scholarly journals Effect of Loading Rate on the Fracture Behavior of Nuclear Piping Materials Under Cyclic Loading Conditions

2016 ◽  
Vol 48 (6) ◽  
pp. 1376-1386 ◽  
Author(s):  
Jin Weon Kim ◽  
Myung Rak Choi ◽  
Yun Jae Kim
Keyword(s):  
Cyclic Loading ◽  
Fracture Behavior ◽  
Loading Rate ◽  
Loading Conditions

J-R Fracture Toughness of Nuclear Piping Materials Under Excessive Seismic Loading Condition

2016 ◽  
Author(s):  
Jin Weon Kim ◽  
Myung Rak Choi ◽  
Sang Bong Lee ◽  
Yun Jae Kim
Keyword(s):  
Fracture Toughness ◽  
Cyclic Loading ◽  
Fracture Resistance ◽  
Cyclic Load ◽  
Fracture Behavior ◽  
Loading Rate ◽  
Seismic Loading ◽  
Monotonic Loading ◽  
Rate Effect ◽  
Loading Conditions

This study investigated the loading rate effect on the fracture resistance under cyclic loading conditions to clearly understand the fracture behavior of piping materials under excessive seismic conditions. J-R fracture toughness tests were conducted under monotonic and cyclic loading conditions at various displacement rates at room temperature (RT) and the operating temperature of nuclear power plants (NPPs), i.e., 316°C. SA508 Gr. 1a lo w-alloy steel (LAS) and SA312 TP316 stainless steel (SS) piping materials were used for the tests. The fracture resistance under a reversible cyclic load was considerably lower than that under monotonic load regardless of test temperature, material, and loading rate. Under both cyclic and monotonic loading conditions, the fracture behavior of SA312 TP316 SS was independent of the loading rate at both RT and 316°C. For SA508 Gr. 1a LAS, the loading rate effect on the fracture behavior was appreciable at 316°C under both cyclic and monotonic loading conditions. However, the loading rate effect diminished when the cyclic load ratio (R) was −1. Thus, it was recognized that the fracture behavior of piping materials, including seismic loading characteristics, can be evaluated when tested under a cyclic load of R = −1 at a quasi-static loading rate.

scholarly journals Mechanical Response of Castlegate Sandstone under Hydrostatic Cyclic Loading

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
William M. Kibikas ◽  
Stephen J. Bauer
Keyword(s):  
Cyclic Loading ◽  
Mechanical Behavior ◽  
Loading Rate ◽  
Confining Pressure ◽  
Petrophysical Properties ◽  
Loading Conditions ◽  
Hydrostatic Loading ◽  
Stress Cycling ◽  
Stress Cycles ◽  
Static Conditions

The stress history of rocks in the subsurface affects their mechanical and petrophysical properties. Rocks can often experience repeated cycles of loading and unloading due to fluid pressure fluctuations, which will lead to different mechanical behavior from static conditions. This is of importance for several geophysical and industrial applications, for example, wastewater injection and reservoir storage wells, which generate repeated stress perturbations. Laboratory experiments were conducted with Castlegate sandstone to observe the effects of different cyclic pressure loading conditions on a common reservoir analogue. Each sample was hydrostatically loaded in a triaxial cell to a low effective confining pressure, and either pore pressure or confining pressure was cycled at different rates over the course of a few weeks. Fluid permeability was measured during initial loading and periodically between stress cycles. Samples that undergo cyclic loading experience significantly more inelastic (nonrecoverable) strain compared to samples tested without cyclic hydrostatic loading. Permeability decreases rapidly for all tests during the first few days of testing, but the decrease and variability of permeability after this depend upon the loading conditions of each test. Cycling conditions do affect the mechanical behavior; the elastic moduli decrease with the increasing loading rate and stress cycling. The degree of volumetric strain induced by stress cycles is the major control on permeability change in the sandstones, with less compaction leading to more variation from measurement to measurement. The data indicate that cyclic loading degrades permeability and porosity more than static conditions over a similar period, but the petrophysical properties are dictated more by the hydrostatic loading rate rather than the total length of time stress cycling is imposed.

Fracture Behavior of Aged CF8A Austenite Cast Stainless Steel Under Dynamic and Cyclic Loading Conditions

2017 ◽  
Author(s):  
Jin Weon Kim ◽  
Myung Rak Choi ◽  
Yun Jae Kim
Keyword(s):  
Fracture Toughness ◽  
Stainless Steel ◽  
Cyclic Loading ◽  
Dynamic Loading ◽  
Thermal Aging ◽  
Fracture Behavior ◽  
Operating Temperature ◽  
Loading Conditions ◽  
Loading Effect ◽  
Loading Rates

This study conducted J-R fracture toughness tests using aged CF8A cast austenitic stainless steel (CASS) under dynamic and cyclic loading conditions at room temperature (RT) and 316°C and investigated the effect of seismic loading characteristics on the fracture behavior of age-related degraded material. For comparison, J-R fracture tests were also conducted on unaged CF8A CASS. CF8A CASS was made as a static casting, and it was aged thermally at 400°C for 175 days, which is equivalent to thermal aging at the operating temperature of nuclear power plants (NPPs) for 32 effective full power years (EFPYs). Monotonic J-R tests were conducted at both quasi-static and dynamic loading rates, and cyclic J-R tests were conducted at a quasi-static loading rate. The results showed that the fracture resistance of aged CF8A CASS under monotonic load was lower, by ∼35%, than that of unaged CF8A CASS, regardless of test temperatures and loading rates. The dynamic loading effect on fracture behavior was almost negligible for both unaged and aged CF8A CASSs at RT and 316°C. Cyclic loading reduced J-R fracture toughness of unaged CF8A CASS considerably at both test temperatures. Such a cyclic loading effect on fracture behavior was still observed from aged CF8A CASS. Thus, we conclude that the dynamic and cyclic loading effects on fracture behavior of CF8A CASS were not altered by thermal aging at the operating temperature of NPPs for 32 EFPYs.

Loading rate effect on fracture behavior of fiber reinforced high strength concrete using a semi-circular bending test

2020 ◽  
Vol 240 ◽  
pp. 117681
Author(s):  
Mehran Aziminezhad ◽  
Sahand Mardi ◽  
Pouria Hajikarimi ◽  
Fereidoon Moghadas Nejad ◽  
Amir H. Gandomi
Keyword(s):  
High Strength Concrete ◽  
Fracture Behavior ◽  
Loading Rate ◽  
High Strength ◽  
Rate Effect ◽  
Bending Test ◽  
Fiber Reinforced ◽  
Strength Concrete

scholarly journals In situ monitoring of dislocation, twinning, and detwinning modes in an extruded magnesium alloy under cyclic loading conditions

2021 ◽  
Vol 806 ◽  
pp. 140860
Author(s):  
Di Xie ◽  
Zongyang Lyu ◽  
Yuan Li ◽  
Peter K. Liaw ◽  
Huck Beng Chew ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Cyclic Loading ◽  
In Situ Monitoring ◽  
Loading Conditions
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