Annals of Biomedical Engineering

, Volume 45, Issue 4, pp 1148–1160

Modeling and Optimization of Airbag Helmets for Preventing Head Injuries in Bicycling

  • Mehmet Kurt
  • Kaveh Laksari
  • Calvin Kuo
  • Gerald A. Grant
  • David B. Camarillo

DOI: 10.1007/s10439-016-1732-1

Cite this article as:
Kurt, M., Laksari, K., Kuo, C. et al. Ann Biomed Eng (2017) 45: 1148. doi:10.1007/s10439-016-1732-1


Bicycling is the leading cause of sports-related traumatic brain injury. Most of the current bike helmets are made of expanded polystyrene (EPS) foam and ultimately designed to prevent blunt trauma, e.g., skull fracture. However, these helmets have limited effectiveness in preventing brain injuries. With the availability of high-rate micro-electrical-mechanical systems sensors and high energy density batteries, a new class of helmets, i.e., expandable helmets, can sense an impending collision and expand to protect the head. By allowing softer liner medium and larger helmet sizes, this novel approach in helmet design provides the opportunity to achieve much lower acceleration levels during collision and may reduce the risk of brain injury. In this study, we first develop theoretical frameworks to investigate impact dynamics of current EPS helmets and airbag helmets—as a form of expandable helmet design. We compared our theoretical models with anthropomorphic test dummy drop test experiments. Peak accelerations obtained from these experiments with airbag helmets achieve up to an 8-fold reduction in the risk of concussion compared to standard EPS helmets. Furthermore, we construct an optimization framework for airbag helmets to minimize concussion and severe head injury risks at different impact velocities, while avoiding excessive deformation and bottoming-out. An optimized airbag helmet with 0.12 m thickness at 72 ± 8 kPa reduces the head injury criterion (HIC) value to 190 ± 25 at 6.2 m/s head impact velocity compared to a HIC of 1300 with a standard EPS helmet. Based on a correlation with previously reported HIC values in the literature, this airbag helmet design substantially reduces the risks of severe head injury up to 9 m/s.


Traumatic brain injury Concussion Head trauma Bicycle helmets Airbag helmets 

Funding information

Funder NameGrant NumberFunding Note
National Institute of Biomedical Imaging and Bioengineering
  • 3R21EB01761101S1
David and Lucile Packard Foundation
  • 38454
Children’s Health Research Institute

    Copyright information

    © Biomedical Engineering Society 2016

    Authors and Affiliations

    1. 1.Department of BioengineeringStanford UniversityStanfordUSA
    2. 2.Department of Mechanical EngineeringStanford UniversityStanfordUSA
    3. 3.Department of Neurosurgery, School of MedicineStanford UniversityStanfordUSA

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