From the viewpoint of production engineering, microforming is considered as an effective process to fabricate various microparts. Several key problems in microforming processes were investigated. A new microforming ap...From the viewpoint of production engineering, microforming is considered as an effective process to fabricate various microparts. Several key problems in microforming processes were investigated. A new microforming apparatus with a high stiffness piezoelectric actuator as the punch driver was developed to produce microparts.To improve the forming abilities and locate the billets, a floating microdie was designed. The size effects of the billets and die cavities on the microforming abilities were studied with upsetting and coining tests, respectively.And the isothermal microforming process of microgears was performed with the developed microforming apparatus. Several analysis methods were used to evaluate the forming quality of the microparts.展开更多
The mechanical behavior of superplastic 5083 aluminum alloy during microforming process was investigated by finite element analysis.A micro V-groove die was modeled to analyze the effects of forming time,load and temp...The mechanical behavior of superplastic 5083 aluminum alloy during microforming process was investigated by finite element analysis.A micro V-groove die was modeled to analyze the effects of forming time,load and temperature on the microformability of the 5083 aluminum alloy.First,the microformability of the 5083 aluminum alloy was estimated using a microformability index.The simulation results show that the microformability increases with the forming load,time and temperature increasing.Superplasticity of the 5083 aluminum alloy during microforming using the V-groove die was also investigated in terms of the effective strain rate.The results show that the superplasticity of the 5083 aluminum alloy occurs in a specific part of the material for a specific period during the microforming process depending on the forming conditions and the microformability index.展开更多
Peculiar properties of morphological structures of organelle membranes were studied by fluorescent confocal microscopy. The list of objects in our experiments was represented by mitochondria, chloroplasts and vacuoles...Peculiar properties of morphological structures of organelle membranes were studied by fluorescent confocal microscopy. The list of objects in our experiments was represented by mitochondria, chloroplasts and vacuoles. During this study, identification of lipid microinclusions having the form of such lipid-protein structural microformations as lipid-protein microdomains, vesicles and membrane tubular structures (cytoplasmic transvacuolar strands and nanotubes) located in organelle membranes or bound up with them was conducted. Such membrane probes as laurdan, DPH, ANS and bis-ANS were used. Comparison of fluorescence intensity of these membrane probes was conducted. This investigation of the morphological properties of lipid-protein structural microformations was accompanied with analysis of 1) the phase state and 2) dynamics of microviscosity variations in the membrane elements of isolated plant cell organelles. Distributions of laurdan fluorescence generalized polarization (GP) values for the membrane on the whole and for the intensively fluorescing membrane segments were obtained. It was discovered that the microviscosity of intensively fluorescing membrane segments essentially differed from the microviscosity of the rest part of the membrane. In conclusion, some results of the study of peculiar properties of lipid-protein structural microformations related to the structure of organelle membranes and the discoveries made in this investigation are discussed.展开更多
Research on microforming of fine-grained superplastic Zn-AI22 alloy was carried out in this paper by means of superplastic forming. With the selected material, microformability tests have been carried out with the spe...Research on microforming of fine-grained superplastic Zn-AI22 alloy was carried out in this paper by means of superplastic forming. With the selected material, microformability tests have been carried out with the specially developed evaluation method by using two kinds of stainless steel dies. With these dies, micro-extrusion tests have been carried out and the characteristics of microformability of the material have been clarified. Effects of processing parameters and die structure on forming have been analyzed. SEM and metallographic microscope have been used to analyze the formed specimens. Through analysis of flow lines of the formed specimen, behavior of material could be understood well.展开更多
