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Honeycomb sandwich structures, composed of many regularly arranged hexagonal cores and two skins, show excellent impact performance due to strong energy absorption capability under impact loads. In this paper, a numerical study of low velocity impact on honeycomb sandwich panels filled with circular tubes in the in-plane direction was performed. To calibrate the numerical model, simulation results in the out-of-plane direction are compared with the experimental ones. The numerical modelling of the drop weight test was carried out using the nonlinear explicit finite element code Abaqus/Explicit. The impact responses are presented as the contact force between the impactor and the panel versus the time. It was concluded that the filled honeycomb panel absorbs the same amount of impact energy in a shorter time than an empty one. In addition, the deflections of the front and back face-sheets are investigated. The panel degradation and the stress distribution during the crushing are also discussed.

This paper presents the methodology for the rapid estimation of the single rotor helicopter parasite drag in the forward flight in the preliminary design phase. The aerodynamic drag of fuselage, main rotor hub, landing gear and the other, non-rotating defective surfaces contribute with more than 50% of the total power required for the forward flight at higher cruising speeds and therefore requires a more approximate determination in the design stages before the prototype development. The parasite drag determination is based on the evaluation of the basic value of The Equivalent Parasite Drag Flat Plate Area and its changes depending on the fuselage angle of attack. Plenty of the statistical indicators, aerotunnel tests results and the recent CFD investigations were taken into consideration during the process of developing and testing this methodology.

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Copyright of FME Transactions is the property of University of Belgrade, Faculty of Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)