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Development, calibration and validation of a three-dimensional finite element model of the head-neck sub-assemblies of the THOR 50th percentile male dummy are presented. The model provides, in conjunction with the use of the physical dummy, a computational tool for head-neck injury studies related to motor vehicle, rail, or aircraft crashes. Physical dummy CAD data is used to construct the finite element mesh. Mass and inertia properties of the model are consistent with those of the hardware. The THOR head spring-cable system, designed to produce a neck that gives more biofidelic head trajectories, is properly represented in the model. Several modelling methods are discussed in detail. The deformable components of the model include head skin (vinyl), face foam (Confor foam), face pad (silicone rubber), head springs, neck cables and neck discs (neoprene rubber). The material properties are determined, or calibrated, mainly from system identifications with data from material tests, head and face impact tests on a full dummy and sled tests on stand-alone head-neck sub-assemblies. The model is validated with the remaining sled test data and head-neck pendulum test data. Key simulation results such as head spring forces, motion trajectories, accelerations at head centre of gravity, and neck forces and moments are compared with the corresponding experimental data, and error analyses are conducted for the presented results.

The purpose of this study was to document and compare the architectural parameters (fibre bundle length, angle of pennation) of human skeletal muscle in cadaveric specimens and live subjects. The medial (MG) and lateral (LG) gastrocnemius, and posterior (PS) and anterior (AS) soleus were examined bilaterally in 5 cadavers (mean age 72.6, range 65–83 y) and 9 live subjects (mean age 76.3, range 70–92 y). Data were obtained from direct measurement of cadaveric specimens and from ultrasonographic scans of the live subjects. In cadaveric muscle, fibre bundles were isolated; their length was measured in millimetres and pennation angles were recorded in degrees. In live muscle, similar measurements were taken from ultrasonographic scans of relaxed and contracted muscle. For the scans of relaxed muscle, subjects were positioned prone with the foot at a 90° angle to the leg, and for scans of contracted muscle, subjects were asked to sustain full plantarflexion during the scanning process. Fibre bundle length and angle of pennation were compared at matched locations in both groups. It was found that the relationship between cadaveric and in vivo values for fibre length and angle of pennation varied between muscle parts. The cadaveric architectural parameters did not tend to lie consistently towards either extreme of relaxation or contraction. Rather, within MG, PS and AS, cadaveric fibre bundle lengths lay between those for relaxed and contracted in vivo muscle. Similarly both the anterior and posterior cadaveric fibre angles of pennation lay between the in vivo values within LG and PS. In summary, architectural characteristics of cadaveric muscle differ from both relaxed and contracted in vivo muscle. Therefore, when developing models of skeletal muscle based on cadaveric studies, the architectural differences between live and cadaveric tissue should be taken into consideration.