Joints between two different grades of aluminium alloys are need of the hour in many light weight military structures.In this investigation,an attempt has been made to join the heat treatable(AA 6061) and non-heat tre...Joints between two different grades of aluminium alloys are need of the hour in many light weight military structures.In this investigation,an attempt has been made to join the heat treatable(AA 6061) and non-heat treatable(AA 5086) aluminium alloys by friction stir welding(FSW)process using three different tool pin profiles like straight cylindrical,taper cylindrical and threaded cylindrical.The microstructures of various regions were observed and analyzed by means of optical and scanning electron microscope.The tensile properties and microhardness were evaluated for the welded joint.From this investigation it is founded that the use of threaded pin profile of tool contributes to better flow of materials between two alloys and the generation of defect free stir zone.It also resulted in higher hardness values of 83 HV in the stir zone and higher tensile strength of 169 MPa compared to other two profiles.The increase in hardness is attributed to the formation of fine grains and intermetallics in the stir zone,and in addition,the reduced size of weaker regions,such as TMAZ and HAZ regions,results in higher tensile properties.展开更多
The fusion welding of dissimilar heat treatable and non-heat treatable aluminium alloy faced many problems related to solidification. The difficulties can be overcome to achieve the combined beneficial properties of b...The fusion welding of dissimilar heat treatable and non-heat treatable aluminium alloy faced many problems related to solidification. The difficulties can be overcome to achieve the combined beneficial properties of both aluminium alloys using friction stir welding(FSW). The microstructural features and tensile properties of friction stir welded(FSW) similar and dissimilar joints made of AA6061 and AA5086 aluminium alloys were investigated. The microstructures of various regions were observed and analyzed by means of optical and scanning electron microscopy. Microhardness was measured at various zones of the welded joints. The tensile properties of the joints were evaluated and correlated with the microstructural features and microhardness values. The dissimilar joint exhibits a maximum hardness of HV 115 and a joint efficiency of 56%. This was attributed to the defect free stir zone formation and grain size strengthening.展开更多
The novelty of this research lies in the successful fabrication of a 3D-printed honeycomb structure filled with nanofillers for acoustic properties,utilizing an impedance tube setup in accordance with ASTM standard E ...The novelty of this research lies in the successful fabrication of a 3D-printed honeycomb structure filled with nanofillers for acoustic properties,utilizing an impedance tube setup in accordance with ASTM standard E 1050-12.The Creality Ender-3,a 3D printer,was used for printing the honeycomb structures,and polylactic acid(PLA)material was employed for their construction.The organic,inorganic,and polymeric compounds within the composites were identified using fourier transformation infrared(FTIR)spectroscopy.The structure and homogeneity of the samples were examined using a field emission scanning electron microscope(FESEM).To determine the sound absorption coefficient of the 3D printed honeycomb structure,numerous samples were systematically developed using central composite design(CCD)and analysed using response surface methodology(RSM).The RSM mathematical model was established to predict the optimum values of each factor and noise reduction coefficient(NRC).The optimum values for an NRC of 0.377 were found to be 1.116 wt% carbon black,1.025 wt% aluminium powder,and 3.151 mm distance between parallel edges.Overall,the results demonstrate that a 3Dprinted honeycomb structure filled with nanofillers is an excellent material that can be utilized in various fields,including defence and aviation,where lightweight and acoustic properties are of great importance.展开更多
Copper alloyed with various compositions of nickel and tin were cast into molds under argon atmosphere.The cast rods were homogenized,solution heat treated,followed by aging for different time duration.The specimens w...Copper alloyed with various compositions of nickel and tin were cast into molds under argon atmosphere.The cast rods were homogenized,solution heat treated,followed by aging for different time duration.The specimens were characterized for microstructure and tested for microhardness and wear rate.A hybrid model with a linear function and radial basis function was developed to analyze the influence of nickel,tin,and aging time on the microhardness and tribological behavior of copper-nickel-sin alloy system.The results indicate that increase in the composition of nickel and tin increases the microhardness and decreases the wear rate of the alloy.The increase in the concentration of nickel and tin decreases the peak aging time of the alloy system.展开更多
About 400 pumice clasts collected from the Central Indian Ocean Basin（CIOB）were studied for their morphology and were classified based on their shape and size.A majority of the samples range between1 cm and 36 cm an...About 400 pumice clasts collected from the Central Indian Ocean Basin（CIOB）were studied for their morphology and were classified based on their shape and size.A majority of the samples range between1 cm and 36 cm and in the Zinggs shape diagram plot in the equant and oblate fields.The Corey Shape Factor for most of the samples is close to 0.7,which is common for volcaniclastic material. The physical properties such as density,specific gravity,void ratio,porosity,moisture content and degree of saturation,were determined for 30 pumice samples.Density varies from 0.21 to 0.74 g/cm^3 specific gravity 1.84 to 3.27,void ratio 2.21 to 10.67,porosity 67%to 91%,moisture content during sinking 0.44 to 2.35 and degree of saturation varies from 26.5%to 86%.Binocular and electron microscopy studies reveal that 60%of the vesicles are elongated,30%are spherical and 10%are fibrous.Petrography of the pumices exhibits vitrophyric texture with phenocrysts of feldspars and clinopyroxenes.X-ray diffractrogram and mineral analyses confirm plagioclase to be a major phase, while quartz and orthoclase are not uncommon.Todorokite is commonly present in the ferromanganese oxide coating present over some of the pumices.This paper also delves into some details concerning the controversial origin of the pumices and glass shards in the CIOB.展开更多
