Capture of 2-D Crack Growth Path by the Polygonal Numerical Manifold Method

2012 ◽  
Vol 166-169 ◽  
pp. 3224-3227
Author(s):  
Hui Hua Zhang
Keyword(s):  
Crack Propagation ◽  
Crack Growth ◽  
High Efficiency ◽  
Numerical Manifold Method ◽  
Growth Path ◽  
Great Flexibility ◽  
Materials Modeling ◽  
Polygonal Elements ◽  
Crack Growth Path ◽  
Numerical Manifold

Due to the independence of physical domain and the mathematical cover system, the numerical manifold method (NMM) can efficiently simulate crack propagation without remeshing. At the same time, the polygonal elements are also very attractive due to their great flexibility in meshing and high efficiency in materials modeling. In the present paper, the NMM is applied to solve 2-D crack propagation problems on polygonal elements. Our numerical results show that the proposed method can well capture the crack growth trajectory compared with the reference solution

scholarly journals Numerical Analysis of Fatigue Crack Growth Path and Life Predictions for Linear Elastic Material

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3380
Author(s):  
Abdulnaser M. Alshoaibi ◽  
Yahya Ali Fageehi
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Propagation ◽  
Crack Growth ◽  
Mixed Mode ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Growth Path ◽  
Linear Elastic ◽  
Crack Growth Path

The main objective of this work was to present a numerical modelling of crack growth path in linear elastic materials under mixed-mode loadings, as well as to study the effect of presence of a hole on fatigue crack propagation and fatigue life in a modified compact tension specimen under constant amplitude loading condition. The ANSYS Mechanical APDL 19.2 is implemented for accurate prediction of the crack propagation paths and the associated fatigue life under constant amplitude loading conditions using a new feature in ANSYS which is the smart crack growth technique. The Paris law model has been employed for the evaluation of the mixed-mode fatigue life for the modified compact tension specimen (MCTS) with different configuration of MCTS under the linear elastic fracture mechanics (LEFM) assumption. The approach involves accurate evaluation of stress intensity factors (SIFs), path of crack growth and a fatigue life evaluation through an incremental crack extension analysis. Fatigue crack growth results indicate that the fatigue crack has always been attracted to the hole, so either it can only curve its path and propagate towards the hole, or it can only float from the hole and grow further once the hole has been lost. In terms of trajectories of crack propagation under mixed-mode load conditions, the results of this study are validated with several crack propagation experiments published in literature showing the similar observations. Accurate results of the predicted fatigue life were achieved compared to the two-dimensional data performed by other researchers.

Research on Microstructure Dependence of Near-Threshold Fatigue Crack Propagation by Combined Analyses of Fracture Surface and Fatigue Crack Growth Path

2009 ◽  
Author(s):  
Ming-Liang Zhu ◽  
Fu-Zhen Xuan ◽  
Guo-Zhen Wang ◽  
Zheng-Dong Wang
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Crack Advance ◽  
Growth Path ◽  
Austenite Grain Size ◽  
Fatigue Crack Growth Resistance ◽  
Crack Growth Path ◽  
Near Threshold

Near-threshold fatigue crack growth behavior was investigated in a newly developed steel 25Cr2NiMo1V with different heat treatments to meet different property requirements of high-pressure (HP) and low-pressure (LP) parts in the combined steam turbine rotor. The load-shedding method was adopted in the near-threshold fatigue crack growth experiment at room temperature with a constant load ratio of 0.1. Combined analyses of crack surface and fatigue crack growth path were carried out to identify the dominant crack growth mechanisms in both HP and LP. Results show that in the threshold regime, fatigue crack growth resistance of the HP is clearly superior to that of LP and hence shows strongly dependence on the microstructure of 25Cr2NiMo1V. The distributed bainitic microstructures and larger prior austenite grain size in HP result in more tortuous crack propagation path than that in LP. Compared with ferritic blocks in HP, the tempered martensitic laths in LP do not play a dominate role in stopping the fatigue crack advance.

scholarly journals Two- and Three-Dimensional Numerical Investigation of the Influence of Holes on the Fatigue Crack Growth Path

2021 ◽  
Vol 11 (16) ◽  
pp. 7480
Author(s):  
Yahya Ali Fageehi
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Fracture Mechanics ◽  
Crack Propagation ◽  
Crack Growth ◽  
Three Dimensional ◽  
Real Life ◽  
Growth Path ◽  
Crack Growth Path

