Estimation of stress redistribution for the extraction of power law creep parameters from bending. (9th February 2023)

• Record Type: Journal Article
• Authors: Goel, Priya; Kumar, Praveen; Jayaram, Vikram
• Is Part Of: Mechanics of materials. Volume 177(2023)
• Publication Date: 2023-02-09
• Subjects: Creep -- Bending -- Stress redistribution -- Step loading; Strength of materials -- Periodicals; Mechanics, Applied -- Periodicals; Résistance des matériaux -- Périodiques; Mécanique appliquée -- Périodiques; Mechanics, Applied; Strength of materials; Periodicals; Electronic journals; 620.11
• DOI: 10.1016/j.mechmat.2022.104518
• Languages: English
• ISSNs: 0167-6636

Abstract

Abstract: A numerical method is developed to calculate stress distribution and its evolution throughout the beam during power-law creep deformation. A constitutive law containing primary and secondary terms is considered and strain hardening approach of stress redistribution is used. Time for stress redistribution to saturate is defined in terms of a parameter, stress saturation time (SST), and its dependence on loading and material properties is studied for ferritic steels P91 and T22 using the model. It is observed that SST has a power law dependence on the applied moment and it can be as high as 3300 h at 0.33 σ Y S ( σ Y S is yield strength) for P91 steel leading to misinterpreted results at low loads if strain rate is measured much earlier. In contrast, at high loads, as shown for T22 steel, the loading must be redesigned from a continuous ramp to step-loading in order to ensure that the maximum stress of the extreme locations do not exceed yield strength at any instant. Therefore, testing methodologies are developed using the model to aid in the efficient design of the testing procedure for a broadened testing range with a meaningful interpretation of the test results. Graphical abstract: Highlights: Time to reach saturation stress has a power law dependence on the moment. Due to geometrical effects, transient in bending creep is affected by stress and microstructural evolutions. At high stresses, step-loading avoids exceeding yield strength.