Duration-of-load and creep effects in strand-based wood composite: a creep-rupture model

Abstract The materials used previously for steam generator tubes around the world have been replaced and will be replaced by Alloy 690 given its improved corrosion resistance relative to that of Alloy 600. However, studies of the high- temperature creep and creep-rupture characteristics of steam generator tubes made of Alloy 690 are insufficient compared to those focusing on Alloy 600. In this study, several creep tests were conducted using half tube shape specimens of the Alloy 690 material at temperatures ranging from 650 to 850C and stresses in the range of 30 to 350 MPa, with failure times to creep rupture ranging from 3 to 870 hours. Based on the creep test results, creep life predictions were then made using the well-known Larson Miller Parameter method. Steam generator tube rupture tests were also conducted under the conditions of a constant temperature and pressure ramp using steam generator tube specimens. The rupture test equipment was designed and manufactured to simulate the transient state (rapid temperature and pressure changes) in the event of a severe accident condition. After the rupture test, the damage to the steam generator tubes was predicted using a creep rupture model and a flow stress model. A modified creep rupture model for Alloy 690 steam generator tube material is proposed based on the experimental results. A correction factor of 1.7 in the modified creep rupture model was derived for the Alloy 690 material. The predicted failure pressure was in good agreement with the experimental failure pressure.

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Long-term bending properties of cross-laminated timber made from Japanese larch under constant environment

Journal of Wood Science ◽

10.1186/s10086-021-01997-1 ◽

2021 ◽

Vol 67 (1) ◽

Author(s):

Ryuya Takanashi ◽

Yoshinori Ohashi ◽

Wataru Ishihara ◽

Kazushige Matsumoto

Keyword(s):

Load Capacity ◽

Creep Rupture ◽

Japanese Larch ◽

Larix Kaempferi ◽

Loading Capacity ◽

Loading Test ◽

Cross Laminated Timber ◽

Duration Of Load ◽

Rupture Behavior

AbstractCross-laminated timber (CLT) has been used extensively in timber construction. CLT panels are typically used in roofs and floors that carry a continuous load, and it is important to examine the long-term loading capacity of CLT. However, studies that focus on the long-term loading capacity of CLT are limited. To this end, we conducted long-term out-of-plane bending tests on seven-layer CLT made from Japanese larch (Larix kaempferi) under constant environmental conditions, investigated creep performance and duration of load, and experimentally analyzed creep rupture behavior. The mean estimated relative creep after 50 years was 1.49. The sample showed a satisfactory resistance to creep as a building material. The duration of load of most of the specimens in this study was shorter than the conventional value of small clear wood specimens. Specimens had a lower duration of load capacity than solid lumber. According to the results of survival analysis, a loading level of 70% or more caused the initial failure of specimens. Creep rupture of most of the specimens occurred at less deflection than displacement at failure in the short-term loading test. Additional studies focusing on the effects of finger joints, transverse layers, and width of a specimen on creep rupture behavior are suggested.

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Creep–rupture model of aluminum alloys: Cohesive zone approach

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406214543413 ◽

2014 ◽

Vol 229 (8) ◽

pp. 1343-1347 ◽

Cited By ~ 1

Author(s):

Kyungmok Kim

Keyword(s):

Aluminum Alloys ◽

Cohesive Zone ◽

Rupture Life ◽

Stress Rupture ◽

Creep Rupture ◽

Time Dependent ◽

Element Analysis ◽

Rupture Model ◽

Term Creep

In this article, a creep–rupture model of aluminum alloys is developed using a time-dependent cohesive zone law. For long-term creep rupture, a time jump strategy is used in a cohesive zone law. Stress–rupture scatter of aluminum alloy 4032-T6 is fitted with a power law form. Then, change in the slope of a stress-rupture line is identified on a log–log scale. Implicit finite element analysis is employed with a model containing a cohesive zone. Stress–rupture curves at various given temperatures are calculated and compared with experimental ones. Results show that a proposed method allows predicting creep–rupture life of aluminum alloys.

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