Bicycle helmet foam liners absorb energy during impacts. Our goal was to determine if the impact attenuation properties of expanded polystyrene (EPS) foam used in bicycle helmets change with age. Foam cores were extracted from 63 used and unused bicycle helmets from ten different models spanning an age range of 2–20 yrs. All cores were impact tested at a bulk strain rate of 195 s−1. Six dependent variables were determined from the stress–strain curve derived from each impact (yield strain, yield stress, elastic modulus, plateau slope, energy at 65% compression, and stress at 65% compression), and a general linear model was used to assess the effect of age on each dependent variable with density as a covariate. Age did not affect any of the dependent variables; however, greater foam density, which varied from 58 to 100 kg/m3, generated significant increases in all of the dependent variables except for yield strain. Higher density foam cores also exhibited lower strains at which densification began to occur, tended to stay within the plateau region of the stress–strain curve, and were not compressed as much compared with the lower density cores. Based on these data, the impact attenuation properties of EPS foam in field-used bicycle helmets do not degrade with the age.
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April 2016
Research-Article
Age Does Not Affect the Material Properties of Expanded Polystyrene Liners in Field-Used Bicycle Helmets
Shannon G. Kroeker,
Shannon G. Kroeker
MEA Forensic Engineers & Scientists,
11-11151 Horseshoe Way,
Richmond, BC V7A 4S5, Canada
11-11151 Horseshoe Way,
Richmond, BC V7A 4S5, Canada
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Stephanie J. Bonin,
Stephanie J. Bonin
MEA Forensic Engineers & Scientists,
23281 Vista Grande Drive,
Laguna Hills, CA 92653
23281 Vista Grande Drive,
Laguna Hills, CA 92653
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Alyssa L. DeMarco,
Alyssa L. DeMarco
MEA Forensic Engineers & Scientists,
11-11151 Horseshoe Way,
Richmond, BC V7A 4S5, Canada
11-11151 Horseshoe Way,
Richmond, BC V7A 4S5, Canada
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Craig A. Good,
Craig A. Good
Collision Analysis,
43 Skyline Crescent NE,
Calgary, AB T2K 5X2, Canada;
43 Skyline Crescent NE,
Calgary, AB T2K 5X2, Canada;
Schulich School of Engineering,
University of Calgary,
2500 University Drive NW,
Calgary, AB T2N 1N4, Canada
University of Calgary,
2500 University Drive NW,
Calgary, AB T2N 1N4, Canada
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Gunter P. Siegmund
Gunter P. Siegmund
MEA Forensic Engineers & Scientists,
11-11151 Horseshoe Way,
Richmond, BC V7A 4S5, Canada;
11-11151 Horseshoe Way,
Richmond, BC V7A 4S5, Canada;
School of Kinesiology,
University of British Columbia,
210-6081 University Boulevard,
Vancouver, BC V6T 1Z1, Canada
e-mail: gunter.siegmund@meaforensic.com
University of British Columbia,
210-6081 University Boulevard,
Vancouver, BC V6T 1Z1, Canada
e-mail: gunter.siegmund@meaforensic.com
Search for other works by this author on:
Shannon G. Kroeker
MEA Forensic Engineers & Scientists,
11-11151 Horseshoe Way,
Richmond, BC V7A 4S5, Canada
11-11151 Horseshoe Way,
Richmond, BC V7A 4S5, Canada
Stephanie J. Bonin
MEA Forensic Engineers & Scientists,
23281 Vista Grande Drive,
Laguna Hills, CA 92653
23281 Vista Grande Drive,
Laguna Hills, CA 92653
Alyssa L. DeMarco
MEA Forensic Engineers & Scientists,
11-11151 Horseshoe Way,
Richmond, BC V7A 4S5, Canada
11-11151 Horseshoe Way,
Richmond, BC V7A 4S5, Canada
Craig A. Good
Collision Analysis,
43 Skyline Crescent NE,
Calgary, AB T2K 5X2, Canada;
43 Skyline Crescent NE,
Calgary, AB T2K 5X2, Canada;
Schulich School of Engineering,
University of Calgary,
2500 University Drive NW,
Calgary, AB T2N 1N4, Canada
University of Calgary,
2500 University Drive NW,
Calgary, AB T2N 1N4, Canada
Gunter P. Siegmund
MEA Forensic Engineers & Scientists,
11-11151 Horseshoe Way,
Richmond, BC V7A 4S5, Canada;
11-11151 Horseshoe Way,
Richmond, BC V7A 4S5, Canada;
School of Kinesiology,
University of British Columbia,
210-6081 University Boulevard,
Vancouver, BC V6T 1Z1, Canada
e-mail: gunter.siegmund@meaforensic.com
University of British Columbia,
210-6081 University Boulevard,
Vancouver, BC V6T 1Z1, Canada
e-mail: gunter.siegmund@meaforensic.com
1Corresponding author.
Manuscript received November 8, 2015; final manuscript received February 4, 2016; published online March 3, 2016. Assoc. Editor: Barclay Morrison.
J Biomech Eng. Apr 2016, 138(4): 041005 (9 pages)
Published Online: March 3, 2016
Article history
Received:
November 8, 2015
Revised:
February 4, 2016
Citation
Kroeker, S. G., Bonin, S. J., DeMarco, A. L., Good, C. A., and Siegmund, G. P. (March 3, 2016). "Age Does Not Affect the Material Properties of Expanded Polystyrene Liners in Field-Used Bicycle Helmets." ASME. J Biomech Eng. April 2016; 138(4): 041005. https://doi.org/10.1115/1.4032804
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