Scale modelling of aircraft fuselage: an innovative approach to evaluate and improve crashworthiness

Abstract

Scale modelling of an aircraft fuselage and its measure of accuracy was investigated and determined with 1/5th, 1/10th, 1/15th and 1/20th times scaled models of an aircraft fuselage. Non-linear Finite Element Method (FEM) solver LS DYNA 3-D has been employed to analyse the experimental 1/20th scale aircraft fuselage model. The results were validated with the experimental scaled drop test model. The focus of this paper is to evaluate the scaling concept and its possible incorporation into the crashworthiness evaluation of fuselage as a potential crashworthiness evaluation tool. The impact design requirement for the 1/20th scale model fuselage section is to maintain 500 g floor-level acceleration for a 30 ft/s vertical impact velocity onto a rigid surface. This impact requirement corresponds to 25 g floor-level acceleration for a geometrically and constitutively similar full-scale fuselage section. Sub-floor concepts were then evaluated by conducting dynamic tests and confirmed with analytical calculations by performing finite element analysis using LS-DYNA. Finally, an assessment of model accuracy is provided with suggestions for improvements to achieve a better correlation result. These tests are carried out to determine the fuselage crashworthiness level and safe limit loads prescribed by the Federal Aviation Administration (FAA), and to satisfy the design goals for improved crashworthiness. A thorough investigation has been made on the existence of scaling effects and to demonstrate the application of scale model technology in the development of a new feasible methodology to evaluate the crashworthiness of the transport aircraft fuselage. Percentage error linearity of scaling is a major achievement of this study. This innovative and cost-effective crash test technique has a great potential to play a major role in the cost-saving methodology to evaluate the structure crashworthiness of the aircraft fuselage. The 1/20th scale model was built, tested and simulated with the LS-DYNA FEM package and the results were validated with the experimental drop test.

Keywords:

• aircraft crashworthiness
• nonlinear finite element modelling
• scaling technique