Location of Repository

This thesis is concerned with the development of computational procedures in the assessment of the structural integrity and lifetime of cracked bodies subjected to cyclic variable loads and temperatures.\ud The foundation of these techniques is the Linear Matching Method (LMM), related to the methods of elastic compensation and Gloss r-node, used in design calculations for a number of years. It involves matching the behaviours of a non-linear material to that of a linear material, whereby sequences of linear solutions with spatially varying linear moduli are produced. The developed iterative programming algorithms, implemented within the finite element scheme, ABAQUS, would then generate a monotonically reducing sequence of upper bounds, ultimately converging to the least upper bound loads.\ud In their applications, the significance of these programming methods is two-fold. The first is the investigations into the overall behaviour of cracked structures under the combined actions of mechanical and thermal loads. The numerical limit loads and ratchet limits so identified, which describe the onset of plastic collapse and the unlimited accumulation of plastic strains respectively, were found to be stable, with good converged solutions achieved within 40-60 iterations. The analyses also revealed the insensitivity of the ratchet boundaries to cyclic hardening, as the perfectly plastic and complete cyclic hardening limits yielded almost identical results.\ud The other is the examination into the relationship between the near crack tip fields and the cyclic loading histories, in creep and plasticity conditions. It was established that the HRR field criterion is an appropriate representation of the behaviour of the mechanically and thermally induced crack tip fields. This enabled the crack tip fracture criterion to be evaluated in all conditions, with the observed phenomenon described by two distinct behaviours; strongly influenced by the effect of the elastic stress intensity factor and the reference stress respectively.\ud The analyses conducted demonstrated the capability of the adopted numerical procedures in appraising the behaviour of cracked structures under cyclic loading histories, with the conservativeness of current solution procedures in R5 clearly evident in the results enclosed

Publisher: University of Leicester

Year: 2003

OAI identifier:
oai:lra.le.ac.uk:2381/8248

Provided by:
Leicester Research Archive

- 5 "An iterative elastic analysis procedurefor establishing lower bound limit loads",
- (1985). 5 "Application of the kinematical theorem to rolling and slidingpoint contacts",
- (1994). 5 "Computation of shakedown limits for structural components,
- 5 "Creepfatigue crack growth: Crack tipfields and growth mechanisms",
- (1971). 5 "Design for creep ",
- 5 "Efficient evaluation of stress intensity technique ", Computers and Structures, Vol 79, pp 2705-2715,2001. factors using virtual crack extension
- (1997). 5 "High temperature crack tipfields in cyclically hardening engineering alloys
- (1990). 5 "Mechanics ofsolid materials",
- 5 "Review of limit loads ofstructures containing defects, 3rd edition", Central Electricity Generating Board (CEGB) internal report.
- (1968). 9 "A path independent integral and the approximate analysis of strain concentration by notches and cracks ",
- 9 "Evaluation of deformation or load control of stresses under inelastic conditions using the elasticfinite element stress analysis",
- (1992). 9 "Finite elements in solids and structures",
- (1994). 9 "High temperature component life assessment',
- (1975). 9 "Plasticity: Fundamentals and general results",
- 9 "Somejurther results on J-integral analysis and estimates Fracture Toughness,
- 9 "Thermal-stress ratchet mechanism in pressure vessels
- (2001). A direct method for the evaluation of properties of the cyclic behaviour of structures ",
- An extended shakedown theory for structures that suffer cyclic thermal loading",
- An extended shakedown theory for structures that suffer cyclic thermal loadingý', Part 2,
- (2002). An introduction to direct methodsfor limit and shakedown analysis", In
- Application of the kinematical theorem to pavement design", In
- Approximate non-linear ftacture mechanics calculations using reference stress techniques ",
- (1990). Boiler andpressure vessel code. Code case: Nuclear components, Case N-47-29, Class I components in elevated temperature service", Section 11, Division Iý
- (2000). Computational modelling ofshakedown",
- Crack tipfinite elements are
- Deformation boundsfor the Bailey Orowan theory of creep
- (1985). Design and construction rulesfor mechanical components ofFBR nuclear islands RCC-MR, AFCEN,
- Design i. mplications of recent advances in elevated temperature bounding technique Report sponsored by the sub-committee on
- (1996). Design rules for cylindrical shells subjected to axisymmetric temperature histories",
- (1926). Die Tragrahigkeit Statisch Unbestimmter Tragwerke aus Stahl bei Beliebig Haufig Weiderholter Belastuni', Julius Springer,
- Dynamic shakedown and bounding theory for a class of non-linear hardening discrete structural models "
- (1983). Effect of creep recovery and hardening on stress and strain rate fields near a crack tip in creeping materials ",
- (1978). Elementary engineeringfracture mechanics Sitjhoff and Noordholf, Alphen aan den Rijn,
- (1969). Engineering plasticity",
- Finite element modelingfor limit analysis by the Elastic Compensation Method',
- (1998). Finite element state solutions: Accuracy of an iterative method',
- (1985). General review of available results ofprogressive tests of structures and structural components ", In: Ratchetting in the creep range by
- (1991). High-temperatureflaw assessment procedure ",
- Integrity assessmentfor 3D tube-plate using linear matching method, Report 2: Creep relaxation and reverse-plasticity ",
- (1980). Limit analysis ofstructures at thermal cycling", Sijthoff and Noorhoff, Alpen aan den Rijrn, The Netherlands,
- Limit loads of mechanical components and structures using the Gloss R-node method",
- Mathematical programming methodsfor deformation analysis atplastic collapse", Computers and Structures, Vol 7, pp 599-612,1977. '17
- (2002). Minimum t heorems a nd t he 1 inear m atching m ethodfor b odies ina cyclic s tate of creep ",
- Minimum theorems and iterative solutions methods for creep cyclic loading problems ",
- On numerically accuratefinite element solutions in thefully plastic range
- On the use of isoparametricfinite elements in linearfracture mechanics
- Plane strain deformation near a crack tip in a power law hardening material
- Reference stressfor redistribution time in creep ofstructures Intemational.
- (1987). Shakedown of elastic-plastic structures", P)AN-Polish Scientific Publishers,
- Singular behaviour at the end of a tensile crack in a hardening material"
- Some trends in constitutive equation model development for high temperature behaviour offast-reactor structural alloys Vol 48,
- (1997). Southpointe, 275 Technology Drive,
- The analysis of cyclically loaded structuresfor short cycle times
- (1987). The computation of shakedown limitsfor structural components subjected to variable thermal loading-Brussels diagrams
- The development of high temperature design methods based on reference stresses and bounding theorems ",
- The elastic compensation methodfor limit and shakedown analysis: a review",
- (2002). The linear matching methodfor the evaluation of limit loads, shakedown limits and relatedproblems ",
- Theorie Statisch Unbestimmter Systeme aus Ideal-Plastischem Bastoff Sitzungsberichte der Akadenüe der Wissenschaft,
- Wings under repeated thermal stress
- ý "Assessment of the integrity ofstructures containing defects",
- (1973). ý "Fundamentals offracture mechanics Butterworths,
- ý "Modelling of voids/cracks and their interactions Theoretical and Applied Fracture Mechanics, Vol 38,
- (1983). ý "Tables ofHutchinson-Rice-Rosengren singularfield quantities Brown University Report,
- (1950). ý "The mathematical theory ofplasticity",

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.