June 22, 2003
June 22, 2003
June 25, 2003
8.173.1 - 8.173.15
AIRCRAFT SEAT CUSHION PERFORMANCE EVALUATION AND REPLACEMENT IMPLEMENTATION
A. ADAMS, H. M. LANKARANI National Institute for Aviation Research Wichita State University Wichita, KS 67260-0093, U.S.A.
Dr. Nick M. SAFAI Chair of Engineering Department Salt Lake Community College SLC,UT 84123, U.S.A.
The seat cushion on an aircraft seat acts as a spring/damper that is located in the primary load path between the seat occupant and the seat structure. The seat cushion is considered a primary component in the seat system. It must be included and certified as part of the seat system during the seat dynamic test program. It has been demonstrated that the seat cushion’s physical properties, if improperly chosen, can amplify the lumbar-column pelvic load of the seated occupant during a vertical impact condition. The lumbar load response of an occupant on a seat is dependent on the combined stroking distance of the seat structure, pan and cushion. The stroking distance reduces the velocity build-up experienced by the occupant prior to bottoming- out, and is desirable in limiting the magnitude of the lumbar load. In the absence of a stroking seat structure, the seat pan and cushion combination determines the outcome of the spine load response. The behavior of the seat cushion depends primarily on the property of the foam materials, which in-turn, is characterized by the compressive load versus deflection response of the material. Seat cushions that are fabricated from different foam materials will have the same influence on the spine load if the load-deflection characteristics of the foams are similar. Component tests will be performed to determine an equivalent foam build-up substitution for repeating time consuming and expensive full-scale test method.
Introduction The purpose of this paper was to evaluate the dynamic performance of the typical aircraft seat cushions utilized in airline industry. Method described here defines the test procedures in order to replace the seat cushion foam build-up on a dynamically certified seat. The general test methodology is based on finding material equivalent properties, where the previously certified foam build-up and the new foam build-up have similar material behavior. In order to ensure that the replacement foam build-up is equivalent to the current passenger seat build-up, their performance under dynamic loading must be closely matched.
This procedure is aimed at replacing the full-scale testing of the new setup. At later stages, full- scale sled tests will be conducted to validate a comparable foam build-up substitute. Figure 1 illustrates a flowchart of a methodology to authenticate the replacement of the seat cushion on a dynamically certified seat without conducting the full-scale tests. The material equivalency is the main objective of this methodology 8. The new seat cushion should possess the same load deflection as of the current certified cushions 5. Proceedings of the 2003 American Society for Engineering Education Annual Conference & Exposition Copyright © 2003, American Society for Engineering Education
Adams, A., & Safai, N. (2003, June), Aircraft Seat Cushion Performance Evaluation Paper presented at 2003 Annual Conference, Nashville, Tennessee. 10.18260/1-2--12667
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