Papers by Keyword: Linear Elastic Fracture Mechanics (LEFM)

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Authors: Akihide Saimoto, Fumitaka Motomura, Hironobu Nisitani
Abstract: Practically exact solutions of stress intensity factor for several two-dimensional standard specimens were calculated and shown in numeric tables. The solutions were confirmed to converge until 6 significant figures through a systematical computation of discretization analysis. The convergence analyses were carried out by using a general purpose program based on a body force method.
Authors: K. Zarrabi, W.W. Lu, A.K. Hellier
Abstract: This paper proposes a new three-layer artificial neural network (ANN) to predict the fatigue crack length under constant amplitude mode I cyclic loading. It is shown that the proposed model predicts the crack length with an error of less than 0.05%, and more accurately than the current commonly-used models.
Authors: Zheng Wen Jiang, Shui Wan, Chen Cheng
Abstract: Abstract. The fatigue crack propagation life-span of the engineering structure is studied. Linear elastic fracture mechanics is applied to analyze the life-span of fatigue crack growth of specimen, which is under constant amplitude load. The software of Fatigue is used to calculate the life-span of a center crack plate steel specimen. The result show that the calculated values of the life-span are basically well with the experimental data.
Authors: Gyula Nagy, János Lukács, Imre Török
Abstract: This paper presents two basic methods for the assessment of failed girth welds of steel hydrocarbon transporting pipelines. One of them is based on the principles of linear elastic fracture mechanics (LEFM) and stress intensity factor conception for planar material discontinuities, and the other can be used for the complex assessment of all kinds of occurring defects. The results of the presented methods are compared to the results of burst test of pipeline sections containing a failed girth weld and cut from a Hungarian gas pipeline.
Authors: Ruslizam Daud, Ahmad Kamal Ariffin, Shahrum Abdullah, A.E. Ismail
Abstract: This paper presents the extensions of newly developed finite element (FE) formulation to evaluate fracture behavior of parallel edge cracks problems. The numerical formulation used Barsoum singular finite elements to compute fracture parameters in two dimensional finite element models subjected to different crack-width ratio and cracks interval ratio. Mixed mode stress intensity factors (SIFs) of parallel edge cracks are computed in extending of FE formulation for pure Mode I formulation proposed by authors. In 2D linear elastic problem under mixed mode condition, the variation of SIF value near crack tips are discussed comprehensively. The newly finite element formulations are resulted with remarkable agreement with energy release rate based method compared to analytical solution available in the literatures.
Authors: Ruslizam Daud, Ahmad Kamal Ariffin, Shahrum Abdullah, Al Emran Ismail, A. Zulkifli
Abstract: The simplification of two dimensional approaches in singular finite elements has promoted the method to be used in the formulation of stress intensity factor (SIF) of multiple cracks in finite body. The effect of shielding and amplification are considered in defining the SIF. As been observed, the current available analytical approximations are more restricted to several assumptions. The more accurate and less restricted method has motivated this study. This paper presents the investigation of singular finite elements applied in two dimensional finite element models subjected to different crack-width ratio and cracks interval ratio. The newly finite element formulations are resulted with good agreement with theoretical statement compared to analytical solution. The weak points of presented analytical solution are discussed regards to the influence of crack width ratio and cracks interval ratio.
Authors: Ruslizam Daud, Ahmad Kamal Ariffin, Shahrum Abdullah, Al Emran Ismail
Abstract: This paper explores the initial potential of theory of critical distance (TCD) which offers essential fatigue failure prediction in engineering components. The intention is to find the most appropriate TCD approach for a case of multiple stress concentration features in future research. The TCD is based on critical distance from notch root and represents the extension of linear elastic fracture mechanics (LEFM) principles. The approach is allowing possibilities for fatigue limit prediction based on localized stress concentration, which are characterized by high stress gradients. Using the finite element analysis (FEA) results and some data from literature, TCD applications is illustrated by a case study on engineering components in different geometrical notch radius. Further applications of TCD to various kinds of engineering problems are discussed.
Authors: Zheng Yun, Lie Ping Ye, Xin Zheng Lu, Qing Rui Yue
Abstract: The experimental research on six steel plates strengthened with CFRP plates, loaded in tension, shows that their fatigue lives can be greatly increased compared with un-strengthened specimens. Linear elastic fracture mechanics (LEFM) is adopted to explain the mechanism of CFRP plates strengthening. The stress intensity factors of the steel plates are calculated with finite element method (FEM), and Paris law on crack propagation is used to predict the fatigue life of strengthened specimens. The comparison between experimental results and numerical predictions shows good agreements on the fatigue crack propagation.
Authors: Miloud Souiyah, Andanastuti Muchtar, Ahmad Kamal Ariffin
Abstract: The indentation method is able for use in determining the fracture properties of materials. In the present work, a source code programme for two-dimensional finite element method has been applied to simulate cracking behaviour during indentation on brittle specimens under static loading conditions. The study also aims to predict the crack propagation trajectories under Linear Elastic Fracture Mechanics (LEFM). The source code is written in FORTRAN language. The FE mesh is generated using an advancing front method, where the generation of the background mesh and the construction of singular elements are also added to this developed programme to realise the fracture analysis. In evaluating the accuracy of the crack path predictions, the results are compared and validated with the sets of experimental data of relevant published research work. Upon comparison, it is proven that this developed source code programme is capable of demonstrating the crack indentation in terms of predicting the crack trajectories as well as the evaluation of the stress intensity factors.
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