Optimisation of IMPAXX EPS Foam Energy Absorber with Applications for Amphibian Aircraft Landing on Water

Abstract

The research aims to optimise the design of IMPAXX EPS foam energy absorber for enhanced landing performance of an amphibian aircraft. Extensive transient dynamic simulations have been carried out to investigate the effect of IMPAXX EPS foam layer arrangements to landing performance with LS-DYNA. The design parameters of the IMPAXX EPS foam were systematically assessed for impact performance using LS-DYNA simulation. The research started with material characterisation of IMPAXX EPS foam related to impact application. Three IMPAXX EPS foams of different densities were tested at 2 m/s, 3 m/s, and 4 m/s impact velocity for blocks with various combinations of foam types. There were 12 flat layered design of foams that were evaluated through experiment and simulation to observe the characteristic of IMPAXX EPS foams. Later, optimised design of flat layer configuration were selected. The selected design then were used with shape configurations such as Arc (ARC), Sinusoidal (SIN), square (SQ) and Trapezium (TR). These shapes were then incorporated with space (S) and no-space (NS) design respectively. The final optimised foam design was then installed at the front (FRONT) and back (BACK) position of the amphibian aircraft. This is to determine the best installation location based on acceleration (g) and displacement (mm) with specified impact load. A statistical analysis has been carried out to determine the optimum value of acceleration (g) and displacement (mm) effects through experiment and simulation. Average approach and time (t) average approach has been used to determine the best design. Results showed the design configuration of square space (SQ-S) with CBA design is the best material configuration and has been used for the landing performance analysis of the full aircraft. Hence, position of the energy absorber gives significant effect in reducing the acceleration (g) impact towards the structure and occupant for 3 m/s and 4 m/s impact velocity. For these impact velocities, it is found that foams installed at BOTH position provides a significant reduction of acceleration (g) to the occupant which is 8.82 g for 3 m/s and 14.5 g for 4 m/s. Meanwhile, for 2 m/s, it does not provide any improvement to the structure and occupant.