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Note: This article was authored by students from Biomedical Engineerings of Virginia Commonwealth University, USA. Faculty Advisor(s): Michael J. McClure, Ph.D. Thea Pepperl, Ph.D. Laleh Golshahi, Ph.D. Sponsor: FlexRod Mentor: Howard Peace
Skiers are prone to injuries due to the nature of their sport. Especially for beginners and experts. Neck injuries are one of the most common injuries. Neck acute injuries often lead to chronic pain. Currently, helmets are the only source of protection for skiers amidst matters to the head.
However, the helmet, in its current state, does not offer much protection for the neck. Leaving the neck as the primary source for absorbing the energy created on impact.
The FlexRod is a patent pending device incorporating a shear-thickening fluid intended to reduce neck movement and prevent compression injuries in the sport by providing a force-dampening effect.
Medical Disclaimer: The information and other content provided in this article, or in any linked materials, are not intended and should not be construed as medical advice, nor is the information a substitute for professional medical expertise or treatment.
A shear-thickening fluid is a non-Newtonian fluid that exhibits increased viscosity in response to an increased shear rate, such as a sudden impact. We hypothesize an impact on the helmet drives a rod-plate assembly down into a canister filled with the shear-thickening fluid that increases viscosity at the time of the impact and absorbs force via the displacement of the fluid by the rod-plate.
This force transfer effect leads to a reduction in an impulse to the neck and therefore reduces the potential for neck and spinal injuries. Which can also reduce the chance of concussion. This novel technology explores the usage of bulk shear thickening fluid for impact dampening, an idea that has not been implemented in the material sciences industry so far.
The proposed design uses commonly available materials such as stainless steel, carbon fiber, silica gel, and polyethylene glycol. Some welding and machining are currently required to produce our design. Our product uses fumed silica which is commonly used in toothpaste, and cosmetics as an abrasive material, as a thickening agent, and as a desiccant.
Polyethylene glycol is commonly used for industrial, chemical, and medical products and is biologically inert. These materials are not harmful to the environment in small quantities, but special care must be taken if the design was to be mass-produced to be disposed of properly and treated as industrial waste since large amounts of silica or polyethylene glycol entering waterways could lead to unintended effects.
To properly dispose of the substances, discarded units of the design can be recycled back to the manufacturer. – a small financial incentive for returning the units would increase the likelihood of proper return and disposal.
General consumer guidelines for handling silica and polyethylene glycol is to dilute them before release into the environment. This suggests that the product will maintain water quality standards since these units are not intended to be disposed of en-mass, they are intended to be active long enough such that negligible amounts of the substances described enter waterways at a time.
Care must be taken with fumed silica as inhaling the dust for prolonged periods can cause silicosis, but proper safety precautions mitigate this. The design does not negatively affect nor improve environmental air quality beyond the immediate area of its production.
Given that the stated purpose of our product is to reduce neck injuries, it is explicitly designed to protect and sustain human health. PPE to reduce neck injury for construction workers and athletes such as skiers is especially sought after, meaning that our product can be specifically designed to protect human health in these professions.
In addition to directly aiding product users, our product development has been transparent with the objective of providing stakeholders with engaging information on how the product functions.
Once product development is complete, we intend to make all documents relevant to development, especially those which pertain to the function of non-newtonian fluid components, available to support stakeholder confidence in the product.
The most efficient way by which this will be accomplished is via a presentation to stakeholders containing consolidated documentation on product development, testing, and function to ensure transparency and promote shareholder engagement.
Key Takeaway: Our product is explicitly designed to protect human health and therefore has the potential to strengthen community relations among its users.
This statement is especially true in skiing applications because this product can alleviate fear amongst new skiers that malpractice will lead to injury of themselves or their loved ones.
This is not to say that our product will lead to ski negligence, but rather that it provides an additional safety measure as PPE to reduce neck injuries and therefore has the potential to strengthen community relations through increased mutual trust.
Finally, our product will be accessible to all regardless of individual characteristics as its design allows it to be attached to any helmet, regardless of the wearer’s physical dimensions.
