Download or read book Evaluation of Creep Fatigue Damage Based on Simplified Model Test Approach written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Current methods used in the ASME Code, Subsection NH for the evaluation of creep-fatigue damage are based on the separation of elevated temperature cyclic damage into two parts, creep damage and fatigue damage. This presents difficulties in both evaluation of test data and determination of cyclic damage in design. To avoid these difficulties, an alternative approach was identified, called the Simplified Model Test or SMT approach based on the use of creep-fatigue hold time test data from test specimens with elastic follow-up conservatively designed to bound the response of general structural components of interest. A key feature of the methodology is the use of the results of elastic analysis directly in design evaluation similar to current methods in the ASME Code, Subsection NB. Although originally developed for current material included in Subsection NH, recent interest in the application of Alloy 617 for components operating at very high temperatures has caused renewed interest in the SMT approach because it provides an alternative to the proposed restriction on the use of current Subsection NH simplified methods at very high temperatures. A comprehensive review and assessment of five representative simplified methods for creep-fatigue damage evaluation is presented in Asayama [1]. In this review the SMT methodology was identified as the best long term approach but the need for test data precluded its near term implementation. Asayama and Jetter [2] is a summary of the more comprehensive report by Asayama [1] with a summary of the SMT approach presented by Jetter [3].
Download or read book Creep Fatigue Fracture Analysis of Internal Damage written by Weisheng Zhou and published by Springer Nature. This book was released on with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Simplified Methods for Creep Fatigue Damage Evaluations and the Application to Life Extension written by M. J. Manjoine and published by . This book was released on 1994-08-01 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design for Creep written by R.K. Penny and published by Springer Science & Business Media. This book was released on 1995-07-31 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our rationale for the second edition remains the same as for the first edition, which appeared over twenty years ago. This is to offer simplified, useful and easily understood methods for dealing with the creep of components operating under conditions met in practice. When the first edition was written, we could not claim that the methods which were introduced were well-tried. They were somewhat conjectural, although firmly based, but not sufficiently well devel oped. Since that time, the Reference Stress Methods (RSM) introduced in the book have received much scrutiny and development. The best recognition we could have of the original methods is the fact that they are now firmly embedded in codes of practice. Hopefully, we have now gone a long way towards achieving our original objectives. There are major additions to this second edition which should help to justify our claims. These include further clarification regarding Reference Stress Methods in Chapter 4. There are also new topics which depend on RSM in varying degrees: • Creep fracture is covered in Chapter 7, where methods for assessing creep crack initiation and crack growth are fully described. This chapter starts with a review of the basic concepts of fracture mechanics and follows with useful, approximate methods, compatible with the needs of design for creep and the availability of standard data. • Creep/fatigue interactions and environmental effects appear in Chapter 8.
Download or read book Component Assessment Data Requirements from Creep Fatigue Tests written by S. R. Holdsworth and published by . This book was released on 2011 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Typically, the lifetime assessment of high temperature components, for which both creep and fatigue are principal damage mechanisms, involves (1) the determination of the stress/strain state at critical locations and (2) a numerical evaluation of the consequential damage condition. Until recently, there has not been a standard procedure specifically covering creep-fatigue testing practices. Creep-fatigue tests had been performed for many years, but the reliability and the form of the information generated was dependent on the expertise and specific interests of individual test laboratories. This situation is now resolved by the publication of a new ASTM standard based on an Electrical Power Research Institute (EPRI) led initiative. The way in which the guidance contained in this new standard specifically aims to provide creep-fatigue data requirements for defect-free component assessment is examined. Cyclic/hold tests, usually involving a simple cycle shape representative of the service transients experienced by the target component, are particularly informative in the provision of data to indicate the concurrent influences of cyclic loading on creep deformation characteristics and creep deformation on cyclic plastic response. The crack initiation endurances of such tests also provide the basis of creep-fatigue damage summation representations for a given material. Sequential creep-fatigue testing can be used to quantify the effects of prior cyclic deformation on creep rupture or prior creep deformation on fatigue endurance. The use of such test methods is also considered.
Download or read book Evaluation of the Effect of Creep and Mean Stress on Fatigue Life Using a Damage Mechanics Approach written by NM. Abuelfoutouh and published by . This book was released on 1992 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: A method for fatigue life prediction of high temperature polycrystalline materials under high rate fully reversed strain cycles (HRSC) was previously derived using a continuum damage mechanics approach. The method is generalized in this paper to predict the fatigue life of balanced cyclic creep rupture (BCCR), tensile cyclic creep rupture (TCCR), and compressive cyclic creep rupture (CCCR). It is assumed that creep deformation mechanisms dominate during the creep portion of the fatigue cycle and that plasticity mechanisms dominate during the plastic portion of the cycle. The interaction of plasticity and creep with the mean applied stress and the effect of this interaction on the fatigue life are investigated. A sample calculation is applied to René 80 at 1255 K (1800°F).
Download or read book Numerical Evaluation of Two Creep fatigue Damage Models Under Complex Loading Histories and Multiaxial States of Stress written by Leonardo Bertini and published by . This book was released on 1988 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue Strength and Evaluation of Creep Damage During Fatigue Cycling of Inconel Alloy 625 written by and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Evaluation of high strain rate and corresponding low strain rate tests indicate no creep-fatigue interaction. For T greater than or equal to 900°C, creep damage predominates during the cyclic straining. For tests in which creep damage is largely suppressed - for example in high-frequency reverse bend fatigue tests - the cycles to fatigue failure were found to increase directly with the degree of suppression of creep damage. However, a practical limit exists for suppression of creep damage at 1100°C; at that temperature, even for the high frequency reverse bend tests (approx. 1000 rpm with .sigma. = 12.3% s−1), the creep damage predominated over the fatigue damage.
