Project Overview

Why do we care?

Every year, an estimated 1.6-3.8 million sports related concussions are reported in the United States alone, many of which occur while a helmet is being worn (Daneshvar, et al., 2011). Though the purpose of a helmet is to provide safety during potentially dangerous activities, their design helps reduce the risk of skull fractures but still proves to be ineffective for brain injuries. With the current testing being done for helmet standards, there are some factors that are not considered that could potentially reduce the number of concussions obtained. For example, many of the current methods only test for a linear impact on a flat metal surface, not taking into account the head rotation that takes place during impact. This is a crucial element for scientists to understand as this additional motion is the reason for shearing and in turn tissue damage to occur. In addition, current standards are not testing helmets on compliant surfaces, such as dirt or snow, but instead on metal causing the results to be less accurate for real life implications.

Developing a testing apparatus that would incorporate these missing pieces to create a fuller picture for helmet is essential. With this project, our design aims to test a headform impact on a compliant surface at an oblique angle, incorporating both linear and rotational kinematics.

How do we solve it?

In order to solve the issue of incorporating a shearing or rotational aspect into helmet testing, a new approach needs to be taken for the design. Instead of current testing which uses a vertical monorail system, the solution is an angled rail system that moves an aluminum carriage, which carries a headform and sits on linear bearings, downward toward a compliant surface.

The movement of the carriage is initiated by an electromagnetic release that initially connects the carriage to a cable wire holding the system at the top. The cable wire on the upward slant side is wound around a hand crank that is used to hold the system in place at the top and to bring the carriage back up after each trial. On the other side of the carriage, an extension spring is attached which connects the rest of the system to the front end bar. After the electromagnet is turned off, allowing the carriage to move from the top of the rails, the extension spring is free to pull the system to a designated speed by the time it reaches the bottom of the rails. The speed is obtained by extending the spring a set distance before each trial using a crank.

One important feature of this design is it allows the user to change the speeds of the impact, accommodating for a number of falls a jockey may experience. The headform is attached using a T joint connected to the carriage by two metal sheets and a shaft. The purpose of this setup is to allow the headform to have different angles of impact while keeping it stationary. Connected to the T joint is the rod that holds the headform. The headform is able to be rotated as well allowing the compliant surface to hit at different points of the helmet. Inside the helmet, an accelerometer monitors both the linear and rotational motion upon impact. While the structure is movable by forklift and has the ability to be taken on and off a field, test trials will be done using square meter boxes to hold the different equine surfaces.

Designs

Design 1: The first design focuses on the acceleration and force of a head during the rotational component of a fall. This is simulated by placing the headform in a pendulum-like motion. The headform starts at a right angle from the floor and falls on the angle-adjustable impact surface. A feature in this design and the others to follow is the ball and socket joint within the headform allowing the head to move with the impact, absorbing the shock and allowing the shear and rotation to occur.

Design 2: This design resembles a miniature trebuchet. However, unlike the trebuchet, the headform does not act as a projectile. The headform is directly attached to the arm but where the trebuchet uses an additional weight to create motion a spring is used instead. This spring helps not only control for velocity, but it also creates a consistent starting point which allows the experiment to be repeated.

Design 3: The third design is a combination of the first design and current testing designs. This system involves both a monorail system and a rotational bar that would act in a sequence of events. This design would most closely relate to real-life falls as there is a forward motion that initiates and contributes to the rotational aspect of the impact.