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Figure 1. THOR Alpha Cutaway Model
Figure 1. THOR Alpha Cutaway Model
   As a component of a long-term research program dedicated to the reduction of automotive crash trauma, the National Transportation Biomechanics Research Center of the NHTSA Research and Development Office has directed the development of an advanced crash test dummy, denoted as THOR. THOR has been designed to assist both the development and the evaluation of advanced vehicle occupant safety systems, and incorporates significantly improved biofidelity and greatly expanded injury assessment capabilities in all body regions. Though designed specifically for use in frontal and oblique crash environments, the design offers multi-directional capabilities in several of its components. GESAC, Inc., of Boonsboro, MD, served as prime contractor to the NHTSA for engineering development of this crash test device.
As an integral part of the THOR development program, the NHTSA has actively involved the participation of worldwide automotive manufacturers, research organizations, and government agencies in extensive test and evaluation trials. Through the generosity and cooperative efforts of expert individuals and institutions in North America, Japan, Europe, and Australia, many useful refinements have been identified and incorporated into the current THOR Alpha version (see Figure 1).

Functional Capabilities of THOR Alpha
By virtue of its enhanced design and measurement capabilities, THOR Alpha offers numerous functional benefits as compared with previously existing crash test dummy technology:
  • Assistance in optimization of "smart" occupant restraint systems, including setting of air bag deployment thresholds and design of integrated advanced belt/ bag restraint systems;
  • Improved assessment of belt/ bag interactions;
  • Improved head kinematics, as a result of new neck and spine designs;
  • Improved neck injury assessment, including out-of-position injury assessment;
  • More realistic spinal kinematics, as a result of added spine flexibility;
  • Facility for assessment of seated posture effects upon restraint performance;
  • Detection of air bag, belt, and wheel rim interaction with the abdomen;
  • Facility for injury assessment at the hip joint;
  • Detailed assessment of foot motions and ankle/foot/tibia injury potential;
  • Facility for localized facial injury assessment

    Figure 2. THOR Alpha Components
    Figure 2. THOR Alpha Components



    To realize the above functional benefits, THOR Alpha incorporates new design approaches in many component parts, (Figure 2), as follows:

    Figure 3. Load sensing face with regional measurement capability
    • Load sensing face with regional measurement capability (Figure 3);
    Figure 4. Multi-directional head/ neck design
    • Multi-directional head/ neck design with a) kinematic performance matched to human volunteer frontal, lateral, and rear impact data, and b) distinct cervical column and "muscular" load paths (Figure 4);
    Figure 5. Human-like thoracic structure
    • Human-like thoracic structure with clavicle representation, multiple high-speed 3D deflection instruments at four locations on the anterior ribcage, and optional mid-sternum uni-directional displacement measurement (Figure 5);

  • Articulating spine with adjustable vehicle-seated posture (Figure 6);


  • Figure 6. Articulating spine

    Figure 7. Improved shoulder design
    • Improved shoulder design with more human-like mobility (Figure 7);
    Figure 8. Restorable abdomen design
    • Restorable abdomen design featuring an upper module with compression measurement and a lower module with continuous bilateral 3D deflection measurements (Figure 8);
    Figure 9. Pelvis design
    • Pelvis design with revised anthropometry and flesh configuration, injury assessment capability at the hips, and submarining detection features (Figure 9);

    Figure 10. Compliant femur design
    • Compliant femur design to assist in generation of more realistic femur loads (Figure 10);
    Figure 11. Lower extremity design
    • Lower extremity design (Thor-Lx) with more human-like ankle/ foot motions, a representation of the Achilles tendon load path, and substantially advanced injury assessment capabilities (Figure 11);

  • A design intended for ease of calibration, maintenance, and use.

THOR Alpha Instrumentation
THOR Alpha is capable of carrying a total of 134 channels of data; see Figure 12 for details of instrument locations. (Note: thorax mid-sternum x-displacement (optional), knee shear displacement, knee angular displacement (optional), and Achilles tendon tension (optional) instruments are not shown).

