A cellulosic fibre foam as a bicycle helmet impact liner for brain injury mitigation in oblique impacts
Journal article, 2025

Bulky cellulosic network structures (BRC) with densities between 60 and 130 g/l were investigated as a sustainable alternative to fossil-based foams for impact liners in bicycle helmets. The mechanical properties of BRC foams were characterized across a wide range of strain rates and incorporated into a validated finite element model of a hardshell helmet. Virtual impact tests simulating both consumer information and certification scenarios were conducted to compare BRC-lined helmets against conventional expanded polystyrene (EPS) designs. Results showed that BRC outperformed EPS in oblique impacts, reducing angular accelerations and velocity changes by approximately 33 %, particularly for z-axis rotations. The average risk of sustaining AIS2 injuries and concussions was lower for BRC (8 % and 34 % respectively) compared to EPS (13 % and 46 %). However, BRC helmets exhibited bottoming out in certain straight impacts, potentially failing certification tests. This limitation was addressed through design modifications. The study demonstrates that cellulosic fibre network structures have the potential to replace fossil-based foams in bicycle helmets while providing adequate protection and improved performance in mitigating rotational forces.

Head injury

Network-structure

Bicycle-helmet

Fibre

Cellulose

Pulp

Split-Hopkinson bar

EN1078

Author

Florian Feist

Technische Universität Graz

Markus Wagner

Technische Universität Graz

Georg Baumann

Technische Universität Graz

Stefan Spirk

Technische Universität Graz

Veronika Biegler

University of Vienna

Qixiang Jiang

University of Vienna

Tiina Nypelö

Aalto University

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry

Heliyon

24058440 (eISSN)

Vol. 11 1 e40790

Upgrading of cellulose fibers into porous materials.Acronym: BreadCell

European Commission (EC) (EC/H2020/964430), 2021-04-01 -- 2025-03-31.

Subject Categories (SSIF 2025)

Polymer Chemistry

Paper, Pulp and Fiber Technology

DOI

10.1016/j.heliyon.2024.e40790

Related datasets

Simulation Input data for: A Cellulosic Fibre Foam as a Bicycle Helmet Impact Liner for Brain Injury Mitigation in Oblique Impact [dataset]

DOI: 10.5281/zenodo.15018019

More information

Latest update

3/24/2025