Given that our product’s primary function will be to serve as PPE for construction workers, regulatory standards will play a major role in how the product is sold and implemented in construction workplaces.
Currently, the owner of FlexRod plans to lobby for OSHA to mandate his PPE system as an addition to helmets as a means to reduce neck injuries, assuming our product can produce sufficiently appealing data on impact force reduction.
OSHA is therefore a critical institution when considering the implementation of our device as it will be required to comply with existing OSHA regulations and potentially present new regulations with the objective of improving safety and device sales.
Furthermore, the device will need to be mounted to existing helmets in such a way that the helmets remain in compliance with OSHA regulations, and the back brace used to mount the flex rod canister cannot interfere with other forms of regulated PPE.
Article Name: Neck Protection Development and a Proposal of the Association Standard for the Motorcyclist
- Even though the article is about testing motorcycle helmets, it has good information about neck anatomy and injuries and ways to test the effectiveness of helmet and neck protection.
- Motorcyclists use neck braces to restrict acceleration of the head in a controlled manner and therefore reduce the bending forces of the cervical spine and limit compression/hyper-flexion/hyper-extension movements … could this be something we can try to incorporate in our design?
Article Name: Assessment of Kinematic Brain Injury Metrics for Predicting Strain Responses in Diverse Automotive Impact Conditions
In this study, 15 kinematic-based metrics were compared to FE model-predicted brain strain results from simulations using a broad range of head impacts taken from different automotive crash modes.
The relative performance of each kinematic metric was evaluated based on correlations with two strain-based predictors of brain injury, MPS (maximum principal strain) and CSDM (cumulative strain damage measure). BrIC (Brain Injury Criterion) was the overall best correlated with MPS, while RVCI (Rotational Velocity Change Index) correlated slightly better with CSDM.
- BrIC is formulated using the maximum magnitudes of the three orthogonal head angular velocity components where x icr is directionally dependent critical values that were determined using FE modeling
- RVCI was formulated by assuming that brain tissue strain was analogous to deformation from a simple spring-mass model where R i are weighting factors about each orthogonal axis determined using a FE model of the head. A duration constraint of t 2 – t 1 £ 10 ms was used since it resulted in the highest correlation between RVCI and FE strains for both occupant and pedestrian crash simulations
BrIC and RVCI have their limitations:
- For pedestrian impact events, which had head angular velocities longer in duration than the other three crash modes, BrIC was not well correlated with MPS and CSDM. A previous parametric study using SIMon demonstrated that for a given magnitude of angular head velocity, brain strain decreased as the duration of the velocity pulse increased beyond 50 ms. Thus, the critical angular velocity values of BrIC are too low for impacts exceeding 50 ms in duration, and BrIC would overestimate the amount of brain deformation in these cases…would our crash incidents be considered long duration?
- For shorter duration head impacts, mainly those generated from pendulum impact, RVCI did not correlate as well as BrIC (and thus, BrIC was overall a more predictive metric).
Validation and Verification
For our rheometry testing, we conducted analyses at increasing shear rates over three-second intervals to determine if our fluid is non-Newtonian. Non-Newtonian fluids have a “Goldilocks Zone” where the fluid is shear-thinning at lower RPMs and reaches a shear-thickening potential at said zone.
The rheometer we were using was not able to make it to a high enough RPM to reach shear-thickening, but it does show evidence of shear-thinning, indicating that the fluid is indeed non-Newtonian (Figure 5).
We have a functional prototype and are in the development of a marketable product. As you can see in the picture to the left the canister is connected to a shoulder harness, with a rod protruding from the helmet to the canister.
This prototype is not what the final product will look like, this is what we used as a proof of concept.
This prototype was made of a carbon fiber canister and rod, the entire assembly weighed less than a pound and actually performed exceptionally well, although it is not yet a marketable product.
We know skiers and snowboarders tend to fall on their backs a lot and the product will be ergonomically designed for the sport.
With designs currently being tested, is this product something the skiing world wants? Our next ski season is looking to be a safer slope.
If you are interested in this product please send an email to the authors, being that we are a college we can only continue to pursue the product if our investors see there is a market for our FlexRod. For enquiries contact: [email protected]