Real 3D Crack-Front and Crack Trajectory Analyses of Single-Side Repaired Thick Aluminium Panels

2008 ◽  
Vol 47-50 ◽  
pp. 777-780 ◽  
Author(s):  
Hossein Hosseini-Toudeshky ◽  
Masoud Saber ◽  
Bijan Mohammadi
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Front ◽  
Three Dimensional ◽  
Growth Trajectories ◽  
Crack Trajectory ◽  
Single Side ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

In this paper, fatigue crack growth trajectories, crack-front shape and life of the single-side repaired thick aluminium panels with glass/epoxy patch are analyzed. This investigation is performed using three dimensional finite element fracture analyses in general mixed-mode conditions (Mode I, II and III). The obtained fatigue crack growth trajectories, crack-front shapes and lives of the repaired panels with the patch lay-ups of [90]4 and [-45]4 are compared with the available experimental results produced by the authors.

Three-Dimensional Study of Fatigue Crack Growth in a Rotating Disc

2013 ◽  
Vol 3 (2) ◽  
pp. 45-62
Author(s):  
Eskandari Hadi ◽  
Nami Mohammad Rahim
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Front ◽  
Numerical Technique ◽  
Three Dimensional ◽  
Crack Orientation ◽  
Rotating Disc ◽  
Mesh Density ◽  
Three Dimensional Finite Element

The problem of fatigue-crack-growth in a rotating disc at different crack orientation angles is studied by using an automated numerical technique, which calculates the stress intensity factors on the crack front through the three-dimensional finite element method. Paris law is used to develop the fatigue shape of initially semi-elliptical surface crack. Because of needs for the higher mesh density and accuracy near the crack, the sub-modeling technique is used in the analysis. The distribution of SIF’s along the crack front at each step of growth is studied and the effect of crack orientation on the rate of crack-growth is investigated. The calculated SIF’s are reasonable and could be used to predict the probable crack growth rates in fracture mechanics analysis and can help engineers to consider in their designing and to prevent any unwanted failure of such components.

Fatigue Crack Growth Life Prediction for Surface Crack Located in Stress Concentration Part Based on the Three-Dimensional Finite Element Method

2004 ◽  
Vol 126 (1) ◽  
pp. 160-166 ◽  
Author(s):  
Y. Yamashita ◽  
M. Shinozaki ◽  
Y. Ueda ◽  
K. Sakano
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Surface Crack ◽  
Three Dimensional ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Element Method

Fatigue crack growth prediction methods using three-dimensional finite element analyses were investigated to improve the predictability of part-through surface crack growth life. First, a direct analysis method of cyclic finite element analysis was adopted. Fatigue crack growth was predicted on a step by step basis from the Paris’ law using stress intensity factor range ΔK calculated by the three-dimensional finite element method. This method takes the procedure of cyclic operation of finite element analysis modeled with crack tip elements, crack growth increment calculation and remeshing of the finite element model. Second, a method based on the influence function method for the ΔK calculation directly using three-dimensional finite element method analysis result has been developed and applied. It was found that crack growth prediction based on the step by step finite element method and the method based on the influence function method showed good correlation with the experimental results if Paris’ law coefficient C, determined by CT specimen, was appropriately used for a semi-elliptical surface crack.

Direct simulation of fatigue crack growth for arbitrary-shaped defects in pressure vessels

1998 ◽  
Vol 213 (2) ◽  
pp. 175-189 ◽  
Author(s):  
X. B. Lin ◽  
R. A. Smith
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Front ◽  
Three Dimensional ◽  
Longitudinal Crack ◽  
Internal Surface ◽  
Pressure Vessels ◽  
Advanced Technique

An advanced technique has been developed by the authors to predict fatigue crack growth for longitudinal and circumferential planar defects with arbitrary shape in pressure vessels. This is based on the step-by-step integration of an experimental fatigue crack growth law at a set of points along the crack front, enabling the crack shape developed during the fatigue process to be predicted. The stress intensity factors along the crack front are calculated by a three-dimensional finite element method. Automatic regeneration of finite element models for propagating cracks designed for this technique makes the simulation technique highly efficient. In this paper, following a description of the principle of the technique, some typical crack geometries are investigated. These include external and internal surface longitudinal cracks, an embedded longitudinal crack, a twin crack configuration and two circumferential surface cracks. The results obtained are compared with both the widely used ASME XI and BSI PD6493 guidelines, and some discussion on the safe use of the two guidelines is made.

