Analysis of energy-absorbing seat configurations for aircraft

Abstract

The vertical component of impact forces that is often present in aircraft crashes makes an energy absorption capability essential for seats in small aircraft and helicopters. The US Army has required dynamic testing of seats for its aircraft since 1971, and the energy-absorbing seats that have been designed to meet its requirements have proven successful. Amendment of the Federal Aviation Regulations (FAR) in 1988 and 1989 to require dynamic testing of civil aircraft seats has generated increased interest among airframe and seat manufacturers in development of new energy-absorbing seat concepts. New analytical techniques are required to model these new seat concepts efficiently. The research effort described in this paper has involved a comparison of the performance of various energy-absorbing seat concepts with respect to the FAR-specified dynamic test criteria for general aviation and for rotorcraft. Three different energy-absorbing configurations were modelled using the SOMLA program, which has been developed for aircraft seat analysis. For a type of seat with guided energy-absorbing stroke, energy absorber parameters were determined that would limit the maximum lumbar force in the 50th-percentile dummy to 1500 lb (6.7 kN), as required by the FAR. Seats with energy absorption systems designed for the 50th-percentile occupant were found to limit lumbar force to tolerable levels for other sizes of occupant as well, based on assumptions of simple scaling rules. The seat models and results obtained with the models are described.

The effect of FRP thickness on energy absorption of metal-FRP square tubes subjected to axial compressive loading

“…In this case, the energy absorption in this case came from the composite fracturing and fiber kinking. The effect of high maximum load during accidents on lumbar spine of passengers was reported by Laananen et al [14]. Therefore, in an ideal energy absorber, the ratio of mean crushing to maximum load upon sudden crash should approach unity because of safety concerns.…”

Hybrid Composite‐Polypropylene Sandwich‐Based Design for the Fuselage Panel in Commercial Aircraft to Increase the Passive Safety of Passengers

“…[1,2] A key issue in the passive safety for passengers is the introduction of solutions able to absorb part of the impact energy through deformation and failure mechanisms, reducing the loads transferred to passengers during a crash event or ditching. [3][4][5] A valuable method for investigating the effectiveness of a new design for a passive safety system or the improvement of an existing one is provided by anthropomorphic test devices (ATDs) available for most of the FE codes. [6][7][8] Vertical impact phenomena are typically considered in the investigation of a structure's crashworthiness through dummies.…”

Design method for expandable tubular energy absorber in crashworthy seat of civilian helicopter

“…Its crash-resistant capacity determines the survival rate of occupants. 1,2 Energy absorbers are the core elements of crashworthy seats, which can decrease the load transmitted to occupants during a helicopter crash. 3,4…”

“…Its crash-resistant capacity determines the survival rate of occupants. 1,2 Energy absorbers are the core elements of crashworthy seats, which can decrease the load transmitted to occupants during a helicopter crash. 3,4 Expandable tubular energy absorber (ETEA) is widely adopted in transportation vehicles, which mainly consists of an expansion tube and a cone head.…”