FEM solution of a dynamic elastoplastic problem of fracture mechanics. 2. Supercritical crack propagation

1990 ◽  
Vol 22 (7) ◽  
pp. 943-953 ◽  
Author(s):  
V. I. Kostylev ◽  
V. Z. Margolin
Keyword(s):  
Fracture Mechanics ◽  
Crack Propagation ◽  
Elastoplastic Problem

Corrosion Fatigue Mechanisms and Fracture Mechanics Based Modelling for Subsea Pipeline Steels

2017 ◽  
Author(s):  
Ankang Cheng ◽  
Nian-Zhong Chen
Keyword(s):  
Fracture Mechanics ◽  
Crack Propagation ◽  
Corrosion Fatigue ◽  
Fatigue Cracking ◽  
Crack Propagation Rate ◽  
Propagation Rate ◽  
Propagation Time ◽  
Loading Frequency ◽  
Pipeline Steels ◽  
Driving Mechanisms

Subsea structures such as pipelines are vulnerable to environment-assisted crackings (EACs). As a type of EAC, corrosion fatigue (CF) is almost inevitable. For such a process, stress corrosion (SC) and hydrogen-assisted cracking (HAC) are the two mainly driving mechanisms. And it was further pointed out that slip dissolution (SD) and hydrogen embrittlement (HE) should be responsible for SC and HAC respectively. Based on such a fact, a two-component physical model for estimating the CF crack propagation rate was proposed. The proposed model was built in a frame of fracture mechanics integrated with a dissolution model for C-Mn steel and a newly established model by the authors accounting for the influence from HE upon crack propagation. The overall CF crack propagation rate is the aggregate of the two rates predicted by the two sub-individual models, and then the crack propagation time is calculated accordingly. The model has been proven to be capable of capturing the features of HE influenced fatigue cracking behaviour as well as taking mechanical factors such as the loading frequency and stress ratio into account by comparison with the experimental data of X42 and X65 pipeline steels.

The Bridged Crack Model for the Analysis of Brittle Matrix Fibrous Composites Under Repeated Bending Loading

2007 ◽  
Vol 74 (6) ◽  
pp. 1239-1246 ◽  
Author(s):  
Alberto Carpinteri ◽  
Simone Puzzi
Keyword(s):  
Reinforced Concrete ◽  
Fracture Mechanics ◽  
Crack Propagation ◽  
Composite Beam ◽  
Crack Model ◽  
Brittle Matrix ◽  
Cyclic Bending ◽  
Mechanics Model ◽  
Bending Loading ◽  
Bridged Crack

In this paper, we present a fracture-mechanics based model, the so-called bridged crack model (Carpinteri, A., 1981, “A Fracture Mechanics Model for Reinforced Concrete Collapse,” Proc. of IABSE Colloquium on Advanced Mechanics of Reinforced Concrete, Delft, I.A.B.S.E., Zürich, pp. 17–30; Carpinteri, A., 1984, “Stability of Fracturing Process in R.C. Beams,” J. Struct. Engng. (A.S.C.E.), 110, pp. 544–558) for the analysis of brittle matrix composites with discontinuous ductile reinforcements under the condition of repeated bending loading. In particular, we address the case of composites with very high number of reinforcements (i.e., fiber-reinforced composites, rather than conventionally reinforced concrete). With this aim, we propose a new iterative procedure and compare it to the algorithm recently proposed by Carpinteri, Spagnoli, and Vantadori (2004, “A Fracture Mechanics Model for a Composite Beam with Multiple Reinforcements Under Cyclic Bending,” Int. J. Solids Struct., 41, pp. 5499–5515), showing the advantages in terms of computational efficiency. Furthermore, we analyze the combined effects of crack length, brittleness number, and fiber number on the cyclic behavior of the composite beam, showing the conditions enhancing the energy dissipation in the composite system. Eventually, we analyze crack propagation and propose, consistently with the model premises, a fracture-mechanics-based crack propagation criterion that allows one to simulate cyclic bending tests under the fixed grip condition.

Application of Multi-Parameter Fracture Mechanics to Study of Crack Propagation Angle in Selected Mixed-Mode Geometry

2013 ◽  
Vol 592-593 ◽  
pp. 209-212 ◽  
Author(s):  
Lucie Šestáková Malíková ◽  
Václav Veselý
Keyword(s):  
Fracture Mechanics ◽  
Crack Propagation ◽  
Mixed Mode ◽  
Initial Crack ◽  
Propagation Angle ◽  
Linear Elastic ◽  
Higher Order Terms ◽  
Elastic Fracture ◽  
Cracked Specimens ◽  
Crack Propagation Angle

The multi-parameter fracture mechanics becomes more and more significant, because it is shown that it can help to describe fracture processes occurring in cracked specimens more precisely than conventional linear elastic fracture mechanics. In this paper, the concept based on the Williams expansion derived for approximation of stress/displacement crack-tip fields is presented and applied on a mixed-mode configuration. Two fracture criteria for estimation of the initial crack propagation angle are introduced. A parametric study is performed in order to investigate the dependence of the crack propagation angle on the stress intensity factors ratio. Influence and importance of taking into account the so-called higher-order terms of the Williams expansion are discussed and some recommendations are stated.

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