Papers by Author: Ruslizam Daud

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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.
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Authors: Al Emran Ismail, Ahmad Kamal Ariffin, Shahrum Abdullah, Mariyam Jameelah Ghazali, Ruslizam Daud
Abstract: An elastic-plastic finite element analysis (FEA) is used to determine the J-integral around the crack front of 3-dimensional semi-elliptical surface crack in a round bar under torsion loading. Crack geometries are based on the experimental observation. The present model is validated using the SIF under bending loading since no suitable SIF for torsion is available. Lack of numerical solution of elastic and plastic stress parameters under torsion are found. The FE J values are normalized by dividing with the estimation J value using a reference stress method. It is found that higher J values are obtained for deep cracks and the maximum J changed from the deepest point along the crack front to the outer point at the free surface when a/D > 0.2. J values can be estimated for all type of crack geometries under consideration with a correction factor, h1.
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Authors: A. Zulkifli, Ahmad Kamal Ariffin, A.E. Ismail, Ruslizam Daud, M.R.M. Akramin
Abstract: The objectives of this study were to determine the stress concentration of the lumbar vertebra and the probability of failure associated with finite element method. The lumbar vertebra model was constructed in SolidWorks software and imported by ANSYS software for the analysis. In this work, all the model components were meshed using the tetrahedral solid element (SOLID186). In order to simplify the model, all the spinal components were modeled as an isotropic and elastic material. Monte Carlo Simulation (MCS) technique was performed to conduct the probabilistic analysis using a built-in probabilistic module in ANSYS with attempt for 100 trials. The results were observed that the highest stress concentrations were found in the adjacent posterior vertebral body with 1.2117 MPa and the corresponding probability of failure for the model is 3%. Sensitivity analysis had been revealed that the force applied to the facet (FORFCT) variable was sensitive to the stress and displacement output parameters and need to be emphasized. The current probabilistic study was very useful as a tool to understand the inherent uncertainties and variations in biological structures.
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