فهرس المقالات Stress Concentration Factor

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  1 - Effect of Burr Grinding on Fatigue Strength of Steel Butt-Welded Connections
  Abbas Fadaei Annette Betkhoodu
  Among assembling methods, welding is most widely used in various industries. During the welding operation, material is heated to a temperature above the melting point and melted material forms a weld pool. This leads to the formation of tensile residual stresses in the أکثر

  Among assembling methods, welding is most widely used in various industries. During the welding operation, material is heated to a temperature above the melting point and melted material forms a weld pool. This leads to the formation of tensile residual stresses in the weld toe. In this paper, effect of burr grinding technique on fatigue strength of butt-welded joint has been evaluated. Burr grinding is one of the weld geometry modification methods that with removing small crack-like defects at the weld toe and increasing weld toe radius leads to reduction of stress concentration factor (SCF) and improvement of fatigue strength of weld. Also, the finite element simulation was performed by using ABAQUS software and stress concentration factor was chosen as a criterion. This factor was calculated using analytical and numerical methods for samples before and after grinding. Burr grinding procedure on welded samples was done using an electric grinder and different conical burrs. Burrs with different radii have been selected in order to provide a better comparison. Fatigue life of samples before and after grinding was determined by fatigue tests under constant amplitude loading. The results show 43.72 percent improvement in stress concentration factor and 50.61 percent improvement in fatigue life of samples. In experimental study, the best result belongs to grinding with a 3 mm tapered burr leading to an improvement of 50.61% in fatigue life while grinding with 1 mm tapered gives the worst result of 8.88% improvement in fatigue life. تفاصيل المقالة
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  2 - Effect of TID-dressing on Fatigue Life Stress Concentration Factor in St37-2Butt Weldments
  Abbas Fadaei Mostafa Jalalizadeh Faeze Mohammad Zaheri
  The researchers have shown that there are cracks in the toe weld and they have an important role in the welding failure. The elimination of these shortcomings and the improvement of the fatigue life have always been a concern for the industrial designers. One method of أکثر

  The researchers have shown that there are cracks in the toe weld and they have an important role in the welding failure. The elimination of these shortcomings and the improvement of the fatigue life have always been a concern for the industrial designers. One method of improving the fatigue life of the welded joint at its geometry branch is to remelt the toe region of the steel weldments using the Tungsten Inert Gas (TIG) method or TIG-dressing. This method affects the material structure, hardness, stress coefficient and welding shape. In this study, the effectiveness of this method on fatigue and stress concentration at the weld toe was investigated. The experimental results showed that the toe weld form was changed by TIG – dressing and thus increased the radius and decreased the toe weld’s angle, so that the stress was reduced by TIG – dressing. Also, the fatigue tests showed that the fatigue life increased by an average of approximately 30 percent. Finally, the stress concentration factors were obtained using ABAQUS finite element analysis. The amount of stress concentration factors in weldments before and after TIG – dressing were respectively achieved to be 2.4 and 1.3. تفاصيل المقالة
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  3 - Stress Concentration Factor of Single-Layered Graphene Sheets Containing Elliptical Vacancies
  S.K Jalali M.J Beigrezaee
  10.22034/jsm.2019.667250
  In the present study, potential of finite element based molecular structural mechanics (MSM) for evaluating stress concentration factor of single-layered graphene sheets (SLGSs) with elliptical vacancies is successfully addressed. The MSM approach mimics the interatomic أکثر

  In the present study, potential of finite element based molecular structural mechanics (MSM) for evaluating stress concentration factor of single-layered graphene sheets (SLGSs) with elliptical vacancies is successfully addressed. The MSM approach mimics the interatomic forces of the nanostructure by defining an equivalent frame structure containing beam elements. To obtain the mechanical and cross sectional properties of the equivalent beam, the potential energies of chemical bonds between carbon atoms in the hexagonal lattice of SLGSs are equaled to the strain energies of the beams. This novel proposed approach accurately predicts the stress concentration in graphene sheets with significantly less computational effort in comparison to computational physics methods. Both armchair and zigzag configurations are considered. Furthermore, a comparison between the results obtained by presented MSM approach and theory of elasticity for thin infinite panels having elliptical holes is presented. Influence of chirality, and geometry of elliptical vacancies are investigated in details. Results reveal that MSM approach can successfully predicts stress concentration factor phenomena in nano structures, especially SLGSs. It is seen that chirality has a significant effect on the stress concentration factor so that armchair SLGSs show a larger value of stress concentration. تفاصيل المقالة
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  4 - Stress Concentration Factor in a Functionally Graded Material Plate around a Hole
  Javad Jafari Fesharaki Seyed Ghasem Madani Davood Seydali
  Stress concentration factors have been examined in a functionally graded material (FGM) plate withcentral holes in different shapes in this essay. The material properties change along the thickness ofplate. ABAQUS software has been utilized for modeling of problem in wh أکثر

  Stress concentration factors have been examined in a functionally graded material (FGM) plate withcentral holes in different shapes in this essay. The material properties change along the thickness ofplate. ABAQUS software has been utilized for modeling of problem in which subroutine ofABAQUS sub-program was used for modeling of the targeted material. The considering shapes forhole in plate are circular and elliptical in which stress concentration factors have been studied indifferent modes in respective of ellipse diameters. Similarly, stress concentration factors have beenanalyzed in the plate for various coefficients of FGM function. The results show that changes inmaterial properties and the shape of hole in plate affect the stress concentration factor around thehole. An experiment was implemented to determine verification of results from Finite ElementMethod (EFM). تفاصيل المقالة
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  5 - Using finite element model in calculation of stress concentration factor around an elliptical hole in composite hybrid lamina
  Pedram Lorzadeh
  The hybrid composites have exceptional properties such as strength to weight and hardness ratios. These characteristics make the application of these materials in the aerospace industry. In composite materials, there are various fittings, such as a bolt and a rivet, whi أکثر

  The hybrid composites have exceptional properties such as strength to weight and hardness ratios. These characteristics make the application of these materials in the aerospace industry. In composite materials, there are various fittings, such as a bolt and a rivet, which is the focus of stress concentration in the joints because the fibers are damaged. In this research in hybrid composite materials, a high elastic modulus fiber (HM) and a low elastic modulus fiber (LM) are used. It is also assumed that the length of the sheet is infinite. The force on the lamina is tensile force which applies on matrix and fibers while the fibers in the layers are one directed. In this paper the effects of different parameters such as ,number of broken fibers and the ratio of (LM) to (HM) fiber extensional stiffness.By using finite element method (FEM) modeling and investigation geometrical and crack modeling, stress concentration factor (SCF) around a elliptical hole is calculated and compared with the results obtained from reference.The results of the validation showed that compared to the reference data are close to each other, indicating the correctness of the code written for the analysis. تفاصيل المقالة