Now showing 1 - 3 of 3
  • Publication
    The Influence of Impact Angle on the Dynamic Response of a Hybrid III Headform and Brain Tissue Deformation
    (ASTM International, 2014-03-12) ; ;
    The objective of this study was to investigate the influence of impact angle on the dynamic response of a Hybrid III headform and brain tissue deformation by impacting the front and side of the headform with four angle conditions (0° at the impact site and 5°, 10° and 15° counter-clockwise rotations from 0°) as well as three additional angles of -5°, -10° and -15° (clockwise rotations from 0°) at the side location to examine the effect of direction. The acceleration-time curves were used as input into a finite element model of the brain where maximum principal strain was calculated. The results from this study show that impact angle has an asymmetrical influence on headform dynamic responses and strain. An increase in impact angle tends to result in a growth of headform linear and rotational acceleration and maximum principal strain for the front location as well as the negative angles (0 to -15°) at the side, however varying trends were observed for the positive angles (from 0° to 15°) at the side. When developing sophisticated impact protocols and undertaking head injury reconstruction research, it is important to be aware of impact angle.
    Scopus© Citations 2  359
  • Publication
    A Comparison of the Head Dynamic Response and Brain Tissue Deformation from Impacts Resulting in Concussion, Concussion with Persistent Post-Concussive Symptoms, and Subdural Hematoma
    (American Association of Neurological Surgeons, 2015-08) ; ; ; ;
    Objective: Concussions typically resolve within a few days however in a few cases the symptoms last for a month or longer and are termed persistent post-concussive symptoms (PPCS) with more serious brain trauma resulting in bleeds, such as subdural hematoma (SDH). Dynamic response and brain tissue deformation characteristics may provide a means of distinguishing between these three types of injuries. Methods: Reconstruction cases were recruited from sports medicine clinics and hospitals along with medical reports, video footage, and medical imaging. All subjects received a direct blow to the head resulting in head trauma symptoms, those that resolved in 9 days were termed concussions, those with symptoms longer than 18 months were PPCS and those presenting with subdural hematoma (SDH). An anthropometric dummy headform was dropped onto various impact surfaces using a monorail drop rig. Headform dynamic response data was collected and used as input into the University College Dublin Brain Trauma Model to obtain maximum principal strain and von Mises stress. Results: Both linear and rotational acceleration of the head increased in magnitude with an increase in injury severity (from concussion, to PPCS, and SDH). The PPCS group had peak resultant rotational accelerations similar to SDH and significantly higher than concussions. There were no significant differences for peak resultant linear accelerations between the two concussion groups however they were both significantly lower than the SDH group. Brain tissue deformation measures however, did not follow the same trend as dynamic response and resulted with SDH having the lowest values of stress and strain. PPCS had significantly higher values of strain than the SDH group, where both the concussion and PPCS groups had significantly higher stress values than the SDH group. Conclusion: This study supports the notion that there is a positive relationship between an increase in the dynamic response and the risk for more serious brain injury. Peak resultant linear acceleration may be more related to SDH meanwhile rotational acceleration may be more relatedto severity of concussion. Despite SDH being the more severe brain injury, on average this group had the lowest values for stress and strain as compared to concussion and PPCS. Finite element analysis of the SDH injuries examined brain tissue values for the group of elements in the model than corresponded to the location of the bleed which may not be reflective of the highest values if the entire cerebrum was considered. More importantly, SDH injuries are vascular injuries and may not necessarily result in damage to the brain. In summary, this study found that the dynamic response of an impact is reflective of injury severity. Understanding the relationship between the dynamic response and the nature of the injury provides important information for developing strategies for injury prevention.
      342Scopus© Citations 43
  • Publication
    The influence of impact angle on the dynamic response of a Hybrid III headform and brain tissue deformation
    The objective of this study was to investigate the influence of impact angle on the dynamic response of a Hybrid III headform and brain tissue deformation by impacting the front and side of the headform using four angle conditions (0°, at the impact site and 5, 10 and 15° rightward rotations of the headform from 0°) as well as three additional angle conditions of -5, - 10 and -15° (leftward rotations from 0°) at the side location to examine the effects of the neckform. The acceleration-time curves were used as input into a finite element model of the brain where maximum principal strain was calculated. The study found that an impact angle of 15° significantly influencesthe results when measured using linear and rotational acceleration and maximum principal strain. When developing sophisticated impact protocols and undertaking head injury reconstruction research, it is important to be aware of impact angle.
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