The first part of this paper introduces a FE modeling effort of the lower extremity of Thor dummy, Thor-Lx Hybrid III retrofit. The FE model consists of 9,800 nodes and 8,300 elements, of which 2,900 are deformable solid elements. Three kinematic ankle joint elements are respectively used to represent dorsiflexion, inversion/eversion, and internal/external rotation of the foot. In addition to kinematic joint elements which represent the initial linear resistance developed by continuous joint stop, sliding contact interfaces are also defined between neoprene rubber and rotating center blocks for the subsequent non-linear stage. This two-stage joint definition then provides the precise description of ankle joint characteristics both in loading and unloading phases. The simulated outcomes of FE model have been validated for the performance of the ankle under different rotation motions and showed good agreement with both quasi-static and dynamic test results.

The second part of the paper deals with a practical application of the FE Thor-Lx model. Numerical simulations of a NCAP frontal 40% offset crash with a small size sedan are performed. A sub-structuring scheme for isolating the occupant compartment from the full car crash simulation is then adopted in order to facilitate the parametric study in which the various levels of structural deformations are attempted. The FE model of Hybrid III 50th percentile male upper body including knees and femurs is utilized to mount Thor-Lx and Hybrid III leg for the quantitative and comparative analyses of both legs. The Hybrid III leg mostly produces higher tibia index values than Thor-Lx due to its simple ankle joint structure which might result in steep increase of moments at the end of the range of motion. The paper concludes with the improved capabilities of Thor-Lx for the injury risk assessment compared with Hybrid III leg.