“ … Helmet Design using Shear Resistant Dilatant Fluids Landon Tucker Mechanical Engineering, class of 2022 … ”
Abstract
This study investigates the causes of concussions and design methods that reduce the shear forces experienced during head impact. This ongoing project has allowed me to research the cause and effects of head injuries, past and present helmet designs, and alternative and innovative ways of thinking about how concussions may be prevented in the future. The next steps include testing on various shear resistant fluids to help us determine materials that may be able to propagate the shear forces experienced by the brain during impact and implement this fluid in a new helmet design. Concussions occur when the brain moves inside the skull and causes internal damage. Previous experimental data and simulated finite element analysis of the brain revealed that shear forces were highest at the core of the brain during a concussion-like impact. Maximum shear forces are found where medical professionals suspect Chronic Traumatic Encephalopathy (CTE) forms in the brain. Over time, the shear force the brain experiences begins to stretch the center of the brain and enlarge the area known as the corpus callosum, which can be linked to memory loss. The effectiveness of propagating the shear forces experienced by a skull-protecting helmet is critical to reduce how much trauma the brain experiences. The goal of the current study is to decrease the shear forces experienced by the skull during impact by exploring fluids as a buffer to propagate forces non-linearly to the brain and thereby reduce the probability of concussions. The shearing properties of dilatant non-newtonian fluids are being explored for their tendencies to change viscosity under varying loading situations. The current focus to test various fluids using industry standards will allow us to examine the liquid's shear force properties. The viscosity of liquids under varying loading situations will be related to their shearing properties and the optimal shear reducing liquid will be evaluated for potential incorporation into a helmet design.
“ … , Quinlan Goddard, LandonTucker, and Justin Paschke for their help in building … ”
Abstract
The effect of heterogeneities within submergent canopies resembling river vegetation was studied using 2D particle image velocimetry (PIV) within the 0.2 m x 0.2 m x 2 m Union College water channel. The goal of these experiments was to characterize the flow behavior prior to, within, and proceeding a local height heterogeneity. This allowed a better understanding of the flow dynamics and turbulence caused by the heterogeneities. The canopy models were made of rectangular elements within a staggered pattern; the homogenous canopy height h = 37.5 mm was used with a disturbance height hd that varied between cases. Both gap (hd/h < 1) and protrusion (hd/h > 1) cases were studied at a submergence depth H/h = 3.0. Specifically, heterogeneous cases hd/h = 0, 0.5, 1.25, 1.5, 2.0, and 3.0 were investigated and compared to the homogenous hd/h = 1 case. The results from the experiments suggest that, macroscopically, the gaps minimally affect the shear layer that has previously developed over the homogenous canopy. However, local height heterogeneities in the form of protrusions result in a separate shear layer formation past the heterogeneous section. The larger the protrusion, the stronger and more spatially compact the new shear layer is, therefore taking longer to dissipate and reconnect with the homogeneous shear layer.
