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This study reanalyzes the data from a recent experimental report from the University of Utah investigating the effect on driving performance of auditory-vocal secondary tasks (such as cell phone and passenger conversations, speech-to-text, and a complex artificial cognitive task). The current objective is to estimate the relative risk of crashes associated with such auditory-vocal tasks. Contrary to the Utah study's assumption of an increase in crash risk from the attentional effects of cognitive load, a deeper analysis of the Utah data shows that driver self-regulation provides an effective countermeasure that offsets possible increases in crash risk. For example, drivers self-regulated their following distances to compensate for the slight increases in brake response time while performing auditory-vocal tasks. This new finding is supported by naturalistic driving data showing that cell phone conversation does not increase crash risk above that of normal baseline driving.

A key aim of research into cell phone tasks is to obtain an unbiased estimate of their relative risk (RR) for crashes. This paper re-examines five RR estimates of cell phone conversation in automobiles. The Toronto and Australian studies estimated an RR near 4, but used subjective estimates of driving and crash times. The OnStar, 100-Car, and a recent naturalistic study used objective measures of driving and crash times and estimated an RR near 1, not 4 - a major discrepancy. Analysis of data from GPS trip studies shows that people were in the car only 20% of the time on any given prior day at the same clock time they were in the car on a later day. Hence, the Toronto estimate of driving time during control windows must be reduced from 10 to 2 min.

Lower extremity injuries in frontal automotive crashes usually occur with footwell intrusion where both the knee and foot are constrained. In order to identify factors associated with tibial shaft injury, a series of numerical simulations were conducted using a finite element model of the whole human body. These simulations demonstrated that tibial mid-shaft injuries in frontal crashes could be caused by an abrupt change in velocity and a high rate of footwell intrusion.

Various types of padding have been used in side impact sled tests with cadavers. This paper presents a summary of performance of the padding used in NHTSA and WSU/CDC sled tests, and a summary of material properties of padding used in cadaveric sled tests. The purpose of this paper is to provide information on padding performance in cadavers, rather than optimum padding performance in dummies.

Heidelberg-type side impact sled tests were conducted using SID side impact dummies. These tests were run under similar conditions to a series of cadaveric sled tests funded by the Centers for Disease Control in the same lab. Tests included 6.7 and 9 m/s (15 and 20 mph) unpadded and 9 m/s padded tests. The following padding was used at the thorax: ARSAN, ARCEL, ARPAK, ARPRO, DYTHERM, 103 and 159 kPa (15 and 23 psi) crush strength paper honeycomb, and an expanded polystyrene. In all padded tests the dummy Thoracic Trauma Index, TTI(d) was below the value of 85 set by federal rulemaking (49 CFR, Part 571 et al., 1990). In contrast, cadavers in 9 m/s sled tests did not tolerate ARSAN 601 (MAIS 5) and 23 psi (159 kPa) paper honeycomb (MAIS 5), and 20 psi (138 kPa) Verticel™ honeycomb (MAIS 4), but tolerated 15 psi (103 kPa) paper honeycomb (average thoracic MAIS 2.3 in six tests).

Auto racing has been in vogue from the time automobiles were first built. With the dawn of modern cars came higher engine capacities; the speeds involved in these races and crashes increased as well. However, the advent of passive restraint systems such as the helmet, HANS (Head and Neck Support device), multi-point harness system, roll cage, side and frontal crush zones, racing seats, fire retardant suits, and soft-wall technology, have greatly improved the survivability of the drivers in high-speed racing crashes. Three left lateral crashes from Begeman and Melvin (2002), Case #LAS12, #IND14 and #99TX were used as inputs to the Wayne State Human Body Model (WSHBM) in a simulated racing buck. Twelve simulations with delta-v, six-point harness and shoulder pad as design variables were analyzed for the average maximum principal strain (AMPS) in the aorta. The average AMPS for the high-speed crashes were 0.1551±0.0172 while the average maximum pressure was 110.50±4.25 kPa.

Injuries to the thorax and abdomen comprise a significant percentage of all occupant injuries in motor vehicle accidents. While the percentage of internal chest injuries is reduced for restrained front-seat occupants in frontal crashes, serious skeletal chest injuries and abdominal injuries can still result from interaction with steering wheels and restraint systems. This paper describes the design and performance of prototype components for the chest, abdomen, spine, and shoulders of the Hybrid III dummy that are under development to improve the capability of the Hybrid III frontal crash dummy with regard to restraint-system interaction and injury-sensing capability.

