Aircraft corrosion and fatigue damage assessment (USAF ASIP Publication)

This paper reviews currently available information on corrosion and fatigue in aircraft as a background to discussing the assessment of corrosion and fatigue damage. The main topics are: - aircraft operating environments and loads - corrosion - fatigue - corrosion and fatigue - corrosion and fatigue damage assessment. Aircraft structures are...

Aircraft corrosion and fatigue damage assessment

This report reviews currently available information on corrosion and fatigue in aircraft as a background to discussing the assessment of corrosion and fatigue damage. The main topics are: * aircraft operating environments and loads * corrosion * fatigue * corrosion and fatigue * corrosion and fatigue damage assessment. Aircraft structures are...

Fractographic examination of specimens from lEPG TA 31 creep tests

The NLR examined by fractography nine ruptured creep specimens supplied by EGT. Three specimens had been tested at 600° C and six specimens had been tested at 650° C. Internal (creep) cracking occured by transgranular microvoid coalescence, which is likely to be characteristic for standard heat treatment Inconel 718. One specimen tested at 600°...

The Methylene Blue adsorption test applied to geomaterials

Review of the application of the Methylene Blue adsorption test (titration spot method) applied to geomaterials (soils and rocks). With this method the Cation Exchange Capacity (CEC) of fine soils or fine grounded rock powder can be determined. Swelling clays have a high CEC and even small quantities (less than 1 mass % can be detected by this...

The use of load enhancement factors in the certification of composite aircraft structures

In the full scale durability and damage tolerance tests of composite aircraft structures, the US and European certification requirements demand among other things that the number of cycles applied are statistically significant and that the influence of the environment has been taken into account. Several certification methods are described which...

Damage tolerance and durability evaluation of aluminium-lithium alloys

New impetus to continued use of alximinium alloys in major structural areas of aircraft has been given by the development of aluminium-lithium alloys. However, qualification of these new materials for service requires extensive testing and evaluation, preferably in international cooperative programmes. The evaluation of aluminium-lithium alloys...

Rock Armouring to unconventional breakwaters: The design implications for rock durability

This paper identifies the need for quantitative durability testing of rock for use on dynamically stable rock armoured slopes. The derivation and use of a suite of engineering tests for rock quality is considered, and the limitations of Simple accept/reject criteria discussed. Recent developments in techniques for the quantification of armour...

Corrosion fatigue crack arrest in aluminium alloys: basic data

Constant amplitude low stress Intensity fatigue crack growth for 2024-T3 and 7475-T761 aluminium alloys In laboratory air, sump tank water and synthetic seawater was Investigated. Corrosion fatigue crack grouwt retardation and arrest occurred In both sump tank water and synthetic seawater, resulting In higher AKth values than In air. Crack...

Loads and damage tolerance for helicopters

This report reviews the applicability of damage tolerance concepts to helicopter structures. After a general discussion of the damage tolerance concept, attention is paid to the specific aspects of the helicopter loading environment. Examples are presented of damage tolerant design, both in metal and in composite structures. However, it is felt...

Lifetime prediction methods for corner cracks at holes

An application of linear elastic fracture mechanics to 3-dimensional crack growth prediction was developed in two phases. In the first phase finite element techniques for accurate stress intensity (S.I.) calculation were evaluated and the Virtual Crack Extension (V.C.E.)-method was selected for further work. In the second phase the process of...

Flight simulation environmental fatigue crack propagation in 2024-T3 and 7475-T761 aluminium

Flight simulation fatigue crack propagation tests on 202U-T3 and 7475-T761 aluminum alloy sheet were carried out using a gust spectrum representative of the load history of an under wing skin in a transport aircraft. The investigation included tests at several design stress levels and in environments of laboratory air and air plus water spray....

Influence of environmental ageing and displacement rate on crack resistance of adhesives, as determined on adhesive bonded TDCB-specimens

Fracture toughness measurements were carried out to test the ageing behaviour of three adhesives in different environments. It was possible to compare and evaluate adhesives and surface pretreatments. It is doubtful whether the derived R-curves could be used for residual strength calculations in certain environments. Phosphoric acid anodizing...