristics and to investigate the mechanical responses of the abdomen of obese subjects. Four Post Mortem Human Subjects (PMHS) with BMI ranging from 31 to 46 kg/m2 were collected. CT-scans performed in the seated position revealed that the antero-posterior depth of the abdominal fold (from the inguinal region to the most anterior point of the abdominal surface) was much greater (170 mm max., 127 mm average) than the thickness of subcutaneous adipose tissues (85 max., 38 mm in average). Each PMHS was subjected to three infra-injurious antero-posterior belt pulls in a seated posture with a lap belt positioned (C1) superior to the umbilicus, (C2) inferior to the umbilicus, (C3) inside the abdominal fold between the abdomen and the thigh.

Relative motion between the brain and skull and brain deformation are biomechanics aspects associated with many types of traumatic brain injury (TBI). Thus far, there is only one experimental endeavor (Hardy et al., 2007) reported brain strain under loading conditions commensurate with levels that were capable of producing injury. Most of the existing finite element (FE) head models are validated against brain-skull relative motion and then used for TBI prediction based on strain metrics. However, the suitability of using a model validated against brain-skull relative motion for strain prediction remains to be determined. To partially address the deficiency of experimental brain deformation data, this study revisits the only existing dynamic experimental brain strain data and updates the original calculations, which reflect incremental strain changes. The brain strain is recomputed by imposing the measured motion of neutral density target (NDT) to the NDT triad model.

in situ

Experimentally derived brain response envelopes are needed to evaluate and validate existing finite element (FE) head models. Motion of the brain relative to the skull during rotational input was measured using high-speed biplane x-ray. To generate repeatable, reproducible, and scalable data, methods were developed to reduce experimental variance. An “extreme-energy” device was developed to provide a controlled input that is unaffected by specimen characteristics. Additionally, a stereotactic frame was used to deploy radiopaque markers at specific, pre-determined locations within the brain. One post-mortem human surrogate (PMHS) head specimen was subjected to repeat tests of a half-sine rotational speed pulse in the sagittal plane. The desired pulse had a peak angular speed of 40 rad/s and duration of 30 ms. Relative motion of the brain was quantified using radiopaque targets and high-speed biplane x-ray. Frontal and occipital intracranial pressure (ICP) were also measured.

High-speed biplane x-ray was used to research the kinematics of the small intestine in response to seatbelt loading. Six driver-side 3-point seatbelt simulations were conducted with the lap belt routed superior to the pelvis of six unembalmed human cadavers. Testing was conducted with each cadaver perfused, ventilated, and positioned in a fixed-back configuration with the spine angled 30° from the vertical axis. Four tests were conducted with the cadavers in an inverted position, and two tests were conducted with the cadavers upright. The jejunum was instrumented with radiopaque markers using a minimally-invasive, intraluminal approach without inducing preparation-related damage to the small intestine. Tests were conducted at a target peak lap belt speed of 3 m/s, resulting in peak lap belt loads ranging from 5.4-7.9 kN. Displacement of the radiopaque markers was recorded using high-speed x-ray from two perspectives.

A blast buck (Accelerative Loading Fixture, or ALF) was developed for studying underbody blast events in a laboratory-like setting. It was designed to provide a high-magnitude, high-rate, vertical loading environment for cadaver and dummy testing. It consists of a platform with a reinforcing cage that supports adjustable-height rigid seats for two crew positions. The platform has a heavy frame with a deformable floor insert. Fourteen tests were conducted using fourteen PMHS (post mortem human surrogates) and the Hybrid III ATD (Anthropomorphic Test Device). Tests were conducted at two charge levels: enhanced and mild. The surrogates were tested with and without PPE (Personal Protective Equipment), and in two different postures: nominal (knee angle of 90°) and obtuse (knee angle of 120°). The ALF reproduces damage in the PMHS commensurate with injuries experienced in theater, with the most common damage being to the pelvis and ankle.

Pedestrian protection systems, both active and passive systems, are being introduced in the EU and Japan to comply with regulatory requirements. Their designs are specific and, in general, reflect an accident scenario of the pedestrian being struck on the side by a vehicle traveling at a maximum travel speed of 40 kph. The present study is an effort to quantify the effects of pedestrian reaction prior to an accident and identify characteristics that may help minimize or prevent the pedestrian to vehicle interaction. Accident situations were simulated with volunteers using a non-impacting methodology. Fifty one reactions from 23 volunteers of two age groups were observed. Most of the volunteers were found to run, step-back or stop in fright in a dangerous situation. Volunteer speed was an important parameter which could help in differentiating these reactions. Age related differences were also observed, both for reaction strategy and reaction times.