A 3-D finite element human head model has been developed to study the dynamic response of the human head to direct impact by a rigid impactor. The model simulated closely the main anatomical features of an average adult head. It included the scalp, a three-layered skull, cerebral spinal fluid (CSF), dura mater, falx cerebri, and brain. The layered skull, cerebral spinal fluid, and brain were modeled as brick elements with one-point integration. The scalp, dura mater, and falx cerebri were treated as membrane elements. To simulate the strain rate dependent characteristics of the soft tissues, the brain and the scalp were considered as viscoelastic materials. The other tissues of the head were assumed to be elastic. The model contains 6080 nodes, 5456 brick elements, and 1895 shell elements. To validate the head model, it was impacted frontally by a cylinder to simulate the cadaveric tests performed by Nahum et. al. (8).

There are many mechanisms for ankle injury to front seat occupants involved in automotive impacts. This study addresses injuries to the ankle joint involving inversion or eversion, in particular at high rates of loading such as might occur in automotive accidents. Injuries included unilateral malleolar fractures and ligament tears, and talus and calcaneous avulsions. Twenty tests have been performed so far, two of them using Hybrid III lower leg and the rest using cadaveric specimens. The specimens were loaded dynamically on the bottom of the foot via a pneumatic cylinder in either an inversion or eversion direction at fixed dorsiflexion and plantarflexion angles. The applied force and accelerations have been measured as well as all the reaction forces and moments. High-speed film was used to obtain the inversiordeversion angle of the foot relative to the tibia and for following ligament stretch.

Thirty-seven SID side impact sled tests were performed using a rigid wall and a padded wall with fourteen different padding configurations. The Thoracic Trauma Index (TTI) and Average Spine Acceleration (ASA) were measured in each test. TTI and ASA were evaluated in terms of their ability to predict injury in identical cadaver tests and in terms of their ability to predict the harm or benefit of padding of different crush strengths. SID ASA predicted the injury seen in WSU-CDC cadaver tests better than SID TTI. SID ASA predicted that padding of greater than 20 psi crush strength is harmful (ASA > 40 g's). SID TTI predicted that padding of greater than 20 psi crush strength is beneficial (TTI < 85 g's). SID TTI predicts the benefit of lower impact velocity. However, SID ASA appears more useful in assessing the harm or benefit of door padding or air bags.

Side impact pendulum tests were conducted on Eurosid I and Biosid to assess the biofidelity of the thorax, abdomen and pelvis, and determine injury tolerance levels. Each body region was impacted at 4.5, 6.7, and 9.4 m/s using test conditions which duplicate cadaver impacts with a 15 cm flat-circular 23.4 kg rigid mass. The cadaver database establishes human response and injury risk assessment in side impact. Both dummies showed better biofidelity when compared to the lowest-speed cadaver response corridor. At higher speeds, peak force was substantially higher. The average peak contact force was 1.56 times greater in Biosid and 2.19 times greater in Eurosid 1 than the average cadaver response. The Eurosid I abdomen had the most dissimilar response and lacks biofidelity. Overall, Biosid has better biofidelity than Eurosid I with an average 21% lower peak load and a closer match to the duration of cadaver impact responses for the three body regions.

After a rear end impact, various clinical symptoms are often seen in car occupants (e.g. neck stiffness, strain, headache). Although many different injury mechanisms of the cervical spine have been identified thus far, the extent to which a single mechanism of injury is responsible remains uncertain. Apart from hyperextension or excessive shearing, a compression of the cervical spine can also be seen in the first phase of the impact due to ramping or other mechanical interactions between the seat back and the spine. It is hypothesized that this axial compression, together with the shear force, are responsible for the higher observed frequency of neck injuries in rear end impacts versus frontal impacts of comparable severity. The axial compression first causes loosening of cervical ligaments making it easier for shear type soft tissue injuries to occur.

A sled-to-sled subsystem side impact test methodology has been developed by using two sleds at the WSU Bioengineering Center in order to simulate a car-to-car side impact, particularly in regards to the door velocity profile. Initially this study concentrated on tailoring door pulse to match the inner door velocity profile from FMVSS 214 full-scale dynamic side impact tests. This test device simulates a pulse quite similar to a typical door velocity of a full size car in a dynamic side impact test. Using the newly developed side impact test device three runs with a SID dummy were performed to study the effects of door padding and spacing in a real side impact situation. This paper describes the test methodology to simulate door intrusion velocity profiles in side impact and discusses SID dummy test results for different padding conditions.