Figure 12. THOR Alpha Instrumentation
Figure 12. THOR Alpha Instrumentation


THOR Alpha Instrumentation by Body Region

Head: 9 Uniaxial Accelerometers
1 Biaxial Tilt Sensor
Face: Five Uniaxial Load Cells
Neck: Upper Neck Load Cell (6 channels)
Lower Neck Load Cell (6 channels)
Front Neck Cable Load Cell
Rear Neck Cable Load Cell
Head Rotation Potentiometer
Thorax: CRUX Deflection Units - 3 Dimensional Displacement at each of Four Locations (UL, UR, LL, LR)- 4 CRUX units @ 3 channels each;
Two Uni-directional Displacement String Potentiometers at Mid-Sternum Location (optional);
1 Triaxial Accelerometer at the C.G.
Mid Sternum: 1 Uniaxial Accelerometer
Upper Abdomen: Uni-directional Displacement String Potentiometer
Uniaxial Accelerometer
Lower Abdomen: DGSP Deflection Units - 3 Dimensional Displacement at L & R Locations (2 DGSP units @ 3 channels each)
Spine: 1 Triaxial Accelerometer at T1 location
1 Triaxial Accelerometer at T12 location
T12 (5-axis) Load Cell
4 Biaxial Tilt Sensors
Pelvis: Acetabulum Load Cell (left and right, 3 channels each)
Iliac Crest Load Cells (1 each left and right)
1 Triaxial Accelerometer at Pelvis C.G.
Femur: Femur Load Cell (left and right, 6-axis each)
Knee: Knee Shear Displacement, L&R
Knee Rotation (L&R, optional)
Lower Extremities: Upper Tibia Load Cell (L&R, 4 channels each)
Lower Tibia Load Cell (L&R, 5 channels each)
Tibia Acceleration (X, Y), each leg
Achilles Tendon Load Cell (each leg, optional)
Ankle Joint Rotation Potentiometers (X, Y, Z), each leg
Foot Acceleration (X, Y, Z), each leg



Two multi-point 3D displacement measurement systems are utilized in THOR Alpha.  The CRUX precision solid link design is utilized within the thorax at four locations (see Figure 13 for schematic right side installation), while the DGSP telescoping joystick design is utilized within the lower abdomen (see Figure 14 for schematic right side installation).   Multiple static tilt sensors are also installed on THOR to assist laboratory personnel in precise pre-test dummy positioning.

Figure 13. CRUX 3D Multi-Point Thorax Deflection Measurement System
Figure 13. CRUX 3D Multi-Point Thorax Deflection Measurement System

Figure 14. DGSP 3D Multi-Point Abdominal Measurement System
Figure 14. DGSP 3D Multi-Point Abdominal Measurement System

Scope of International THOR Test and Evaluation
During the period of THOR development, an extensive database of test results was acquired with the contributions of numerous participating organizations and laboratories. Some 150 sled test exposures at impact speeds ranging from 48 kmph to 64 kmph were conducted, with peak decelerations ranging up to 30g. Frontal, oblique, and rear tests were conducted in a variety of restraint systems: 3- point belts, force-limiting belts, and belt + air bag combinations. Out of position static air bag tests were also conducted to assess ATD durability and response characteristics in this test environment.

In addition, fifteen full-scale vehicle crash tests were conducted, both in U.S. NCAP and offset deformable barrier test conditions.

Acknowledgement
The process leading up to the development and release of the THOR Alpha design has involved close cooperation and consultation with many research organizations and automotive engineering personnel worldwide. The NHTSA and THOR program principals extend their sincere appreciation to the many individuals, research organizations, and automotive manufacturers worldwide who have shared their advice and expertise with the THOR project team:

Europe Renault, Volvo Car, SAAB, Autoliv Research AB, Chalmers University

EEVC/ADRIA: Transport Research Laboratory, TNO, Polytechnic University of Madrid

North America NHTSA Vehicle Research and Test Center

Transport Canada

USCAR (GM, Ford, Daimler-Chrysler)

Honda Research of America

University of Virginia

U.S. Federal Aviation Administration

U.S. Department of Defense

Asia/ Pacific JAMA/ Japan Automobile Research Institute

Australia (FORS)

Autoliv Australia

THOR Alpha Documentation Release
As of December 14, 2001, NHTSA has released version 1.1 of the THOR Advanced Crash Test Dummy (50th Percentile Adult Male, Alpha Version) design to the public domain.

This version 1.1 release consists of the following components (available in ZIP format). Drawing Package, Documentation, THORTEST Programs

THOR Alpha DRAWING PACKAGE, in AutoCAD 2000 format

  • Supporting Text Documents
    • Bill of Materials
    • Drawing Index Document
    • Drawing Arrangement Document
    • Title Page
  • THOR Alpha USERS' MANUAL
  • THOR Alpha CERTIFICATION PROCEDURES DOCUMENT
  • THOR Alpha BIOMECHANICAL REQUIREMENTS DOCUMENT
  • THOR Alpha THORTEST PROGRAMS
  • THOR Alpha THORTEST PROGRAMS-USERS' MANUAL

PLEASE NOTE: The NHTSA has stipulated that all THOR Alpha components and assemblies 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 Alpha hardware.

For further information and a bibliography relevant to THOR origins, engineering development, and refinement, see Foundations and Elements of the NHTSA THOR Alpha ATD Design, presented at the 17th International Technical Conference on the Enhanced Safety of Vehicles, in Amsterdam, Holland.  For additional information with regard to the THOR Alpha Advanced Crash Test Dummy, THOR-Lx/ Hybrid III Retrofit Version, or the THOR-FLx Hybrid III Retrofit Version, please contact Mr. Peter Martin, Thor Program Manager, NHTSA National Transportation Biomechanics Research Center, at (202) 366-4719 (phone) or by e-mail at peter.martin @nhtsa.dot.gov.




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