Damage Tolerance of Metallic Structures: Analysis Methods and Applications

1984 ◽  
Keyword(s):  
Damage Tolerance ◽  
Metallic Structures ◽  
Analysis Methods

Recently-Developed Aluminium Solutions for Aerospace Applications

2006 ◽  
Vol 519-521 ◽  
pp. 1271-1278 ◽  
Author(s):  
Timothy Warner
Keyword(s):  
New Technologies ◽  
Damage Tolerance ◽  
Grain Structure ◽  
Space Applications ◽  
Metallic Structures ◽  
Performance Improvements ◽  
The Past ◽  
Aerospace Applications ◽  
Aerospace Alloys ◽  
Damage Tolerant

Two principal approaches are available to materials’ engineers to improve the overall cost-weight balance of metallic airframe structures: improving alloy performance and optimising materials’ utilisation. Although both approaches have been successful in the past, they are most effective when applied concomitantly. The Aluminium industry has a long record of improving aerospace alloys’ performance. Nevertheless, even in apparently well-explored alloy systems such as the 7xxx family, products with improved damage tolerance-strength balances have recently been developed, thanks to an improved understanding of the optimum Zn-Mg-Cu combinations for the required property balances but also to developments in casting capability. Novel dispersoids and dispersoid combinations have enabled further improvements of the performance of existing alloy families. For example, appropriate Sc and Zr additions have a significant impact on the grain structure of 2xxx alloys and thus on performance. Another high potential approach for alloy performance improvements is the optimisation of Al-Cu-Li-(Mg-Ag-Zn) alloys. These so-called “third generation Al-Li alloys” were principally developed for military and space applications; in order to meet the demands of future commercial airframes, more damage tolerant variants are being developed. AA2198 and AA2050 are used to illustrate the potential of these higher damage tolerance Al-Cu-Li alloys. However, materials performance improvements are only part of the potential developments of metallic solutions for airframes. Further gains of a similar magnitude in component weight and cost can be achieved by applying new technologies and new design solutions to metallic structures. The future of metallic airframes will depend on the concomitant application of both these approaches.

Fracture mechanical behaviour of laser beam-welded AA2198 butt joints and integral structures

2015 ◽  
Vol 6 (6) ◽  
pp. 787-798 ◽  
Author(s):  
Nikolai Kashaev ◽  
Stefan Riekehr ◽  
Kay Erdmann ◽  
Alexandre Amorim Carvalho ◽  
Maxim Nurgaliev ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Laser Beam ◽  
Damage Tolerance ◽  
Fracture Behaviour ◽  
Butt Joints ◽  
Metallic Structures ◽  
Mechanical Fracture ◽  
Content Type ◽  
Integral Structures

Purpose – Composite materials and metallic structures already compete for the next generation of single-aisle aircraft. Despite the good mechanical properties of composite materials metallic structures offer challenging properties and high cost effectiveness via the automation in manufacturing, especially when metallic structures will be welded. In this domain, metallic aircraft structures will require weight savings of approximately 20 per cent to increase the efficiency and reduce the CO2 emission by the same amount. Laser beam welding of high-strength Al-Li alloy AA2198 represents a promising method of providing a breakthrough response to the challenges of lightweight design in aircraft applications. The key factor for the application of laser-welded AA2198 structures is the availability of reliable data for the assessment of their damage tolerance behaviour. The paper aims to discuss these issues. Design/methodology/approach – In the presented research, the mechanical properties concerning the quasi-static tensile and fracture toughness (R-curve) of laser beam-welded AA2198 butt joints are investigated. In the next step, a systematic analysis to clarify the deformation and fracture behaviour of the laser beam-welded AA2198 four-stringer panels is conducted. Findings – AA2198 offers better resistance against fracture than the well-known AA2024 alloy. It is possible to weld AA2198 with good results, and the welds also exhibit a higher fracture resistance than AA2024 base material (BM). Welded AA2198 four-stringer panels exhibit a residual strength behaviour superior to that of the flat BM panel. Originality/value – The present study is undertaken on the third-generation airframe-quality Al-Li alloy AA2198 with the main emphasis to investigate the mechanical fracture behaviour of AA2198 BMs, laser beam-welded joints and laser beam-welded integral structures. Studies investigating the damage tolerance of welded integral structures of Al-Li alloys are scarce.

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