scholarly journals A modified maximum tangential tensile stress criterion for three-dimensional crack propagation

2012 ◽  
Vol 4 (1) ◽  
pp. 62-72 ◽  
Author(s):  
Dunfu Zhang ◽  
Weishen Zhu ◽  
Shucai Li ◽  
Bo Zhang ◽  
Weidong Wang
Keyword(s):  
Tensile Stress ◽  
Crack Propagation ◽  
Three Dimensional ◽  
Stress Criterion

scholarly journals Mechanical Mechanism and Propagation Law of Fissure-Tip Cracks of Large-Size Rock Specimens with Two Precut Fissures

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Liming Yin ◽  
Ming Li ◽  
Wenbin Sun ◽  
Juntao Chen ◽  
Bin Liu ◽  
...  
Keyword(s):  
Rock Mass ◽  
Tensile Stress ◽  
Crack Propagation ◽  
Main Crack ◽  
Similarity Theory ◽  
Three Dimensional ◽  
Structural Defects ◽  
Two Dimensional ◽  
Propagation Law ◽  
Balance State

The rock is a kind of geological medium with damages of different degrees including fissures, faults, joints, and other structural defects. Many underground rock engineering projects, such as mining and tunnel excavation, can break the three-dimensional stress balance state of rock mass and make it subject to two-dimensional or even one-dimensional stress, thus inducing stress concentration which leads to rapid failure. In order to investigate the failure law of the rock mass with such defects under two-dimensional stress, based on the similarity theory, we first prepared rocklike specimens with fissures featuring actual mechanical properties and then systematically analyzed the fissure-tip crack propagation and specimen failure law and mechanical mechanism under two-dimensional stress in view of the stress field theory. The results demonstrate that with the increase of load, the microcracks developed and propagated gradually, during which a number of branch paths were generated from the fissure tips of the specimens; the upper and lower cracks were connected first due to the main crack propagation, forming a sliding surface which caused the failure of the specimens, and the strengths of the specimens also fluctuated according to the different combinations of the fissure dip angles and rock bridge dip angles. In view of acoustic emission (AE), we calculated and obtained the spatial positions of stress peaks in each direction at the fissure tips; through comparison and analysis, the angle corresponding to the negative angle peak of the maximum circumferential tensile stress and the maximum radial tensile stress is basically the same as the angle of the main crack propagation direction generated from the preexisting fissure; it can be inferred that the tensile stress is the main stress inducing crack initiation and specimen failure, which is consistent with the physical characteristics of rock (resistant to compression but not tension). This may serve as a guidance for judging the direction along which new cracks are generated in a rock mass with double structural planes.

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.

Shape and energies of a dynamically propagating crack under bending

2003 ◽  
Vol 18 (10) ◽  
pp. 2379-2386 ◽  
Author(s):  
Dov Sherman ◽  
Ilan Be'ery
Keyword(s):  
Crack Propagation ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Crack Front ◽  
Three Dimensional ◽  
Strain Energy Release ◽  
Governing Parameter ◽  
Propagating Crack ◽  
Front Shape

We report on the exact shape of a propagating crack in a plate with a high width/thickness ratio and subjected to bending deformation. Fracture tests were carried out with brittle solids—single crystal, polycrystalline, and amorphous. The shape of the propagating crack was determined from direct temporal crack length measurements and from the surface perturbations generated during rapid crack propagation. The shape of the crack profile was shown to be quarter-elliptical with a straight, long tail; the governing parameter of the ellipse axes is the specimen's thickness at most length of crack propagation. Universality of the crack front shape is demonstrated. The continuum mechanics approach applicable to two-dimensional problems was used in this three-dimensional problem to calculate the quasistatic strain energy release rate of the propagating crack using the formulations of the dynamic energy release rate along the crack loci. Knowledge of the crack front shape in the current geometry and loading configuration is important for practical and scientific aspects.

scholarly journals Knitting Technologies And Tensile Properties Of A Novel Curved Flat-Knitted Three-Dimensional Spacer Fabrics

