Creep in Structures

There is a tradition to organize IUTAM Symposia "Creep in Structures" every ten years: the first Symposium was organized by N.J. Hoff in Stan­ ford (1960), the second one by J. Hult in Goteborg (1970), and the third one by A.R.S. Ponter in Leicester (1980). The fourth Symposium in Cracow, September 1990, gathered 123 par­ ticipants from 21 countries and reflected rapid development of the theory, experimental research and structural applications of creep and viscoplas­ ticity, including damage and rupture. Indeed, the scope of the Sympo­ sium was broad, maybe even too broad, but it was kept according to the tradition. Probably the chairman of "Creep in Structures V" in the year 2000 (if organized at all) will be forced to confine the scope substantially. Participation in the Symposium was reserved for invited participants, suggested by members of the Scientific Committee. Total number of sug­ gestions was very large and the response - unexpectedly high. Apart from several papers rejected, as being out of scope, over 100 papers were accepted for presentation. A somewhat unconventional way of presenta­ tion was introduced to provide ample time for fruitful and well prepared discussions: besides general lectures (30 minutes each), all the remain­ ing papers were presented as short introductory lectures (10 minutes) followed by a I-hour poster discussion with the authors and then by a general discussion. Such an approach made it possible to present general ideas orally, and then to discuss all the papers through and through.

I: Constitutive Equations, Combined Loadings.- Applications of tensor functions in creep mechanics ― (general lecture).- A unified mathematical model for plasticity and creep under variable-repeated loading ― (general lecture).- Anisotropic creep modeling for f.c.c. single crystals.- On the creep-ratchetting of AlMgSi 0.5 at elevated temperature; experimental investigations.- Compressive creep tests on porous ceramic notched specimens.- Some new aspects of the nonlinear characterization of creep and stress relaxation of polymers.- Constitutive equations of nonstationary metal creep.- Creep of metals under variable complex loadings.- Theory of creep and long-term strength of isotropic hardening media.- A constitutive equation for non-linear, compressible viscoelastic materials with fading memory.- Transient creep in rock salt structure.- A hybrid constitutive model for cyclic, and creep deformation.- Anisotropic creep behaviour induced by plastic deformation.- The influence of deformation history on creep of pure copper.- Modeling of recovery of state using the viscoplasticity theory based on overstress.- Some attempts to describe distortional hardening in viscoplasticity.- A viscoplasticity theory of irradiated materials.- Diffusional transformation and creep in steels.- Effects of slip system and lattice rotation on combined tension-torsion creep of a directionally solidified alloy.- Nonlinear constitutive equations for creep of structural materials.- Intergranular and transgranular hardening in viscoplasticity.- On the state equations for anisotropic elasto-visco-plastic bodies.- Effects of prior plastic strain path shapes on creep behaviour of incompressible materials.- Some unification of creep theories based on internal time concept.- Characterization of nonlinear viscoelastic materials for a special class of loading histories.- Constitutive law and force recovery for large strain problems.- Creep of isotropic and anisotropic materials with different behaviour in tension and compression.- II: Damage, Creep Crack Growth, Creep Rupture.- Localization phenomena in thermo-elastoplasticity ― (general lecture).- Mechanical modeling of irradiation creep and its application to the analysis of creep crack growth ― (general lecture).- Fatigue crack propagation behavior under creep conditions- (general lecture).- Creep life estimates for defective structures.- Non-stationary nucleation of cavities at grain boundaries.- A non-unilateral damage in creeping plates.- On microcracking due to cavitation and grain boundary sliding in creeping polycrystals.- An assessment procedure for the high temperature response of structures.- Creep continuum damage mechanics ― studies of size effects and weldments.- Crack growth in linearly viscoelastic media.- Mixed-mode creep and creep/fatigue crack growth.- Theoretical, experimental and numerical investigations of creep crack growth.- Characterization of creep-fatigue failure process based on stochastic behavior of small crack initiation and growth.- A new damage approach for creep crack growth prediction.- Small-scale and large-scale creep predictions of notch stress and strain under creep conditions.- Creep rupture of metals under tri-axial state of stress.- The investigation of the metal damage at the creep by the method of electrical resistance measuring.- Creep of concrete during load-controlled experiments.- Evaluation of creep damage in some major components of steam turbine.- Uniaxial viscoplastic experiments of predamaged AISI 316H.- Creep rupture in fibre bundles with hardening-softening fibre material.- Creep-fatigue life and cyclic constitutive relation of MAR-M247 directionally solidified superalloy at high temperature.- Percolation models as a basis of material failure.- Global and local approaches to creep crack initiation and creep crack growth.- The assessment of creep-fatigue initiation and crack growth.- A constitutive model for creep and damage in composite materials.- III: Structures, Analytical and Numerical Methods, Optimal Design.- Advances in finite element methods for elasto-plastic and creep analysis ― (general lecture).- Large displacements and rotations for shells of revolution due to axisymmetric elastic, creep and plastic deformation ― (general lecture).- Finite element methods in stress analysis for creep- (general lecture).- Thermal, mechanical & creep behavior of metal matrix composites ― (general lecture).- Problems of structural optimization under creep conditions ― (general lecture).- Modelling of viscoelastic behaviour of plates.- The verification of the solutions of large problems of discontinuous creeping structures.- Creep analysis in a large strain context by unified constitutive equations.- The large time increment method applied to cyclic loadings.- Some analytic results pertaining to stress redistribution in a class of structures undergoing primary or secondary creep.- On optimal design of disk with respect to creep rupture.- Prediction of macroscopic and local creep behavior of perforated plates.- A viscoplastic constitutive relationship and the finite element implementation of stress/strain concentration in notched component.- Creep buckling of inelastic plates.- Contributions to robust methods of creep analysis.- On the stability of viscoelastic beams under a stochastic excitation.- On the non-linear creep flow potential.- Bending of orthotropic viscoelastic plates with thermal effects.- Stress concentrations resulting from longitudinal butt-welds in piping at elevated temperatures.- Bars of uniform strength vs. optimal with respect to ductile creep rupture time.- A numerical method of nonlinear viscoelastic structural analysis.- Stability and bounds on motion of viscoelastic columns with imperfections and time-dependent forces.- Nonlinear instability induced by creep.- Finite element-implementation of creep of concrete for thin-shell analysis using nonlinear constitutive relations and creep compliance functions.- Optimal design of annular plates against creep buckling.- Dynamic response of a viscoelastic circular plate on a viscoelastic half space foundation.- Low-stress level of a compound wedge under steady creep.- Creep instability of spinning viscoelastic rod.