ASME 2009 International Manufacturing Science and Engineering Conference, Volume 1, 2009
In this paper, numerical simulation of nanoparticle integrated laser shock peening of aluminum al... more In this paper, numerical simulation of nanoparticle integrated laser shock peening of aluminum alloys was carried out. A “tied constraint” was used to connect the matrix and nanoparticle assembly in ABAQUS package. Different particle size and particle volumes fraction (PVF) were studied. It was found that there is significant stress concentration around the nanoparticles. The existence of nanoparticle will influence the stress wave propagation and thus the final stress and strain state of the material after LSP. In addition, particle size, ...
Journal of Manufacturing Science and Engineering, 2013
ABSTRACT A magnetic field-assisted laser drilling process has been studied, where nanosecond lase... more ABSTRACT A magnetic field-assisted laser drilling process has been studied, where nanosecond laser ablation is performed under an external magnetic field. The study shows that the magnetic field-assisted laser drilling process produces deeper drilling depth and generates more confined plasma plume and relative less residual, as compared with laser drilling without magnetic field. This phenomenon has been rarely reported in the literature. The magnetic field effects on laser ablation have been analyzed analytically and a hypothesized explanation has been proposed based on the effect of the magnetic field on the plasma produced during laser ablation.
Journal of Manufacturing Science and Engineering, 2010
Résumé/Abstract Laser shock induced plastic deformation has been used widely, such as laser shock... more Résumé/Abstract Laser shock induced plastic deformation has been used widely, such as laser shock peening (LSP), laser dynamic forming (LDF), and laser peen forming. These processes have been extensively studied both numerically and experimentally at room temperature. Recently, it is found that at elevated temperature, laser shock induced plastic deformation can generate better formability in LDF and enhanced mechanical properties in LSP. For example, warm laser shock peening leads to improved residual stress stability ...
Journal of Manufacturing Science and Engineering, 2010
Résumé/Abstract Nanocomposite and multiphase structures have become more important nowadays to en... more Résumé/Abstract Nanocomposite and multiphase structures have become more important nowadays to enhance the mechanical properties of materials. Laser shock peening (LSP) is one of the most efficient ways to increase component fatigue life. In this paper, numerical and experimental studies have been carried out to study the effects of nanoparticles integrated structures during the laser shock peening of aluminum alloys. The LSP experiment of aluminum samples with different particle densities was carried out. The ...
Journal of Biomedical Materials Research Part A, 2010
Coating of bioceramic material, Hydroxyapatite (HAp), on metal implant has attracted many attenti... more Coating of bioceramic material, Hydroxyapatite (HAp), on metal implant has attracted many attentions in biomedical industry recently because its combination of good mechanical property and biocompatibility. However, most of current HAp coatings lack coating/substrate interfacial strength, and/or biocompatibility. The cell-tissue attachment is affected by the degraded biocompatibility due to decomposition of HAp during high temperature processing. In this article, an innovative method, transmission laser coating (TLC), is investigated to coat HAp on Ti substrate with low temperature processing. This process enhances the HAp/Metal interfacial property of current coatings, while maintaining good biocompatibility. Experiments are conducted using a continuous neodymium-doped yttrium aluminium garnet (Nd-YAG) laser. Multiphysics simulation is conducted to simulate the temperature distribution in coatings and substrates during TLC processing. X-ray energy dispersion spectrum is used to measure the chemical composition of HAp coatings after TLC process. Pull-out tests are conducted to measure the interfacial strength between the HAp coating and Ti substrate. Cell culture study is conducted to qualitatively evaluate the biocompatibility after TLC of HAp particles. These results show that TLC processing will open new ways of producing biocompatible bioceramic coatings with controlled thickness, and at low processing temperature.
Traditional numerical study of the temperature field of laser thermal processing is based on two ... more Traditional numerical study of the temperature field of laser thermal processing is based on two assumptions: 1. heat source is a surface heat flux, and 2. uniform material properties. This method is not accurate when it comes to the laser sintering of nanoparticle integrated bioceramics coating with certain porosity. In this paper, Heat transfer (HT) model and electromagnetic (EM) model is coupled to investigate the temperature field of bioceramics nanoparticles. The heat source calculated from EM field is simultaneously input into the ...
Warm laser shock peening (WLSP) integrates the advantages of laser shock peening and thermal-mech... more Warm laser shock peening (WLSP) integrates the advantages of laser shock peening and thermal-mechanical treatment (TMT) to improve material fatigue performance. Compared to traditional laser shock peening (LSP), warm laser shock peening, ie LSP at elevated temperature, leads to better performance in many aspects. WLSP can induce nanoscale precipitations by dynamic precipitation and high density dislocation by dynamic strain aging (DSA), resulting in higher surface strength, which is beneficial for fatigue life improvement. ...