This paper analyses the seismic performance of exterior beam-column joints strengthened with unconventional reinforcement detailing. The beam-column joint specimens were tested with reverse cyclic loading applied at t...This paper analyses the seismic performance of exterior beam-column joints strengthened with unconventional reinforcement detailing. The beam-column joint specimens were tested with reverse cyclic loading applied at the beam end. The samples were divided into two groups based on the joint reinforcement detailing. The first group (Group A) of three non-ductility specimens had joint detailing in accordance with the construction code of practice in India IS456-2000, and the second group (Group B) of three ductility specimens had joint reinforcement detailed as per IS13920-1993, with similar axial load cases as the first group. The experimental studies are proven with the analytical studies carried out by finite element models using ANSYS. The results show that the hysteresis simulation is satisfactory for both un-strengthened and ferrocement strengthened specimens. Furthermore, when ferrocement strengthening is employed, the strengthened beam-column joints exhibit better structural performance than the un-strengthened specimens of about 31.56% and 38.98 for DD-T1 and DD-T2 respectively. The analytical shear strength predictions were in line with the test results reported in the literature, thus adding confidence to the validity of the proposed models.展开更多
Zinc-aluminum alloys have been used as bearing materials in the past. In recent years, binary Al-Zn alloys and Al-Zn-Cu alloys are being used as an alternative to the Zn-Al alloys for bearing applications. In this stu...Zinc-aluminum alloys have been used as bearing materials in the past. In recent years, binary Al-Zn alloys and Al-Zn-Cu alloys are being used as an alternative to the Zn-Al alloys for bearing applications. In this study, both binary Al-25 Zn and Al-3 Cu were prepared using stir casting process. Homogenization of the as-cast alloys was performed at 350oC for 8 h and then, the alloys were furnace-cooled to 50oC. The homogenization led to the removal of the dendritic structure of the as-cast alloys. After homogenization, wear parameters optimization was carried out using Taguchi technique. For this purpose, L9 orthogonal array was selected, and the control parameters selected are load, velocity, and sliding distance. The optimum parametric condition was obtained using signal-to-noise(S/N) ratio analysis, and specific wear rate(SWR) is the selected response. The "smaller-the-better" is the goal of the experiment for S/N ratio analysis. After the optimization, confirmation tests were carried out using analysis of variance(ANOVA) from the developed regression equation. Finally, wear mechanism studies were conducted using scanning electron microscopy(SEM) and energy-dispersive X-ray spectroscopy(EDX) images.展开更多
基金the support extended by the Centre for Materials Joining & Research (CEMAJOR), Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar, India to carry out this research
文摘Joints between two different grades of aluminium alloys are need of the hour in many light weight military structures.In this investigation,an attempt has been made to join the heat treatable(AA 6061) and non-heat treatable(AA 5086) aluminium alloys by friction stir welding(FSW)process using three different tool pin profiles like straight cylindrical,taper cylindrical and threaded cylindrical.The microstructures of various regions were observed and analyzed by means of optical and scanning electron microscope.The tensile properties and microhardness were evaluated for the welded joint.From this investigation it is founded that the use of threaded pin profile of tool contributes to better flow of materials between two alloys and the generation of defect free stir zone.It also resulted in higher hardness values of 83 HV in the stir zone and higher tensile strength of 169 MPa compared to other two profiles.The increase in hardness is attributed to the formation of fine grains and intermetallics in the stir zone,and in addition,the reduced size of weaker regions,such as TMAZ and HAZ regions,results in higher tensile properties.
基金the support extended by the Centre for Materials Joining & Research (CEMJOR)
文摘The fusion welding of dissimilar heat treatable and non-heat treatable aluminium alloy faced many problems related to solidification. The difficulties can be overcome to achieve the combined beneficial properties of both aluminium alloys using friction stir welding(FSW). The microstructural features and tensile properties of friction stir welded(FSW) similar and dissimilar joints made of AA6061 and AA5086 aluminium alloys were investigated. The microstructures of various regions were observed and analyzed by means of optical and scanning electron microscopy. Microhardness was measured at various zones of the welded joints. The tensile properties of the joints were evaluated and correlated with the microstructural features and microhardness values. The dissimilar joint exhibits a maximum hardness of HV 115 and a joint efficiency of 56%. This was attributed to the defect free stir zone formation and grain size strengthening.
