Imperial College London

ProfessorGeorgeWebster

Faculty of EngineeringDepartment of Mechanical Engineering

Distinguished Research Fellow
 
 
 
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Contact

 

+44 (0)20 7594 7018g.webster

 
 
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Assistant

 

Miss Valerie Crawford +44 (0)20 7594 7083

 
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Location

 

759City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

137 results found

Mehmanparast A, Davies CM, Webster GA, Nikbin KMet al., 2014, Creep crack growth rate predictions in 316H steel using stress dependent creep ductility, Materials at High Temperatures, Vol: 31, Pages: 84-94, ISSN: 0960-3409

Short and long term trends in creep crack growth (CCG) rate data over test times of 500–30 000 h are available for Austenitic Type 316H stainless steel at 550°C using compact tension, C(T), specimens. The relationship between CCG rate and its dependence on creep ductility, strain rate and plastic strain levels has been examined. Uniaxial creep data from a number of batches of 316H stainless steel, over the temperature range 550–750°C, have been collected and analysed. Power-law correlations have been determined between the creep ductility, creep rupture times and average creep strain rate data with stress σ normalised by flow stress σ0·2 over the range 0·2<σ/σ0·2<3 for uniaxial creep tests times between 100 and 100 000 h. Creep ductility exhibits upper shelf and lower shelf values which are joined by a stress dependent transition region. The creep strain rate and creep rupture exponents have been correlated with stress using a two-stage power-law fit over the stress range 0·2<σ/σ0·2<3 for temperatures between 550 and 750°C, where it is known that power-law creep dominates. For temperature and stress ranges where no data are currently available, the data trend lines have been extrapolated to provide predictions over the full stress range. A stress dependent creep ductility and strain rate model has been implemented in a ductility exhaustion constraint based damage model using finite element (FE) analysis to predict CCG rates in 316H stainless steel at 550°C. The predicted CCG results are compared to analytical constant creep ductility CCG models (termed NSW models), assuming both plane stress and plane strain conditions, and validated against long and short term CCG test data at 550°C. Good agreement has been found between the FE predicted CCG trends and the available experimental data over a wide stress range although it has been shown tha

Journal article

Mehmanparast A, Davies CM, Nikbin KM, Webster GAet al., 2014, CREEP CRACK GROWTH PREDICTIONS IN 316H STEEL OVER A WIDE RANGE OF STRESSES AND TEMPERATURES, ASME 2014 Pressure Vessels and Piping Conference (PVP-2014), Publisher: AMER SOC MECHANICAL ENGINEERS

Conference paper

Tarnowski KM, Davies CM, Webster GA, Dean DWet al., 2014, PREDICTIONS OF CREEP CRACK INITIATION PERIODS IN PRE-COMPRESSED 316H STAINLESS STEEL, ASME Pressure Vessels and Piping Conference (PVP-2013), Publisher: AMER SOC MECHANICAL ENGINEERS

Conference paper

Webster GA, Davies CM, Nikbin KM, 2011, Prediction of creep crack growth in the presence of residual stress, MATERIALS AT HIGH TEMPERATURES, Vol: 28, Pages: 165-171, ISSN: 0960-3409

Journal article

Wasmer K, Nikbin KM, Webster GA, 2010, Influence of reference stress formulae on creep and creep-fatigue crack initiation and growth prediction in plate components, INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING, Vol: 87, Pages: 447-456, ISSN: 0308-0161

Journal article

Webster GA, Davies CM, Nikbin KM, 2010, Assessment of creep crack growth due to stress relief, INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, Vol: 47, Pages: 881-886, ISSN: 0020-7683

Journal article

Webster GA, Dean DW, Spindler MW, Smith NGet al., 2010, METHODS FOR DETERMINING CREEP DAMAGE AND CREEP-FATIGUE CRACK GROWTH INCUBATION IN AUSTENITIC STAINLESS STEEL, Pressure Vessels and Piping Conference of the American-Society-of-Mechanical-Engineers, Publisher: AMER SOC MECHANICAL ENGINEERS, Pages: 671-683

Conference paper

Davies CM, Webster GA, Nikbin KM, 2010, PREDICTIONS OF CREEP CRACK INITIATION PERIODS, ASME Pressure Vessels and Piping Division/K-PVP Conference, Publisher: AMER SOC MECHANICAL ENGINEERS, Pages: 313-322

Conference paper

Skelton RP, Webster GA, 2009, Extensometer probe indentation during low-cycle fatigue of plain and circumferentially notched cylindrical bars at 550 degrees C, INTERNATIONAL JOURNAL OF FATIGUE, Vol: 31, Pages: 1505-1516, ISSN: 0142-1123

Journal article

Davies CM, O'Dowd NP, Nikbin KM, Webster GAet al., 2007, An analytical and computational study of crack initiation under transient creep conditions, INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, Vol: 44, Pages: 1823-1843, ISSN: 0020-7683

Journal article

Davies CM, Mueller F, Nikbin KM, O'Dowd NP, Webster GAet al., 2007, Analysis of creep crack initiation and growth in different geometries for 316H and carbon manganese steels, 5th International ASTM/ESIS Symposium on Fatigue and Fracture, Publisher: AMER SOCIETY TESTING AND MATERIALS, Pages: 115-+, ISSN: 0066-0558

Conference paper

Wasmer K, Nikbin KM, Webster GA, 2007, Prediction of scatter in creep crack growth data from creep failure strain properties, 5th International ASTM/ESIS Symposium on Fatigue and Fracture, Publisher: AMER SOCIETY TESTING AND MATERIALS, Pages: 102-+, ISSN: 0066-0558

