Verified fuselage section water impact modelling

ABSTRACTAlong many flight corridors, bodies of water serve as preferred emergency landing options. Thus, relevant scenarios must be investigated to improve aircraft crashworthiness in the event of an impact landing on water. Enhancing the damage tolerance of aircraft structures through repetitive experiments can, however, prove highly uneconomical. Such large-scale trials can be influenced by many factors of uncertainty adversely affecting the quality of the results. Therefore, the work presented in this study focuses in particular on evaluating a computational methodology perfected for aircraft water ditching using Coupled Lagrangian-Eulerian (CLE) that allows detailed prediction of structural response of a verified deformable fuselage section during such events. Validation of the fluid-structure interactive (FSI) strategy developed is conducted, thoroughly comparing the method against the analytical and experimental results of multiple wedge drop tests. Finally, the validated FSI strategy is applied to a high-fidelity fuselage section model impacting water to simulate and assess a realistic ditching scenario.

Kajian Desain Kelaiktabrakan Pesawat Terbang

Lalu lintas penerbangan di Indonesia mengalami tren peningkatan dari tahun ke tahun. Peningkatan frekuensi penggunaan pesawat terbang tentunya akan meningkatkan kemungkinan kejadian kecelakaan. Konsep kelaiktabrakan pesawat terbang menjadi hal penting yang perlu mendapat perhatian untuk mencegah kerusakan struktur dan cedera pada penumpang. Desain kelaiktabrakan struktur pesawat berada pada tahapan desain awal yang terintegrasi kedalam proses desain pesawat secara keseluruhan. Struktur subfloor pada pesawat terbang menjadi bagian yang digunakan untuk menyerap energi kinetik tabrakan dalam kasus pembebanan vertikal pada pesawat terbang. Crash box merupakan komponen pada subfloor yang akan menyerap energi kinetik tabrakan dengan mengubahnya menjadi deformasi plastis. [A Review of Aircraft Crashworthiness Design] Air traffic in Indonesia is experiencing a positive trend in recent years. The increase in the frequency of aircraft operation might particularly increase the possibility of accidents occurrence. Aircraft crashworthiness concept becomes an important matter that need to be considered in order to prevent structural damage and injuries to the passengers. Aircraft structural crashworthiness design is developed in the aircraft preliminary design phase which is, later, integrated into the overall aircraft design process. Aircraft subfloor structure is the part of the aircraft that is used to restrain the kinetic energy of a collision in the case of vertical loading on the aircraft. Subsequently, crash box is a component of the subfloor that will absorb collisions kinetic energy by turning it into plastic deformation.

Energy absorption structures design of civil aircraft to improve crashworthiness

To improve the crashworthiness of civil aircraft, the design concept of energy absorption structure for civil aircraft is investigated. Two typical different design principles could be identified. The first category includes Helicopter and Light fixed-wing Aircraft (HLA), and Transport, Mid-size and Commuter type Aircraft (TMCA) are classified into the second group. Frame, strut and bottom structure are the three kinds of energy absorption structure for TMCA. The strut layout of conventional civil aircraft is studied and some energy absorption devices are adopted. High efficiency energy absorption structures such as the foam and sine-wave beam are employed as the bottom structure for both of HLA and LMCA. The finite element method is used to analyse and design energy absorption structure in aircraft crashworthiness problem. Results show that the crashworthiness of civil aircraft could be largely improved by using proper strut layout and excellent energy absorption device. The stiffness combination of frame and strut should be considered to get better global aircraft deformation. Supporting platform and failure model are the two core problems of bottom energy absorption structure design. Foam and sine-wave beam under the lifted frame could improve the crashworthiness of civil aircraft.

A systematic approach to aircraft crashworthiness and impact surface material models

The underlying objective of this paper is to describe an approach adopted for investigating the crashworthiness of an airliner fuselage. It is based on detailed Finite Element (FE) modelling and supported by a series of static and dynamic tests on a subfloor section. The detailed FE analysis was undertaken to predict the dynamic collapse mechanism of a fuselage section. A parametric analytical study was performed for one of the dynamic tests modelled here to verify the results by taking into consideration the influence of modelling techniques. The structural response of an aircraft during an impact with the ground is highly dependent upon the terrain encountered. Significant structural response difference are likely to be produced when the impact surface is of a soft soil type as against a rigid surface such as concrete. The methodology to develop ground models was based on extending the problem from a simple to a complex structure/ground interaction.