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The head, neck and trunk kinematic responses of four volunteer test subjects, recorded during a series of experimental low velocity motor vehicle collisions, have been measured and analyzed. Using data obtained from multiple high speed film, video and electronic accelerometer measurements of the test subjects, it was found that the actual kinematic responses of the human head, neck and trunk that occur during low velocity rearend collisions are more complex than previously thought. Our findings indicate that the time-honored description of the cervical “whiplash” response is both incomplete and inaccurate. Although the classic “whiplash” neck response to rearend collisions and the widely accepted hyperextension/hyperflexion cervical injury mechanism have been extensively written and speculated about, there have been little human experimental data available, especially for low velocity collisions.

Google Earth is a map and geographical information application created and maintained by Google Corporation. The program displays maps of the Earth using images obtained from available satellite imagery, aerial photography and geographic information systems (GIS) 3D globe. Google Earth has become a tool often used by accident reconstructionists to create site drawings and obtain dimensional information. In some cases, a reconstructionist will not be able to inspect the site of the crash due to various circumstances. For example, a reconstruction may commence after the roadway on which the accident occurred has been modified. In other cases, the time and expense required to physically inspect the incident site is not justifiable. In these instances, a reconstructionist may have to rely on Google Earth imagery for dimensional information about the site. The accuracy of Google Earth is not officially documented.

This is the complete manuscript and replacement for SAE paper 2014-01-0482, which has been retracted due to incomplete content. This paper reports on 76 quasi-static tests conducted to investigate the behavior of road vehicle bumper systems. The tests are a quasi-static replication of real world low speed collisions. The tests represented front to rear impacts between various vehicles. Force and deflection were captured in order to quantify the stiffness characteristics of the bumper-to-bumper system. A specialized test apparatus was constructed to position and load bumper systems into each other. The purpose was to replicate or exceed damage that occurred in actual collisions. The fixture is capable of positioning the bumpers in various orientations and generates forces up to 50 kips. Various bumper-to-bumper alignments were tested including full overlap, lateral offset, and override/underride configurations.

It has been proposed that low speed collisions in which the damage is isolated to the bumper systems can be reconstructed using data from customized quasistatic testing of the bumper systems of the involved vehicles. In this study, 10 quasistatic bumper tests were conducted on 7 vehicle pairs involved in front-to-rear collisions. The data from the quasistatic bumper tests were used to predict peak bumper force, vehicle accelerations, velocity changes, dynamic combined crush, restitution, and crash pulse time for a given impact velocity. These predictions were compared to the results measured by vehicle accelerometers in 12 dynamic crash tests at impact velocities of 2 - 10 mph. The average differences between the predictions using the quasistatic bumper data and the dynamic crash test accelerometer data were within 5% for bumper force, peak acceleration, and velocity change, indicating that the quasistatic bumper testing method had no systematic bias compared to dynamic crash testing.

Biomechanical data are often assumed to be doubly censored. In this paper, this assumption is evaluated critically for several previously published sets of data. Injury risk functions are compared using simple logistic regression and using survival analysis with 1) the assumption of doubly censored data and 2) the assumption of right-censored (uninjured specimens) and uncensored (injured) data. It is shown that the injury risk functions that result from these differing assumptions are not similar and that some experiments will require a preliminary assessment of data censoring prior to finalizing the experimental design. Some types of data are obviously doubly censored (e.g., chest deflection as a predictor of rib fracture risk), but many types are not left censored since injury is a force-limiting phenomenon (e.g., axial force as a predictor of tibia fracture). Guidelines for determining the censoring for various types of experiment are presented.

A second series of low speed rear end crash tests with seven volunteer test subjects have delineated human head/neck dynamics for velocity changes up to 10.9 kph (6.8 mph). Angular and linear sensor data from biteblock arrays were used to compute acceleration resultants for multiple points on the head's sagittal plane. By combining these acceleration fields with film based instantaneous rotation centers, translational and rotational accelerations were defined to form a sequential acceleration history for points on the head. Our findings suggest a mechanism to explain why cervical motion beyond the test subjects' measured voluntary range of motion was never observed in any of a total of 28 human test exposures. Probable “whiplash” injury mechanisms are discussed.

The kinematic response of vehicle occupants involved in tractor-to-passenger vehicle sideswipes was examined through a series of 13 crash tests. Each test vehicle and its occupants were instrumented with accelerometer arrays to measure and quantify the impact severity at various inter-vehicular angles and impact velocities. The passenger vehicle was occupied by a volunteer test subject in the driver and right-front passenger positions. The impact angle was varied between 3° and 11° to produce a sideswipe collision between the front bumper, steered wheel, and side components of the tractor and the side panels of the struck vehicle. The passenger vehicles were struck at different locations along their longitudinal axis at impact velocities between 3 mph and 11.5 mph. Accelerations were measured at the lumbar, cervicothoracic, and head regions of the driver and right-front passenger of the struck vehicle and the tractor driver.