Download or read book Discussion of the Test Method and Equipment for the Evaluation of Low Cycle Creep Fatigue Failure Criteria written by AP. Gusenkov and published by . This book was released on 1973 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The formulation of failure criteria for cyclic loading at elevated temperature must be based on a large quantity of experimental data. The design of the experiments and the particular test method used for such formulation is the subject of this paper. Several schemes for controlling the independent variables are described, and the requirements for isothermal and cyclic thermal creep and fatigue tests with load or strain control provision are illustrated by equipment developed at the author's laboratory.
Download or read book Nondestructive Evaluation of Creep fatigue Damage written by Robert E. Nickell and published by . This book was released on 1977 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this interim report some preliminary results on magnetic force and ultrasonic evaluation of creep-fatigue damage in an LMFBR steam generator material are presented. These results indicate that the non-destructive evaluation of pure creep damage will be extremely difficult. A set of biaxial creep-fatigue tests that are designed to discriminate between various failure theories is also described.
Download or read book FY16 Status Report on Development of Integrated EPP and SMT Design Methods written by and published by . This book was released on 2016 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of the Elastic-Perfectly Plastic (EPP) combined integrated creep-fatigue damage evaluation approach is to incorporate a Simplified Model Test (SMT) data based approach for creep-fatigue damage evaluation into the EPP methodology to avoid the separate evaluation of creep and fatigue damage and eliminate the requirement for stress classification in current methods; thus greatly simplifying evaluation of elevated temperature cyclic service. The EPP methodology is based on the idea that creep damage and strain accumulation can be bounded by a properly chosen "pseudo" yield strength used in an elastic-perfectly plastic analysis, thus avoiding the need for stress classification. The original SMT approach is based on the use of elastic analysis. The experimental data, cycles to failure, is correlated using the elastically calculated strain range in the test specimen and the corresponding component strain is also calculated elastically. The advantage of this approach is that it is no longer necessary to use the damage interaction, or D-diagram, because the damage due to the combined effects of creep and fatigue are accounted in the test data by means of a specimen that is designed to replicate or bound the stress and strain redistribution that occurs in actual components when loaded in the creep regime. The reference approach to combining the two methodologies and the corresponding uncertainties and validation plans are presented. Results from recent key feature tests are discussed to illustrate the applicability of the EPP methodology and the behavior of materials at elevated temperature when undergoing stress and strain redistribution due to plasticity and creep.
Download or read book An Integrated Approach to Creep Fatigue Life Prediction written by P. Agatonovic and published by . This book was released on 1988 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: There has been special interest recently in developing new, reliable analytical design methods for components under higher temperature conditions. However, at present, the use of material properties is still limited to arrays of single characteristics which do not interact with each other. In this work, several creep fatigue experiments on smooth specimens of IN 800 H have been carried out at 830°C. In some tests, these have also been combined with inside hysteresis loops to investigate the different effects on deformation and damage behavior which originate in a creep and fatigue environment. As a result of these tests, it has been found that the material behavior under creep-fatigue conditions can be significantly changed compared to the material behavior under simple load conditions. Therefore there is a need for life analysis methods to be expanded to include possible variations in properties; for greater accuracy, the material properties must be treated as a complex interacting system of parameters. The examination has been extended to a typical component used under high-temperature conditions. The results of the numerical analysis show that the stress-strain history in the critical area of that component is not simply strain controlled, as it is in the typical laboratory creep-fatigue interaction life test containing a tensile or compressive dwell at constant peak strain level. At high temperatures, the conditions in the component are more severe, causing the life to be reduced compared with the typical laboratory test. In this paper, these conditions are successfully simulated with the help of a generalized Neuber law: ? . ?p = constant. Based on this ratio, the engineering method for evaluating component geometry and loading conditions and their effects on material behavior can be established.
Download or read book Fatigue Performance Evaluation of WesTrack Asphalt Mixtures Using Viscoelastic Continuum Damage Approach written by Y. Richard Kim and published by . This book was released on 2002 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction -- Objectives and summary -- Theoretical background -- Test methods -- Materials and specimen fabrication -- Uniaxial testing -- Determination of viscoelastic properties from IDT test -- Development of a simple performance test and validation -- Conclusions and recommendations -- Implementation and technology transfer plan -- References -- Appendices.
Download or read book Unified and mechanistic approach to creep fatigue damage Argonne National Lab ANL 76 58 written by S. Majumdar and published by . This book was released on 1976 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evaluation of Low Cycle Creep Fatigue Degradation for Notched Components written by Tait RA and published by . This book was released on 1988 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: Four approaches have been examined to predict the endurance of circumferentially notched, uniaxially loaded test pieces subjected to fully reversed strain-controlled cyclic loading at elevated temperatures. Results are compared with uniaxial data derived from smooth test pieces. The strain-time waveforms include both trapezoidal and triangular shapes to distinguish between fatigue and fatigue-creep damage. The four materials investigated are HP-45 (1144 K), Incoloy 800H (1144 K), Incoloy 800 (922 K), and 11⁄4Cr-1⁄2Mo (811 K). The analysis has reflected the various degrees of cyclic hardening and creep deformation exhibited by these materials. The predictive approaches include Neuber notch strain analysis and finite element analyses to identify the maximum plastic strain range, the equivalent plastic strain range, and the total plastic work per cycle.
Download or read book Study of Damage Approaches for Life Assessment in the Creep fatigue Range written by and published by . This book was released on 1995 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A method of creep damage summation based on accumulated strain for the assessment of creep fatigue endurance written by R. Hales and published by . This book was released on 1982 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
