MULTI-STABLE BEAM-TYPE ENERGY ABSORPTION STUDY METASTRUCTURE (MBM) WITH TRACTRIX GEOMETRY ON HELICOPTER SUBFLOOR STRUCTURE

• Main Author: Nurahman, Aprilian
• Format: Final Project
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/57140
• Institution: Institut Teknologi Bandung

With the increase in the number of helicopters every year, it is necessary to improve the crashworthiness system to ensure the safety of passengers when accidents occur. One of the crashworthiness systems in helicopters is an energy-absorbing structure located on the subfloor structure. This study is conducted to observe the performance of energy absorption of helicopter subfloor structure by applying the Multi-stable beam-type Metastructure (MBM) structure. In this study, tractrix geometry was applied to the unit cell of MBM to see the effect of beam geometry on the energy absorption performance of the structure. Taguchi optimization and Analysis of Variance (ANOVA) are carried out to get the optimum parameter of the unit cell by using 4 control factors consisting of material, tangential tractrix line length, horizontal beam length, and the beam thickness with a total of 3 levels for each of the control factor. From optimization, the result obtained that unit cell optimum is made from Aluminium Alloy 5754 with the beam thickness 1.5 mm, horizontal length 10 mm, and the tangential tractrix line length 16 mm. The increase of the specific energy absorption value is gotten by using this unit cell with the gain value of 10.49 dB. Furthermore, from the comparison results between tractrix geometry and ordinary polynomial geometry, it is found that the MBM structure with tractrix had better energy absorption performance with an increase in SEA of 31.4%. The optimum unit cell is then applied to the subfloor structure of the helicopter by constructing it into columns. After that, a comparison of the energy absorption performance between the MBM column and the conventional crash box was carried out. However, the simulation results show that the designed MBM column has a lower SEA value with a significant difference. This shows that the designed MBM structure cannot be used to replace the crash box as an energy-absorbing structure.