Dr. Md. Shafiul Ferdous | University of the Ryukyus (original) (raw)
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Papers by Dr. Md. Shafiul Ferdous
TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series A, 2013
International Journal of Modern Physics: Conference Series, 2012
A method of improving the fatigue life and crack growth behavior of a center holed specimen was i... more A method of improving the fatigue life and crack growth behavior of a center holed specimen was investigated. Local plastic deformation was applied around the hole by indentation to achieve the purpose. A series of fatigue tests was conducted on aluminum-alloy 2024-T3. Push-pull tests were performed under a stress ratio of R= -1 and a frequency of 10Hz. The observations of the crack initiation and growth were performed with a microscope, and hardness around the hole was measured by Vickers hardness testing machine. In the present study, the longest fatigue life was observed in the case of an indentation specimen with the highest load. The indentation was performed on both sides of the hole edges. The crack growth rate was decreased by indentation or expansion of the material around the hole. From the experimental results, it is found that the fatigue life and crack growth behavior of a holed or notched specimen can be improved by a simple technical method that is related to the local plastic working.
Advanced Materials Research, 2015
International Journal of Fatigue, 2015
ABSTRACT
Key Engineering Materials, 2012
The improvement of acceleration behavior of crack growth was investigated with constant stress am... more The improvement of acceleration behavior of crack growth was investigated with constant stress amplitude under negative stress ratio R=-1. Then a technical method to detect the fatigue crack growth was discussed. For example, when the stress amplitude exceeds a critical value, crack growth rate of overloaded specimen became higher than that of baseline which was obtained by crack growth test without applying overload. In some experimental cases, the acceleration of crack growth was observed and that could be happened on practical cases. Stop-holes were drilled at crack tips or in the vicinity of crack tips to remove the plastic zone and the effect of that on crack growth behavior were investigated. Also, steel pins were inserted into the stop-holes and its effect was discussed. Finite element method (FEM) was used to analyze the stress concentration at the edge of stop-holes. Positions of center of the stop-holes were varied at different distance from the crack tips to investigate the effect of stop-holes on fatigue crack growth. Also, stress intensity of base and stop-holed specimen was calculated. Then, the effect of stop-hole was discussed by both the experimental and analytical results. Specially, it was discussed whether the crack growth behavior was improved or not in the case of relatively smaller width specimen.
Procedia Materials Science, 2014
The role of small cracks on fatigue life and loss of ductility are discussed to understand the re... more The role of small cracks on fatigue life and loss of ductility are discussed to understand the reality of fatigue damage in low cycle fatigue. The series of low cycle fatigue tests were carried out paying attention to the role of small cracks and its influence on ductility loss. These tests showed that the fatigue lives were pronouncedly extended by removing surface cracks. Also, it was quantified that the loss of fracture ductility was correlated with crack length but not with the number of fatigue cycles. From those results, it is elucidated that the behavior of small cracks is crucial to explain the mechanism of low cycle fatigue damage rather than the crack initiation process and change in bulk material properties.
Mechanical Engineering Journal, 2014
Key Engineering Materials, 2010
Page 1. Hole Expansion by using Al-alloy Specimen and 0.45% Carbon Steel Specimen Muhammed Sohel ... more Page 1. Hole Expansion by using Al-alloy Specimen and 0.45% Carbon Steel Specimen Muhammed Sohel Rana 1, a , Md. Shafiul Ferdous 1, b , Chobin Makabe 2, c ... 23 (2001), p. 161. [5] M. Sohel Rana, C. Makabe, G. Fujiwara, 2009., Eng Fail Ana, vol. 16 (2009), p. 2081. ...
Modern Physics Letters B, 2013
The fatigue and fracture behavior of C/C composites fabricated using fine-woven carbon fiber lami... more The fatigue and fracture behavior of C/C composites fabricated using fine-woven carbon fiber laminates with α = 0/90 • direction were investigated. Also, the phenomenon of crack growth behavior and the shear damage in the fiber bundle was discussed. Slits of several sizes were cut on both sides of a test section and different sizes of slit length were chosen. The effect of the slit configuration on crack initiation and growth behavior was observed. Specimens with blunt-notches and center-holes were also used to compare the fatigue strength and crack growth behavior. Non-propagating cracks were observed and fatigue limit was defined as the maximum stress at which specimen did not break for N = 10 7 cycles stress application. The longest fatigue life was obtained in the case of specimens with shorter slits. The relationships between fatigue strengths and specimen shapes were analyzed by stress concentration, Kt, and stress intensity factor, K I . The effect of slit configuration on fatigue strength was then discussed regarding both the experimental and calculated consequences.
Engineering Failure Analysis, 2011
A series of tests were conducted in aluminum alloy 2024-T3 to investigate the effect of additiona... more A series of tests were conducted in aluminum alloy 2024-T3 to investigate the effect of additional holes and notches on the fatigue behavior of double hole specimens. Also, circular pins were inserted into the additional holes, but not removed before testing in some cases. Basic specimen has dual holes and their cracks interacted with the specimen edge. Within the present study conditions, the longest fatigue life was observed where dual holes had a shorter distance between their edges and a longer distance from specimen edge to holes. The shortest fatigue life was observed where there was a longer distance between the hole edges. This paper describes how the improvement of fatigue life in the shorter life case of a basic specimen was examined by applying additional holes or notches. The crack initiation and growth behavior was observed and the mechanism of the extension of the fatigue life was investigated. The finite element method (FEM) was used to analyze the stress concentration around the basic dual holes, additional holes and notches in the present specimens. Then it was discussed how the reduction of stress concentration around the basic dual holes affected the fatigue life of the double holed specimens. A method of enhancement of fatigue life of notched material is discussed in the present study.
TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series A, 2013
International Journal of Modern Physics: Conference Series, 2012
A method of improving the fatigue life and crack growth behavior of a center holed specimen was i... more A method of improving the fatigue life and crack growth behavior of a center holed specimen was investigated. Local plastic deformation was applied around the hole by indentation to achieve the purpose. A series of fatigue tests was conducted on aluminum-alloy 2024-T3. Push-pull tests were performed under a stress ratio of R= -1 and a frequency of 10Hz. The observations of the crack initiation and growth were performed with a microscope, and hardness around the hole was measured by Vickers hardness testing machine. In the present study, the longest fatigue life was observed in the case of an indentation specimen with the highest load. The indentation was performed on both sides of the hole edges. The crack growth rate was decreased by indentation or expansion of the material around the hole. From the experimental results, it is found that the fatigue life and crack growth behavior of a holed or notched specimen can be improved by a simple technical method that is related to the local plastic working.
Advanced Materials Research, 2015
International Journal of Fatigue, 2015
ABSTRACT
Key Engineering Materials, 2012
The improvement of acceleration behavior of crack growth was investigated with constant stress am... more The improvement of acceleration behavior of crack growth was investigated with constant stress amplitude under negative stress ratio R=-1. Then a technical method to detect the fatigue crack growth was discussed. For example, when the stress amplitude exceeds a critical value, crack growth rate of overloaded specimen became higher than that of baseline which was obtained by crack growth test without applying overload. In some experimental cases, the acceleration of crack growth was observed and that could be happened on practical cases. Stop-holes were drilled at crack tips or in the vicinity of crack tips to remove the plastic zone and the effect of that on crack growth behavior were investigated. Also, steel pins were inserted into the stop-holes and its effect was discussed. Finite element method (FEM) was used to analyze the stress concentration at the edge of stop-holes. Positions of center of the stop-holes were varied at different distance from the crack tips to investigate the effect of stop-holes on fatigue crack growth. Also, stress intensity of base and stop-holed specimen was calculated. Then, the effect of stop-hole was discussed by both the experimental and analytical results. Specially, it was discussed whether the crack growth behavior was improved or not in the case of relatively smaller width specimen.
Procedia Materials Science, 2014
The role of small cracks on fatigue life and loss of ductility are discussed to understand the re... more The role of small cracks on fatigue life and loss of ductility are discussed to understand the reality of fatigue damage in low cycle fatigue. The series of low cycle fatigue tests were carried out paying attention to the role of small cracks and its influence on ductility loss. These tests showed that the fatigue lives were pronouncedly extended by removing surface cracks. Also, it was quantified that the loss of fracture ductility was correlated with crack length but not with the number of fatigue cycles. From those results, it is elucidated that the behavior of small cracks is crucial to explain the mechanism of low cycle fatigue damage rather than the crack initiation process and change in bulk material properties.
Mechanical Engineering Journal, 2014
Key Engineering Materials, 2010
Page 1. Hole Expansion by using Al-alloy Specimen and 0.45% Carbon Steel Specimen Muhammed Sohel ... more Page 1. Hole Expansion by using Al-alloy Specimen and 0.45% Carbon Steel Specimen Muhammed Sohel Rana 1, a , Md. Shafiul Ferdous 1, b , Chobin Makabe 2, c ... 23 (2001), p. 161. [5] M. Sohel Rana, C. Makabe, G. Fujiwara, 2009., Eng Fail Ana, vol. 16 (2009), p. 2081. ...
Modern Physics Letters B, 2013
The fatigue and fracture behavior of C/C composites fabricated using fine-woven carbon fiber lami... more The fatigue and fracture behavior of C/C composites fabricated using fine-woven carbon fiber laminates with α = 0/90 • direction were investigated. Also, the phenomenon of crack growth behavior and the shear damage in the fiber bundle was discussed. Slits of several sizes were cut on both sides of a test section and different sizes of slit length were chosen. The effect of the slit configuration on crack initiation and growth behavior was observed. Specimens with blunt-notches and center-holes were also used to compare the fatigue strength and crack growth behavior. Non-propagating cracks were observed and fatigue limit was defined as the maximum stress at which specimen did not break for N = 10 7 cycles stress application. The longest fatigue life was obtained in the case of specimens with shorter slits. The relationships between fatigue strengths and specimen shapes were analyzed by stress concentration, Kt, and stress intensity factor, K I . The effect of slit configuration on fatigue strength was then discussed regarding both the experimental and calculated consequences.
Engineering Failure Analysis, 2011
A series of tests were conducted in aluminum alloy 2024-T3 to investigate the effect of additiona... more A series of tests were conducted in aluminum alloy 2024-T3 to investigate the effect of additional holes and notches on the fatigue behavior of double hole specimens. Also, circular pins were inserted into the additional holes, but not removed before testing in some cases. Basic specimen has dual holes and their cracks interacted with the specimen edge. Within the present study conditions, the longest fatigue life was observed where dual holes had a shorter distance between their edges and a longer distance from specimen edge to holes. The shortest fatigue life was observed where there was a longer distance between the hole edges. This paper describes how the improvement of fatigue life in the shorter life case of a basic specimen was examined by applying additional holes or notches. The crack initiation and growth behavior was observed and the mechanism of the extension of the fatigue life was investigated. The finite element method (FEM) was used to analyze the stress concentration around the basic dual holes, additional holes and notches in the present specimens. Then it was discussed how the reduction of stress concentration around the basic dual holes affected the fatigue life of the double holed specimens. A method of enhancement of fatigue life of notched material is discussed in the present study.