Creep Behavior and Defect Interference of Volume Defect Under High Temperature

2016 ◽  
Author(s):  
Ping Tang ◽  
Min Wang ◽  
Zhangwei Ling ◽  
Nanhui Jin ◽  
Weican Guo
Keyword(s):  
High Temperature ◽  
Creep Behavior ◽  
Great Influence ◽  
Creep Model ◽  
Temperature Structure ◽  
Theoretical Support ◽  
Pressure Pipeline ◽  
Volume Defect ◽  
High Temperature Components ◽  
Safety Operation

Volume defect is the common defect in high temperature pressure pipeline. Those defects have a great influence on stress redistribution of the pipes in high temperature, and affect the integrity and safety operation of high temperature components. In this paper, the defects were regularized, and a high temperature creep model was established. Based on this model, creep behavior of high temperature pressure pipeline with volume defect was studied, and the stress concentration of the main feature points in the defect was researched. Then, defects interference effect was discussed, and the critical interference distance was given. The results provide theoretical support to the safety assessment of high temperature structure with defects.

Numerical Simulation of Welding Residual Stress and its Creep Strain for Cr5Mo Steel Welded Joint

2011 ◽  
Vol 55-57 ◽  
pp. 41-46
Author(s):  
Ling Cheng ◽  
Zheng Nan Chen ◽  
Jian Gao
Keyword(s):  
Residual Stress ◽  
High Temperature ◽  
Welded Joint ◽  
Great Influence ◽  
Welding Residual Stress ◽  
Element Analysis ◽  
Creep Analysis ◽  
The Finite Element Analysis ◽  
Sequential Coupling ◽  
High Temperature Components

By the finite element analysis codes ABAQUS and the function of RESTART, a sequential coupling calculating program for creep based on welding residual stress has been developed by establishing the model of temperature field, residual field and creep analysis. The welding residual stress and creep of welded joint for Cr5Mo furnace tubes was simulated by the program. This method established the basis for calculating the effects of welding residual stress on the creep of welded joint. A creep comparison between the welded joint tubes with welding residual stress and with internal pressure was made in the paper. The results show that although the residual stress is greatly decreased due to the creep relaxation behavior at high temperature, the initial welding residual stress has a great influence on the tube creep. The research results provide a reference for strength design of high temperature components.

Plastic Limit Analysis of Modified 9Cr-1Mo Steel Pressure Vessel Containing Volume Defect with Creep Damage Law

2017 ◽  
Vol 09 (02) ◽  
pp. 1750025 ◽  
Author(s):  
Xianhe Du ◽  
Jie Zhang ◽  
Heng Peng ◽  
Yinghua Liu
Keyword(s):  
High Temperature ◽  
Service Time ◽  
Pressure Vessel ◽  
Creep Damage ◽  
Limit Load ◽  
Creep Model ◽  
Creep Process ◽  
Plastic Limit ◽  
Plastic Limit Load ◽  
Volume Defect

A numerical method for evaluating the plastic limit load of modified 9Cr-1Mo steel pressure vessel structures containing volume defect at [Formula: see text]C is proposed based on the plastic limit load concept under high temperature. Firstly, the creep analysis of the defected pressure vessel is conducted with the Liu–Murakami creep model to obtain the creep damage after a prescribed service time. Secondly, the obtained creep damage is introduced into Ramberg–Osgood model through the hardness ratio to characterize the material deterioration during the creep process. Thirdly, the plastic limit load of the defected pressure vessel under high temperature is obtained through the classic zero curvature criterion with the modified Ramberg–Osgood model. The numerical examples for the pressure vessels with different sizes of volume defects are performed, and the failure modes of pressure vessel structures at the limit state are revealed and the fitting formulae between the plastic limit load ratio and the dimensionless defect factor are established based on the numerical results. Results show that the plastic limit load and the service time of pressure vessel structures under high temperature are sensitive to the volume defect ratio and can be determined easily through the fitting formulae which are convenient for engineering applications.

