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In this study a mathematical model was developed for the BIOSID dummy using the CAL3D simulation program. This model was correlated to the dummy impact response using pendulum tests on various body regions, and a side sled test. Favorable comparisons were achieved between the test results and the model responses. This model was then used for identifying optimal side airbag designs for a large car.

The ‘Harness Model’ in the CAL3D occupant simulation program is improved to incorporate a reference point generation scheme and a new belt slip algorithm. The reference point generation scheme results in more accurate belt geometry and alleviates the need to manually specify the reference points coordinates on the occupant body. The new belt slip algorithm balances the belt force and the friction force at each reference point in a successive fashion. This approach gives satisfactory results and does not have the convergence problem found in the old slip algorithm. These new enhancements were used to developed a model to simulate the Hybrid III dummy response in a barrier test. Good correlation was obtained between the model response and the test results. Parametric studies indicated that the shoulder belt stiffness has a significant effect on the head motion, the abdomen deformation, and the peak shoulder belt force.

A previously developed finite element human head/cervical spine model was further enhanced to include the major muscles in the neck. The head/cervical spine model consists of the skull, C1-C7, disks, facets, and all the ligaments in this region. The vertebral bodies are simulated by deformable bodies and the soft tissues in the cervical spine are modeled by nonlinear anisotropic viscoelastic material. The motion segments in the cervical spine model were validated against three-dimensional cadaver test data reported in the literature. To simulate the passive and active muscle properties, the classical Hill muscle model was implemented in the LS-DYNA code and model parameters were based on measurements of cadaver neck musculature. The head/neck model was used to simulate a human volunteer flexion whiplash test reported in the literature. Simulation results showed that the neck muscle contraction and relaxation activities had a significant effect on the head/neck motion.

A set of algorithms was developed in the CAL3D occupant simulation program to allow belt sliding in a direction perpendicular to the beltline. Such algorithms were used to construct a belt-restrained occupant model that would predict the occurrence of submarining. The lower torso of the previously developed Hybrid III dummy model was improved for more detailed description of the geometry and assessment of abdominal compression due to submarining. The simulation results compared favorably with two sled tests having two different seat angles; one resulted in occupant submarining, one did not. The model was then used to examine a number of design parameters which may influence the occupant submarining tendency. The most dominant design parameters for the vehicle investigated in this study appear to be the the seat back angle (which determines the occupant upper torso angle), and the lap belt angle.

The Cal3D simulation program was used to study the interaction between the belt restraint systems and a Hybrid III dummy in two sled tests. The elastic properties of the dummy joints and thorax were obtained from static tests. The two belt algorithms in the Cal3D program were compared and simulation results indicated that the “harness model”, which utilizes multi-segment representation for the belt is more suitable than the “simple belt model”, which has only one fixed point on the torso. Simulating a frontal impact of a lap belt restrained dummy indicated that the dummy motion consists of two distinct phases; a forward translation followed by a rotation. During forward translation the belt is primarily in contact with the abdomen while during rotation the belt is interacting with the upper legs. For a lap and shoulder belt restrained dummy, considerable head acceleration was induced by chin/chest impact.

A previously developed car-to-car side impact model was further exercised in this study. This model consists of a vehicle with a deformable side structure representation, and an occupant simulating the SID dummy impact response. It has been demonstrated that the vehicle model correlates well with side impact test data. The occupant model has similar impact acceleration response as the SID dummy in the head, thorax and pelvis regions. In addition, good correlations were also found in the force-time histories of the thorax region when compared to cadaver drop tests. The model provided insights to the effects of various design parameters such as side structure stiffness and padding. Examining the side structure stiffness effect shows that there is a significant benefit for occupant protection by reducing the amount of intrusion until it is roughly equal to the initial distance between the occupant and the door inner panel.

A finite element human thorax model was developed for predicting thoracic injury and studying the injury mechanisms under impact. Digital surface images of a human skeleton and internal organs were used to construct the three-dimensional finite element representation of the rib cage, the heart, the lungs, and the major blood vessels. The mechanical properties of the biological tissues in this model were based on test data found in the literature. The constitutive equations proposed in the literature for describing the mechanical behavior of the heart and the lungs were implemented in the code for modeling these organs. The model was validated against cadaver responses for both frontal and lateral impact. Good correlation between the model and the cadaver responses were achieved for the force and deflection time-histories.

The purpose of this study is to help understand the thoracic response and injury mechanisms in high-energy, limited-stroke, lateral velocity pulse impacts to the human chest wall. To impart such impacts, a linear impactor was developed which had a limited stroke and minimally decreased velocity during impact. The peak impact velocity was 5.6 ± 0.3 m/s. A series of BioSID and cadaver tests were conducted to measure biomechanical response and injury data. The conflicting effects of padding on increased deflection and decreased acceleration were demonstrated in tests with BioSID and cadavers. The results of tests conducted on six cadavers were used to test several proposed injury criteria for side impact. Linear regression was used to correlate each injury criterion to the number of rib fractures. This test methodology captured and supported a contrasting trend of increased chest deflection and decreased TTI when padding was introduced.