There is a paucity of recent data quantifying the injury risk of forces and accelerations that act on the whole body in a back-to-front direction. The purpose of this study was to quantify the level of back-to-front accelerations that volunteers felt were tolerable and non-injurious. Instrumented volunteers were dropped supine onto a mattress, and their accelerations during the impact with the mattress were measured. Accelerometers were located on the head, upper thoracic and lower lumbar regions. Drop heights started at 0.6 m (2 ft) and progressed upward as high as 1.8 m (6 ft) based on the test subjects' consent. The test panel was comprised of male and female subjects whose ages ranged from 25 to 63 years of age and whose masses ranged from 62 to 130 kg (136 to 286 lb). Peak head, upper thoracic and lower lumbar accelerations of 25.9 g, 29.4 g and 39.6 g were measured.

The purpose of this study was to determine the frictional properties between the exterior surface of a motorcycle helmet and ‘typical’ roadway surfaces. Motorcycle helmet impacts into asphalt and concrete surfaces were compared to abrasive papers currently recommended by government helmet safety standards and widely used by researchers in the field of oblique motorcycle helmet impact testing. A guided freefall test fixture was utilized to obtain nominal impact velocities of 5, 7 and 9 m/s. The impacting surfaces were mounted to an angled anvil to simulate an off-centered oblique collision. Helmeted Hybrid III ATD head accelerations and impact forces were measured for each test. The study was limited to a single helmet model and impact angle (30 degrees). Analysis of the normal and tangential forces imparted to the contact surface indicated that the frictional properties of abrasive papers differ from asphalt and concrete in magnitude, duration and onset.

The purpose of this study was to develop a numerical analytical model of collinear low-speed bumper-to-bumper crashes and use the model to perform parametric studies of low-speed crashes and to estimate the severity of low-speed crashes that have already occurred. The model treats the car body as a rigid structure and the bumper as a deformable structure attached to the vehicle. The theory used in the model is based on Newton's Laws. The model uses an Impact Force-Deformation (IF-D) function to determine the impact force for a given amount of crush. The IF-D function used in the simulation of a crash that has already occurred can be theoretical or based on the measured force-deflection characteristics of the bumpers of the vehicles that were involved in the actual crash. The restitution of the bumpers is accounted for in a simulated crash through the rebound characteristics of the bumper system in the IF-D function.

The longitudinal motion of the head, thorax and lumbar spine of two test subjects was measured in low-speed rear-end collisions in order to understand the effect of the head-to-head restraint distance (backset) on the occupant kinematics. The two test subjects were exposed to three rear-end impacts at two crash severities, nominal changes in velocity (ΔV) of 1.11 (low ΔV) and 2.22 m/s (high ΔV). The backset was hypothesized to be an independent variable that would affect the head and neck motion and was set at 0, 5 or 10 cm. The x and z-axis accelerations of the impacted vehicle and the anatomical x and z-axis accelerations of each test subjects’ upper thorax and L5-S1 region were measured and then transformed to an earth-based coordinate system. Head accelerations were measured at the mouth and these accelerations were transformed to an earth-based coordinate system at the head center of gravity (CG).

Anticipated high agility aircraft will require pilot training and acceleration research to investigate the human capacity to function in the projected environment. Existing man-rated centrifuges and fixed-base simulators are capable of imposing only a portion of the entire envelope of accelerations, and often produce significant artifactual accelerations and illusions. Simulations and engineering analysis of a large radius track centrifuge indicate such a device could impose an acceleration environment suitable for training and research. The technology required for the concept is estimated to be feasible in the near future.

The restitution or rebound that occurs as the final phase of a vehicle-to-vehicle collision is quantified by the coefficient of restitution, which is the ratio of the closing velocity to the post-impact separating velocity of the two colliding vehicles. The coefficient of restitution of medium and high velocity collisions is low, [approximately 0.1] since these collisions are quite inelastic, whereas collisions at extremely low velocities are relatively elastic with the coefficient of restitution theoretically approaching 1.0. However, the actual collision restitution magnitude in the low velocity range has not been adequately established. A series of vehicle-to-vehicle and vehicle-to-barrier collisions resulting in velocity changes in the 2 to 5 miles per hour range was conducted in which vehicles with various bumper configurations [factory standard equipment] were utilized to study the coefficient of restitution at low closing velocities.