High-speed biplane x-ray was used to investigate relative kinematics of the thoracoabdominal organs in response to blunt loading. Four post-mortem human surrogates instrumented with radiopaque markers were subjected to eight crash-specific loading scenarios, including frontal chest and abdominal impacts, as well as driver-shoulder seatbelt loading. Testing was conducted with each surrogate perfused, ventilated, and positioned in an inverted, fixed-back configuration. Displacement of radiopaque markers recorded with high-speed x-ray in two perspectives was tracked using motion analysis software and projected into calibrated three-dimensional coordinates. Internal organ kinematics in response to blunt impact were quantified for the pericardium, lungs, diaphragm, liver, spleen, stomach, mesentery, and bony structures.

From the many sub-tasks of the four study areas of the EC CASPER project, this paper presents the following point: • Child protection improvements as a result of accident reconstructions and development of injury risk curves. The first step in achieving this aim was to collect real world in-depth road accident data involving restrained children, with injuries systematically coded using the AIS (Abbreviated Injury Scale, AAAM 1998). This activity identified the priority body regions to be protected (therefore requiring injury risk curves) and provided cases to be reconstructed in full scale crash tests. In such reconstructions dummy readings were correlated with the occupants' injuries in the real accident to develop injury risk curves (after validation checks for crash severity and dummy kinematics). At the same time, online and field surveys were carried out to identify the safety of children when travelling in cars.

A total of eight low-speed, rear-end impact tests using two Post Mortem Human Subjects (PMHS) in a seated posture are reported. These tests were conducted using a HYGE-style mini-sled. Two test conditions were employed: 8 kph without a headrestraint or 16 kph with a headrestraint. Upper-body kinematics were captured for each test using a combination of transducers and high-speed video. A 3-2-2-2-accelerometer package was used to measure the generalized 3D kinematics of both the head and pelvis. An angular rate sensor and two single-axis linear accelerometers were used to measure angular speed, angular acceleration, and linear acceleration of T1 in the sagittal plane. Two high-speed video cameras were used to track targets rigidly attached to the head, T1, and pelvis. The cervical spine kinematics were captured with a high-speed, biplane x-ray system by tracking radiopaque markers implanted into each cervical vertebra.

The objectives of this study were to examine the response, repeatability, and injury predictive ability of the Hybrid III small-female dummy to static out-of-position (OOP) deployments using a depowered driver-side airbag. Five dummy tests were conducted in two OOP configurations by two different laboratories. The OOP configurations were nose-on-rim (NOR) and chest-on-bag (COB). Four cadaver tests were conducted using unembalmed small-female cadavers and the same airbags used in the dummy tests under similar OOP conditions. One cadaver test was designed to increase airbag loading of the face and neck (a forehead-on-rim, or FOR test). Comparison between the dummy tests of Lab 1 and of Lab 2 indicated the test conditions and results were repeatable. In the cadaver tests no skull fractures or neck injuries occurred. However, all four cadavers had multiple rib fractures.

High-speed biplane x-ray and neutral density targets were used to examine brain displacement and deformation during impact. Relative motion, maximum principal strain, maximum shear strain, and intracranial pressure were measured in thirty-five impacts using eight human cadaver head and neck specimens. The effect of a helmet was evaluated. During impact, local brain tissue tends to keep its position and shape with respect to the inertial frame, resulting in relative motion between the brain and skull and deformation of the brain. The local brain motions tend to follow looping patterns. Similar patterns are observed for impact in different planes, with some degree of posterior-anterior and right-left symmetry. Peak coup pressure and pressure rate increase with increasing linear acceleration, but coup pressure pulse duration decreases. Peak average maximum principal strain and maximum shear are on the order of 0.09 for CFC 60 Hz data for these tests.

Knee injuries represent about 10% of all injuries suffered during car crashes. Efforts to assess the injury risk to the posterior cruciate ligament (PCL) have been based on a study available in the literature (Viano et al., 1978), in which only two of the five knees tested had PCL ruptures. The aims of the current study were to repeat the study with a higher number of samples, study the effects of other soft tissues on knee response, and assess the adequacy of the experimental setup for the identification of a PCL tolerance. A total of 14 knees were tested using a high-speed materials testing machine. Eight were intact knees (with the patella and all the muscular and ligamentous structures), three were PCL-only knees (patella and all the muscular and ligamentous structures other than the PCL removed), and the last three were PCL-only knees with the tibia protected from bending fracture.

