Kazuhiro Seki

UPPER EXTREMITY INTERACTION WITH A DEPLOYING SIDE AIRBAG: A CHARACTERIZATION OF ELBOW JOINT LOADING

Computer simulations, dummy experiments with a new enhanced upper extremity and small female cadaver experiments were used to analyze the small female upper extremity response under side airbag loading. After establishing a worst case initial position, three tests were performed with the fifth percentile female hybrid III anthropometric test dummy and six experiments with small female cadaver subjects. A new fifth percentile female enhanced upper extremity was developed for the dummy experiments that included a two-axis wrist load cell in addition to the existing six-axis load cells in both the forearm and humerus. Forearm pronation was also included in the new dummy upper extremity to increase the biofidelity of the interaction with the handgrip. Instrumentation for both the cadaver and dummy tests included accelerometers and MHD angular rate sensors on the forearm, humerus, upper and lower spine. In order to quantify the applied loads to the cadaver hand and wrist from the door mounted handgrip, the handgrip was mounted to the door through a five-axis load cell and instrumented with accelerometers for inertial compensation. All six of the cadaver tests resulted in upper extremity injuries including comminuted mid-shaft humerus fractures, osteochondral fractures of the elbow joint surfaces, a transverse fracture of the distal radius and an osteochondral fracture of the lunate carpal bone. The results from the 6 cadaver tests presented in this study were combined with the results from 12 previous cadaver tests. A multivariate logistic regression analysis was performed to investigate the correlation between observed injuries and measured occupant response. Using inertially compensated force measurements from the dummy mid-shaft forearm load cell, the linear combination of elbow axial force and shear force was significantly (P=0.05) correlated to the observed elbow injuries.

Comparison of the Q3 and Hybrid III 3-year-old dummy head and neck response during side air bag loading

Abstract This paper presents the results of 20 tests designed to compare the head and neck response of the Q3 dummy and the Hybrid III 3-year-old dummy subject to loading by a deploying side air bag. In a static test environment, experiments were conducted in two positions using three seat-mounted thoracic side air bags that varied only in the level of inflator output. Substantial kinematic and kinetic differences were observed owing to differences in head geometry and mass, and neck stiffness between the two dummies. The Hybrid III head is 18 per cent heavier than the Q3 and resulted in peak head centre of gravity accelerations significantly lower (p = 0.01) than those observed in the Q3. The stiffer Hybrid III neck resulted in 41 ± 29 per cent higher neck flexion moment compared with the Q3. While the stiffness properties for the Q3 neck are similar in all directions, the Hybrid III neck has preferred anterior-posterior stiffness properties. This difference was observed in tests where lateral loading of the head forced lateral bending in which the Hybrid III recorded a 101 ± 80 per cent higher lateral bending moment compared with the Q3. Although there is considerable uncertainty as to the validity of published injury criteria owing to the lack of child biomechanical data, these tests suggest that separate injury criteria are needed for each dummy.

Dynamic response of the Hybrid III three year old dummy head and neck during side air bag loading

Abstract This paper presents the results from 14 tests designed to evaluate the response and injury potential of a Hybrid III three year old dummy subject to loading by a deploying seat mounted side air bag. An instrumented Hybrid III three year old dummy was used for tests in two different occupant positions chosen to maximize head and neck loading. Four seat mounted thoracic side air bags were used that varied only in the level of inflator output. The National Highway Traffic Safety Administrations neck injury criteria for complex loading were modified to include moment values for both anterioposterior and lateral directions. The results indicate that side air bags may be designed so that the forces and moments in the child dummys neck are below injury threshold values during a side air bag deployment. While there is considerable uncertainty as to the validity of published injury criteria owing to the lack of child biomechanical data, this study demonstrates the sensitivity of child response to initial position which provides insight into placement and geometry of side airbag systems. Furthermore, the data indicate a relationship between airbag inflator properties and child dummy response for a given airbag geometry.

Fifth percentile female dummy upper extremity interaction with a deploying side air bag

Abstract This paper presents the results from experiments designed to characterize the upper extremity response of the small female during side air bag loading. A seat-mounted thoracic side air bag was deployed statically using three different inflators. The aggressivity of the inflators varied in peak pressure and pressure onset rate. The fifth percentile female HIII dummy was utilized in three positions, which were chosen to maximize loading of the humerus and elbow joint. Two had the dummy positioned outboard with the forearm on the armrest, and the third had the dummy inboard such that the humerus was positioned horizontally in front of the air bag module with the forearm supported above the armrest. Instrumentation for the fifth percentile female dummy included the fully instrumented SAE upper extremity with six axis load cells in the humerus and forearm as well as accelerometers and angular rate sensors attached to each segment. All inflators produced resultant humerus moments below published injury tolerance values for the small female, with the more aggressive air bags producing higher responses. The upper extremity proved useful in evaluating injury risk relative to side air bag design.