Development Of New Crashworthiness Evaluation Strategy For Advanced General Aviation

Aircraft seats have traditionally been designed to comply with static strength requirements. Aircraft seat dynamic performance that shows both seat strength and the occupant impact protection characteristics must be a priority design objective. Crash safety of aircraft, specifically the protection of the occupants during a crash, is becoming increasingly important due to drastic increases in the number of severe injuries among the flying passengers. The goal of this paper is to contribute to low-cost advanced general aviation and transport crashworthiness compliance methodologies. The first approach is by constructing nonlinear seat model using LS-DYNA, a 3D non-linear Finite Element Method package to analyze the dynamic behavior of the seat under direct impact. From the analysis the properties of the seat are obtained and then used for analysis of biodynamic test configurations in the second phase of simulation. This approach uses the more versatile Kinematics and Dynamic crash simulation program, MADYMO (Mathematical Dynamic Model). Multi-body dynamic techniques are utilized to characterize the occupant behavior in event of a crash on two different seat configurations, one with standard rigid seat and the other utilizing a seat cushion. The occupant model is set up for a 50th percentile Part 572 Hybrid II anthropomorphic test dummy (ATD). In both approaches, FAR Part 23.562, a 15g crash pulses at 60° pitch angle with a initial velocity of 31 ft/sec for general aviation aircraft category under Test I and Test II dynamic conditions are simulated . The dynamic behavior of the occupant and performance of both configurations seat are then obtained. Finally, to increase simulation accuracy, a third method is introduced, coupling the two previous methods, which combines a three-dimensional dynamic model of the human body with the finite element model of the seat structure to accurately simulate an aircraft/occupant at the crash event. The final results show the computer models can be used as a simple and fast seat design tool, which could predict the dynamic responses including the occupant spinal injury severity and the seat condition, when subjected to a crash event.