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 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...

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...

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...