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Articles by A. Muchtar
Total Records ( 2 ) for A. Muchtar
  Miloud Souiyah , A. Muchtar , Abdulnaser Alshoaibi and A.K. Ariffin
  Problem statement: The use of fracture mechanics techniques in the assessment of performance and reliability of structure is on increase and the prediction of crack propagation in structure play important part. The finite element method is widely used for the evaluation of SIF for various types of crack configurations. Source code program of two-dimensional finite element model had been developed, to demonstrate the capability and its limitations, in predicting the crack propagation trajectory and the SIF values under linear elastic fracture analysis.
Approach:Two different geometries were used on this finite element model in order, to analyze the reliability of this program on the crack propagation in linear and nonlinear elastic fracture mechanics. These geometries were namely; a rectangular plate with crack emanating from square-hole and Double Edge Notched Plate (DENT). Where, both geometries are in tensile loading and under mode I conditions. In addition, the source code program of this model was written by FORTRAN language. Therefore, a Displacement Extrapolation Technique (DET) was employed particularly, to predict the crack propagations directions and to, calculate the Stress Intensity Factors (SIFs). Furthermore, the mesh for the finite elements was the unstructured type; generated using the advancing front method. And, the global h-type adaptive mesh was adopted based on the norm stress error estimator. While, the quarter-point singular elements were uniformly generated around the crack tip in the form of a rosette. Moreover, make a comparison between this current study with other relevant and published research study.
Results: The application of the source code program of 2-D finite element model showed a significant result on linear elastic fracture mechanics. Based on the findings of the two different geometries from the current study, the result showed a good agreement. And, it seems like very close compare to the other published results.
A developed a source program of finite element model showed that is capable of demonstrating the SIF evaluation and the crack path direction satisfactorily. Therefore, the numerical finite element analysis with displacement extrapolation method, had been successfully employed for linear-elastic fracture mechanics problems.

  S. Abdullah , E. Adril , A. Muchtar and A.K. Ariffin
  In order to combat dry lubrication occurred in the combustion chamber of a compressed natural gas direct injection engine, the piston or piston rings have to be equipped with measures to address this boundary lubrication issue. Hence, the aim of the study is to address the issue which can minimize sliding friction in the combustion chamber between the piston ring and the cylinder liner. To solve this problem, the wear resistance level toward friction for piston ring during its interaction with the cylinder liner was enhanced using diffusion coating technique. The piston ring is made of ASSAB DF-3 steel and several substances such as 0.9% carbon (C), 0.85% chromium (Cr), 96.6% ferric (Fe), 1.2% manganese (Mn) and 0.55% titanium. The chemical substance which is used for the diffusion process are the mixture of three substances i.e., chromium, ammonium chloride (NH4Cl) and aluminum oxide (Al2O3). The piston ring together with the chromium mixtures were heated at different periods of time. In order to improve friction and wear, the piston ring which is coated with 99.5% chromium dust using a diffusion coating technique yields higher hardness compared to the original piston ring due to its resistance toward wear. The hardness depends on the time maintained during heating. Furthermore, it was also shown that the modified piston ring led to better reduction in coefficient of friction as well as less weight loss due to wear. These characteristics can result in better endurance during engine operation and prevent damage due to lubrication failure.
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