Laser Shock Peening (LSP) has been successfully used to improve component fatigue performance by ... more Laser Shock Peening (LSP) has been successfully used to improve component fatigue performance by bringing beneficial compressive residual stress to material surface since the 1990s. However, it has been found that the compressive residual stress generated by room temperature LSP (RT-LSP) is not stable during cyclic loading. Thus, it is necessary to improve the stability of the compressive residual stress generated by RT-LSP.^ In this study, Warm Laser Shock Peening (WLSP) is proposed as a potential approach to ...
ASME 2012 International Manufacturing Science and Engineering Conference, 2012
ABSTRACT We report a method to half-embed nanoparticles into metallic materials. Transparent and ... more ABSTRACT We report a method to half-embed nanoparticles into metallic materials. Transparent and opaque nanoparticle (laser wavelength 1064 nm) were both successfully half-embedded (partial part of nanoparticles embedded into matrix while other parts still stay above the matrix) into metallic materials. Nanoparticles were coated on sample surface by dip coating before laser irradiation. After laser irradiation of different pulses and laser fluencies, nanoparticles were embedded into metal. The mechanism and process of embedding were investigated.
ASME 2012 International Manufacturing Science and Engineering Conference, 2012
ABSTRACT In this study, aluminum alloy 7075 (AA 7075) is processed by WLSP and compared with LSP ... more ABSTRACT In this study, aluminum alloy 7075 (AA 7075) is processed by WLSP and compared with LSP at room temperature (RT-LSP). The microstructure of AA 7075 after processing is characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Tensile test and hardness test were carried out to investigate the effect of WLSP to material strength and ductility. It has been found that highly dense nanoscale precipitate particles are generated after WLSP. These nanoscale precipitate particles effectively block dislocations and thus increase the material strength.
Abstract An indentation-planarization method for NiTi shape memory alloys has been developed that... more Abstract An indentation-planarization method for NiTi shape memory alloys has been developed that produces a robust surface topographical memory effect that we call" surface form memory", or SFM. Surface form memory entails reversible transitions between one surface form (flat) and another (say, wavy) that occur on changing temperature. These transitions are cyclically stable and exhibit very high mechanical energy density. Our previous study has demonstrated SFM transitions in NiTi alloys derived from quasistatic ( ...
Journal of Manufacturing Science and Engineering, 2009
Résumé/Abstract Microscale laser dynamic forming (μLDF) is a novel microfabrication technique to ... more Résumé/Abstract Microscale laser dynamic forming (μLDF) is a novel microfabrication technique to introduce complex 3D profiles in thin films. This process utilizes pulse laser to generate plasma to induce shockwave pressure into the thin film, which is placed above a micro-sized mold. The strain rate in μLDF reaches 10 6―10 7 S―1. Under these ultrahigh strain rates in microscale, deformation behaviors of materials are very complicated and almost impossible to be measured in situ experimentally. In this paper, a finite element ...
Journal of Biomedical Materials Research Part B: Applied Biomaterials, 2008
The copper-containing intrauterine devices (Cu-IUDs) are being increasingly used worldwide as an ... more The copper-containing intrauterine devices (Cu-IUDs) are being increasingly used worldwide as an effective contraceptive for family planning. To avoid abnormal bleeding, pain, and partial and complete expulsion which are associated with the burst release of copper during the first few days, a novel crosslinked composite based on poly(vinyl alcohol) that contained cupric ions, but not metallic copper, was synthesized. It is hypothesized that the burst release of cupric ions could be avoided and the utility of the cupric ions could be improved by this novel composite. To evaluate these effects of the composite, the corrosion products and the release rate of cupric ions after soaking in simulated body fluid (SBF) for different time spans were studied by environmental scanning electron microscopy, X-ray energy dispersive spectroscopy, X-ray diffraction, and atomic absorption spectrophotometer. In the first week, the release amount of cupric ions in the composite was 0.486 microg/mm(2). In the fifth week, it decreased to 0.0278 microg/mm(2). But for metallic copper, these were 5.93 microg/mm(2) and 0.041 microg/mm(2), respectively. No significant change on time-dependence was found for the release rates of cupric ions in the composite compared with that of metallic copper. Moreover, no other new elements, such as P, Cl, and Ca, appeared on the surface of the composite, and no Cu2O was formed after immersing in SBF for 90 days. All of these results suggested that burst release of cupric ions could be avoided and the effective utility of copper could be improved in this composite. In view of the earlier results, this novel copper-containing composite might serve as a potential substitute for conventional materials of IUDs in the future.
