Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications
In this article, the stress–time or speed–time relations for steady weak shock wave fronts and th... more In this article, the stress–time or speed–time relations for steady weak shock wave fronts and their effective parameters were studied for solid metals (except alkaline metals). The purpose was to determine the effective parameters for steady shock wave fronts and find the relations for prediction of the shape of these profiles in pure metals. First, the range of the steady weak shock wave was determined. Then, based on an empirical relationship for the maximum strain rate in the weak shock wave regime, a relation was assumed for the whole weak shock wave front. Then by utilizing simplified assumptions, such as elastic-perfectly plastic material model, a stress change equation and by integration, two implicit equations were obtained for describing the weak shock wave front profile that one of them was used in the calculations. Subsequently, the strain-hardening material model was used. The strain-hardening material model was further simplified as piecewise linear functions. The same...
Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications
This paper develops a new physically based model to investigate face centered cubic (FCC) metals ... more This paper develops a new physically based model to investigate face centered cubic (FCC) metals and alloys under high strain rate loadings (\gt104 s−1) which includes kinematics and constitutive equations for the propagation of elastic and steady plastic waves. The model’s formulations are based on the rate of the conservation energy law that includes the rate of the input energy, internal energy, and entropy generation. This formulation is obtained by incorporating the viscous drag effects and associating the entropy generation to the generation, glide, and annihilation of dislocations. The model is used for 6061-T6 aluminum alloys and the results are verified with the published theoretical models and experimental tests. Also, the effect of different parameters, such as the particle velocity, shear flow stress, shear strain rate and temperature are investigated. As a result, the presented model shows good capability in describing the mentioned parameters.
Powder bed fusion is an additive manufacturing method which allows production of complex parts, i... more Powder bed fusion is an additive manufacturing method which allows production of complex parts, in a shorter time compared to the conventional fabrication methods. During the last 60 years, Fe-Cu powders were widely used because of their anti-friction behavior and superior mechanical properties. Therefore, Fe-Cu powder has been selected as the basic material for the powder bed fusion process. In the present study, laser-assisted powder bed fusion of Fe-Cu powder mixture has been studied experimentally. Nd:YAG laser with a maximum power of 75 W has been used to melt the powder. The effects of volume fraction of the Cu powder in the mixture and applied energy density on thickness, surface concavity and geometrical accuracy of manufactured parts have been investigated. Results show that higher values of energy density lead to lower geometrical accuracy, higher thickness and surface concavity.
The ablation properties, thermal resistance and micro structural behavior of the phenolic resin (... more The ablation properties, thermal resistance and micro structural behavior of the phenolic resin (Resole) composites have been investigated in this research. Different materials, such as carbon fabrics, glass fabrics, also silica and zirconia powders have been used as reinforcements for synthesis of the composites. The specimens were prepared with three sets of compositions. The first set was produced with 37.5 wt% of Resole and 62.5 wt% of reinforcements. Another set of specimens were produced with 40wt% Resole, 40 wt% of silica and 20 wt% of zirconia. Also to achieve high insulation index in Resole/carbon fabrics composites a thin film of zirconia coated at the back side of the specimens. To explore the ablation characteristics of the composites in terms of insulation index, erosion rate and microscopic pattern of ablation, an oxyacetylene torch flame with heat flux of 10 Mw/m2 at approximately 2800°C was used. The ablation behavior and microstructure of the burnt-through specimens...
... loading Experimentelle Analyse der Kra¨ fte zur Faltenbildung in du¨ nnwandigen extrudierten ... more ... loading Experimentelle Analyse der Kra¨ fte zur Faltenbildung in du¨ nnwandigen extrudierten Zellen unter Beanspruchung in der Schalenebene J. Zamani, A. Fakhri, AK Ghamsari ... 17 2466.33 Energy 14.83 J 178 J. Zamani, A. Fakhri, AK Ghamsari Mat.-wiss. u. Werkstofftech. ...
Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications
In this article, the stress–time or speed–time relations for steady weak shock wave fronts and th... more In this article, the stress–time or speed–time relations for steady weak shock wave fronts and their effective parameters were studied for solid metals (except alkaline metals). The purpose was to determine the effective parameters for steady shock wave fronts and find the relations for prediction of the shape of these profiles in pure metals. First, the range of the steady weak shock wave was determined. Then, based on an empirical relationship for the maximum strain rate in the weak shock wave regime, a relation was assumed for the whole weak shock wave front. Then by utilizing simplified assumptions, such as elastic-perfectly plastic material model, a stress change equation and by integration, two implicit equations were obtained for describing the weak shock wave front profile that one of them was used in the calculations. Subsequently, the strain-hardening material model was used. The strain-hardening material model was further simplified as piecewise linear functions. The same...
Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications
This paper develops a new physically based model to investigate face centered cubic (FCC) metals ... more This paper develops a new physically based model to investigate face centered cubic (FCC) metals and alloys under high strain rate loadings (\gt104 s−1) which includes kinematics and constitutive equations for the propagation of elastic and steady plastic waves. The model’s formulations are based on the rate of the conservation energy law that includes the rate of the input energy, internal energy, and entropy generation. This formulation is obtained by incorporating the viscous drag effects and associating the entropy generation to the generation, glide, and annihilation of dislocations. The model is used for 6061-T6 aluminum alloys and the results are verified with the published theoretical models and experimental tests. Also, the effect of different parameters, such as the particle velocity, shear flow stress, shear strain rate and temperature are investigated. As a result, the presented model shows good capability in describing the mentioned parameters.
Powder bed fusion is an additive manufacturing method which allows production of complex parts, i... more Powder bed fusion is an additive manufacturing method which allows production of complex parts, in a shorter time compared to the conventional fabrication methods. During the last 60 years, Fe-Cu powders were widely used because of their anti-friction behavior and superior mechanical properties. Therefore, Fe-Cu powder has been selected as the basic material for the powder bed fusion process. In the present study, laser-assisted powder bed fusion of Fe-Cu powder mixture has been studied experimentally. Nd:YAG laser with a maximum power of 75 W has been used to melt the powder. The effects of volume fraction of the Cu powder in the mixture and applied energy density on thickness, surface concavity and geometrical accuracy of manufactured parts have been investigated. Results show that higher values of energy density lead to lower geometrical accuracy, higher thickness and surface concavity.
The ablation properties, thermal resistance and micro structural behavior of the phenolic resin (... more The ablation properties, thermal resistance and micro structural behavior of the phenolic resin (Resole) composites have been investigated in this research. Different materials, such as carbon fabrics, glass fabrics, also silica and zirconia powders have been used as reinforcements for synthesis of the composites. The specimens were prepared with three sets of compositions. The first set was produced with 37.5 wt% of Resole and 62.5 wt% of reinforcements. Another set of specimens were produced with 40wt% Resole, 40 wt% of silica and 20 wt% of zirconia. Also to achieve high insulation index in Resole/carbon fabrics composites a thin film of zirconia coated at the back side of the specimens. To explore the ablation characteristics of the composites in terms of insulation index, erosion rate and microscopic pattern of ablation, an oxyacetylene torch flame with heat flux of 10 Mw/m2 at approximately 2800°C was used. The ablation behavior and microstructure of the burnt-through specimens...
... loading Experimentelle Analyse der Kra¨ fte zur Faltenbildung in du¨ nnwandigen extrudierten ... more ... loading Experimentelle Analyse der Kra¨ fte zur Faltenbildung in du¨ nnwandigen extrudierten Zellen unter Beanspruchung in der Schalenebene J. Zamani, A. Fakhri, AK Ghamsari ... 17 2466.33 Energy 14.83 J 178 J. Zamani, A. Fakhri, AK Ghamsari Mat.-wiss. u. Werkstofftech. ...
Uploads
Papers by J. Zamani