Search Results

In order to assess the seating comfort design of a vehicle seat system, a full finite element occupant model, with anatomically precise features and deformable tissues, has been developed. This paper describes the experiments which were performed in order to assess the biofidelic accuracy of this model. First, static pressure distribution measurements, with human volunteers, have been performed. People of different morphological types were asked to sit on a PU foam cushion with various postures, which were captured by photographs and X-Ray measurements. Pressure sensors were used to determine the corresponding pressure distribution patterns. Then, the FE occupant model was used to simulate the same experiments, and the numerical results were compared to the experimental ones.

Crash injuries in lower extremities are usually not fatal but may result in long-term impairment and immobility. Current understanding of these injuries is still quite limited from the biomechanical point of view. It is known that they occur often during frontal offset collisions in which intrusion of the toe pan and instrument panel frequently occur but are not always associated with their causation. Assessment of these injuries using the Hybrid III dummy is limited because of its limited biofidelic structure and inaccurate injury criteria. Accordingly, THOR-LX, the retrofit of the lower leg of the Hybrid III, has been introduced with an improved design for ankle motion and capacity of injury prediction. In this study, the different ankle joint characteristics and outcomes of both the Hybrid III and the THOR/LX have been quantitatively analyzed for an NCAP 40% offset crash with a small size sedan.

Whiplash injuries due to automotive collisions have occupied a major portion of the insurance claims in Korea and other nations. In this study, a survey of head restraint use in the field was performed by measuring the positions of head restraints in 1,100 passenger vehicles in the downtown and outskirts areas of Seoul. Using an international protocol published by the Research Council for Automobile Repairs (RCAR), 19% of the measured head restraint positions were evaluated as “good” and 36% were evaluated as “poor”. This result differentiates a recent report of the improvement in design of head restraints geometry and reveals that motorists are not appropriately utilizing head restraints. Statistical analysis of the survey results revealed valid correlations between the measurements and subjective questions. Simulations with various parameters such as impact speed, direction and head restraint positions were also performed utilizing an FE human model.

Owing to the lack of biofidelity in mechanical dummy, the current trend is to utilize anatomic dummy models as a human surrogate in computer simulations involving automobile crash. The lack of biofidelity implies that mechanical dummies cannot adequately express crash injuries, which mainly consist of bone fracture and soft tissue damage. Accordingly, there is a pressing demand for an anatomic human model that can replace mechanical dummies in order to gain insight into the damage mechanisms and help establish tolerance limits for crash injuries.

The mechanisms of knee fracture were studied experimentally using cadaveric knees and analytically by computer simulation. Ten 90 degree flexed knees were impacted frontally by a 20 kg pendulum with a rigid surface, a 450 psi (3.103 MPa) crush strength and a 100 psi (0.689 MPa) crush strength aluminum honeycomb padding and a 50 psi (0.345 MPa) crush strength paper honeycomb padding at a velocity of about five m/s. During rigid surface impact, a patella fracture and a split condylar fracture were observed. The split condylar fracture was generated by the patella pushing the condyles apart, based on a finite element model using the maximum principal stress as the injury criterion. In the case of the 450 psi aluminum honeycomb padding, the split condylar fracture still occurred, but no patella fractures were observed because the honeycomb provided a more uniform distribution of patella load. No bony fractures in the knee area occurred for impacts with a 50 psi paper honeycomb padding.