Failure analysis of an aluminum extrusion aircraft wing component

Abstract

Purpose The purpose of this paper is to deal with the failure analysis of a fractured spar stiffener, extruded from 7075-T6 aluminum alloy, which was found in the central wing, trailing edge structure of a military transport aircraft. The previous loading history and the dominant environmental factors (corrosive and humid atmosphere, water entrapment, etc.) suggest corrosion and fatigue as the principal failure modes, synergistically acting on the wing component. Design/methodology/approach This study presents the failure analysis concentrated on finding evidence of failure mechanisms and plausible root-cause(s) of the fractured spar stiffener. Chemical analysis, stereo and scanning electron microscopy, as well as finite element analysis employed as the main analytical tools for material characterization and failure investigation. Findings The overall evaluation of the findings suggest that the failure caused by a synergy of two mechanisms; a crack initiated in the longitudinal, extrusion direction by an environmentally assisted corrosion attack, then propagated by the superimposed transverse stress field, branched/deflected due to a low crack driving force and extended in a transverse path through a high cycle fatigue process. Finally, the complete fracture occurred as fast fracture, resulted by a ductile overload. Originality/value This paper deals with an industrial damage case study, providing analysis and modeling from structural engineering standpoint. The aforementioned findings concerning the fractured aircraft component allow gaining a deeper knowledge about the mechanisms of crack initiation and propagation which, in turn, can produce a valuable feedback to design, inspection and maintenance procedures. This includes a modified heat treatment from T6 to T73 temper for the redesigned component.

Researching on the Effect of Input Parameters on the Quality and Manufacturability of 3D-Printed Cellular Samples from Nylon 12 CF in Synergy with Testing Their Behavior in Bending

“…Based on the energy approach, the three-point flexural test can also be used to determine the modulus of elasticity, E (Young's modulus, MPa), the bending stiffness (N/m) and the flexural rigidity (Nm 2 ). If the elastic deflection, ue, is expressed by the equation 𝑢 = (mm), (6) then Young's modulus can be expressed as 𝐸 = (MPa), (7) where Fe denotes the applied elastic force (N), l is a supporting span and I is the area moment of inertia. The moduli of elasticity in flexure for individual types of cellular structured beams were calculated in accordance with Equation (7), and they are listed in Table 7.…”

“…A cellular structure can be considered a medium that consists of a solid and a gas phase. The latter consists of an interconnected network of rigid struts or plates that form the edge0s and surfaces of the cells [6][7][8][9].…”

Analisis Kegagalan Material Pada Sayap Pesawat Terbang (Review)

“…3.2 Pemeriksaan Visual dan Makro-fraktograf Selain melakukan pemeriksaan visual, dilakukan serangkaian pengujian lainnya baik yang tidak merusak maupun merusak, berupa pengujian SEM, analisis termal-mekanik, kalorimeter pemindaian diferensial, dan pengujian kelelahan [13]. Analisis fraktografi digunakan sebagai teknik analisis utama untuk memperoleh bukti yang cukup mengenai mekanisme patah yang berevolusi dan proses yang terjadi terhadap komponen [12].…”

“…Gambar 2. Pengamatan Makro Fraktografi mengungkapkan mekanisme kegagalan dan berkontribusi pada fraktur akhir [12] Pada Gambar 2(a) menunjukkan morfologi permukaan rekahan secara keseluruhan yang disebabkan oleh IGC atau SCC yang dikenal dengan retak intergranular karena kelemahan mikrostruktur yang melekat, kemudian pada Gambar 2(b) merupakan area degradasi kasar, lalu Gambar 2(c) menunjukkan area fatigue fracture dan panah hitam menunjukkan arah kelelahan dan Gambar 2(d) yaitu area degradasi permukaan yang menunjukkan lubang-lubang dan rongga yang terisolasi dan bertindak sebagai pemicu stress dan merupakan proses degradasi kimia atau elektrokimia, lalu Gambar 2(e) yaitu makrograf yang menggambarkan garis kasar struktur butir komponen Al.…”

“…Potongan yang hampir tidak berbentuk dan rusak parah akibat gesekan-gesekan serta tingkat plastisitas yang terbatas pada zona geser patahan cepat yang kemungkinan besar merupakan bagian dari kegagalan akhir yang dihasilkan oleh beban lebih elastis (Gambar 9) Gambar 3. Pengamatan Makro Fraktografi mengungkapkan mekanisme kegagalan dan berkontribusi pada fraktur akhir [12] Gambar 3(a) merupakan Mikrograf SEM yang dekat dengan area tepi granular kasar yang memiliki pola patahan kasar, sedangkan Gambar 3(b) merupakan rincian dari Gambar 3(a) yaitu tindakan retakan karena kontak fracture dan pola tekstur, kemungkinan didapatkan dari proses deformasi.…”