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Technical Paper

A Data-Based Model of the Impact Response of the SID

A simple spring-mass model of the impact response of the side impact dummy (SID) is established. The spring and mass constants of the model are established through system identification methodology based on data from impact tests. The tests are performed in laboratory with hydraulically driven impactors impacting the chest and pelvis of the SID. The input data to the model consist of measured contact force or impactor velocity time histories, and the output data are accelerations on the rib, spine, and pelvis of the SID. The established model appears to predict the test results with reasonable accuracy. The main purpose of this study, however, is to use this simple model to carry out parametric studies of the response of the dummy with changing impact parameters, the result of which would be useful in understanding vehicle crash tests using the SID.
Technical Paper

Data-Based Models for Spine Acceleration Response of the Side Impact Dummy

The response of the spine acceleration to rib and pelvis acceleration input of the side impact dummy (SID) is modeled using system identification methods. The basis for the modeling is a simplified representation of the SID by a 3-mass, 2-spring system. Based on this spring-mass representation, two types of response models are established. The first is a "gray-box" type with rib/pelvis-spine relationship modeled by Auto Regression with eXogeneous (or eXtra) input (ARX) type system models. The structure of these models is partially based on the spring-mass simplified representation, hence the notion "gray- box." The parameters of these models are identified through linear regression from test data. The second type of models is noted "physical model" here, since it is strictly a state- space form of the equation of motion of the simple spring-mass representation.
Technical Paper


A comparison of the NHTSA advanced dummy and the Hybrid III is presented in this paper based on their performance in twenty four frontal impact sled tests. Various time histories pertaining to accelerations, angular velocities, deflections and forces have been compared between the two dummies in light of their design differences. This has lead to some understanding about the differences and similarities between the NHTSA advanced dummy and the Hybrid III. In general, the chest as well as the head motion in the NHTSA advanced dummy are greater. The lumbar moments in the NHTSA advanced dummy are lower than that in the Hybrid III. The upper and lower spine segments in the NHTSA advanced dummy, generally rotate more than the spine of the Hybrid III.
Technical Paper

Critical Limitations on Significant Factors in Head Injury Research

The response of the head to blunt impact was investigated using anesthetized live and repressurized- and unrepressurized-postmortem Rhesus. The stationary test subject was struck on the occipital by a 10 kg guided moving impactor. The impactor striking surface was fitted with padding to vary the contact force-time characteristics. A nine-accelerometer system, rigidly affixed to the skull, measured head motion. Transducers placed at specific points below the skull recorded epidural pressure. The repressurization of postmortem subjects included repressurization of both the vascular and cerebrospinal systems.
Technical Paper

UMTRI Experimental Techniques in Head Injury Research

This paper discusses techniques developed and used by the Biosciences Group at the University of Michigan Transportation Research Institute (UMTRI) for measuring three-dimensional head motion, skull bone strain, epidural pressure, and internal brain motion of repressurized cadavers and Rhesus monkeys during head impact. In the experimental design, a stationary test subject is struck by a guided moving impactor of 10 kg (monkeys) and 25 or 65 kg (cadavers). The impactor striking surface is fitted with padding to vary the contact force-time characteristics. The experimental technique uses a nine-accelerometer system rigidly affixed to the skull to measure head motion, transducers placed at specific points below the skull to record epidural pressure, repressurization of both the vascular and cerebrospinal systems, and high-speed cineradiography (at 1000 frames per second) of radiopaque targets.
Technical Paper

Head impact Response—Skull Deformation and Angular Accelerations

The response of the head to impact was investigated using live anesthetized and postmortem Rhesus monkeys and repressurized cadavers. The stationary test subject was struck by a guided moving impactor of 10 kg for monkeys; 25 or 65 kg for cadavers. The impactor striking surface was fitted with padding to vary the contact force-time characteristics. The experimental technique used a nine-accelerometer system rigidly mounted on the head to measure head motion, transducers placed at specific points below the skull to record epidural pressure, repressurization of both the vascular and cerebral spinal systems of the cadaver model, and high-speed cineradiography (at 400 or 1000 frames per second) of selected test subjects. The results of the tests demonstrate the potential importance of skull deformation and angular acceleration on the injury produced in the live Rhesus and the damage produced in both the post-mortem Rhesus and the cadaver as a result of impact.
Technical Paper

Significance of Head-to-Knee impacts—A Comparison of Dummy and Cadaver Responses

Head-to-knee interaction of the right front passenger dummy can occur in some 30-35 MPH crash barrier tests. The biofidelity and significance of these interactions as related to predicting human response was addressed in this study. In a series of laboratory experiments an instrumented headform was dropped on the dummy knee to simulate the barrier interactions. These test results were then related to the human by dropping the same headform on the cadaver leg. The instrumented headform was dropped from three heights to impact the Part 572 dummy knee at three velocities. Two impact sites and two impact angles were used. These test parameters bracketed the barrier conditions. Measurements from headform accelerometers permitted calculation of HIC value for comparison to barrier values. Comparable experiments were subsequently performed with three unembalmed cadaver subjects using the same headform and test procedures.
Technical Paper

Head and Neck Response to Axial Impacts

Two series of impacts to the head in the superior-inferior direction using 19 unembalmed cadavers are reported. The first series of five tests was aimed at generating kinematic and dynamic response to sub-injurious impacts for the purpose of defining the mechanical characteristics of the undamaged head-neck-spine system in the S-I direction. The second series of fourteen tests was intended to define injury tolerance levels for a selected subject configuration. A 10-kg impactor was used to deliver the impact to the crown at a nominal velocity of 8 m/s for the first series, and between 7 and 11 m/s for the second series. Measurements made in the first series include the impact velocity, force, and energy, the head three-dimensional kinematics, forces and moments at the occipital condyles, and accelerations of the T1, T6, and T12 vertebrae. Impact impedance curves were also generated.
Technical Paper

Impact Response and Injury of the Pelvis

Multiple axial knee impacts and/or a single lateral pelvis impact were performed on a total of 19 cadavers. The impacting surface was padded with various materials to produce different force-time and load distribution characteristics. Impact load and skeletal acceleration data are presented as functions of both time and frequency in the form of mechanical impedance. Injury descriptions based on gross autopsy are given. The kinematic response of the pelvis during and after impact is presented to indicate the similarities and differences in response of the pelvis for various load levels. While the impact response data cannot prescribe a specific tolerance level for the pelvis, they do indicate variables which must be considered and some potential problems in developing an accurate injury criterion.
Technical Paper

Head Impact Response Comparisons of Human Surrogates

The response of the head to impact in the posterior-to-anterior direction was investigated with live anesthetized and post-mortem primates.* The purpose of the project was to relate animal test results to previous head impact tests conducted with cadavers (reported at the 21st Stapp Car Crash Conference (1),** and to study the differences between the living and post-mortem state in terms of mechanical response. The three-dimensional motion of the head, during and after impact, was derived from experimental measurements and expressed as kinematic quantities in various reference frames. Comparison of kinematic quantities between subjects is normally done by referring the results to a standard anatomical reference frame, or to a predefined laboratory reference frame. This paper uses an additional method for describing the kinematics of head motion through the use of Frenet-Serret frame fields.