Comfort Evaluation of Slow-Recovery Ejection Seat Cushions Based on Sitting Pressure Distribution

Sitting discomfort not only affects the health of pilots carrying out long-endurance missions but also affects operational performance. The experimental objects included four ejection seat cushions: N1 was a fast-recovery foam as the comparison group, and the experimental groups were slow-recovery foams with different indentation force deflection (IFD), named N2 (hard), N3 (mid), and N4 (soft). The sitting comfort of 20 participants was tested on the four cushions by using subjective rating and sitting pressure distribution analysis. The results showed that compared with fast-recovery cushion N3 and N4 slow-recovery cushions have lower contact pressure and more uniform pressure distribution. Slow-recovery cushions that were too soft or too hard would reduce the comfort. No matter from the subjective rating or the analysis of the contact pressure data, the N3 cushion with a thickness of 3 cm and 65% IFD of 280 N had the highest comfort. In addition, the seat pressure distribution (SPD%) has a significant correlation with the subjective rating (p = 0.019, R = −0.98), which is more suitable for evaluating the comfort of the cushions. However, the slow-recovery cushions would show a decrease in support after a period of sitting, while the fast-recovery cushion could always maintain constant support.

Model construction and analysis of ride comfort for high-speed railway seat cushions

BACKGROUND: More and more people choose to travel by high-speed railway. The seats in these vehicles are an important contact point and comfort of the seat cushions needs attention. OBJECTIVE: The aim of this study is to choose among three seat cushions, the one that creates most comfort for a high-speed train. METHODS: Twelve healthy volunteers were selected to participate in the experiment. Three different surface shape models of high-speed railway seat cushions were used. The Seat Pressure Distribution Index (SPD%) was calculated and analysed. A 7-point Likert scale questionnaire was applied for subjective evaluation. RESULTS AND CONCLUSION: The evaluation is based on subjective and objective data. The results showed that the front protruding cushion made the pressure distribution more even, while the flat cushion had the smallest SPD% and the static pressure was most evenly distributed. This knowledge was beneficial for the design of comfortable high-speed railway seat cushions.

FEM Simulation of Composite Polyurethane Foam for Car Seat Cushion

Reduction of both harmful emissions and energy performance intensity of transportation currently ranks among the most important factors influencing the current trends in the development of components used in the automotive industry, particularly due to the legislative regulations concerning the reduction of greenhouse gases. For car producers is one of the possible ways of how to achieve such a goal is to reduce the weight of individual car components while maintaining or improving their in-use material properties. Therefore, the requirement of weight reduction also applies to car seat cushions. FEM a very powerful tool of mechanical parts design. A composite material model has been designed and verified. There were created structural models enabling us to study and visualize the stress distribution between the fibers and the polyurethane foam structure, the structural models were created by means of model simulations using the finite elements. Several configurations of structural models with horizontal and vertical threads were created. Then were developed FEM simulations corresponding with real geometry of the composite seat cushion and their results were evaluated.