Tag Archives: bike helmet testing

Biomechanics Laboratory

I employ state-of-the-science biomechanics resources in my evaluations, as depicted in the following figure. This biomechanics laboratory includes various certified biofidelic mannequins, dedicated test apparatus, data acquisition hardware, software and calibrated sensor instrumentation, professional photography and high speed and videography equipment.

Dr. John Lloyd-biomechanics laboratory

Much of my research and work for civil law suits focusses on biomechanical evaluation of helmets, in particular sports helmets, including football and ski helmets.

Dr. John Lloyd-biomechanics laboratory helmets

For helmet testing, we have a standard NOCSAE (National Operating Committee for Standards in Athletic Equipment) head drop system

Dr. John Lloyd-biomechanics laboratory NOCSAE test

However, the standard NOCSAE system only measures forces associated with linear acceleration, which are attributed with focal head injuries, such as skull fractures. This system has a rigid neck and therefore cannot measure rotational or angular accelerations, which are associated with traumatic brain injuries, such as concussion and subdural hematomas. We have a modified helmet drop test system, developed in collaboration with the University of Maine, Advanced Manufacturing Center, validation of which has been published in a peer-reviewed journal.Dr. John Lloyd-biomechanics laboratory modified helmet test

The following image shows both the NOCSAE and modified helmet test systems in parallel.

Dr. John Lloyd-biomechanics laboratory modified helmet test

Recent research shows that standard linear impact tests may not fully account for impact forces as they do not incorporate angular velocity. Therefore, I have created an inverted pendulum system, which is more representative of a standing fall

 Dr. John Lloyd-biomechanics laboratory inverted pendulum

Additionally, the biomechanics laboratory is equipped with the following resources:

  • Monorail head drop assembly
  • Twin wire guided drop system (NOCSAE)
  • Weighted pendulum impactor
  • Linear bearing table
  • Height-adjustable, eletromagenetically-controlled freefall drop platform
  • 20,000N impact force plate
  • 880lb ceiling mounted lift system
  • Certified biofidelic adult headforms
  • CRABI12 biofidelic infant mannequin
  • Hybrid III 3-yr old biofidelic mannequin (KSS)
  • National Instruments 32 channel USB-6343 X-series data acquisition system
  • LabView 2009 data acquisition software.
  • Calibrated sensors, including Kistler and PCB Piezotronics tri-axial accelerometers, MEMS triple axis digital gyroscopes, and PCB Piezotronics uni-axial and tri-axial load cells.
  • Selection of flooring materials, including carpeting, wood and laminates as well as concrete and wood sub-flooring surrogates
  • Professional still photography equipment
  • Normal speed and high speed (up to 1kHz) videography equipment
  • Photography flash and ‘hot’ lighting

Brain Injury in Sports

Dr. Lloyd’s research article “Brain Injury in Sports”, co-authored with Dr. Frank Conidi has been published in the Journal of Neurosurgery.

Please email me at DrJohnLloyd@Tampabay.RR.com  if you would like to receive a full copy of the published article.

Abstract

BACKGROUND
Helmets are used for sports, military, and transportation to protect against impact forces and associated injuries. The common belief among end users is that the helmet protects the whole head, including the brain. However, current consensus among biomechanists and sports neurologists indicates that helmets do not provide significant protection against concussion and brain injuries. In this paper the authors present existing scientific evidence on the mechanisms underlying traumatic head and brain injuries, along with a biomechanical evaluation of 21 current and retired football helmets.

METHODS
The National Operating Committee on Standards for Athletic Equipment (NOCSAE) standard test apparatus was modified and validated for impact testing of protective headwear to include the measurement of both linear and angular kinematics. From a drop height of 2.0 m onto a flat steel anvil, each football helmet was impacted 5 times in the occipital area.

Brain Injury in Sports - apparatus

RESULTS
Skull fracture risk was determined for each of the current varsity football helmets by calculating the percentage reduction in linear acceleration relative to a 140-g skull fracture threshold. Risk of subdural hematoma was determined by calculating the percentage reduction in angular acceleration relative to the bridging vein failure threshold, computed as a function of impact duration. Ranking the helmets according to their performance under these criteria, the authors determined that the Schutt Vengeance performed the best overall.

Brain Injury in Sports - results

CONCLUSIONS
The study findings demonstrated that not all football helmets provide equal or adequate protection against either focal head injuries or traumatic brain injuries. In fact, some of the most popular helmets on the field ranked among the worst. While protection is improving, none of the current or retired varsity football helmets can provide absolute protection against brain injuries, including concussions and subdural hematomas. To maximize protection against head and brain injuries for football players of all ages, the authors propose thresholds for all sports helmets based on a peak linear acceleration no greater than 90 g and a peak angular acceleration not exceeding 1700 rad/sec2.

 

Please call Dr. Lloyd at 813-624-8986 or email  DrJohnLloyd@Tampabay.RR.com if you would like to receive a full copy of the published article “Brain Injury in Sports”