Does preferred seat pan inclination minimize shear force?

Xuguang Wang*, Michelle Cardosso, Ilias Theodorakos, Georges Beurier

*Corresponding author for this work

Research output: Contribution to book/anthology/report/conference proceedingArticle in proceedingResearchpeer-review

2 Citations (Scopus)


Past biomechanical studies on seated postures showed that effects of seat parameters, such as seat pan angle, back angle and friction coefficient, on muscle activities, shear force between buttocks and seat and spinal loads are complex. Reducing all these biomechanical loads at the same time may not be possible. Lowered muscle activation may require higher frictional shear force. It is interesting to investigate how people behave compared to biomechanical simulations. In this paper, the question whether sitters prefer a seat pan angle for reducing shear force was investigated using the data collected from a multi-adjustable experimental seat. Two imposed seat pan angles (A_SP = 0°, 5°) and one self-selected were tested for two backrest angles (A_SB = 10°, 20°, from the vertical). A flat seat pan surface was used. Other seat parameters such as seat height, length and position of three back supports were defined with respect to each participant’s anthropometry. As expected, results showed that shear force increased with backrest recline and decreased with seat pan recline. No significant difference in self-selected seat pan angle was found between two backrest angles. An average of 6.2° (±3°) was observed. The lowest shear was observed for the condition of self-selected seat pan angle, supporting the idea that seat pan should be oriented to minimize shear force. However, self-selected angle did not completely remove the shear. A zero shear would require a more reduced trunk-thigh angle, suggesting a minimum trunk-thigh angle should also be maintained.

Original languageEnglish
Title of host publicationProceedings of the 20th Congress of the International Ergonomics Association (IEA 2018) - Volume V : Human Simulation and Virtual Environments, Work With Computing Systems WWCS, Process Control
EditorsYushi Fujita, Sebastiano Bagnara, Riccardo Tartaglia, Sara Albolino, Thomas Alexander
Number of pages6
Publication date2019
ISBN (Print)9783319960760
Publication statusPublished - 2019
Event20th Congress of the International Ergonomics Association, IEA 2018 - Florence, Italy
Duration: 26 Aug 201830 Aug 2018


Conference20th Congress of the International Ergonomics Association, IEA 2018
SeriesAdvances in Intelligent Systems and Computing

Bibliographical note

Funding Information:
Acknowledgement. The work is partly supported by Direction Générale de l’Aviation Civile (project n°2014 930818).

Publisher Copyright:
© Springer Nature Switzerland AG 2019.


  • Airplane passenger
  • Biomechanics
  • Discomfort
  • Seating
  • Shear force


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