Manufacture of a rotor blade pitch horn using binder yarn fabrics

The use of binder yarn fabrics in rotor blade applications is investigated in this work. A preforming procedure is incorporated in manufacturing, resulting in higher degree of automation and a reduction of process steps. The performance of the process is evaluated with respect to cost savings compared to prepregging technologies

Prediction of crack growth following a single overload in aluminum alloy with sheet and plate microstructure

The fatigue crack growth behavior under constant amplitude and under single overload of 2024 aluminum alloy in sheet and plate product form has been investigated. Constant amplitude fatigue crack growth tests showed superior crack growth resistance of the plate attributed to a pronounced roughness induced crack closure as a result of the coarse and elongated grain structure. Crack growth tests with single overload showed that the retardation effect caused by the overload is not primarily influenced by roughness crack closure at the crack path. In this case, the sheet material with lower yield strength revealed a higher retardation effect than the plate material. The observed crack growth behavior has been simulated with the LTSM-F model, which accounts for retardation of crack growth after an overload due to material strain hardening at the crack front. Dissimilar strain hardening at the crack tip due to different yield strength for the sheet and plate has been considered by means of strength gradients inside the overload plastic zone. The analytical results confirmed the observed material crack growth trends. © 2011 Elsevier Ltd

Fatigue crack growth assessment of corroded aluminum alloys

The fatigue crack growth behaviour of pre-corroded aluminum alloy has been investigated analytically. For this purpose the fatigue crack growth LTSM-F model has been implemented and upgraded to account for the local material properties of the pre-corroded material ahead of the crack tip. In the model the local fracture behaviour at the crack tip of the corroded alloy is governed by the local fracture toughness of the material. The analytical results obtained show good correlation with fatigue crack growth experiments under irregular aircraft service spectra from the literature and demonstrate the significance to consider the degradation of local material properties of structural members including corroded areas. © Springer Science+Business Media B.V. 2009

Preface

The 10th EASN International Conference on "Innovation in Aviation & Space to the Satisfaction of the European Citizens", took place between the 2nd and 4th of September 2020. Due to the COVID pandemic, it was the first time in the history of the EASN Conference series that the event was held virtually. EASN yearly gatherings enhance physical networking and connection among peers, however pivoting from an in-person event into a compelling virtual experience with the same structure as a typical EASN Conference has surely been a challenge for the EASN team. In this frame, the EASN Association was honoured and proud to organize the sole aviation & space related conference during the challenging times of COVID-19 and thus offer a small contribution to Europe’s efforts back to normality

Effect of novel paint removal processes on the fatigue behavior of aluminum alloy 2024

Conventional paint removal processes, based on application of chemicals and abrasion, are becoming inadequate for modern aircraft structures. In addition they are associated with severe environmental problems, mainly due to the production of hazardous waste. Several alternative novel techniques are being developed. However, the aspect of material property degradation due to the application of these new paint removal techniques has not been addressed adequately. The application of laser radiation (carbon dioxide and excimer), as well as plasma etching, has recently been associated with significant ductility deterioration and fatigue life extension. Residual stress measurements, roughness measurements and fractographic analysis were employed in order to rationalize the effect of these novel paint removal processes on the fatigue behavior of aluminum alloy 2024. The observed enhancement of fatigue life is attributed to the development of compressive residual stresses during paint removal processing At low fatigue stresses, the magnitude of the residual stress correlates with the relative enhancement in fatigue life for the three processes investigated. The effect of surface roughening towards decreasing fatigue life is surpassed by the effect of residual stresses in extending fatigue life. Finally, the decrease of toughness and associated damage tolerance ability which follows the application of paint removal processes has been confirmed by fractographic measurements. (C) 1998 Elsevier Science S.A

Effect of corrosion on the mechanical behaviour of aircraft aluminum alloys

A brief overview of aircraft aluminum alloys, along with a discussion of their susceptibility to corrosion and the various types of corrosion damage is provided. The significance of the effect of corrosion on mechanical behaviour under static and fatigue loading conditions is demonstrated. For this purpose, experimental results concerning the tensile and fatigue behaviour of pre-corroded aluminum specimens are presented. The results, which are supported by metallographic observations, are discussed in terms of the synergetic effect of corrosion damage and corrosion-induced hydrogen embrittlement of the material. The fatigue crack growth and fracture behaviour of pre-corroded aluminum alloys is also examined. Experimental results demonstrate the essential influence of prior corrosion exposure on the material's damage tolerance performance. Corrosion, being a time-dependent and diffusion-controlled process degrades the material properties in a local scale. To describe the fracture behaviour of pre-corroded aluminum alloys, the concept of local fracture toughness is introduced. A mechanical model for assessing the local fracture toughness is presented and incorporated into a fatigue crack growth code for fatigue life assessment of pre-corroded material under irregular loading. © 2009 Woodhead Publishing Limited. All rights reserved