A humerus provisional reference value (PRV) based on human surrogate data was developed to help evaluate upper arm injury potential. The proposed PRV is based on humerus bone bending moments generated by testing pairs of cadaver arms to fracture in three-point bending on an Instron testing machine in either lateral-medial (L-M) or anterior-posterior (A-P) loading, at 218 mm/s and 0.635 mm/s loading rates. The results were then normalized and scaled to 50th and 5th percentile sized occupants. The normalized average L-M bending moment at failure test result was 6 percent more than the normalized average A-P bending moment. The normalized average L-M shear force at failure was 23 percent higher than the normalized average A-P shear force. The faster rate of loading resulted in a higher average bending moment overall - 8 percent in the L-M and 14 percent in the A-P loading directions.

Previously, a 10-year-old (YO) pediatric thorax finite element model (FEM) was developed and verified against child chest stiffness data measured from clinical cardiopulmonary resuscitation (CPR). However, the CPR experiments were performed at relatively low speeds, with a maximum loading rate of 250 mm/s. Studies showed that the biomechanical responses of human thorax exhibited rate sensitive characteristics. As such, the studies of dynamic responses of the pediatric thorax FEM are needed. Experimental pediatric cadaver data in frontal pendulum impacts and diagonal belt dynamic loading tests were used for dynamic validation. Thoracic force-deflection curves between test and simulation were compared. Strains predicted by the FEM and the injuries observed in the cadaver tests were also compared for injury assessment and analysis. This study helped to further improve the 10 YO pediatric thorax FEM.

This paper focuses on the role and significance of linear momentum and kinetic energy in controlling air bags aboard vehicles. Among the results of the study are analytic and geometric models that characterize crash behavior and control algorithms that quantify crash severity and identify crash configurations. These results constitute an effective basis for crash-data design and air-bag control.

Finite element models of human body segments have been developed in recent years. Numerical simulation could be helpful when understanding injury mechanisms and to make injury assessments. In the lower leg injury research in NISSAN, a finite element model of the human ankle/foot is under development. The mesh for the bony part was taken from the original model developed by Beaugonin et al., but was revised by adding soft tissue to reproduce realistic responses. Damping effect in a high speed contact was taken into account by modeling skin and fat in the sole of the foot. The plantar aponeurosis tendon was modeled by nonlinear bar elements connecting the phalanges to the calcaneus. The rigid body connection, which was defined at the toe in the original model for simplicity, was removed and the transverse ligaments were added instead in order to bind the metatarsals and the phalanges. These tendons and ligaments were expected to reproduce a realistic response in compression.

Numerical analyses of head and neck response during side impact are presented in this paper. A mathematical human model for side impact simulation was developed based on previous studies of other researchers. The effects of muscular activities during severe side impact were analyzed with the use of this model. This study shows that the effect of muscular activities is significant especially if the occupant is prepared to resist the impact. This result suggests that the modeling of muscles is important for the simulation of real accident situation.

Seventeen Heidelberg type cadaveric side impact sled tests, two sled-to-sled tests, and forty-four pendulum tests have been conducted at Wayne State University, to determine human responses and tolerances in lateral collisions. This paper describes the development of a simplified finite element model of a human occupant in a side impact configuration to simulate those cadaveric experiments. The twelve ribs were modeled by shell elements. The visceral contents were modeled as an elastic solid accompanied by an array of discrete dampers. Bone condition factors were obtained after autopsy to provide material properties for the model. The major parameters used for comparison are contact forces at the level of shoulder, thorax, abdomen and pelvis, lateral accelerations of ribs 4 and 8 and of T12, thoracic compression and injury functions V*C, TTI and ASA.

Previous studies have hypothesized that the shoulder may be used to absorb some impact energy and reduce chest injury due to side impacts. Before this hypothesis can be tested, a good understanding of the injury mechanisms and the kinematics of the shoulder is critical for occupant protection in side impact. However, existing crash dummies and numerical models are not designed to reproduce the kinematics and kinetics of the human shoulder. The purpose of this study was to develop a finite element model of the human shoulder in order to achieve a deeper understanding of the injury mechanisms and the kinematics of the shoulder in side impact. Basic anthropometric data of the human shoulder used to develop the skeletal and muscular portions of this model were taken from commercial data packages. The shoulder model included three bones (the humerus, scapula and clavicle) and major ligaments and muscles around the shoulder.