Improving Aircraft Passenger Seat Comfort with Biomechanical Models and Numerical Simulation

Zodiac Seats France (ZSFR - now Safran Seats) is a supplier of upscale passenger seats. With world-renowned expertise in business class, Safran Seats designs, certifies and assembles innovative, customizable and high-added-value products. The division draws on a strong international presence and provides its expertise to customers from all markets. Employing several teams of designers, their products offer state-of-the-art design that incorporates high-tech equipment and reflects the determination to find solutions to three fundamental challenges of the seat market: Continuous improvement in passenger seat comfort and ergonomics, offering differentiation to its airline company customers with customizable products, and ongoing research to optimize the available cabin space.

Zodiac Seats France (ZSFR - now Safran Seats), a supplier of upscale passenger seats, aimed to improve seat comfort in airplanes. The challenge was to develop a new kind of airplane seat that would significantly increase passengers’ comfort. The development of airplane seats involves several key factors such as ergonomics, cabin layout, and eco-design. ZSFR also wanted to consider environmental issues and put eco-design and light-weighting at the forefront of its product development plans. Lighter seats help to reduce an aircraft’s fuel consumption and the seats are predominantly produced using recyclable materials. A major concern for the company was the optimization of the comfort of aircraft passengers. The airplane seat market is highly competitive and new, high-quality seats have to be brought to market as quickly as possible. To assess the ergonomic quality of a seat, the engineers needed a tool with which they could simulate all biomechanical discomfort sources for factors such as internal thighs soft tissue compression for a seated passenger.

To improve the quality and comfort for aircraft passengers, Zodiac Seats used numerical simulation and the Altair HyperWorksTM suite to design, evaluate and optimize the seats. This enabled the designers at ZSFR to evaluate the behavior of their seat structures under static and dynamic stress as well as the feasibility of thermal molding and stamping the seat components. Designers relied on the Altair HyperWorks suite to simulate the biomechanical factors. Soft tissue compression, the factor under investigation, can be estimated by applying two parameters: the external contact pressure and the direct tissue strain. To handle this simulation engineers created two kinds of models with which they could estimate each of the discomfort factors. By employing the Altair solutions and incorporating the relation between simulation outputs and the several discomfort factors, the tool was able to deliver a quantification of the ergonomic quality. With these results and insights, the engineers were able to optimize the seat design and material, hence the potential discomfort of the passengers sitting in these seats could be reduced.

• Using the Altair HyperWorks Suite of products, Safran Seats was able to gain deep insight into various fields of interest, such as contact pressure or structural strain. Altair software enabled the design team to evaluate the overall behavior of the seat structure under static and dynamic stress as well as thermal molding and stamping feasibility. By developing biomechanical models with Altair HyperWorks, they were able to achieve a mean error of the estimated maximal pressure of 16% and an internal strain estimated with an error lower than 19%. In addition to providing deeper insights, numerical simulation helped the engineers to resolve development issues quickly and efficiently. Due to their high level of satisfaction with the results, Safran Seats will continue to employ Altair tools in the future to optimize foam thickness, characteristics, and weight to further improve the comfort of aircraft passenger seats. Increasing the use of simulation, in particular, the Altair HyperWorks Suite, will lead their engineers to faster development and hence to a shorter time to market.

• Evaluation of the overall structural behavior of seats
• Deep insights into biomechanical discomfort factors
• Mean error of the estimated maximal pressure of 16%