Significance Of Creep Research Articles

Low temperature creep and irradiation creep in nuclear reactor applications: A critical review

The mechanisms and characteristics of low temperature creep and irradiation creep of structural alloys in light water reactor service are briefly reviewed. The significance of creep is made clear in relation to the environmentally-assisted cracking (EAC). It is shown that while total creep itself may not be significant the attendant slow strain rates are likely contributors critical to the manifestation of EAC. This interrelation of the creep and EAC is further assessed with validation of a continuum damage mechanics approach to quantify the EAC kinetics. Limitations of the formulation and other approaches are discussed, with a note that the influence of irradiation creep on EAC appears not to have been taken into account at present. These aspects are discussed identifying possible useful refinements in assessing the role of creep in EAC.

Significance and Assessment of Low Temperature Creep and Irradiation Creep in Nuclear Reactor Applications

The mechanisms and characteristics of low temperature creep and irradiation creep of structural alloys in light water reactor service are briefly reviewed. The significance of creep is made clear in relation to the environmentally-assisted cracking (EAC). It is shown that while total creep itself may not be significant the attendant slow strain rates are likely contributors critical to the manifestation of EAC. This interrelation of the creep and EAC is further assessed with validation of a continuum damage mechanics approach to quantify the EAC kinetics. Limitations of the formulation and other approaches are discussed, with a note that the influence of irradiation creep on EAC appears not to have been taken into account at present. These aspects are discussed identifying possible useful refinements in assessing the role of creep in EAC.

Identifying the Significance of Factors Affecting Creep of Concrete: A Probabilistic Analysis of RILEM Database

Modeling creep of concrete has been one of the most challenging problems in concrete. Over the years, research has proven the significance of creep and its ability to influence structural behavior through loss of prestress, violation of serviceability limit states or stress redistribution. Because of this, interest in modeling and simulation of creep has grown significantly. A research program was planned to investigate the significance of different factors affecting creep of concrete. This research investigation is divided into two folds: first, an in-depth study of the RILEM creep database and development of a homogenous database that can be used for blind computational analysis. Second: developing a probabilistic Bayesian screening method that enables identifying the significance of the different factors affecting creep of concrete. The probabilistic analysis revealed a group of interacting parameters that seem to significantly influence creep of concrete.

Use of quasi-static nanoindentation data to obtain stress–strain characteristics for metallic materials

This paper concerns optimization of procedures and algorithms for extraction of stress–strain relationships from quasi-static nanoindentation experiments, using finite element method modelling. Several issues are highlighted, including the usefulness of incorporating residual indent shape in the comparisons, as well as load–displacement–time data, and the significance of creep and interfacial friction. The study is focused on extruded copper bar, using a spherical indenter and assuming transverse isotropy throughout. It is shown that, using the methodology presented here, experimental nanoindentation data could be used to estimate the yield stress and work-hardening rate, with good accuracy, i.e. the yield stress could have been obtained to a precision of about ±10%, and the work-hardening rate to about ±25%. Such inferred constitutive relations are more likely to be reliable if the comparisons are made in regimes within which creep does not significantly influence the behaviour, and in general the timescale of measurement is important.

Creep Effects in Plain and Fiber-Reinforced Polymer-Strengthened Reinforced Concrete Beams

This study considers the potential effects of creep on reinforced concrete (RC) beams strengthened with externally applied fiber reinforced polymer (FRP) strips. The significance of creep in the epoxy adhesive and whether such creep might allow the FRP strips to unload over time is assessed. The long-term deflection behavior of two RC beams with similar dimensions and material properties was monitored. One beam was externally strengthened with fiber-reinforced polymer (FRP) strips, while the other was used as a control specimen. Both beams have been subjected to sustained loading for over 6-1/2 years. Slip movements at the ends of the FRP strips were also monitored. The experimental deflections have been compared to deflection predictions using ACI 209R-92 and CEB-FIP MC 90. The creep deformations of the FRP-strengthened beam are not as predicted from the control beam. A step-by-step in-time analysis and finite element modeling are used in the analysis, and both showed good ability to simulate long-term effects in RC beams strengthened with FRP. Results from both techniques show that creep of the adhesive layer can account for the differences observed between the predicted and actual behaviors of the beam, and that this creep should be included when assessing the long-term effects of strengthening a beam with externally applied FRP.

Medial Collateral Ligament Reconstruction

Medial Collateral Ligament Reconstruction

EFFECT OF CREEP AND MECHANO-SORPTIVE EFFECT ON STRESS DEVELOPMENT DURING DRYING

ABSTRACT Constitutive equations to quantify wood deformation under combined mechanical loading and moisture content change (1] were coupled with the moisture distribution developed during drying to predict stress and strain in 50 by 190-mm Douglas-fir heartwood lumber. Two combinations of temperature and relative humidity were used to dry the wood. The overall board shrinkage and the immediately released and set strains were measured as a function of time. Those strains were compared with analytic results, which showed good agreement. The roles that four strain components played in the development of stress-both at board surface and center were compared for different drying conditions. The significance of creep and mechano-sorptive strain in relieving the stress was demonstrated by varying the model parameters.

Problems in all-paper construction: a pilot study

The structural properties of paper as low-cost building material are investigated in a pilot study which gives the results of a limited number of tension, creep, and flexure tests. Certain problems encountered in all-paper construction are discussed, the significance of creep is considered, and a mode of failure peculiar to all-paper construction is observed. The structural integrity and flexibility of form available with paper are illustrated by the fabrication and testing of a cylindrical shell.

Paper 14: The Significance of Creep in Cooled Gas Turbine Blades

Paper 14: The Significance of Creep in Cooled Gas Turbine Blades