scholarly journals Probabilistic fatigue damage prognosis using surrogate models trained via three-dimensional finite element analysis

2016 ◽  
Vol 16 (3) ◽  
pp. 291-308 ◽  
Author(s):  
Patrick E Leser ◽  
Jacob D Hochhalter ◽  
James E Warner ◽  
John A Newman ◽  
William P Leser ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Crack ◽  
Crack Growth ◽  
Three Dimensional ◽  
High Fidelity ◽  
Probabilistic Prediction ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Utilizing inverse uncertainty quantification techniques, structural health monitoring (SHM) can be integrated with damage progression models to form a probabilistic prediction of a structure’s remaining useful life (RUL). However, damage evolution in realistic structures is physically complex. Accurately representing this behavior requires high-fidelity models which are typically computationally prohibitive. In this paper, high-fidelity fatigue crack growth simulation times are reduced by three orders of magnitude using a model based on a set of surrogate models trained via three-dimensional finite element analysis. The developed crack growth modeling approach is experimentally validated using SHM-based damage diagnosis data. A probabilistic prediction of RUL is formed for a metallic, single-edge notch tension specimen with a fatigue crack growing under mixed-mode conditions.

The Effect of the Singularity Induced by the Free Surface on Fatigue Crack Growth in Thin Structures

2008 ◽  
Vol 385-387 ◽  
pp. 317-320 ◽  
Author(s):  
Pavel Hutař ◽  
Luboš Náhlík ◽  
Zdeněk Knésl
Keyword(s):  
Fatigue Crack ◽  
Free Surface ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Front ◽  
Three Dimensional ◽  
Stress Singularity ◽  
Thin Structures ◽  
Crack Behavior ◽  
Vertex Singularity

In many industrial applications is necessary to predict fatigue lifetime of thin structures, where the stress field near the crack front have a real three-dimensional nature. Due to the existence of vertex singularity in the point where the crack front touching free surface, crack propagation in 3D structures cannot be reduced to a series of plane strain or plane stress problems along the crack front edge. The paper describes the influence of vertex singularity on the distribution of the stresses around the crack front for three-dimensional body. The distribution of the stress singularity through the thickness of the specimen gives us indication of the crack behavior in thin structures. The estimation of the thickness of the specimen where the change of singularity plays an important role on fatigue crack growth rate (in dependence on Poisson’s ratio) is carried out. The results contribute to a better understanding of the crack behavior in thin structures, and can help to more reliable estimates of their residual fatigue life.

Comparison of DBEM and FEM Crack Path Predictions with Experimental Findings for a SEN-Specimen under Anti-Plane Shear Loading

2007 ◽  
Vol 348-349 ◽  
pp. 129-132 ◽  
Author(s):  
Roberto G. Citarella ◽  
Friedrich G. Buchholz
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Front ◽  
Crack Path ◽  
Shear Loading ◽  
Crack Growth Behaviour ◽  
3D Crack Growth ◽  
Corner Points ◽  
Experimental Findings

In this paper detailed results of computational 3D fatigue crack growth simulations will be presented. The simulations for the crack path assessment are based on the DBEM code BEASY, and the FEM code ADAPCRACK 3D. The specimen under investigation is a SEN-specimen subject to pure anti-plane or out-of-plane four-point shear loading. The computational 3D fracture analyses deliver variable mixed mode II and III conditions along the crack front. Special interest is taken in this mode coupling effect to be found in stress intensity factor (SIF) results along the crack front. Further interest is taken in a 3D effect which is effective in particular at and adjacent to the two crack front corner points, that is where the crack front intersects the two free side surfaces of the specimen. Exactly at these crack front corner points fatigue crack growth initiates in the experimental laboratory test specimens, and develops into two separate anti-symmetric cracks with complex shapes, somehow similar to bird wings. The computational DBEM results are found to be in good agreement with these experimental findings and with FEM results previously obtained. Consequently, also for this new case, with complex 3D crack growth behaviour of two cracks, the functionality of the proposed DBEM and FEM approaches can be stated.

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