ASME 2009 International Manufacturing Science and Engineering Conference, Volume 1, 2009
In this paper, numerical simulation of nanoparticle integrated laser shock peening of aluminum al... more In this paper, numerical simulation of nanoparticle integrated laser shock peening of aluminum alloys was carried out. A “tied constraint” was used to connect the matrix and nanoparticle assembly in ABAQUS package. Different particle size and particle volumes fraction (PVF) were studied. It was found that there is significant stress concentration around the nanoparticles. The existence of nanoparticle will influence the stress wave propagation and thus the final stress and strain state of the material after LSP. In addition, particle size, ...
Journal of Manufacturing Science and Engineering, 2013
ABSTRACT A magnetic field-assisted laser drilling process has been studied, where nanosecond lase... more ABSTRACT A magnetic field-assisted laser drilling process has been studied, where nanosecond laser ablation is performed under an external magnetic field. The study shows that the magnetic field-assisted laser drilling process produces deeper drilling depth and generates more confined plasma plume and relative less residual, as compared with laser drilling without magnetic field. This phenomenon has been rarely reported in the literature. The magnetic field effects on laser ablation have been analyzed analytically and a hypothesized explanation has been proposed based on the effect of the magnetic field on the plasma produced during laser ablation.
Journal of Manufacturing Science and Engineering, 2010
Résumé/Abstract Laser shock induced plastic deformation has been used widely, such as laser shock... more Résumé/Abstract Laser shock induced plastic deformation has been used widely, such as laser shock peening (LSP), laser dynamic forming (LDF), and laser peen forming. These processes have been extensively studied both numerically and experimentally at room temperature. Recently, it is found that at elevated temperature, laser shock induced plastic deformation can generate better formability in LDF and enhanced mechanical properties in LSP. For example, warm laser shock peening leads to improved residual stress stability ...
Journal of Manufacturing Science and Engineering, 2010
Résumé/Abstract Nanocomposite and multiphase structures have become more important nowadays to en... more Résumé/Abstract Nanocomposite and multiphase structures have become more important nowadays to enhance the mechanical properties of materials. Laser shock peening (LSP) is one of the most efficient ways to increase component fatigue life. In this paper, numerical and experimental studies have been carried out to study the effects of nanoparticles integrated structures during the laser shock peening of aluminum alloys. The LSP experiment of aluminum samples with different particle densities was carried out. The ...
Journal of Biomedical Materials Research Part A, 2010
Coating of bioceramic material, Hydroxyapatite (HAp), on metal implant has attracted many attenti... more Coating of bioceramic material, Hydroxyapatite (HAp), on metal implant has attracted many attentions in biomedical industry recently because its combination of good mechanical property and biocompatibility. However, most of current HAp coatings lack coating/substrate interfacial strength, and/or biocompatibility. The cell-tissue attachment is affected by the degraded biocompatibility due to decomposition of HAp during high temperature processing. In this article, an innovative method, transmission laser coating (TLC), is investigated to coat HAp on Ti substrate with low temperature processing. This process enhances the HAp/Metal interfacial property of current coatings, while maintaining good biocompatibility. Experiments are conducted using a continuous neodymium-doped yttrium aluminium garnet (Nd-YAG) laser. Multiphysics simulation is conducted to simulate the temperature distribution in coatings and substrates during TLC processing. X-ray energy dispersion spectrum is used to measure the chemical composition of HAp coatings after TLC process. Pull-out tests are conducted to measure the interfacial strength between the HAp coating and Ti substrate. Cell culture study is conducted to qualitatively evaluate the biocompatibility after TLC of HAp particles. These results show that TLC processing will open new ways of producing biocompatible bioceramic coatings with controlled thickness, and at low processing temperature.
Traditional numerical study of the temperature field of laser thermal processing is based on two ... more Traditional numerical study of the temperature field of laser thermal processing is based on two assumptions: 1. heat source is a surface heat flux, and 2. uniform material properties. This method is not accurate when it comes to the laser sintering of nanoparticle integrated bioceramics coating with certain porosity. In this paper, Heat transfer (HT) model and electromagnetic (EM) model is coupled to investigate the temperature field of bioceramics nanoparticles. The heat source calculated from EM field is simultaneously input into the ...
Warm laser shock peening (WLSP) integrates the advantages of laser shock peening and thermal-mech... more Warm laser shock peening (WLSP) integrates the advantages of laser shock peening and thermal-mechanical treatment (TMT) to improve material fatigue performance. Compared to traditional laser shock peening (LSP), warm laser shock peening, ie LSP at elevated temperature, leads to better performance in many aspects. WLSP can induce nanoscale precipitations by dynamic precipitation and high density dislocation by dynamic strain aging (DSA), resulting in higher surface strength, which is beneficial for fatigue life improvement. ...
