Crack Propagation Analysis of Statically Indeterminate Beam by Elastic-Plastic Fracture Mechanics

2002 ◽  
Vol 18 (3) ◽  
pp. 119-126
Author(s):  
Sung-Po Liu ◽  
C. J. Shih ◽  
Liang-Yu Kuo
Keyword(s):  
Fracture Mechanics ◽  
Crack Propagation ◽  
Plastic Hinge ◽  
Linear Displacement ◽  
Plastic Collapse ◽  
Rotational Angle ◽  
Elastic Plastic ◽  
Rectangular Beam ◽  
Propagation Analysis ◽  
Leak Before Break

AbstractThis paper develops an analytical model for the plastic collapse of a statically indeterminate rectangular beam containing a crack. Limit analysis, elastic-plastic fracture mechanics, compliance and J-integral concepts are used to study JIC and dJ/da that influence the crack propagation. The relations among the plastic hinge, applied load, linear displacement, rotational angle and crack growth leads to a better understanding of the problem as a consequence of this study. The conclusions are: (1) Unstable ductile fracture occurs at the crack propagates before plastic collapse or at dJ/da is smaller than the minimum critical value. (2) LBB (leak-before-break) characteristic of the statically indeterminate rectangular beam is valid if the crack propagates before plastic collapse.

Cohesive Zone Model and GTN Model Collation for Ductile Crack Growth

2007 ◽  
Vol 567-568 ◽  
pp. 145-148
Author(s):  
Vladislav Kozák ◽  
Ivo Dlouhý ◽  
Zdeněk Chlup
Keyword(s):  
Fracture Mechanics ◽  
Crack Propagation ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Zone Model ◽  
Interface Elements ◽  
Ductile Crack Growth ◽  
Propagation Analysis ◽  
Wide Range ◽  
Finite Element Package

The micromechanical modelling encounters a problem that is different from basic assumptions of continuum mechanics. The material is not uniform on the microscale level and the material within an element has its own complex microstructure. Therefore the concept of a representative volume element (RVE) has been introduced. The general advantage, compared to conventional fracture mechanics, is that, in principle, the parameters of the respective models depend only on the material and not on the geometry. These concepts guarantee transferability from specimen to components over a wide range of dimensions and geometries. The prediction of crack propagation through interface elements based on the fracture mechanics approach (damage) and cohesive zone model is presented. The cohesive model for crack propagation analysis is incorporated into finite element package by interface elements which separations are controlled by the traction-separation law.

Uncertainties of Crack Propagation Analysis in Ship Structures

2016 ◽  
Author(s):  
Wengang Mao ◽  
Jingxia Yue ◽  
Da Wu ◽  
Luis De Gracia ◽  
Naoki Osawa
Keyword(s):  
Fatigue Life ◽  
Fracture Mechanics ◽  
Crack Propagation ◽  
Fatigue Cracks ◽  
Estimation Methods ◽  
Ship Structures ◽  
Residual Fatigue Life ◽  
Propagation Analysis ◽  
Structural Details ◽  
Residual Fatigue

Fatigue cracks can be observed quite frequently on today’s ocean crossing vessels. To ensure the safety of ship structures sailing in the sea, it is important to know the residual fatigue life of these damaged ship structures. In this case, the fracture mechanics theory is often employed to estimate how fast these cracks can propagate along ship structures. However, large uncertainties are always associated with the crack prediction and residual fatigue life analysis. In this study, two uncertainties sources will be investigated, i.e. the reliability of encountered wave environments connected with shipload determinations and different fracture estimation methods for crack propagation analysis. Firstly, different available codes based on fracture mechanic theory are used to compute the stress intensity factor related parameters for crack propagation analysis. The analysis is carried out for both 2D and 3D cases of some typical ship structural details. The comparison is presented to illustrate the uncertainties of crack propagation analysis related with different codes. Furthermore, it is assumed that the structural details will undertake dynamic loading from a containership operated in the North Atlantic. A statistical wave model is used to generate wave environments along recorded ship routes for different years. The uncertainties of crack growth analysis related with encountered weather environments is also investigated in the study. The comparison of these two uncertainties indicated the requirement of further development for the fracture mechanics theory and associated numerical codes, as well as the reliable life-cycle encountered weather environments.

Short-Term Stable Crack Propagation through Polyolefin Single- and Bilayered Structures - Influence of Welding, Composition and Direction of Crack Propagation

2016 ◽  
Vol 258 ◽  
pp. 538-541
Author(s):  
Ralf Lach ◽  
Tobias Krolopp ◽  
Pavel Hutař ◽  
Eva Nezbedova ◽  
Wolfgang Grellmann
Keyword(s):  
Fracture Mechanics ◽  
Crack Initiation ◽  
Crack Propagation ◽  
Crack Resistance ◽  
Crack Initiation And Propagation ◽  
Short Term ◽  
Elastic Plastic ◽  
Stable Crack Propagation ◽  
Initiation And Propagation ◽  
Specimen Shape

The overall stable crack initiation and propagation behaviour of specimens cut from plastic pipes that were composed of different polyolefin materials were investigated using concepts of elastic–plastic fracture mechanics including the crack propagation kinetics. The effect of specimen shape, orientation, welding, lading rate, composition/microstructure and direction of crack propagation on the crack resistance (R) behaviour of these materials has been thereby assessed.

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