Related Experiment Video
Updated: Jan 28, 2026
07:08
Modified Drop Tower Impact Tests for American Football Helmets
Published on: February 19, 2017
11.4K
Relative Motion Between the Helmet and the Head in Football Impact Test.
Hamed Joodaki1, Ann Bailey2, David Lessley3
1Department of Mechanical andAerospace Engineering,Center for Applied Biomechanics,University of Virginia,4040 Lewis and Clark Drive,Charlottesville, VA 22911e-mail: hj2vq@virginia.edu.
Journal of Biomechanical Engineering
|March 6, 2019
Summary
Head and helmet motion differ significantly during impacts. Measuring helmet motion alone is insufficient for understanding head injury biomechanics in sports. Independent head motion measurement is crucial.
Area of Science:
- Biomechanics
- Sports Medicine
- Traumatic Brain Injury
Background:
- Millions of sports-related traumatic brain injuries occur annually in the U.S.
- Understanding head injury biomechanics is vital for developing effective protective equipment.
- Quantifying relative motion between the head and helmet is necessary to assess helmet effectiveness.
Purpose of the Study:
- To compare helmet and head kinematics.
- To quantify the relative motion between helmet and head during simulated American football impacts.
Main Methods:
- Simulated seven helmet-to-helmet impact configurations using helmeted crash test dummies.
- Measured head and helmet kinematics using instrumentation and an optical motion capture system.
Main Results:
- Helmets translated 12-41 mm and rotated up to 37 degrees relative to the head.
- Peak linear acceleration of the helmet was 2-5 times higher than the head.
- Peak angular velocity of the helmet varied significantly compared to the head.
Conclusions:
- Helmet and head kinematics are distinctly different during impacts.
- Helmet rotation relative to the head is significant.
- Independent measurement of head motion is essential for accurate biomechanical analysis; relying solely on helmet motion is insufficient.
More Related Videos
Related Concept Videos
01:10Relative Motion Analysis - Acceleration
860
A slider-crank mechanism converts rotational motion from the crank into linear motion of the slider or vice versa. This mechanism consists of three main parts: the crank, the connecting rod, and the slider. The movement of the slider-crank is an example of general plane motion as the fluctuating angle between the crank and the connecting rod. Consider a segment AB where point A is at the end of the slider and point B is on the diametrically opposite end to point A, on a crack. The variance in...
860
01:24Relative Motion Analysis - Velocity
726
A stroke engine has a slider-crank mechanism that converts rotational motion from the crank into linear motion of the slider or vice versa. This mechanism consists of three main parts: the crank, the connecting rod, and the slider.
When an external force is exerted, it sets the crank into a rotational movement. This, in turn, instigates the motion of the connecting rod, leading to what is referred to as a general plane motion. This process involves two key points - point A on the connecting rod...
When an external force is exerted, it sets the crank into a rotational movement. This, in turn, instigates the motion of the connecting rod, leading to what is referred to as a general plane motion. This process involves two key points - point A on the connecting rod...
726
01:25Relative Motion Analysis using Rotating Axes
916
Consider a component AB undergoing a linear motion. Along with a linear motion, point B also rotates around point A. To comprehend this complex movement, position vectors for both points A and B are established using a stationary reference frame.
However, to express the relative position of point B relative to point A, an additional frame of reference, denoted as x'y', is necessary. This additional frame not only translates but also rotates relative to the fixed frame, making it...
However, to express the relative position of point B relative to point A, an additional frame of reference, denoted as x'y', is necessary. This additional frame not only translates but also rotates relative to the fixed frame, making it...
916
01:22Relative Motion Analysis using Rotating Axes - Acceleration
798
Consider a component AB undergoing a linear motion. Along with a linear motion, point B also rotates around point A. To comprehend this complex movement, position vectors for both points A and B are established using a stationary reference frame. The absolute velocity of point B is determined by adding the absolute velocity of point A, the relative velocity of point B in the rotating frame, and the effects caused by the angular velocity within the rotating frame.
Time differentiation is...
Time differentiation is...
798
01:29Relative Motion Analysis using Rotating Axes-Problem Solving
725
Consider a crane whose telescopic boom rotates with an angular velocity of 0.04 rad/s and angular acceleration of 0.02 rad/s2. Along with the rotation, the boom also extends linearly with a uniform speed of 5 m/s. The extension of the boom is measured at point D, which is measured with respect to the fixed point C on the other end of the boom. For the given instant, the distance between points C and D is 60 meters.
Here, in order to determine the magnitude of velocity and acceleration for point...
Here, in order to determine the magnitude of velocity and acceleration for point...
725
01:19Impact of Groups on Groups
239
Social psychologists analyze how groups influence one another, shaping social structures and interactions through both cooperation and competition. These dynamics manifest in various ways, ranging from economic partnerships to intergroup conflicts that shape societal structures and perceptions.Cooperation and Competition in Intergroup RelationsIntergroup relationships vary across contexts, sometimes fostering cooperation and mutual benefit while at other times leading to conflict and...
239