High-speed impact assessment for composite air inlet

Abstract

Purpose The purpose of this paper is to describe the approach for the design of a jet engine composite air inlet for a new generation of jet trainer aircraft from the perspective of airworthiness requirements regarding high-speed impact resistance. Design/methodology/approach Validated numerical simulation was applied to flat test panels. The final design was optimised and verified by validated numerical simulation and verified by testing on a full-scale demonstrator. High-speed camera measurement and non-destructive testing (NDT) results were used for the verification of the numerical models. Findings The test results of flat test panels confirmed the high durability of the composite structure during inclined high-speed impact with a near-real jet inlet load boundary condition. Research limitations/implications Owing to the sensitivity of the composite material on technology production, the results are limited by the material used and the production technology. Practical implications The application of flat test panels for the verification and tuning of numerical models allows optimised final design of the air inlet and reduces the risk of structural non-compliance during verification tests. Originality/value Numerical models were verified for simulation of the real composite structure based on high-speed camera results and NDT inspection after impact. The proposed numerical model was simplified for application in a real complex design and reduced calculation time.

Application of bird-strike verified analysis for the design of fast helicopter composite cowling

“…The required impact velocity was achieved using a properly pressurized air gun-type pressure vessel. The real bird projectiles (chicken) were used during the experimental verification according to airworthiness requirements (Doubrava et al, 2019). The weight of the bird projectile was 1 kg (European Safety Agency, 2012).…”

“…The tests and analysis were initiated using low impact energy tests on small test specimens according to the procedures given in ASTM D7136M (ASTM D7136M-20, 2020) and can be expanded to high-speed impact tests on flat test specimens to verify the manufacture and performance of a complexly shaped part. The flat and simple curved test specimen used in the high-speed impact resistance verification tests was designed to provide confirmation of the performance of the selected composite material and to assist in the finite element (FE) modelling of the global structure (Doubrava et al, 2019). All numerical models were calibrated based on experimental results gathered with a visual observation toward damage initiation and propagation behaviours.…”

Bird strike analysis of new composite inlet for tilt rotor aircraft

“…The principal objective of the present work is to provide a more universal experimental procedure, applicable e.g., to other types of materials or production technologies. Validated numerical simulation will allow the final prototype design, and its manufacturing, to be optimal and satisfy the certification requirements [19]. The testing program was established to assist in the selection of composite material and optimized lay-up from the point of view of energy absorption from bird impacts on the composite inlet for a new generation of tilt-rotor aircraft.…”

Verification and application of bird strike analysis for the design of high-speed helicopter composite cowlings

“…The tests and analysis were initiated using low impact energy tests on small test specimens according to the procedures given in ASTM D7136M [5] and can be expanded to high-speed impact tests on flat test specimens to verify the manufacture and performance of a complexly shaped part. The flat and simple curved test specimen used in the high-speed impact resistance verification tests was designed to provide confirmation of the performance of the selected composite material and to assist in the finite element modelling of the global structure [6]. All numerical models were calibrated based on experimental results gathered with an visual observation toward damage initiation and propagation behaviours.…”