Crack Propagation Analysis Procedure Using FEM Applied to the Three-Dimensional Stress Field

2005 ◽  
Author(s):  
Yukihiko Okuda ◽  
Yuuji Saito ◽  
Masayuki Asano ◽  
Masakazu Jimbo ◽  
Hiroshi Hirayama ◽  
...  
Keyword(s):  
Stress Field ◽  
Crack Propagation ◽  
Three Dimensional ◽  
Tensile Load ◽  
Analysis Procedure ◽  
Propagation Direction ◽  
Crack Shape ◽  
Weld Joints ◽  
Crack Propagation Direction ◽  
Propagation Analysis

Recently, several cracks have been found on the weld joints of Boiling Water Reactor (BWR) core shrouds during inspection. In order to ensure the continuous operation of nuclear power plants, it is necessary to assess the structural integrity of core shrouds with cracks on the weld joints. In general, a crack propagates in a complicated manner according to three-dimensional stress field and it is difficult to predict crack propagation direction and crack shape change. Usually, half ellipsoid crack shape is assumed and the propagation of the crack is calculated in the constant direction for assessment. In this study, crack propagation analysis procedure using the Finite Element Method (FEM) is developed for general shaped crack, and the procedure is verified by experiments. In this procedure, it is assumed that the crack propagates according to the maximum J-integral under three-dimensional stress fields and the re-mesh technique is used in the FEM analysis in order to calculate crack shape variation during propagation. The fatigue crack propagation tests under cyclic tensile load were performed to verify the analysis procedure. The specimens are made of a plate from 316SS and designed to generate non-uniform stress distribution on the crack front in order to observe continuous crack propagation direction change.

Crack-Propagating Direction of Tire Bead Rubber Determined by Jmax Criterion

2010 ◽  
Vol 43 ◽  
pp. 628-632 ◽  
Author(s):  
Chang Shun Zhu ◽  
Guo Lin Wang ◽  
Ping Ping Li ◽  
Shang Wei Chen
Keyword(s):  
Crack Propagation ◽  
Three Dimensional ◽  
Propagation Direction ◽  
Propagation Path ◽  
Crack Model ◽  
J Integral ◽  
Simulation Data ◽  
Crack Propagation Direction ◽  
Specimen Test ◽  
Set Up

Three-dimensional crack propagating path of tire bead rubber was the premise to study the crack propagation direction of bead. For this reason, Jmax Criterion was put forward. Utilized J integral maximum (Jmax) to determine the crack propagation direction of rubber. Calculated J-integral values of different preset directions by Abaqus built-in algorithm, obtained J (θ) curve which showed the Jmax and direction angle (θ) by fitting simulation data. Using Abaqus to set up two different crack model of bead rubber and simulate the crack propagation path, the results was consistent with the real crack propagation direction of specimen test, validated the applicability of Jmax Criterion..

Cleavage Planes of Icosahedral Quasicrystals: A Molecular Dynamics Study

2003 ◽  
Vol 805 ◽  
Author(s):  
Frohmut Rösch ◽  
Christoph Rudhart ◽  
Peter Gumbsch ◽  
Hans-Rainer Trebin
Keyword(s):  
Molecular Dynamics ◽  
Brittle Fracture ◽  
Crack Propagation ◽  
Three Dimensional ◽  
Propagation Direction ◽  
Mode I ◽  
Dynamic Crack ◽  
Fracture Surfaces ◽  
Icosahedral Quasicrystals ◽  
Crack Tip Plasticity

ABSTRACTThe propagation of mode I cracks in a three-dimensional icosahedral model quasicrystal has been studied by molecular dynamics techniques. In particular, the dependence on the plane structure and the influence of clusters have been investigated. Crack propagation was simulated in planes perpendicular to five-, two- and pseudo-twofold axes of the binary icosahedral model.Brittle fracture without any crack tip plasticity is observed. The fracture surfaces turn out to be rough on the scale of the clusters. These are not strictly circumvented, but to some extent cut by the dynamic crack. However, compared to the flat seed cracks the clusters are intersected less frequently. Thus the roughness of the crack surfaces can be attributed to the clusters, whereas the constant average heights of the fracture surfaces reflect the plane structure of the quasicrystal. Furthermore a distinct anisotropy with respect to the in-plane propagation direction is found.

Automatic 3-D Crack Propagation Calculations in Industrial Components: A Pure Hexahedral versus a Combined Hexahedral-Tetrahedral Approach

2007 ◽  
Vol 348-349 ◽  
pp. 45-48
Author(s):  
Guido Dhondt
Keyword(s):  
Crack Propagation ◽  
Computing Time ◽  
Propagation Direction ◽  
Hexahedral Elements ◽  
Crack Propagation Direction ◽  
Low Weight ◽  
Out Of Plane ◽  
Hexahedral Meshes ◽  
Crack Faces

In recent years, increased loading and low weight requirements have led to the need for automatic crack tracing software. At MTU a purely hexahedral code has been developed in the nineties for Mode-I applications. It has been used extensively for all kinds of components and has proven to be very flexible and reliable. Nevertheless, in transition regions between complex components curved cracks have been observed, necessitating the development of mixed-mode software. Due to the curvature of the crack faces, purely hexahedral meshes are not feasible, and therefore a mixture of hexahedral elements at the crack tip, combined with tetrahedral in the remaining structure has been selected. The intention of the present paper is to compare both methods and to point out the strength and weaknesses of each regarding accuracy, complexity, flexibility and computing time. Furthermore, difficulties arising from the out-of-plane growth of the crack such as the determination of the crack propagation direction are discussed.

Experimental Study and Finite Element Simulation of Heat Build-Up in Rubber Compounds with Application to Fracture

2003 ◽  
Vol 76 (2) ◽  
pp. 386-405 ◽  
Author(s):  
Vladamir Kerchman ◽  
Cheng Shaw
Keyword(s):  
Finite Element ◽  
Crack Propagation ◽  
Numerical Models ◽  
Propagation Direction ◽  
Transient Temperature ◽  
Ir Thermography ◽  
Crack Propagation Direction ◽  
Measure Surface Temperature ◽  
Rubber Compounds ◽  
Heat Build Up

Abstract IR thermography was used to measure surface temperature profiles of cylindrical rubber specimens during cyclic compression. A linearized constitutive approach and finite element analysis were used to evaluate heat generation and associated transient temperature fields. Modeled temperatures compared well with the IR measurements. This led to extended simulation efforts on lab fracture samples. IR thermography was used to measure temperature of filled NR and filled SBR specimens during tensile fatigue cut growth tests. Temperature gradients are expected to relate to kinetics of rubber fracture and identify regions within the sample that are undergoing accelerated damage. The following cut growth issues were addressed: 1) crack propagation direction in a non-uniform stress field; 2) crack propagation direction as a function of the angle of initial cuts; 3) initiation of crack branching; and 4) catastrophic failure. The nonlinear coupled mechanical and thermal FEA was used to evaluate the energy dissipation in the non-homogeneous cyclic deformation of cracked samples. Modeled and measured surface temperatures are in good agreement. Accounting for heat build-up ahead of an advancing crack can improve numerical models that quantify fatigue cut growth behavior in rubber compounds.

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