Laser Shock Peening (LSP) has been successfully used to improve component fatigue performance by ... more Laser Shock Peening (LSP) has been successfully used to improve component fatigue performance by bringing beneficial compressive residual stress to material surface since the 1990s. However, it has been found that the compressive residual stress generated by room temperature LSP (RT-LSP) is not stable during cyclic loading. Thus, it is necessary to improve the stability of the compressive residual stress generated by RT-LSP.^ In this study, Warm Laser Shock Peening (WLSP) is proposed as a potential approach to ...
ASME 2012 International Manufacturing Science and Engineering Conference, 2012
ABSTRACT We report a method to half-embed nanoparticles into metallic materials. Transparent and ... more ABSTRACT We report a method to half-embed nanoparticles into metallic materials. Transparent and opaque nanoparticle (laser wavelength 1064 nm) were both successfully half-embedded (partial part of nanoparticles embedded into matrix while other parts still stay above the matrix) into metallic materials. Nanoparticles were coated on sample surface by dip coating before laser irradiation. After laser irradiation of different pulses and laser fluencies, nanoparticles were embedded into metal. The mechanism and process of embedding were investigated.
ASME 2012 International Manufacturing Science and Engineering Conference, 2012
ABSTRACT In this study, aluminum alloy 7075 (AA 7075) is processed by WLSP and compared with LSP ... more ABSTRACT In this study, aluminum alloy 7075 (AA 7075) is processed by WLSP and compared with LSP at room temperature (RT-LSP). The microstructure of AA 7075 after processing is characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Tensile test and hardness test were carried out to investigate the effect of WLSP to material strength and ductility. It has been found that highly dense nanoscale precipitate particles are generated after WLSP. These nanoscale precipitate particles effectively block dislocations and thus increase the material strength.
Abstract An indentation-planarization method for NiTi shape memory alloys has been developed that... more Abstract An indentation-planarization method for NiTi shape memory alloys has been developed that produces a robust surface topographical memory effect that we call" surface form memory", or SFM. Surface form memory entails reversible transitions between one surface form (flat) and another (say, wavy) that occur on changing temperature. These transitions are cyclically stable and exhibit very high mechanical energy density. Our previous study has demonstrated SFM transitions in NiTi alloys derived from quasistatic ( ...
Journal of Manufacturing Science and Engineering, 2009
Résumé/Abstract Microscale laser dynamic forming (μLDF) is a novel microfabrication technique to ... more Résumé/Abstract Microscale laser dynamic forming (μLDF) is a novel microfabrication technique to introduce complex 3D profiles in thin films. This process utilizes pulse laser to generate plasma to induce shockwave pressure into the thin film, which is placed above a micro-sized mold. The strain rate in μLDF reaches 10 6―10 7 S―1. Under these ultrahigh strain rates in microscale, deformation behaviors of materials are very complicated and almost impossible to be measured in situ experimentally. In this paper, a finite element ...
Journal of Biomedical Materials Research Part B: Applied Biomaterials, 2008
The copper-containing intrauterine devices (Cu-IUDs) are being increasingly used worldwide as an ... more The copper-containing intrauterine devices (Cu-IUDs) are being increasingly used worldwide as an effective contraceptive for family planning. To avoid abnormal bleeding, pain, and partial and complete expulsion which are associated with the burst release of copper during the first few days, a novel crosslinked composite based on poly(vinyl alcohol) that contained cupric ions, but not metallic copper, was synthesized. It is hypothesized that the burst release of cupric ions could be avoided and the utility of the cupric ions could be improved by this novel composite. To evaluate these effects of the composite, the corrosion products and the release rate of cupric ions after soaking in simulated body fluid (SBF) for different time spans were studied by environmental scanning electron microscopy, X-ray energy dispersive spectroscopy, X-ray diffraction, and atomic absorption spectrophotometer. In the first week, the release amount of cupric ions in the composite was 0.486 microg/mm(2). In the fifth week, it decreased to 0.0278 microg/mm(2). But for metallic copper, these were 5.93 microg/mm(2) and 0.041 microg/mm(2), respectively. No significant change on time-dependence was found for the release rates of cupric ions in the composite compared with that of metallic copper. Moreover, no other new elements, such as P, Cl, and Ca, appeared on the surface of the composite, and no Cu2O was formed after immersing in SBF for 90 days. All of these results suggested that burst release of cupric ions could be avoided and the effective utility of copper could be improved in this composite. In view of the earlier results, this novel copper-containing composite might serve as a potential substitute for conventional materials of IUDs in the future.
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