Numerical Study of Crack Propagation in Stiff Clays

2006 ◽  
pp. 201-204
Author(s):  
Shan Yong Wang ◽  
K.C. Lam ◽  
Ivan W.H. Fung ◽  
Wan Cheng Zhu ◽  
Tao Xu ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Numerical Study ◽  
Stiff Clays

Numerical Study of Crack Propagation in Stiff Clays

2006 ◽  
Vol 324-325 ◽  
pp. 201-204
Author(s):  
Shan Yong Wang ◽  
K.C. Lam ◽  
Ivan W.H. Fung ◽  
Wan Cheng Zhu ◽  
Tao Xu ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Numerical Method ◽  
Numerical Study ◽  
Propagation Direction ◽  
Shear Stresses ◽  
Stiff Clays ◽  
Whole Process ◽  
Initiation And Propagation ◽  
Normal And Shear Stresses ◽  
Natural Slopes

Many stiff clays forming part of natural slopes and earth dams exist in the fissured state. When these cracks are subjected to gravity induced normal and shear stresses they may propagate. The present discussion presents a numerical method to study the propagation direction of cracks under stress fields similar to those found in the field. Not only did the results on one crack propagation direction obtained from the numerical method and the analytical results agree well, but numerical results have been used to investigate the mechanisms of the whole process of two horizontal cracks initiation and propagation and coalescence in stiff soils.

Numerical Study on Progressive Failure of the Marble Plate Based on the Thin-Layer Tri-Node Jointed Element

2011 ◽  
Vol 255-260 ◽  
pp. 1867-1872
Author(s):  
Jing Hua Qi ◽  
Zhen Nan Zhang ◽  
Xiu Run Ge
Keyword(s):  
Crack Propagation ◽  
Thin Layer ◽  
Numerical Study ◽  
Progressive Failure ◽  
Triangular Element ◽  
Compressive Loads ◽  
Joint Element ◽  
The Common ◽  
Edge Cracks ◽  
Good Agreement

In order to model the mechanical behavior of joints efficiently, a thin-layer tri-node joint element is constructed. The stiffness matrix of the element is derived in the paper. For it shares the common nodes with the original tri-node triangle element, the tri-node joint element can be applied to model the crack propagation without remeshing or mesh adjustment. Another advantage is that the cracked body is meshed without consideration of its geometry integrity and existence of the joints or pre-existed crack in the procedure of mesh generation, and then the triangular element intersected by the crack or joint is automatically transformed into the tri-node joint element to represent pre-existed cracks. These make the numerical simulation of crack propagation highly convenient and efficient. After CZM is chosen to model the crack tip, the mixed- energy simple criterion is used to determine whether the element is intersected by the extended crack or not, the extended crack is located in the model. By modeling the marble plates with two edge cracks subjected to the uniaxial compressive loads, it is shown that the numerical results are in good agreement with the experimental results, which suggests that the present method is valid and feasible in modeling rock crack propagation.

scholarly journals Dynamic Indentation Characteristics for Various Spacings and Indentation Depths: A Study Based on Laboratory and Numerical Tests

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Jie Liu ◽  
Wen Wan ◽  
Yu Chen ◽  
Jun Wang
Keyword(s):  
Crack Propagation ◽  
Laboratory Tests ◽  
Indentation Depth ◽  
Numerical Study ◽  
Stress Concentrations ◽  
Dynamic Indentation ◽  
Indentation Force ◽  
Numerical Tests ◽  
Crack Tips ◽  
Rock Specimens

Laboratory and numerical study tests were conducted to investigate the dynamic indentation characteristics for various spacings and indentation depths. First, laboratory tests indicate that the increase in the indentation depth first resulted in enlarged groove volumes, caused by fiercer rock breakages between indentations for a fixed spacing; then, the groove volume slightly increased for further increase in indentation depth, whereas the increase in spacing restrained rock breakages and resulted in shrunken grooves. In addition, the numerical study agreed well with laboratory tests that small chips formed at the shallow part of the rock specimen at the early indentation stage, and then, larger chips formed by the crack propagation at deeper parts of the rock specimens when the indentation depth increased. With further increase in indentation depth, crushed powders instead of chips formed. Moreover, the numerical analysis indicates that crack propagation usually leads to the decrease of the indentation force and the dissipation of the stress concentrations at crack tips, whereas the cessation of crack propagation frequently resulted in the increase of the indentation force and the stress concentrations at crack tip with the increase in indentation depth.

Experimental and Numerical Study on the Dynamic Fracture Characteristics of Gray Cast Iron FC200

2014 ◽  
Vol 566 ◽  
pp. 274-280
Author(s):  
Kyuchun Cho ◽  
Chikara Simozono ◽  
Takehiro Fujimoto ◽  
Toshihisa Nishioka
Keyword(s):  
Cast Iron ◽  
Crack Propagation ◽  
Dynamic Fracture ◽  
Fracture Mechanism ◽  
High Speed ◽  
Numerical Study ◽  
Mass Effect ◽  
Fracture Path ◽  
Brittle Behavior ◽  
Machine Performance

Recently, some improvements made to machine performance have caused accidents as a result of impact fracture. These fractures were caused by unexpected dynamic loads. To suppress the damage in these accidents, it is necessary to clarify the dynamic fracture mechanism, many reports have been published on dynamic fracture phenomena [1, 2, 3]. Cast iron is used to repair some structural and mechanical parts following fracture accidents. The brittle behavior of cast iron is not desirable for preventing dynamic fracture. It is necessary to clarify the dynamic fracture mechanism of cast iron for the safety design and maintenance of structures. The dynamic behavior of deformation and fracture depends on the size of a structure. In some cases, an experimental approach using specimens at industrial scale is difficult. As a first step, dynamic fracture without a huge mass effect should be discussed. In this study, a normal sized three point bending specimen consisting of cast iron was used in dynamic experiment. An ultra-high speed camera was used to observe crack propagation. Some fractures were caused under eccentric loading, non-straight cracks propagated in this condition. According to the experimental results, the path and velocity of crack propagation were estimated. Fracture criteria were discussed from the results of numerical simulation. To simulate the behavior of crack propagation a moving finite element method based on Delaunay automatic triangulation was used. The prediction of fracture paths based on the fracture mechanics theory was demonstrated in these numerical simulations. The predicted fracture path agreed with the experimental fracture path.

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