Ductile Fracture Simulation of Mulitple Surface Flaws

2011 ◽  
Author(s):  
Kazuhiro Suga ◽  
Katsumasa Miyazaki ◽  
Ryotaro Senda ◽  
Masanori Kikuchi
Keyword(s):  
Ductile Fracture ◽  
Fracture Behavior ◽  
Tensile Load ◽  
Crack Interaction ◽  
Cracked Plates ◽  
Fracture Simulation ◽  
Crack Problems ◽  
Surface Flaws ◽  
Fracture Processes ◽  
Effect Of Surface

Effect of surface flaw on ductile fracture behavior of non-aligned multiple flaws in plate is studied numerically using Gurson’s constitutive equation. Based on experiments, 2 parallel crack problems are simulated. In experiments and simulation crack coalescence, crack non coalescence and crack interaction was observed. In all cases, ductile fracture processes are obtained and results are compared with experimental ones. In this study, a new alignment rule for the prediction of maximum tensile load or rupture load for multiple cracked plates is compared with the simulation result.

Interaction Effect Evaluation of Plural Surface Cracks in Ductile Fracture Process

2012 ◽  
Author(s):  
Kazuhiro Suga ◽  
Katsumasa Miyazaki ◽  
Ryotaro Senda ◽  
Masanori Kikuchi
Keyword(s):  
Ductile Fracture ◽  
Fracture Process ◽  
Crack Depth ◽  
Maximum Load ◽  
Crack Penetration ◽  
Crack Problems ◽  
Average Crack ◽  
Fracture Processes ◽  
Ductile Fracture Process ◽  
Effect Of Surface

Effect of surface flaw on ductile fracture behavior of non-aligned multiple flaws in plate is studied numerically using Gurson’s constitutive equation. Based on experiments, two parallel non-aligned crack problems are simulated. From experimental and simulation data, crack coalescence, interaction between two cracks and crack penetration was observed. In all cases, ductile fracture processes are obtained and results are compared with experimental ones. Fracture patterns agree well with experimental results. Close qualitative match was obtained by comparing each load displacement curves that are normalized by maximum load. It shows that the mechanism of ductile fracture process is properly captured. By selecting one normalized experimental data as a base setup, maximum load from related simulation results can be predicted. Aligned rules are checked based on these simulations, and H / a criteria verified it’s availability when average crack depth is used as crack depth.

Effect of Flaw Dimensions on Ductile Fracture Behavior of Non-Aligned Multiple Flaws in a Plate

2011 ◽  
Author(s):  
Katsumasa Miyazaki ◽  
Kunio Hasegawa ◽  
Koichi Saito
Keyword(s):  
Ductile Fracture ◽  
Flat Plate ◽  
Fracture Behavior ◽  
Maximum Load ◽  
Surface Flaws ◽  
Fracture Tests ◽  
The Difference ◽  
Almost All ◽  
Maximum Minimum

The fitness-for-service codes require the characterization of non-aligned multiple flaws for flaw evaluation, which is performed using a flaw proximity rule. Worldwide, almost all such codes provide their own proximity rule, often with unclear technical bases of the application of proximity rule to ductile or fully plastic fracture. In particular, the effect of flaw dimensions of multiple surface flaws on fully plastic fracture of non-aligned multiple flaws had not been clear. To clarify the effect of the difference of part through-wall and through-wall flaws on the behavior of fully plastic fracture, the fracture tests of flat plate specimens with non-aligned multiple part through-wall flaws were conducted. When the flaw depth a was shallow with 0.4 in ratio of a to thickness t, the maximum load Pmax occurred at penetration of multiple flaws and the effect of vertical distance of non-aligned multiple flaws H on Pmax was not so significant. However, when flaw depth was deep with 0.8 in a/t, Pmax occurred after penetration of flaws and the effect of H on Pmax could be seen clearly. It was judged that the through-wall flaw tests were appropriate for discussion of the effect of H on Pmax and the alignment rule of multiple flaws. In addition, in order to clarify the appropriate length parameter to estimate Pmax of test specimens with dissimilar non-aligned through-wall multiple flaws, the fracture tests of plate specimens were also conducted. The effect of different flaw length on Pmax was discussed with maximum, minimum and averages of dissimilar non-aligned multiple flaw lengths. Experimental results showed that the maximum length lmax would be an appropriate length parameter to estimate Pmax, when the non-aligned multiple through-wall flaws were dissimilar.

Ductile Fracture Simulation of a Pipe of Steam Generator in PWR

2013 ◽  
Author(s):  
Yuuki Miyajima ◽  
Masanori Kikuchi ◽  
Akiyuki Takahashi
Keyword(s):  
Ductile Fracture ◽  
Large Deformation ◽  
Steam Generator ◽  
High Speed ◽  
Fracture Process ◽  
Burst Fracture ◽  
Final Fracture ◽  
Fracture Simulation ◽  
Inner Pressure ◽  
Crack Problems

Ductile fracture of steam generator pipes may occur due to inner pressure. The final fracture process by inner pressure occurs as a burst of a pipe, and ductile high speed crack growth occurs with large deformation of the structure. For the simulation of such fracture process, Gurson’s yield function is used as a constitutive equation, and large deformation theory is employed. As the simulation is conducted by load control condition, it is difficult to simulate burst phenomenon. Final fracture condition is discussed and finally crack opening displacement is chosen as burst fracture criterion. Fracture simulations of a pipe with multiple through cracks are conducted by changing distances between two crack tips. Burst loads are evaluated, and they are compared with estimated values by Maintenance rules. Surface crack problems are also simulated. Burst loads are also compared with results by limit load analysis method. Conservativeness of conventional evaluation methods are studied and discussed.

scholarly journals Modeling of Ductile Fracture for SS275 Structural Steel Sheets

2021 ◽  
Vol 11 (12) ◽  
pp. 5392
Author(s):  
Yonghyun Cho ◽  
Changkye Lee ◽  
Jurng-Jae Yee ◽  
Dong-Keon Kim
Keyword(s):  
Finite Element ◽  
Ductile Fracture ◽  
Structural Steel ◽  
Fracture Behavior ◽  
Weighted Average ◽  
Image Correlation ◽  
Model Parameters ◽  
Suitable Model ◽  
Element Analysis ◽  
Fracture Simulation

A series of earthquake events give impetus to research on the ductile fracture behavior of steel materials. In the last decades, many fracture models have been developed and utilized in the mechanical or aerospace engineering. Nevertheless, very little application to structural members used in the construction industry has been made due to the lack of a suitable model for the fracture behavior of constructional steel. This paper presents the experimental and finite element (FE) technique to predict ductile fracture in mild carbon structural steel (SS275) sheets, which has been widely used in building structures. The post-necking true stress–strain responses were successfully estimated using the weighted-average method. The Bao and Wierzbicki (BW) model, which requires only two model parameters, was selected for the identification of fracture locus. Each model parameter was calibrated from uniaxial tension and in-plane shear specimens with the aid of digital image correlation (DIC) and finite element analysis. Fracture simulation was then performed and validated based on the experimental results of the specimens under combined tension and shear stress state.

Sign in / Sign up

Export Citation Format

Share Document