The two main motivations for Wayne State University (WSU) and Henry Ford Hospital (HFH) researchers to develop numerical human surrogates are advanced computing technology and a high-speed x-ray imaging device not available just a decade ago. This paper summarizes the capabilities and limitations of detailed component models of the human body, from head to foot, developed at WSU over the last decade (Zhang et al. 2001, Yang et al. 1998, Shah et al. 2001, Iwamoto et al. 2000, Lee et al. 2001 and Beillas et al. 2001). All of these models were validated against global response data obtained from relevant high-speed cadaveric tests. Additionally, some models were also validated against local kinematics of bones or soft tissues obtained using the high-speed x-ray system. All of these models have been scaled to conform to the key dimensions of a 50th percentile male.

Little has been reported in the literature on the compressive properties of muscle. These data are needed for the development of finite element models that address impact of the muscles, especially in the study of pedestrian impact. Tests were conducted to characterize the compressive response of muscle. Volunteers, cadaveric specimens and a Hybrid III dummy were impacted in the posterior and lateral aspect of the lower leg using a free flying pendulum. Volunteer muscles were tested while tensed and relaxed. The effects of muscle tension were found to influence results, especially in posterior leg impacts. Cadaveric response was found to be similar to that of the relaxed volunteer. The resulting data can be used to identify a material law using an inverse method.

A parameterized, or scalable, finite element (FE) model of the human head was developed and validated against the available cadaver experiment data for three impact directions (frontal, occipital and lateral). The brain material properties were modeled using a hyperelastic and viscoelastic constitutive law. The interface between the skull and the brain was modeled in three different ways ranging from purely tied (no-slip) to sliding (free-slip). Two sliding contact definitions were compared with the tied condition. Also, three different stiffness parameters, encompassing the range of published brain tissue properties, were tested. The model using the tied contact definition correlated well with the experimental results for the coup and contrecoup pressures in a frontal impact while the sliding interface models did not. Relative motion between the skull and the brain in low-severity impacts appears to be relatively insensitive to the contact definitions.

Brain tissue architecture consists of a complex network of neurons and vasculature interspersed within a matrix of supporting cells. The role of the relatively suffer blood vessels on the more compliant brain tissues during rapid loading has not been properly investigated. Two 2-D finite element models of the human head were developed. The basic model (Model I) consisted of the skull, dura matter, cerebral spinal fluid (CSF), tentorium, brain tissue and the parasagittal bridging veins. The pia mater was also included but in a simplified form which does not correspond to the convolutions of the brain. In Model II, major branches of the cerebral arteries were added to Model I. Material properties for the brain tissues and vasculature were taken from those reported in the literature. The model was first validated against intracranial pressure and brain/skull relative motion data from cadaveric tests.

This study was conducted to resolve discrepancies and fill in gaps in the biomechanical impact response of the human abdomen to frontal impact loading. Three types of abdominal loading were studied: rigid-bar impacts, seatbelt loading, and close-proximity (out-of-position) airbag deployments. Eleven rigid-bar free-back tests were performed into the mid and upper abdomens of unembalmed instrumented human cadavers using nominal impact speeds of 6 and 9 m/s. Seven fixed-back rigid-bar tests were also conducted at 3, 6, and 9 m/s using one cadaver to examine the effects of body mass, spinal flexion, and repeated testing. Load-penetration corridors were developed and compared to those previously established by other researchers. Six seatbelt tests were conducted using three cadavers and a peak-loading rate of 3 m/s. The seatbelt loading tests were designed to maximize belt/abdomen interaction and were not necessarily representative of real-world crashes.

The Lower Limb Model for Safety (LLMS) is a finite element model of the lower limb developed mainly for safety applications. It is based on a detailed description of the lower limb anatomy derived from CT and MRI scans collected on a subject close to a 50th percentile male. The main anatomical structures from ankle to hip (excluding the hip) were all modeled with deformable elements. The modeling of the foot and ankle region was based on a previous model Beillas et al. (1999) that has been modified. The global validation of the LLMS focused on the response of the isolated lower leg to axial loading, the response of the isolated knee to frontal and lateral impact, and the interaction of the whole model with a Hybrid III model in a sled environment, for a total of nine different set-ups. In order to better characterize the axial behavior of the lower leg, experiments conducted on cadaveric tibia and foot were reanalyzed and experimental corridors were proposed.