Multiple Cracks Interaction Model under Creep Conditions

2013 ◽  
Vol 330 ◽  
pp. 574-579
Author(s):  
Jun Si ◽  
Biao Xiao ◽  
Xiao Ming Luo ◽  
Fu Zhen Xuan
Keyword(s):  
High Temperature ◽  
Interaction Model ◽  
Assessment Method ◽  
Multiple Cracks ◽  
Temperature Structure ◽  
Structural Components ◽  
Time Interaction ◽  
Magnification Factors ◽  
High Temperature Components ◽  
Cracks Interaction

Multiple flaws are often found in many high-temperature structural components. The interaction and coalescence of multiple cracks may significantly influence the service lives of these high-temperature components. In this paper, the interaction effect on multiple cracks is investigated under creep conditions. At the same time, interaction is considered during crack growth calculation by including the appropriate magnification factors in the calculations of creep fracture parameters. Based on these analyses, the assessment method of high-temperature structure containing multiple flaws is developed.

scholarly journals A Phenomenological Primary–Secondary–Tertiary Creep Model for Polymer-Bonded Composite Materials

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2353
Author(s):  
Xiaochang Duan ◽  
Hongwei Yuan ◽  
Wei Tang ◽  
Jingjing He ◽  
Xuefei Guan
Keyword(s):  
Composite Materials ◽  
Creep Behavior ◽  
Reference Model ◽  
Creep Model ◽  
Creep Process ◽  
Validation Dataset ◽  
Testing Conditions ◽  
Proposed Model ◽  
Testing Data ◽  
Bonded Composite

This study develops a unified phenomenological creep model for polymer-bonded composite materials, allowing for predicting the creep behavior in the three creep stages, namely the primary, the secondary, and the tertiary stages under sustained compressive stresses. Creep testing is performed using material specimens under several conditions with a temperature range of 20 °C–50 °C and a compressive stress range of 15 MPa–25 MPa. The testing data reveal that the strain rate–time response exhibits the transient, steady, and unstable stages under each of the testing conditions. A rational function-based creep rate equation is proposed to describe the full creep behavior under each of the testing conditions. By further correlating the resulting model parameters with temperature and stress and developing a Larson–Miller parameter-based rupture time prediction model, a unified phenomenological model is established. An independent validation dataset and third-party testing data are used to verify the effectiveness and accuracy of the proposed model. The performance of the proposed model is compared with that of an existing reference model. The verification and comparison results show that the model can describe all the three stages of the creep process, and the proposed model outperforms the reference model by yielding 28.5% smaller root mean squared errors on average.

Creep Modeling of Welded Joints Using the Theta Projection Concept and Finite Element Analysis

1999 ◽  
Vol 122 (1) ◽  
pp. 22-26 ◽  
Author(s):  
M. Law ◽  
W. Payten ◽  
K. Snowden
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Temperature ◽  
Welded Joints ◽  
Creep Model ◽  
Projection Data ◽  
Predictive Capability ◽  
Element Analysis ◽  
High Temperature And Pressure ◽  
Temperature And Pressure

Modeling of welded joints under creep conditions with finite element analysis was undertaken using the theta projection method. The results were compared to modeling based on a simple Norton law. Theta projection data extends the accuracy and predictive capability of finite element modeling of critical structures operating at high temperature and pressure. In some cases analyzed, it was found that the results diverged from those gained using a Norton law creep model. [S0094-9930(00)00601-6]

High temperature creep behavior of thixoformed nickel-based superalloy parts

2021 ◽  
pp. 141216
Author(s):  
Guanfei Xiao ◽  
Jufu Jiang ◽  
Ying Wang ◽  
Yingze Liu ◽  
Ying Zhang ◽  
...  
Keyword(s):  
High Temperature ◽  
Creep Behavior ◽  
High Temperature Creep ◽  
Temperature Creep ◽  
Nickel Based Superalloy
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