The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Philippa Reed - One of the best experts on this subject based on the ideXlab platform.
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An effective method to investigate short crack Growth Behaviour by reverse bending testing
International Journal of Fatigue, 2007Co-Authors: Nong Gao, K. J. Miller, M. W. Brown, Philippa ReedAbstract:Abstract A reverse bending rig has the advantage of relatively cheap construction compared with servo-controlled machines, and its robustness and reliability make it ideally suited to long-term testing programmes. In this paper, the details of the mechanical mechanism of a bending rig, the methods of its strain measurement and stress–strain analysis have been presented. A series of tests has been carried out to investigate short crack Growth Behaviour of AISI type 316 stainless steel under creep–fatigue conditions at 550 °C. The advantage of this type of test allows a comparison to be made, on one specimen, of the influence of both tensile and compressive hold periods on crack Growth Behaviour. It has been shown that predominantly intergranular long cracks form on the tensile side and transgranular short cracks on the compressive side and these are a prominent feature between 0.9% and 2.5% strain range.
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An investigation of crack Growth Behaviour under creep-fatigue condition
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2005Co-Authors: Nong Gao, Malcolm Brown, K. J. Miller, Philippa ReedAbstract:Abstract An investigation has been carried out on short crack Growth Behaviour of AISI type 316 stainless steel under creep-fatigue conditions at 550 °C for high strain ranges of 0.9–2.5% and 60 min hold-time using a high temperature reverse bending rig. The analysis revealed the dominant failure characteristics to be the individual initiation and Growth Behaviour of many minor cracks in Stage I, and their subsequent coalescence in Stage II. Increasing the strain range increases the number of minor cracks and promotes the process of minor crack coalescence. Predominantly intergranular long cracks are found to form under tensile stresses and transgranular short cracks under compressive stresses.
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Short fatigue crack Growth Behaviour in plain bearings
1999Co-Authors: M.r. Joyce, Stavros Syngellakis, Philippa ReedAbstract:Plain bearings have been in use for many years, over this time their design and the choice of materials used in their construction has been continuously improved. They are currently used as mian and con-rod big end bearings in automotive engines. The service conditions for automotive bearings are becoming more severe with new engine designs, and it is important that new bearing materials are designed to provide the longest possible operating life at these higher loads, and at an economic cost. In order to do this it is necessary to study both the loading conditions and the fatigue failure Behaviour of plain bearings, with a view to optimising their design and the use of appropriate materials. The aim of our research is to evaluate early fatigue initiation and short crack Growth Behaviour in bearing materials to establish the key parameters controlling early crack propagation, hence providing material optimisation data. The approach taken combines experimental fatigue evaluation of the bearing lining and finite element modelling of the local microstructure.
Gerald Pinter - One of the best experts on this subject based on the ideXlab platform.
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Determination of slow crack Growth Behaviour of polyethylene pressure pipes with cracked round bar test
Polymer Testing, 2014Co-Authors: Thomas R. Kratochvilla, Andreas Frank, Gerald PinterAbstract:Abstract In this work, a short time test method to determine the slow crack Growth Behaviour of samples made out of pipes was evaluated. The cracked round bar (CRB) method used provides results below 48 h with brittle fracture surfaces, which indicates the type of slow crack Growth failure. To evaluate the usability of the method, the results were compared with well-known tests such as notch pipe test, 2 notch creep test and instrumented Charpy impact tests. The results indicate that the CRB test can be used to predict long term slow crack Growth Behaviour of PE pipes.
Gilbert Fantozzi - One of the best experts on this subject based on the ideXlab platform.
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Slow crack Growth Behaviour of hydroxyapatite ceramics
Biomaterials, 2017Co-Authors: Chahid Benaqqa, Malika Saadaoui, Jérôme Chevalier, Gilbert FantozziAbstract:Among materials for medical applications, hydroxyapatite is one of the best candidates in orthopedics, since it exhibits a composition similar to the mineral part of bone. Double torsion technique was here performed to investigate slow crack Growth Behaviour of dense hydroxyapatite materials. Crack rate, V, versus stress intensity factor, KI, laws were obtained for different environments and processing conditions. Stress assisted corrosion by water molecules in oxide ceramics is generally responsible for slow crack Growth. The different propagation stages obtained here could be analyzed in relation to this process. The presence of a threshold defining a safety range of use was also observed. Hydroxyapatite ceramics appear to be very sensitive to slow crack Growth, crack propagation occurring even at very low KI. This can be explained by the fact that they contain hydroxyl groups (HAP: Ca10(PO4)6(OH)2), favouring water adsorption on the crack surface and thus a strong decrease of surface energy in the presence of water. This study demonstrates that processing conditions must be carefully controlled, specially sintering temperature, which plays a key role on VKI laws. Sintering at 50 °C above or below the optimal temperature, for example, may shift the VKI law towards very low stress intensity factors. The influence of ageing is finally discussed.
Thomas R. Kratochvilla - One of the best experts on this subject based on the ideXlab platform.
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Determination of slow crack Growth Behaviour of polyethylene pressure pipes with cracked round bar test
Polymer Testing, 2014Co-Authors: Thomas R. Kratochvilla, Andreas Frank, Gerald PinterAbstract:Abstract In this work, a short time test method to determine the slow crack Growth Behaviour of samples made out of pipes was evaluated. The cracked round bar (CRB) method used provides results below 48 h with brittle fracture surfaces, which indicates the type of slow crack Growth failure. To evaluate the usability of the method, the results were compared with well-known tests such as notch pipe test, 2 notch creep test and instrumented Charpy impact tests. The results indicate that the CRB test can be used to predict long term slow crack Growth Behaviour of PE pipes.
Necati Ataberk - One of the best experts on this subject based on the ideXlab platform.
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Fatigue crack Growth Behaviour in ferritic ductile iron with surface crack under reverse bending
Computational Materials Science, 2007Co-Authors: Ahmet Akdemir, Mehmet Tekeli, Necati AtaberkAbstract:Abstract In this paper, fatigue crack Growth Behaviour of ferritic ductile cast iron containing 3.26%C and 4.18%Si was studied. Materials were produced and reverse bending fatigue test specimens were cut from the casting with the thickness of 24 mm. Process annealing heat treatment was applied to the specimens. Semi-elliptical surface cracks were formed and reverse bending fatigue tests were carried out. Fatigue crack Growth rates were determined. Stress intensity factors (Δ K ) were obtained by Newman–Raju’s equations. Fatigue crack Growth material constants ( n and c ) were determined in Paris–Erdogan’s equation. Fractured surfaces of the specimens were examined by using SEM.