2015 ◽  
Vol 15 (3) ◽  
pp. 191-197 ◽  
Author(s):  
Xiaoying Li ◽  
Gaoming Jiang ◽  
Xiaolin Nie ◽  
Pibo Ma ◽  
Zhe Gao
Keyword(s):  
Tensile Stress ◽  
Tensile Properties ◽  
Dimensional Stability ◽  
Three Dimensional ◽  
Tensile Tests ◽  
Weft Direction ◽  
Aramid Fibres ◽  
Spacer Fabric ◽  
Fabric Deformation ◽  
Spacer Fabrics

AbstractThis paper introduces a knitting technique for making innovative curved three-dimensional (3D) spacer fabrics by the computer flat-knitting machine. During manufacturing, a number of reinforcement yarns made of aramid fibres are inserted into 3D spacer fabrics along the weft direction to enhance the fabric tensile properties. Curved, flat-knitted 3D spacer fabrics with different angles (in the warp direction) were also developed. Tensile tests were carried out in the weft and warp directions for the two spacer fabrics (with and without reinforcement yarns), and their stress–strain curves were compared. The results showed that the reinforcement yarns can reduce the fabric deformation and improve tensile stress and dimensional stability of 3D spacer fabrics. This research can help the further study of 3D spacer fabric when applied to composites.

Prediction Method of Three‐Dimensional Crack Propagation Path Based on Deep Learning Application

2020 ◽  
pp. 2001043
Author(s):  
Junxia Wang ◽  
Yuanjie Zheng ◽  
Rong Luo ◽  
Jun Ma ◽  
Yingjie Peng ◽  
...  
Keyword(s):  
Deep Learning ◽  
Crack Propagation ◽  
Three Dimensional ◽  
Prediction Method ◽  
Propagation Path ◽  
Crack Propagation Path

scholarly journals Three Dimensional Simulation of Polycrystalline Cleavage Crack Propagation in Steel

2009 ◽  
Vol 95 (6) ◽  
pp. 498-505 ◽  
Author(s):  
Kei Sugimoto ◽  
Shuji Aihara ◽  
Yoichi Tanaka
Keyword(s):  
Crack Propagation ◽  
Three Dimensional ◽  
Cleavage Crack ◽  
Dimensional Simulation

scholarly journals Finite Element Simulation and Multi-Factor Stress Prediction Model for Cement Concrete Pavement Considering Void under Slab

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5294
Author(s):  
Bangyi Liu ◽  
Yang Zhou ◽  
Linhao Gu ◽  
Xiaoming Huang
Keyword(s):  
Finite Element ◽  
Tensile Stress ◽  
Concrete Slab ◽  
Three Dimensional ◽  
Mesh Size ◽  
Maximum Tensile Stress ◽  
Concrete Pavement ◽  
Slab Thickness ◽  
Void Size ◽  
Tensile Stresses

Uneven support as result of voids beneath concrete slabs can lead to high tensile stresses at the corner of the slab and eventually cause many forms of damage, such as cracking or faulting. Three-dimensional (3D) finite element models of the concrete pavement with void are presented. Mesh convergence analysis was used to determine the element type and mesh size in the model. The accuracy of the model is verified by comparing with the calculation results of the code design standards in China. The reliability of the model is verified by field measurement. The analysis shows that the stresses are more affected at the corner of the slab than at the edge. Impact of void size and void depth at the slab corner on the slab stress are similar, which result in the change of the position of the maximum tensile stress. The maximum tensile stresses do not increase with the increase in the void size for relatively small void size. The maximum tensile stress increases rapidly with the enlargement in the void size when the size is ≥0.4 m. The increments of maximum tensile stress can reach 183.7% when the void size is 1.0 m. The increase in slab thickness can effectively reduce maximum tensile stress. A function is established to calculate the maximum tensile stress of the concrete slab. The function takes into account the void size, the slab thickness and the vehicle load. The reliability of the function was verified by comparing the error between the calculated and simulated results.

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