Application of Energy-Based Damage Model to Simulate Ductile Fracture Under Cyclic Loading and Validation Against Piping System Test Data

Author(s):  
Gyo-Geun Youn ◽  
Hyun-Suk Nam ◽  
Hune-Tae Kim ◽  
Jong-Min Lee ◽  
Yun-Jae Kim

In this paper, a method to predict ductile fracture under low cyclic loading condition is proposed. Then it is compared with test results of surface cracked pipes which is conducted by Battelle Institute. A&F nonlinear kinematic hardening model is adopted to describe material behavior under cyclic loading condition and energy-based damage model is applied to simulate ductile crack growth. The energy-based damaged model is depending on multi-axial fracture strain energy. To apply this model, two parameters should be determined from tensile and C(T) test results under monotonic loading condition. One is multi-axial fracture strain energy Wf and the other is critical damage value ωc. From the determined damaged model, it is enable to simulate surface cracked pipe tests under low cyclic loading condition.

Author(s):  
Jin-Ha Hwang ◽  
Gyo-Geun Youn ◽  
Naoki Miura ◽  
Yun-Jae Kim

To evaluate the structural integrity of nuclear power plant piping, it is important to predict ductile tearing of circumferential cracked pipe from the view point of Leak-Before-Break concept under seismic conditions. CRIEPI (Central Research Institute of Electric Power Industry) conducted fracture test on Japanese carbon steel (STS410) circumferential through-wall cracked pipes under monotonic or cyclic bending load in room temperature. Cyclic loading test conducted variable experimental conditions considering effect of stress ratio and amplitude. In the previous study, monotonic fracture pipe test was simulated by modified stress-strain ductile damage model determined by C(T) specimen fracture toughness test. And, ductile fracture of pipe under cyclic loading simulated using damage criteria based on fracture strain energy from C(T) specimen test data. In this study, monotonic pipe test result is applied to determination of damage model based on fracture strain energy, using finite element analysis, without C(T) specimen fracture toughness test. Ductile fracture of pipe under variable cyclic loading conditions simulates using determined fracture energy damage model from monotonic pipe test.


Author(s):  
J. Oh ◽  
N. Katsube ◽  
F. W. Brust

This paper studies intergranular creep failure of high temperature service material under a stress-controlled unbalanced cyclic loading condition. The grain boundary rupture process was numerically analyzed using Tvergaard’s axisymetric model. The present numerical model incorporated the experimentally verified Murakami-Ohno cyclic strain hardening creep law and Norton’s creep law. The numerical results show that void growth accelerates under cyclic loading condition. Also, analysis shows that a steady state creep law is not sufficient to analyze damage evolution under cyclic loading conditions.


2012 ◽  
Vol 479-481 ◽  
pp. 170-173
Author(s):  
Yu Tian Wang ◽  
Fu Xiang Jiang ◽  
Yan Wang ◽  
Xiu Li Du

A single-span and two-story frame specimen with reinforced beam ends has been tested under low-frequency cyclic loading. Based on the test results, the failure patterns, hysteretic behaviors, energy dissipation and deformation ability were analyzed. The results showed that the failure mode of the test specimen was ductility. Plastic hinges appeared at the changing point of the beam cross section far away from the beam-column joint. Hysteretic curve of the frame was full and the whole ductility coefficient was enough higher than 4.4 under horizontal low-cyclic loading. It can be concluded that the energy dissipation and the deformation ability are both better. So the whole steel frame connected with reinforced beam ends has good seismic performance. And the requirements of anti-seismic ability can be satisfied.


2021 ◽  
Author(s):  
Prasanth Chandrasekar

Engineering materials in their service life undergo symmetric or asymmetric fatigue loading, which leads to fatigue damage in the material. Ratcheting damage is due to the application of mean stress under cyclic loading condition. From deformation behavior perspective, application of mean stress under stress-controlled fatigue loading gives rise to accumulation of plastic strain in the material. Ratcheting strain increases with an increase in applied mean stress and stress amplitude. In addition, ratcheting behavior will increase in cyclic damage with the rise in strain accumulation and it can be illustrated by a shift in the hysteresis loop towards large plastic strain amplitudes. This study focuses on the ratcheting behavior of different steel materials under uniaxial cyclic loading condition and suggests a suitable method to arrest ratcheting by loading the materials at zero ratcheting strain rate condition with specified mean stress and stress amplitudes. The three dimensional surface is created with stress amplitude, mean stress and ratcheting strain rate for different steel materials. This represents a graphical surface zone to study the ratcheting strain rates for various mean stress and stress amplitude combinations.


2019 ◽  
Vol 52 (8) ◽  
pp. 2681-2690 ◽  
Author(s):  
Xuezhen Wu ◽  
Yujing Jiang ◽  
Bin Gong ◽  
Zhenchang Guan ◽  
Tao Deng

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