Bridged crack approach to model materials self-healing

The subject of this paper is the mathematical modelling of the crack self-healing process. For self-healing modeling of cracked structures the bridged crack approach is used. In the frames of this approach is assumed: 1) there is a crack in a structure after service loading; 2) there are bonds between surfaces of a crack (which are induced by a...

The influence of testing parameters on stress corrosion crack growth in the high strength aluminium alloy 7010-T651

An interlaboratory testing programme to evaluate the rising displacement test for stress corrosion crack (SCO growth investigations was carried out within the framework of the "Measurements and Testing" programme of the European Community under BCR contract nr. MATI CT 930038. The contribution of the NLR to the project consisted of testing of...

Damage tolerance analyses of bolt/nut assemblies

Probably one of the most challenging problems in fracture mechanics is related to its application to fastener and joints. By nature, not only the quality such as material, manufacturing and mounting processes, of the fasteners are playing a role, but also the stiffness, surface conditions and geometry of the parts are to be considered. Moreover,...

Outdoor corrosion testing of aluminium-lithium alloys

Outdoor corrosion and stress corrosion tests were conducted on Al-Li plate and sheet materials for 3 and almost 5 years respectively. The results can be summarized as follows: Corrosion: Peak aged XXXA-T651 (8090-T651) exhibited greater exfoliation corrosion resistance than 2024-T351 and 2324-T39 plate. 2091-T3 and 2024-T3 sheet were found to be...

Prediction of fatigue crack growth

As an introduction the practical significance of fatigue crack growth life prediction is related to the service life, the inspection period and the fracture control requirements. Then different aspects of fatigue crack growth in metallic materials are discussed in more detail. Important effects such as chemical environment, short cracks, crack...

Finite element analyses of stable crack growh in thin sheet material

This study deals with fracture mechanics aspects of mode 1 crack growth under montonically increasing (quasi-static) loads. Using the finite element method stable crack growth and the plastic deformation fields associated with this process are analyzed. A two parameter approach is proposed for a description of initiation and subsequent stable...

Residual strength of bonded stiffened panels: prediction and experimental verification

This report presents results of residual strength calculations, carried out on cracked panel configurations of various designs and provided with bonded stiffeners. The calculations were carried out using the computer program BOND. The results of these calculations are compared with results of residual strength tests, performed on panels of...

Heat treatment studies of aluminium alloy type 7050 forgings. Interim report no. 3: Corroded-specimen fatigue tests and SCC propagation tests

The influence of previous corrosion on the fatigue life was investigated. It was foimd that a slight corrosive attack could drastically reduce the fatigue life. The damaging effect of corrosion was greater for the alloy AA 7050 than for AZ 74.61. It could be established that fatigue cracks initiated from various corrosion pits. A second series...

Residual strength of the aluminium alloy 7475-T76 at low temperatures

Residual strength tests have heen performed, on 300 mm wide centrecracked panels of various thicknesses, at room temperature and at -50 C. During the tests, stable crack growth was filmed and recorded with the electric potential method. Fracture toughness was determined using the method of Feddersen.