The Influence of Impactor Mass on the Dynamic Response of the Hybrid III Headform and Brain Tissue Deformation

Abstract

When determining head injury risks through event reconstruction, it is important to understand how individual impact characteristics influence the dynamic response of the head and its internal structures. The effect of impactor mass has not yet been analysed in the literature. The purpose of this study is to determine the effects of inbound mass on the dynamic impact response and brain tissue deformation. A 50 th percentile Hybrid III adult male head form was impacted using a simple pendulum system. Impacts to a centric and a non-centric impact location were performed with six varied inbound masses at a velocity of 4.0 m/s. The peak linear and peak angular accelerations were measured. A finite element model, (UCDBTM) was used to determine brain deformation, namely peak maximum principal strain and peak von Mises stress. Inbound mass produced significant differences for peak linear acceleration for centric (F 5, 24 = 217.55, p=.0005) and non-centric (F 5, 24 = 161.98, p=.0005), and for peak angular acceleration for centric (F 5, 24 = 52.51, p=.0005) and non-centric (F 5, 24 = 4.18, p=.007) impact locations. A change in inbound mass also had a significant effect on peak maximum principal strain for centric (F 5, 24 = 11.04, p=.0005) and non-centric (F 5, 24 = 5.87, p =.001), and for peak von Mises stress for centric (F 5, 24 = 24.01, p=.0005) and non-centric (F 5, 24 = 4.62, p=.004) impact locations. These results confirm the inbound mass of an impact should be of consideration when determining risks and prevention to head and brain injury.

Protective Capacity of Ice Hockey Helmets against Different Impact Events

“…[12][13][14]17,20,28,31,32,49,52,57,58,74,85,87 Falls in ice hockey are typically characterized by the mass of the head impacting a rigid impact surface, 25 resulting in high magnitude and short duration linear and rotational acceleration. 12,53,54,59 Such an event is reflected in the current ice hockey certification standard as it aims to replicate the injurious impact events examined by Gurdjian et al 18 which involved an animal model and cadaver head drops to a rigid surface.…”

Characterization of persistent concussive syndrome using injury reconstruction and finite element modelling

“…From a biomechanical perspective, brain injury, be it transient concussion or PCS, is likely linked to the characteristics of the event that caused the injury . These characteristics have been defined in the past as combinations of mass, velocity, location of impact, and others that determine the stresses and strains in the brain tissue Post et al, 2014;Karton et al, 2013). These brain injuries likely cause a complex series of cellular events that result in the symptomology associated with PCS (Giza and Hovda, 2001).…”

Defining the effective impact mass of elbow and shoulder strikes in ice hockey

“…These parameters can then be reconstructed in a laboratory to quantify the event and establish a link between brain injury metrics and concussion. Variables such as impact velocity, location, orientation, mass, and compliance have been shown to affect the response of the head and brain and should be replicated as accurately as possible when doing a reconstruction of a real-world collision in ice hockey (Fréchède & McIntosh, 2009;Karton, 2012;Walsh, Rousseau, & Hoshizaki, 2011;Zhang, Yang, & King, 2001).…”

“…Considering that an increase in mass was reported to increase head acceleration (Karton, 2012), defining the effective mass of a head collision in ice hockey is important to ensure the validity of a reconstruction. It was hypothesised that effective impact mass would be influenced by striking technique in ice hockey, with shoulder checks involving a higher percentage of the player's mass than elbow strikes.…”