文摘The novelty of this research lies in the successful fabrication of a 3D-printed honeycomb structure filled with nanofillers for acoustic properties,utilizing an impedance tube setup in accordance with ASTM standard E 1050-12.The Creality Ender-3,a 3D printer,was used for printing the honeycomb structures,and polylactic acid(PLA)material was employed for their construction.The organic,inorganic,and polymeric compounds within the composites were identified using fourier transformation infrared(FTIR)spectroscopy.The structure and homogeneity of the samples were examined using a field emission scanning electron microscope(FESEM).To determine the sound absorption coefficient of the 3D printed honeycomb structure,numerous samples were systematically developed using central composite design(CCD)and analysed using response surface methodology(RSM).The RSM mathematical model was established to predict the optimum values of each factor and noise reduction coefficient(NRC).The optimum values for an NRC of 0.377 were found to be 1.116 wt% carbon black,1.025 wt% aluminium powder,and 3.151 mm distance between parallel edges.Overall,the results demonstrate that a 3Dprinted honeycomb structure filled with nanofillers is an excellent material that can be utilized in various fields,including defence and aviation,where lightweight and acoustic properties are of great importance.
文摘Copper alloyed with various compositions of nickel and tin were cast into molds under argon atmosphere.The cast rods were homogenized,solution heat treated,followed by aging for different time duration.The specimens were characterized for microstructure and tested for microhardness and wear rate.A hybrid model with a linear function and radial basis function was developed to analyze the influence of nickel,tin,and aging time on the microhardness and tribological behavior of copper-nickel-sin alloy system.The results indicate that increase in the composition of nickel and tin increases the microhardness and decreases the wear rate of the alloy.The increase in the concentration of nickel and tin decreases the peak aging time of the alloy system.
基金the financial assistance provided under the CSIR(New Delhi) Fellowship scheme
文摘About 400 pumice clasts collected from the Central Indian Ocean Basin（CIOB）were studied for their morphology and were classified based on their shape and size.A majority of the samples range between1 cm and 36 cm and in the Zinggs shape diagram plot in the equant and oblate fields.The Corey Shape Factor for most of the samples is close to 0.7,which is common for volcaniclastic material. The physical properties such as density,specific gravity,void ratio,porosity,moisture content and degree of saturation,were determined for 30 pumice samples.Density varies from 0.21 to 0.74 g/cm^3 specific gravity 1.84 to 3.27,void ratio 2.21 to 10.67,porosity 67%to 91%,moisture content during sinking 0.44 to 2.35 and degree of saturation varies from 26.5%to 86%.Binocular and electron microscopy studies reveal that 60%of the vesicles are elongated,30%are spherical and 10%are fibrous.Petrography of the pumices exhibits vitrophyric texture with phenocrysts of feldspars and clinopyroxenes.X-ray diffractrogram and mineral analyses confirm plagioclase to be a major phase, while quartz and orthoclase are not uncommon.Todorokite is commonly present in the ferromanganese oxide coating present over some of the pumices.This paper also delves into some details concerning the controversial origin of the pumices and glass shards in the CIOB.
文摘This paper analyses the seismic performance of exterior beam-column joints strengthened with unconventional reinforcement detailing. The beam-column joint specimens were tested with reverse cyclic loading applied at the beam end. The samples were divided into two groups based on the joint reinforcement detailing. The first group (Group A) of three non-ductility specimens had joint detailing in accordance with the construction code of practice in India IS456-2000, and the second group (Group B) of three ductility specimens had joint reinforcement detailed as per IS13920-1993, with similar axial load cases as the first group. The experimental studies are proven with the analytical studies carried out by finite element models using ANSYS. The results show that the hysteresis simulation is satisfactory for both un-strengthened and ferrocement strengthened specimens. Furthermore, when ferrocement strengthening is employed, the strengthened beam-column joints exhibit better structural performance than the un-strengthened specimens of about 31.56% and 38.98 for DD-T1 and DD-T2 respectively. The analytical shear strength predictions were in line with the test results reported in the literature, thus adding confidence to the validity of the proposed models.
文摘Zinc-aluminum alloys have been used as bearing materials in the past. In recent years, binary Al-Zn alloys and Al-Zn-Cu alloys are being used as an alternative to the Zn-Al alloys for bearing applications. In this study, both binary Al-25 Zn and Al-3 Cu were prepared using stir casting process. Homogenization of the as-cast alloys was performed at 350oC for 8 h and then, the alloys were furnace-cooled to 50oC. The homogenization led to the removal of the dendritic structure of the as-cast alloys. After homogenization, wear parameters optimization was carried out using Taguchi technique. For this purpose, L9 orthogonal array was selected, and the control parameters selected are load, velocity, and sliding distance. The optimum parametric condition was obtained using signal-to-noise(S/N) ratio analysis, and specific wear rate(SWR) is the selected response. The "smaller-the-better" is the goal of the experiment for S/N ratio analysis. After the optimization, confirmation tests were carried out using analysis of variance(ANOVA) from the developed regression equation. Finally, wear mechanism studies were conducted using scanning electron microscopy(SEM) and energy-dispersive X-ray spectroscopy(EDX) images.
