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. 2023 Jun 5;10:356. doi: 10.1038/s41597-023-02092-4

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© The Author(s) 2023

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

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Fig. 1 — Schematics and photographs of equipment for the dataset and example data. (a) Examples of helmet liner applications for impact protection foams. Left A youth American football helmet with inset highlighting the multilayered pads that include two foams, a comfort layer and a stiffer vinyl nitrile foam protective sub-layer, above an architectured thermoplastic polyurethane backer. Right A youth hockey helmet with inset highlighting softer and stiffer impact protection foam layers. (b) Micro X-ray computed tomography laboratory-scale system, where the specimen is placed either on a freestanding platen (not shown) or inside the Deben load tube for in-situ compression (see inset). In either case these ride on a rotating stage and sequential exposures are taken. This allows the use of a tomographic projection algorithm to reconstruct a volumetric image (shown at right) of the specimen. (c) Displacement-controlled load frame with 2D digital image correlation system to measure stress-strain (shown at bottom) with full-field displacement (shown at right) and strain measurements at a range of applied strain rates. (d) Dynamic mechanical analysis using a paired-type transducer-actuator for small amplitude oscillatory strain, with the specimen epoxied between platens inside an environmental chamber, from which shifted time-temperature superposition data (shown at right) can be obtained.