Biomechanical evaluation of a dual-layer cushion for pilot ejection seats: Full-scale dummy tests and finite element analysis.

Authors

Jin Yan, Pengyan Zhou, Yixuan Guan, Jiayi Bao, Huawei Liu

Published in

Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine. Pages 9544119261498658. Oct 17, 2026. Epub Oct 17, 2026.

Abstract

Spinal and neck injuries are major biomechanical concerns during pilot ejection, particularly under high vertical acceleration. As the main load-transfer interface between the seat pan and the occupant, the cushion affects how impact loads are transmitted to the body. This study evaluated a dual-layer cushion consisting of an N3 slow-recovery contact layer and an N1 high-rebound support layer at a thickness ratio of 2:1, with a single-layer N1 cushion as the reference. Full-scale vertical dummy ejection tests at 10 G and 14 G were used to assess dynamic responses of the spine and neck. A CT-based human-cushion finite element model was also used to analyse static interface pressure and local spinal responses under a representative high-acceleration condition. Compared with the reference cushion, the dual-layer cushion reduced $\mathrm{DRI}$ by 17.6% at 10 G and 7.3% at 14 G, while also reducing the resultant forces and $N_{\mathrm{ij}}$ values in the upper and lower neck. At 14 G, upper- and lower-neck $N_{ij}$ decreased by 19.9% and 27.6%, respectively. The finite element results further showed reductions of 13.1% and 14.5% in peak stress at the L4-L5 and L5-S1 intervertebral discs, respectively. These results indicate that layered cushion materials can alter impact-load transmission at the human-seat interface and reduce biomechanical responses associated with spinal and neck injury. The dummy tests and human finite element analysis provide complementary evidence at the whole-body dynamic and local tissue-mechanical levels for evaluating the biomechanical protection of the dual-layer cushion.

PMID:
42891519
Bibliographic data and abstract were imported from PubMed on 18 Oct 2026.

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