scholarly journals Ring-shaped crack propagation in a cylinder under nonsteady cooling

2006 ◽  
Author(s):  
V. A. Zhornik ◽  
Yu. A. Prokopenko ◽  
A. A. Rybinskaya ◽  
P. A. Savochka
Keyword(s):  
Crack Propagation ◽  
Shaped Crack

scholarly journals Exact Solutions for Interaction of Parallel Screw Dislocations with a Wedge Crack in One-Dimensional Hexagonal Quasicrystal with Piezoelectric Effects

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Xin Lv ◽  
Guan-Ting Liu
Keyword(s):  
Crack Propagation ◽  
Field Line ◽  
Field Intensity ◽  
Wedge Angle ◽  
Image Force ◽  
Intensity Factors ◽  
One Dimensional ◽  
Line Force ◽  
Shaped Crack ◽  
Field Intensity Factors

The purpose of this paper is to consider the interaction between many parallel dislocations and a wedge-shaped crack and their collective response to the external applied generalized stress in one-dimensional hexagonal piezoelectric quasicrystal, employing the complex variable function theory and the conformal transformation method; the problem for the crack is reduced to the solution of singular integral equations, which can be further reduced to solving Riemann–Hilbert boundary value problems. The analytical solutions of the generalized stress field are obtained. The dislocations are subjected to the phonon field line force, phason field line force, and line charge at the core. The positions of the dislocations are arbitrary, but the dislocation distribution is additive. The dislocation is not only subjected to the external stress and the internal stress generated by the crack, but also to the force exerted on it by other dislocations. The closed-form solutions are obtained for field intensity factors and the image force on a screw dislocation in the presence of a wedge-shaped crack and a collection of other dislocations. Numerical examples are provided to show the effects of wedge angle, dislocation position, dislocation distribution containing symmetric configurations and dislocation quantities on the field intensity factors, energy release rate, and image force acting on the dislocation. The principal new physical results obtained here are (1) the phonon stress, phason stress, and electric displacement singularity occur at the crack tip and dislocations cores, (2) the increasing number of dislocations always accelerates the crack propagation, (3) the effect of wedge angle on crack propagation is related to the distribution of dislocations, and (4) the results of the image force on the dislocation indicate that the dislocations can either be attracted or rejected and reach stable positions eventually.

Adhesion Failure in Bonded Rubber Cylinders Part 2: Fatigue Life Prediction of External Ring-Shaped Cracks Using Tearing Energy Approach

2003 ◽  
Vol 76 (2) ◽  
pp. 365-385 ◽  
Author(s):  
Douglas C. Leicht ◽  
C. Rimnac ◽  
R. Mullen
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Propagation ◽  
Crack Length ◽  
Fatigue Crack Propagation ◽  
Shape Factors ◽  
External Ring ◽  
Adhesion Failure ◽  
Shaped Crack ◽  
Tearing Energy

Abstract Rubber disks bonded between flat parallel metal plates are often used as adhesion test specimens; for example, ASTM D 429 1999, Method A. However, the mechanics of adhesion failure (debonding) for this geometry have not previously been fully analyzed. Therefore, a study was conducted to determine the strain energy release rate (tearing energy) for bonded rubber disks having external ring cracks at the rubber-to-metal bond and to develop a method for predicting the fatigue life. Finite element analysis was used to determine the tearing energy as a function of crack length for disks of various dimensions (shape factors). The crack configurations considered were an external-ring-shaped crack located at the outside circumference of either one or both rubber-to-metal bonds. The fatigue crack propagation (FCP) behavior was characterized for a generic filled natural rubber material. The tearing energy was found to be a non-linear function of crack length. For small cracks, the tearing energy was small and approached zero as the crack length decreased. The tearing energy then increased as the crack grew, indicating accelerating growth, until it passed through a maximum value. The peak tearing energy was found to depend on the height of the disk. Finally at large cracks, the tearing energy decreased or was essentially constant as the crack grew. The fatigue life of the rubber cylinders at different shape factors was determined experimentally. An empirical model coupled with the fatigue crack propagation behavior (FCP) for the material at different tearing energies was used to predict the fatigue life. The experimental and predicted fatigue life showed excellent agreement at low and moderate shape factors. However at high shape factors, fatigue life was not well predicted. From the experimental results, it was found that, at high shape factors, cavitation occurs causing a series of “dimples” to form, which leads to the development of an internal penny-crack, thereby violating the assumed model of an external ring-shaped crack.

Simplified SCC Simulation Considering Growth Arrest at Fusion Line of Weld

2019 ◽  
Author(s):  
Hiroshi Okada ◽  
Masayuki Kamaya ◽  
Yasunori Yusa
Keyword(s):  
Crack Propagation ◽  
Weld Metal ◽  
Computational Cost ◽  
Simulation Software ◽  
Fusion Line ◽  
Stress Distributions ◽  
Growth Prediction ◽  
Propagation Analysis ◽  
Shaped Crack ◽  
Growth Analyses

Abstract The authors have carried out a series of developments on methods to perform natural crack propagation analysis in last several years. This paper describes the results of SCC (stress corrosion cracking) growth analyses under some assumptions on the growth behaviors and assumed stress distributions. The SCC growth was assumed to initiate in the weld metal and to be arrested at the fusion line of weld. Although it is possible to model a realistic configuration of weld, it may take a large amount of modeling and computational cost. Thus, an appropriate simplification for the SCC growth prediction is demanded. Hence, two kinds of welds were considered in the present investigation. One had a realistic configuration. The other was a simplified one whose volume of the weld metal had a rectangular shape. Thus, a further simplification was made such that the cracks were assumed to be rectangular in their shapes. SCC growth analyses were performed by finite element based crack propagation simulation software using a remeshing technique that was developed and has been updated by the authors. The paper describes the method of crack propagation analysis briefly and presents the results of the SCC growth analyses. Some discussions on the simplification of the SCC propagation analysis are presented. Then, it is concluded that an appropriate use of rectangular shaped crack may give a conservative prediction on the SCC growth prediction.

