As a component of the Thor advanced crash test dummy development program, the National Transportation Biomechanics Research Center (NTBRC) of the NHTSA Research and Development Office has directed the development of an advanced lower extremity design, denoted as Thor-Lx, which incorporates improved biofidelic features and significantly expanded instrumentation. The Thor-Lx design incorporates new design approaches in the femur segment as well as in the tibia and foot /ankle segments.

The version of the mid-male Thor-Lx presently being released, denoted as Thor-Lx/ HIIIr, is intended for Hybrid III retrofit use, and mounts directly to the distal end of the Hybrid III femur. The Thor-Lx/ HIIIr assembly (see figures 1 and 2) is thus comprised of the Thor-Lx foot and ankle segments, the Thor-Lx tibia segment (with integrated Achilles assembly), the stock Hybrid III knee housing, a modified Hybrid III knee flesh, new molded side knee covers, and the stock Hybrid III ball bearing knee slider assembly.

Thor-LX assembly - no flesh
Figure1. Thor-Lx/HIIIr
Assembly (w/o flesh)
Thor LX-HIIIr fully assembled
Figure2. Thor-Lx/HIIIr
Fully Assembled

Figures 3 and 4 illustrate the mechanical component and instrumentation layouts, respectively, of the Thor-Lx mid-male Hybrid III retrofit assembly.

image - 50th Percentile Thor LX Male HIIIr
Figure 3: Thor-Lx 50th Percentile Male Hybrid III Retrofit
Assembly - Mechanical Components

Instrumentation, 50th Percentile HIIIr
Figure 4: Thor-Lx 50th Percentile Male Hybrid III Retrofit
Assembly - Instrumentation

The Thor-Lx/ Hybrid III retrofit assembly includes the following new elements, as compared to the existing Hybrid III leg design:
bullet Side mounted knee covers, which augment the existing narrow Hybrid III knee housing profile, to improve the realism of knee interaction with vehicle knee bolsters
bullet A compliant tibia element, which modulates tibia response to axial impact to more realistically reflect human data
bullet Provision for independent control of foot mobility about three axes of rotation (dorsiflexion/plantarflexion, inversion/eversion, and internal/external rotation), by means of progressive rubber elements whose characteristics are guided by human data
bullet A representation of the Achilles tendon load path, which contributes to improved realism of tibia axial forces and bending moments
Instrumentation included as part of the Thor-Lx/ Hybrid III retrofit assembly includes:
bullet Knee slider displacement
bullet Upper tibia forces and moments (Fx, Fz, Mx, My)
bullet Lower tibia forces and moments (Fx, Fy, Fz, Mx, My)
bullet Tibia accelerations at mid-shaft (Ax, Ay)
bullet Foot rotations about 3 axes
bullet Mid- foot accelerations (3 axes)
bullet Achilles tension (uniaxial, optional)

A detailed description of the design rationale and the process of development of Thor-Lx may be found in Reference 1.


This version 3.2 release consists of the following downloadable components:

PLEASE NOTE:  The NHTSA has stipulated that all Thor-Lx/ Hybrid III retrofit hardware manufactured and delivered for use must conform to the specifications and certification performance requirements as defined within this release.  Further, the NHTSA has stipulated that all certification performance data must accompany newly manufactured and delivered Thor-Lx/ HIIIr hardware. 

Two related NHTSA technical papers (Kuppa et al, 2001) may be of interest to users of Thor-LX and Thor-FLx hardware, and were presented at the 17th International Technical Conference on the Enhanced Safety of Vehicles, in Amsterdam, Holland:

For further information contact Dan Parent by e-mail at