Proposal And Use Of A Void Model For The Simulation Of Ductile Fracture Behavior In Material Forming

2007 ◽  
Author(s):  
Kazutake Komori
Keyword(s):  
Ductile Fracture ◽  
Fracture Behavior ◽  
Material Forming

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.

Evaluations of Ductile and Cleavage Fracture Using Coupled GTN and Beremin Model in API X70 Pipelines Steel

2019 ◽  
Author(s):  
Youn-Young Jang ◽  
Ji-Hee Moon ◽  
Nam-Su Huh ◽  
Ki-Seok Kim ◽  
Woo-Yeon Cho ◽  
...  
Keyword(s):  
Ductile Fracture ◽  
Cleavage Fracture ◽  
Fracture Behavior ◽  
Pipeline Steel ◽  
Model Parameters ◽  
Experiment Data ◽  
Local Approach ◽  
Gtn Model ◽  
Weibull Parameters ◽  
X70 Pipeline Steel

Abstract This paper is aimed to characterize ductile and cleavage fracture behavior of API X70 pipeline steel and investigate applicability of a micro-damage mechanics model to simulate static and dynamic crack propagation of single-edge notched tension (SENT) and drop-weight tear test (DWTT) specimens, as well as a local approach to describe cleavage fracture behavior. Gurson-Tvergaard-Needleman (GTN) model was applied to simulate ductile fracture behavior of SENT and DWTT specimens, where GTN model has been widely known for well-established model to characterize micro-damage process of void nucleation, growth and coalescence. As for a local approach, Beremin model was considered to estimate probability of cleavage fracture. In this regard, this study was especially focused on abnormal fracture appearance of DWTT specimen. In the present study, firstly, experiment data from tensile specimen test was used to obtain plastic flow curve (i.e. stress and strain curve). And load-CMOD and J-integral/CTOD resistance curves obtained from SENT test were used to characterize static ductile fracture and calibrate GTN model parameters for X70 pipeline steel. And the calibrated GTN model parameters were verified by comparing experiment data from DWTT test such as load-displacement and crack length-time curves with those from FE analysis. To accommodate dynamic effect on material properties, rate-dependent stress-strain curves were considered in FE analyses. To describe cleavage fracture, the Weibull stress was calculated from FE analyses of DWTT and Weibull parameters were calibrated by comparing with probability distribution of cleavage fracture from experiment data of DWTT specimen. Using Weibull parameters, the whole of cleavage fracture probability can be estimated as ductile shear area of DWTT specimen increases.

Experimental Study for Proximity Rule of Multiple Flaws for Ductile Fracture

2004 ◽  
Author(s):  
Katsumasa Miyazaki ◽  
Kunio Hasegawa ◽  
Takeshi Shimamura
Keyword(s):  
Aspect Ratio ◽  
Ductile Fracture ◽  
Fracture Behavior ◽  
Maximum Load ◽  
Tensile Tests ◽  
Fracture Pattern ◽  
The Other ◽  
Plastic Collapse ◽  
Intensity Factors ◽  
Class 1

The proximity rule of multiple flaws in ASME B&PV Code Section XI 2003 addenda was mainly determined by the evaluation of stress intensity factors from the viewpoint of brittle fracture. Since the austenitic steel and carbon steel for class 1 piping shows a ductile manner in fracture, a new proximity rule for ductile fracture is required. To understand the fracture behavior of multiple flaws, tensile tests, using flat plate specimens made of Type 304SS with twin flaws, were conducted. When the shapes of twin flaws were semi-circular with aspect ratio, a/l = 0.5, the effect of the space of multiple flaws on maximum load is clear. On the other hand, the effect of flaw spacing on maximum load was insignificant for flat multiple flaws with 0.167 in a/l. The effect of space of multiple flaws, aspect ratio of multiple flaws on ductile fracture pattern was discussed. Finally, the proximity rule for plastic collapse was proposed in this paper.

scholarly journals Modeling anisotropic ductile fracture behavior of Ti-6Al-4V titanium alloy for sheet forming applications at room temperature

2020 ◽  
Vol 207 ◽  
pp. 178-195
Author(s):  
Bingtao Tang ◽  
Qingfeng Wang ◽  
Ning Guo ◽  
Xinsheng Li ◽  
Qiaoling Wang ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Ductile Fracture ◽  
Fracture Behavior ◽  
Room Temperature ◽  
Sheet Forming

scholarly journals Ductile Fracture Behavior of Bainite-MA Dual Phase Steels

2016 ◽  
Vol 56 (12) ◽  
pp. 2304-2312 ◽  
Author(s):  
Junji Shimamura ◽  
Shusaku Ota ◽  
Kyono Yasuda ◽  
Nobuyuki Ishikawa
Keyword(s):  
Ductile Fracture ◽  
Fracture Behavior ◽  
Dual Phase ◽  
Dual Phase Steels
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