scholarly journals Interpretation of surficial shear crack propagation mechanisms in bending for Zn or AlSi coated hot press forming steels

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Selim Kim ◽  
Min Cheol Jo ◽  
Seongwoo Kim ◽  
Jinkeun Oh ◽  
Sang-Heon Kim ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Shear Crack ◽  
Peak Load ◽  
Crack Tip ◽  
Data Interpretation ◽  
Hot Press ◽  
Bending Angle ◽  
Press Forming ◽  
Shaped Crack ◽  
Hot Press Forming

AbstractThe bending angle at the peak load is regarded as the most important parameter for evaluating bending properties of hot-press-forming (HPF) steels. However, it is not a mechanics-based parameter for the bending criterion, and the data interpretation is difficult because bending criteria in relation with microstructures and associated bending mechanisms have not been verified yet. In this study, effects of coating and baking treatments on bending angles at the peak load of three kinds of 1470 MPa-grade HPF steels were investigated by interrupted three-point bending tests coupled with direct microstructural observation. According to direct observations of sequential cracking processes of V-shaped crack (V-crack), bending procedures were classified into four stages: (1) formation of small V-crack, (2) increase in number and size of V-cracks, (3) initiation of shear-crack propagation from the V-crack tip, and (4) further propagation and opening of the shear crack. The minimum bending angle required for initiating the shear-crack propagation from the V-crack tip was defined as a critical angle, which meant the boundary between the 2nd and 3rd stages. The present bending behavior related with critical bending angle and V-cracking could be interpreted similarly by the fracture-mechanics concept, i.e., the initiation of shear-crack propagation.

scholarly journals Penny-shaped crack propagation in spallation of Zr-BMGs

2015 ◽  
Vol 94 ◽  
pp. 02016 ◽  
Author(s):  
Z. Ling ◽  
X. Huang ◽  
L.H. Dai
Keyword(s):  
Crack Propagation ◽  
Penny Shaped Crack ◽  
Shaped Crack

Mechanism of irregular crack-propagation in thermal controlled fracture of ceramics induced by microwave

2020 ◽  
Vol 21 (6) ◽  
pp. 610
Author(s):  
Xiaoliang Cheng ◽  
Chunyang Zhao ◽  
Hailong Wang ◽  
Yang Wang ◽  
Zhenlong Wang
Keyword(s):  
Crack Propagation ◽  
Industrial Application ◽  
Ceramic Materials ◽  
Advanced Technology ◽  
Analytical Models ◽  
Propagation Mechanism ◽  
Unstable Crack ◽  
Fracture Simulation ◽  
Initial Stage ◽  
Controlled Fracture

Microwave cutting glass and ceramics based on thermal controlled fracture method has gained much attention recently for its advantages in lower energy-consumption and higher efficiency than conventional processing method. However, the irregular crack-propagation is problematic in this procedure, which hinders the industrial application of this advanced technology. In this study, the irregular crack-propagation is summarized as the unstable propagation in the initial stage, the deviated propagation in the middle stage, and the non-penetrating propagation in the end segment based on experimental work. Method for predicting the unstable propagation in the initial stage has been developed by combining analytical models with thermal-fracture simulation. Experimental results show good agreement with the prediction results, and the relative deviation between them can be <5% in cutting of some ceramics. The mechanism of deviated propagation and the non-penetrating propagation have been revealed by simulation and theoretical analysis. Since this study provides effective methods to predict unstable crack-propagation in the initial stage and understand the irregular propagation mechanism in the whole crack-propagation stage in microwave cutting ceramics, it is of great significance to the industrial application of thermal controlled fracture method for cutting ceramic materials using microwave.

Reconstruction of complex shaped crack from ECT signals based on a fast forward solver using an advanced multi-media element

2020 ◽  
Vol 64 (1-4) ◽  
pp. 621-629
Author(s):  
Yingsong Zhao ◽  
Cherdpong Jomdecha ◽  
Shejuan Xie ◽  
Zhenmao Chen ◽  
Pan Qi ◽  
...  
Keyword(s):  
Coefficient Matrix ◽  
Crack Edge ◽  
Numerical Accuracy ◽  
Gauss Point ◽  
Current Testing ◽  
Efficient Simulation ◽  
Shaped Crack ◽  
Multi Media ◽  
Profile Reconstruction ◽  
Crack Profile

In this paper, the conventional database type fast forward solver for efficient simulation of eddy current testing (ECT) signals is upgraded by using an advanced multi-media finite element (MME) at the crack edge for treating inversion of complex shaped crack. Because the analysis domain is limited at the crack region, the fast forward solver can significantly improve the numerical accuracy and efficiency once the coefficient matrices of the MME can be properly calculated. Instead of the Gauss point classification, a new scheme to calculate the coefficient matrix of the MME is proposed and implemented to upgrade the ECT fast forward solver. To verify its efficiency and the feasibility for reconstruction of complex shaped crack, several cracks were reconstructed through inverse analysis using the new MME scheme. The numerical results proved that the upgraded fast forward solver can give better accuracy for simulating ECT signals, and consequently gives better crack profile reconstruction.

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