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Technical Paper

Lower Extremity and Brake Pedal Interaction in Frontal Collisions: Computer Simulation

An Articulated Total Body frontal crash simulation was created with the dummy's right foot placed on the brake pedal. This study examined how interaction of the driver's foot with the brake pedal influenced the behavior of the lower extremities in frontal collisions. Braking parameters considered in the study included foot position on the pedal, whether or not the occupant's muscles were tensed and if the brake pedal was rigid or was allowed to depress. Two basic foot positions were identified as most likely to induce injury of the lower limb. One represented a foot that was pivoted about the heel from the gas pedal to the brake pedal. The other position replicated a foot that was lifted from the gas pedal to the brake pedal, resulting in an initial gap between the heel and floor. Both positions resulted in different loads and behavior of the foot, indicating that driver pre-impact position is a contributing factor to one's injury risk.
Technical Paper

Experimental Testing of the Hybrid III Lower Extremity for Computational Model Development

Experimental testing was performed to provide input data for a new, multi-body computer model of the Hybrid III lower extremity, with the 30 degree dorsiflexion ankle. The leg was disassembled into its components to mass, geometric, and inertial properties for each segment. Stiffness and damping coefficients were measured for the hip, leg, foot, and ankle. Joint rotational and translational properties were measured for the knee and ankle. To characterize interactions of the foot with the footwell, flexion and compression tests of the foot were conducted. The lower extremity was segmented at the joint and load cell locations, to permit rigid body dynamics codes to compute the forces at these locations for comparison to test data and for calculation of injury criteria.
Technical Paper

Lower Extremity and Brake Pedal Interaction in Frontal Collisions: Sled Tests

A series of eight sled tests was conducted using Hybrid III dummies and cadavers in order to examine the influence of foot placement on the brake pedal in frontal collisions. The brake pedal in the sled runs was fixed in a fully depressed position and the occupants' muscles were not tensed. The cadaver limbs and the Hybrid III lower extremities with 45° ankle and soft joint-stop were extensively instrumented to determine response during the crash event. Brake pedal reaction forces were measured using a six-axis load cell and high speed film was used for kinematic analysis of the crashes. Four right foot positions were identified from previous simulation studies as those orientations most likely to induce injury. In each test, the left foot was positioned on a simulated footrest, acting as a control variable that produced repeatable results in all dummy tests. Each of the different right foot orientations resulted in different loads and motions of the right leg and foot.
Technical Paper

A New CVS/ATB Hybrid III Model for Lower Extremity Studies: Development and Validation

A simulation model of the Hybrid III lower extremities with the 30 degree dorsiflexion ankle was developed using the CVS/ATB program. The femur and tibia were modeled as a sequence of rigid beams with a hinge and slider at the knee. Special, locked joints were placed in the femur and tibia at the same locations as the load cells in the actual dummy. Constraint forces and moments at these joints can be compared directly to load cell data. The complex geometry of the foot was divided into five segments representing the heel, toe, forefoot, midfoot, and ankle regions. Two foot models were constructed: one barefoot and one with a Lehigh safety shoe. Good agreement was obtained for most parameters when single-leg pendulum tests, and full-body sled tests, were simulated using the new model.
Technical Paper

Deployment of Air Bags into the Thorax of an Out-of-Position Dummy

The air bag has proven effective in reducing fatalities in frontal crashes with estimated decreases ranging from 11% to 30% depending on the size of the vehicle [IIHS-1995, Kahane-1996]. At the same time, some air bag designs have caused fatalities when front-seat passengers have been in close proximity to the deploying air bag [Kleinberger-1997]. The objective of this study was to develop an accurate and repeatable out-of-position test fixture to study the deployment of air bags into out-of-position occupants. Tests were performed with a 5th percentile female Hybrid III dummy and studied air bag loading on the thorax using draft ISO-2 out-of-position (OOP) occupant positioning. Two different interpretations of the ISO-2 positioning were used in this study. The first, termed Nominal ISO-2, placed the chin on the steering wheel with the spine parallel to the steering wheel.
Technical Paper

Small Female Head and Neck Interaction With a Deploying Side Air Bag

This paper presents dummy and cadaver experiments designed to investigate the injury potential of an out-of-position small female head and neck from a deploying side air bag. Three seat mounted, thoracic type, side air bags were used that varied in inflator aggressivity. The ATB/CVS multi body program was used to identify the worst case loading position for the small female head and neck. Once the initial position was identified, a total of three Hybrid III 5th percentile dummy and three small female cadaver tests (51 ± 9 years, 64 ± 8 kg, 159 ± 10 cm) were performed. Instrumentation for the dummy included upper and lower neck load cells, while both the dummy and the cadavers had accelerometers and angular rate sensors fixed to the head and T1 vertebrae in order to provide head and neck kinematic data. Head center of gravity accelerations for the dummy ranged from 71 g's to 154 g's, and were greater than cadaver values, which ranged from 68 g's to 103 g's.
Technical Paper

Open-Loop Chestbands for Dynamic Deformation Measurements

Originally designed for measuring closed-loop contours such as those around a human thorax, the External Peripheral Instrument for Deformation Measurement (EPIDM), or chestband, was developed to improve the measurement of dummy and cadaver thoracic response during impact. In the closed-loop configuration, the chestband wraps around on itself forming a closed contour. This study investigates the use of the chestband for dynamic deformation measurements in an open-loop configuration. In the open-loop configuration, the chestband does not generally form a closed contour. This work includes enhanced procedures and algorithms for the calculation of chestband deformation contours including the determination of static and dynamic chestband contours under several boundary conditions.
Technical Paper

Multi-Body Model of Upper Extremity Interaction with Deploying Airbag

Three-dimensional simulation models of a driver's right upper extremity interacting with a deploying airbag have been set up and run with the Articulated Total Body program. The goal of this study is to examine the significance of various occupant and airbag parameters during deployment, such as grip strength, upper extremity position, shoulder compliance, flap position, flap aggressivity, and deployment speed. Given a range of 250 N to 650 N, the grip strength did not affect the resultant loads. Also, the contact force and torque at the e.g. of the forearm are not sensitive to shoulder joint compliance. The flap aggressivity and the position of the airbag module relative to the upper extremity are most important in affecting the interaction. This study is used to justify cadaveric experiments involving disarticulated upper extremities.