Isochronous Stress–Strain Method With General State of Stress and Variable Loading Conditions for Creep Evaluation

Zhao, Mingxin; Koves, William J.

doi:10.1115/1.4007038

Cited by 5 publications

(3 citation statements)

References 3 publications

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“…The isochronous stress-strain curve method is an approach that has been used extensively for the creep evaluation of materials [26,27]. As the most widely used and traditional method to confirm the long-term strength of rock, isochronous stress-strain curve method has been introduced into the test specification [28,29].…”

Section: Isochronous Stress-strain Curve Methodmentioning

confidence: 99%

Experimental Researches on Long-Term Strength of Granite Gneiss

Liu

2015

Advances in Materials Science and Engineering

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It is important to confirm the long-term strength of rock materials for the purpose of evaluating the long-term stability of rock engineering. In this study, a series of triaxial creep tests were conducted on granite gneiss under different pore pressures. Based on the test data, we proposed two new quantitative methods, tangent method and intersection method, to confirm the long-term strength of rock. Meanwhile, the isochronous stress-strain curve method was adopted to make sure of the accuracy and operability of the two new methods. It is concluded that the new methods are suitable for the study of the long-term strength of rock. The effect of pore pressure on the long-term strength of rock in triaxial creep tests is also discussed.

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Section: Isochronous Stress-strain Curve Methodmentioning

confidence: 99%

Experimental Researches on Long-Term Strength of Granite Gneiss

Liu

2015

Advances in Materials Science and Engineering

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“…In this paper, the isochronous stress-strain curve method is used to determine the long-term strength of reinforced soil and it is an approach that has been used extensively for the creep evaluation of materials [40,41]. It can be seen from the isochronous stress-strain curve that, under low shear stress, the curve is close to coincidence.…”

Section: Analysis Of Isochronous Stress-strain Curvesmentioning

confidence: 99%

Direct Shear Creep Characteristics and Microstructure of Fiber‐Reinforced Soil

Tang

Duan

et al. 2021

Advances in Civil Engineering

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Fiber-reinforced soil is an excellent engineering material that has become a focus of research. Most studies focus on the conventional mechanical properties of reinforced soil, such as its tensile, compressive, and shear strength, and rarely study its creep-related mechanical properties. However, when such soil is used as backfill, the creep effect should not be ignored. This study explored the characteristics of creep mechanics in reinforced soil, the fiber-reinforcement mechanism, and the dynamics of microstructures before and after creep tests. Direct shear creep tests were carried out using a direct shear creep tester on soil reinforced with natural palm fibers of equal length (1.5 cm) in different amounts (0%, 0.2%, 0.6%, 1.0%). Microscale tests were carried out on the reinforced soil samples before and after the creep tests by polarized light and scanning electron microscopy. The results show that the fiber reinforcement can restrain the deformation and enhance the long-term strength of soil. However, a nonlinear relationship between the reinforcement effect and fiber content was found, with 0.6% being the optimal content. Palm fibers have rough surfaces, grooves, and independent pore chambers, which increase the effective contact area and interaction with the soil. With increases in fiber content, the fibers interweave to form a nestled network structure, which increases the strength and integrity of the soil. Fiber addition changes the microstructure of the soil pores; the proportion of large pores decreases and that of small pores increases. Under the effect of creep, the pore changes follow the principle of pore homogenization; large pores are destroyed and transformed into small pores, causing the porosity of reinforced soil to decrease faster and be less porous than unreinforced soil. This research can provide technical reference for the engineering application of palm fiber-reinforced soil.

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“…and [5] a reasonable simplified inelastic approach to verify inelastic deformation is possible using the isochronous curves of the material as "pseudo stress-strain" curve at a certain level of temperature and of life assessment.…”

Section: Isochronus Strain-stress Curves Approachmentioning

confidence: 99%

A Comparative Creep and Creep Fatigue Analysis of an Austenitic Steam Superheater

Lillo

Gaetani

Germoni

et al. 2014

ASME 2014 Symposium on Elevated Temperature Application of Materials for Fossil, Nuclear, and Petrochemical Industries

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A steam superheater is a component which operates at elevated temperature in the creep regime.The component is normally not working in cycling conditions. Due to operation failures, the component has been subjected to several unplanned start-ups and shutdown. The SSH has reported a very high level of damage of the tubesheet to shell junction in field (high deformation and weld cracks).Several investigations have been performed to analyze the effect of temperature, pressure and external loads on the equipment with finite element techniques and different creep and creep-fatigue evaluation approaches: ASME III subsection NH, simplified inelastic analysis and a full creep model have been used. A comparison of the results is reported in this paper. INTRODUCTIONSteam superheater is a component which operates at elevate temperatures regime (500°C-600°C) at low internal pressure.This equipment is normally not operating in cycling condition so design is focused on primary loads at elevated temperature which are generated by pressure and external connections to the SSH.Austenitic material (SS304) at the operating and design temperature of this equipment assures for good creep strength and durability, nevertheless, excessive inelastic strain caused by temperature, not necessarily in cycling condition, could lead to a premature failure of the SSH. There are possible different approaches to the problem: linear elastic analysis with creep factor correction, equivalent plastic analysis and full inelastic creep analysis have been applied to investigate the structural behavior of the component.Steam superheater for a WHB stirene plant has been designed by formula according to ASME VIII Div.1 ed. 2010 add. 2011.The application is designed as a replacement of an existing component; nevertheless the equipment had to be replaced quite in advance due to the foreseen end of life due to failure at the tubesheet to shell-channel junction.

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Isochronous Stress–Strain Method With General State of Stress and Variable Loading Conditions for Creep Evaluation

Cited by 5 publications

References 3 publications

Experimental Researches on Long-Term Strength of Granite Gneiss

Experimental Researches on Long-Term Strength of Granite Gneiss

Direct Shear Creep Characteristics and Microstructure of Fiber‐Reinforced Soil

A Comparative Creep and Creep Fatigue Analysis of an Austenitic Steam Superheater

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