Conference paper

Webster GA, 2007, Trends in high temperature structural integrity assessment, 5th International ASTM/ESIS Symposium on Fatigue and Fracture, Publisher: AMER SOCIETY TESTING AND MATERIALS, Pages: 3-20, ISSN: 0066-0558

Conference paper

Yatomi M, O'Dowd NP, Nikbin KM, Webster GAet al., 2006, Theoretical and numerical modelling of creep crack growth in a carbon-manganese steel, ENGINEERING FRACTURE MECHANICS, Vol: 73, Pages: 1158-1175, ISSN: 0013-7944

Journal article

Skelton RP, Webster GA, 2006, Axial and diametral cyclic stress-strain response in plain and circumferentially notched cylindrical bars at 550 degrees C, JOURNAL OF STRAIN ANALYSIS FOR ENGINEERING DESIGN, Vol: 41, Pages: 265-286, ISSN: 0309-3247

Journal article

Davies CM, Nikbin KA, O'Dowd NP, Webster GAet al., 2006, Prediction of crack initiation times for high temperature lifetime assessments, 8th International Conference on Engineering Structural Integrity Assessment, Publisher: EMAS PUBL LTD, Pages: 309-320

Conference paper

Davies CM, O'Dowd NP, Nikbin KM, Webster GA, Biglari Fet al., 2005, Comparison of methods for obtaining crack-tip stress distributions in an elastic-plastic material, JOURNAL OF STRAIN ANALYSIS FOR ENGINEERING DESIGN, Vol: 40, Pages: 431-450, ISSN: 0309-3247

Journal article

Wasmer K, Nikbin KM, Webster GA, 2005, Sensitivity of creep crack initiation and growth in plates to material properties variations, Fatigue and Fracture Mechanics, Vol: 34, Pages: 457-471, ISSN: 1040-1695

Journal article

Wasmer K, Nikbin KM, Webster GA, 2005, Sensitivity of creep crack initiation and growth in plates to material properties variations, Fatigue and Fracture Mechanics, Vol: 34, Pages: 457-471, ISSN: 1040-1695

Journal article

Webster GA, Nikbin KM, Biglari F, 2004, Finite element analysis of notched bar skeletal point stresses and dimension changes due to creep, Meeting on High Temperature Multiaxial Creep Testing and Interpretation of the ESIS TC, Publisher: BLACKWELL PUBLISHING LTD, Pages: 297-303, ISSN: 8756-758X

Conference paper

Webster GA, Holdsworth SR, Loveday MS, Nikbin K, Perrin IJ, Purper H, Skelton RP, Spindler MWet al., 2004, A code of practice for conducting notched bar creep tests and for interpreting the data, Fatigue & Fracture of Engineering Materials and Structures, Vol: 27, Pages: 319-342, ISSN: 8756-758X

Journal article

Skelton RP, Goodall IW, Webster GA, Spindler MWet al., 2003, Factors affecting reheat cracking in the HAZ of austenitic steel weldments, INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING, Vol: 80, Pages: 441-451, ISSN: 0308-0161

Journal article

Biglari F, Nikbin KM, Goodall IW, Webster GAet al., 2003, Determination of fracture mechanics parameters J and C* by finite element and reference stress methods for a semi-elliptical flaw in a plate, INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING, Vol: 80, Pages: 565-571, ISSN: 0308-0161

Journal article

Wimpory RC, May PS, O'Dowd NP, Webster GA, Smith DJ, Kingston Eet al., 2003, Measurement of residual stresses in T-plate weldments, JOURNAL OF STRAIN ANALYSIS FOR ENGINEERING DESIGN, Vol: 38, Pages: 349-365, ISSN: 0309-3247

Journal article

Nikbin KM, Yatomi M, Wasmer K, Webster GAet al., 2003, Probabilistic analysis of creep crack initiation and growth in pipe components, INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING, Vol: 80, Pages: 585-595, ISSN: 0308-0161

Journal article

Wasmer K, Nikbin KM, Webster GA, 2003, Creep crack initiation and growth in thick section steel pipes under internal pressure, INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING, Vol: 80, Pages: 489-498, ISSN: 0308-0161

Journal article

Wimpory RC, Stefanescu D, Smith DJ, O'Dowd NP, Webster GA, May PS, Kingston Eet al., 2003, Residual stress distributions in welded ferritic steel T-plate joints, Journal of Neutron Research, Vol: 11, Pages: 201-208, ISSN: 1023-8166

Journal article

Webster GA, Wimpory RC, 2002, Development of procedures for the measurement of residual stress by neutron diffraction, International Conference on Neutron Scattering, Publisher: SPRINGER-VERLAG, Pages: S1227-S1229, ISSN: 0947-8396

Conference paper

Bonner NW, Wimpory RC, Webster GA, Fry AT, Kandil FAet al., 2002, Measurement of residual stress through a shot peened surface subjected to successive material removal, Zurich-Uetikon, 6th European conference on residual stresses (ECRS 6), Coimbra, Portugal, 10 - 12 July 2002, Publisher: Trans Tech Publications, Pages: 653-658

Conference paper

Wasmer K, Nikbin KM, Webster GA, 2002, A sensitivity study of creep crack growth in pipes (PVP2002-1191), New and emerging computational methods: applications to fracture, damage and reliability, 2002, Publisher: ASME, Pages: 17-24

Conference paper

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