Problems in fracture mechanics are difficult when the appropriate analysis is unspecified, which is very common in most real-life situations. Finite element modeling is thus demonstrated to be an essential technique to overcome these problems. There are currently various software tools available for modeling fracture mechanics problems, but they are usually difficult to use, and obtaining accurate results is not an obvious task. This paper illustrates some procedures in two finite element programs to solve problems in two- and three-dimensional linear-elastic fracture mechanics, and an educational proposal is made to use this software for a better understanding of fracture mechanics. Crack modeling was done in a variety of ways depending on the software. The first is the well-known ANSYS, which is usually utilized in industry, and the second was a freely distributed code, called FRANC2D/L, from Cornell University. These software applications were used to predict the fatigue crack growth path as well as the associated stress intensity factors. The predicted results demonstrate that the fatigue crack is turned towards the hole. The fatigue crack growth paths are influenced by the varying positions and sizes of single holes, while two symmetrically distributed holes have no effect on the fatigue crack growth direction. The findings of the study agree with other experimental crack propagation studies presented in the literature that reveal similar crack propagation trajectory observations.

On the Topology Update of the Numerical Manifold Method for Multiple Crack Propagation

2021 ◽  
pp. 2150030
Author(s):  
Jun He ◽  
Shuling Huang ◽  
Xiuli Ding ◽  
Yuting Zhang ◽  
Dengxue Liu
Keyword(s):  
Crack Initiation ◽  
Crack Propagation ◽  
Numerical Method ◽  
Crack Tip ◽  
Search Method ◽  
Numerical Manifold Method ◽  
Crack Initiation And Propagation ◽  
Multiple Crack ◽  
Initiation And Propagation ◽  
Numerical Manifold

Crack initiation and propagation are the two key issues of concern in the geotechnical engineering. In this study, the numerical manifold method (NMM) is applied to simulate crack propagation and the topology update of the NMM for multiple crack propagation is studied. The crack-tip asymptotic interpolation function is incorporated into the NMM to increase the accuracy of the crack-tip stress field. In addition, the Mohr-Coulomb criterion with tensile cut off is adopted to be the crack propagation criterion to judge the direction of crack initiation and propagation. Then a crack tip searching method is developed to automatically update the position of the crack tips. The inapplicability of the original loop search method in the NMM is also illustrated and a novel loop search method based on manifold elements is developed for physical loop updating. Moreover, methods for the manifold element updating and physical cover updating are provided. Based on the above study, the developed numerical method is capable to simulate multiple crack propagation. At last, typical rock rupture problems are numerically simulated to manifest the effectiveness of the developed numerical method.

Morphology Analysis of Mixed Mode Fatigue Crack Growth in a Low Alloy Steel

2013 ◽  
Vol 787 ◽  
pp. 745-749
Author(s):  
Hui Fang Li ◽  
Xiao Ju Sun ◽  
Lan Qing Tang ◽  
Cai Fu Qian
Keyword(s):  
Fatigue Crack ◽  
Fracture Surface ◽  
Crack Growth ◽  
Alloy Steel ◽  
Mixed Mode ◽  
Low Alloy Steel ◽  
Growth Path ◽  
Fatigue Fracture Surface ◽  
Final Fracture ◽  
Crack Growth Path

In this paper, I+II mixed mode fatigue crack propagation in a low alloy steel 16MnDR was experimentally investigated. Morphologies of crack growth path and fracture surface are analyzed. It is found that upon initiation from the inclined pre-crack, the newly formed crack grows in a direction to be perpendicular to the applied load, making crack mode transformation from I+II mixed mode to mode I. The crack growth is transgranular and no clear branches are presented. Striations and dimples are found on the fatigue fracture surface and the final fracture surface, respectively, showing that the material is ductile in nature.

Thermal Effects while Fatigue Cracking Growth under Bending

2013 ◽  
Vol 592-593 ◽  
pp. 700-703
Author(s):  
Dariusz Rozumek ◽  
Norbert Szmolke
Keyword(s):  
Crack Growth ◽  
Thermal Effects ◽  
Fatigue Cracking ◽  
Fatigue Tests ◽  
Temperature Gradients ◽  
Growth Path ◽  
Temperature Changes ◽  
Crack Growth Path ◽  
Molecular Friction

The paper presents the results of fatigue tests where temperature changes on specimen surfaces were registered. Some different materials were tested. A relation between the crack growth and temperature changes in the propagation place was found. The highest temperature gradients were measured on the crack growth path, and it was caused by molecular friction.

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