Modelling of creep, ratchetting and failure in Structural component subjected to thermo-mechanical loading

Experiments have been described in which copper components have been subjected to combined cyclic thermal and constant mechanical loading. Two thermal cycles were employed leading to predominantly cyclic plasticity damage and balanced creep – cyclic plasticity damage loading cycles. The combined loading led to component ratchetting and ultimately to failure. Continuum damage-based finite element techniques have been developed for combined cyclic plasticity, creep and ratchetting in components subjected to thermo-mechanical loading. Cycle jumping techniques have been employed within the finite element formulation to minimise computer CPU times. The finite element methods have been used to predict the behaviour of the copper components tested experimentally and the results compared. Steady-state ratchet rates were found to be well predicted by the models. Modes of failure and component lifetimes were also found to be reasonably well predicted. The experimental results demonstrate the importance of isotropic cyclic hardening on the initial component ratchetting rates.

[1]  David R Hayhurst,et al.  Physically based temperature dependence of elastic-viscoplastic constitutive equations for copper between 20 and 500°C , 1996 .

[2]  J. Chaboche,et al.  Mechanics of Solid Materials , 1990 .

[3]  F. Dunne,et al.  Multiaxial creep and cyclic plasticity in nickel-base superalloy C263 , 2005 .

[4]  Zenon Mróz,et al.  A viscoplastic material model and its application to cyclic loading , 1980 .

[5]  E. Krempl,et al.  A uniaxial viscoplastic model based on total strain and overstress , 1979 .

[6]  J. Chaboche,et al.  On the Plastic and Viscoplastic Constitutive Equations—Part I: Rules Developed With Internal Variable Concept , 1983 .

[7]  David R Hayhurst,et al.  Prediction of Plane-Strain Creep-Crack Growth Using Continuum Damage Mechanics , 1996 .

[8]  David R Hayhurst,et al.  Approximate method for the analysis of components undergoing ratchetting and failure , 1998 .

[9]  Qiang Xu,et al.  Modelling of combined creep and cyclic plasticity in a model component undergoing ratchetting using continuum damage mechanics , 2005 .

[10]  Alan K. Miller,et al.  An Inelastic Constitutive Model for Monotonic, Cyclic, and Creep Deformation: Part I—Equations Development and Analytical Procedures , 1976 .

[11]  D. R. Hayhurst,et al.  Stress Redistribution and Rupture Due to Creep in a Uniformly Stretched Thin Plate Containing a Circular Hole , 1973 .

[12]  F. Dunne,et al.  Continuum damage based constitutive equations for copper under high temperature creep and cyclic plasticity , 1992, Proceedings of the Royal Society of London. Series A: Mathematical and Physical Sciences.

[13]  Jean Lemaitre,et al.  Application of Damage Concepts to Predict Creep-Fatigue Failures , 1979 .

[14]  D. R. Hayhurst,et al.  The use of supercomputer modelling of high-temperature failure in pipe weldments to optimize weld and heat affected zone materials property selection , 1994, Proceedings of the Royal Society of London. Series A: Mathematical and Physical Sciences.

[15]  J. Chaboche.  Continuum Damage Mechanics: Part II—Damage Growth, Crack Initiation, and Crack Growth , 1988 .

[16]  S. R. Bodner,et al.  Constitutive Equations for Elastic-Viscoplastic Strain-Hardening Materials , 1975 .

[17]  K. Runesson,et al.  Computational modeling of inelastic large ratcheting strains , 2005 .

[18]  F. Hall,et al.  Continuum damage mechanics modelling of high temperature deformation and failure in a pipe weldment , 1991, Proceedings of the Royal Society of London. Series A: Mathematical and Physical Sciences.

[19]  David R Hayhurst,et al.  Creep rupture under multi-axial states of stress , 1972 .

[20]  D. R. Hayhurst,et al.  Efficient cycle jumping techniques for the modelling of materials and structures under cyclic mechanical and thermal loading , 1994 .

[21]  F Vakili-Tahami,et al.  Continuum damage mechanics predictions of creep damage initiation and growth in ferritic steel weldments in a medium bore branched pipe under constant pressure at 590 °C using a five-material weld model , 2005, Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[22]  D. R. Hayhurst,et al.  The role of continuum damage in creep crack growth , 1984, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[23]  Ahmed Benallal,et al.  Constitutive Equations for Nonproportional Cyclic Elasto-Viscoplasticity , 1987 .

[24]  David R Hayhurst,et al.  Development of continuum damage in the creep rupture of notched bars , 1984, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[25]  D. R. Hayhurst,et al.  Automated procedures for the determination of high temperature viscoplastic damage constitutive equations , 1992, Proceedings of the Royal Society of London. Series A: Mathematical and Physical Sciences.

[26]  David R Hayhurst,et al.  Aspects of Testpiece Design Responsible for Errors in Cyclic Plasticity Experiments , 1999 .

[27]  D. R. Hayhurst,et al.  Modelling of combined high-temperature creep and cyclic plasticity in components using continuum damage mechanics , 1992, Proceedings of the Royal Society of London. Series A: Mathematical and Physical Sciences.