An impact force transducer for anthropomorphic test dummy headforms: Application to study effects of external helmet accessories on biomechanical measures of head injury risk

• Author / Creator

  Butz, Robert C.

• The first half of this thesis describes the mechanical design, calibration and validation of an in-fibre Bragg grating based impact transducer. The transducer comprises an in-fibre Bragg grating fixed to an aluminum superstructure (12 mm in diameter, 3 mm thickness) designed to withstand typical impact forces in helmeted impact and to have resonances that exceeds industry standards on mechanical resonance. Calibration experiments were used to determine the transducers sensitivity to force measurements, and calibration results are, on average, within 10% of finite-element modelling predictions of force sensitivity. Validation of force transducers indicated excellent repeatability in both the force and time domain for an impact. The maximum standard deviation of force measurements of 0.4% of the net head force applied to the impacted headform and average error in the time duration of the force transients of only 4%.
  The latter components of the thesis describe application of the transducers and HybridIII in a biomechanical study of the effects that external helmet accessories (camera mounts) have on measures of skull fracture and brain injury risk in helmeted head impact. The presence of a helmet accessory reduced peak linear acceleration of the head, and forces on the headform skull did not increase. For low velocity impacts, peak angular acceleration and velocity reduced with the presence of a helmet accessory. For high velocity impacts, the peak angular acceleration and velocity of the head increased with the presence of a helmet accessory. Overall, the impacted helmets protected the head from significant skull fracture risk (regardless of the presence of the camera). Average concussion risk increased in high velocity impacts with cameras fixed to helmets.

• Subjects / Keywords

  • Bragg gratings
  • Force transducer
  • Brain injury
  • Skull fracture
  • Helmet

• Graduation date

  Fall 2015

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R35H7C24M

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.