As one of the indispensable actuating components in micro-systems,the shafted microgear is in great production demand.Microforming is a manufacturing process to produce microgears to meet the needs.Due to the small ge...As one of the indispensable actuating components in micro-systems,the shafted microgear is in great production demand.Microforming is a manufacturing process to produce microgears to meet the needs.Due to the small geometrical size,there are uncertain process performance and product quality issues in this production process.In this study,the shafted microgears were fabricated in two different scaling factors with four grain sizes using a progressively extrusion-blanking method.To explore the unknown of the process,grain-based modeling was proposed and employed to simulate the entire forming process.The results show that when the grains are large,the anisotropy of single grains has an obvious size effect on the forming behavior and process performance;and the produced geometries and surface quality are worsened;and the deformation load is decreased.Five deformation zones were identified in the microstructures with different hardness and distributions of stress and strain.The simulation by using the proposed model successfully predicted the formation of zones and revealed the inhomogeneous deformation in the forming process.The undesirable geometries of microgears including material unfilling,burr and inclination were observed on the shaft and teeth of gear,and the inclination size is increased obviously with grain size.To avoid the formation of inclination and material unfilling,the punch was redesigned,and a die insert was added to constraint the bottom surface of the gear teeth.The new products had then the better forming quality.展开更多
This paper reports a novel micro-blast driven manufacturing process for micro-forming of Aluminum foils. The micro-blast is realized by using a nanoenergetic material system comprising of Bi_2O_3 microrods and aluminu...This paper reports a novel micro-blast driven manufacturing process for micro-forming of Aluminum foils. The micro-blast is realized by using a nanoenergetic material system comprising of Bi_2O_3 microrods and aluminum particles. There is an enhanced need of forming of thin aluminum foil structures in small regions from point of view of drug packaging etc. The process developed caters to this need by using a single shot forming process using a micro-blast source. The micro-blast that is generated from an energetic composite system is made highly tunable by modulating the peak pressure generated through the blasting process and their impact in micro-forming of thin aluminum foils is observed through parametric studies. The engineering challenge involved in these experiments is to tune the blast pressure properties in order to address the forming of thin metal sheets with limiting boundary values as defined by the failure criteria. A variety of characterization techniques related to a thorough analysis of the synthesized material viz. X-ray diffraction(XRD), Scanning Electron Microscopy(SEM) etc, are used to tune the functional properties like gauge blast pressure etc, of material system. We have found a material system that can generate a maximum peak pressure of 73.8 MPa with pressurization rate of 2460 GPas^(-1) and that is able to accomplish micro-forming on thin metal foils(around 0.3 mm thickness). Experimental investigations demonstrate that tunabilty aspect of the energetic composites when exercised can enable variant processes such as embossing, coining, drilling etc. which may be of significant utility to drug packaging industries. A proper mathematical modeling of the forming process and critical process parameters therein have also been detailed.展开更多
In the present work,austenitic stainless steel(ASS)304 foils with a thickness of 50μm were first annealed at temperatures ranging from 700 to 1100℃for 1 h to obtain different microstructural characteristics.Then the...In the present work,austenitic stainless steel(ASS)304 foils with a thickness of 50μm were first annealed at temperatures ranging from 700 to 1100℃for 1 h to obtain different microstructural characteristics.Then the effects of microstructural characteristics on the formability of ASS 304 foils and the quality of drawn cups using micro deep drawing(MDD)were studied,and the mechanism involved was discussed.The results show that the as-received ASS 304 foil has a poor formability and cannot be used to form a cup using MDD.Serious wrinkling problem occurs on the drawn cup,and the height profile distribution on the mouth and the symmetry of the drawn cup is quite non-uniform when the annealing temperature is 700℃.At annealing temperatures of 900 and 950℃,the drawn cups are both characterized with very few wrinkles,and the distribution of height profile,symmetry and mouth thickness are uniform on the mouths of the drawn cups.The wrinkling becomes increasingly significant with a further increase of annealing temperature from 950 to 1100℃.The optimal annealing temperatures obtained in this study are 900 and 950℃for reducing the generation of wrinkling,and therefore improving the quality of drawn cups.With non-optimized microstructure,the distribution of the compressive stress in the circumferential direction of the drawn foils becomes inhomogeneous,which is thought to be the cause of the occurrence of localized deformation till wrinkling during MDD.展开更多
Carbonate pedofeatures were studied in details in a loess-paleosol pedocomplex near Kursk, in the central part of the European Plain. The soils studied included a modern Chernozem and five Pleistocene paleosols. Carbo...Carbonate pedofeatures were studied in details in a loess-paleosol pedocomplex near Kursk, in the central part of the European Plain. The soils studied included a modern Chernozem and five Pleistocene paleosols. Carbonate morphologies and distributions were described in the field. Various morphologies were sampled for further studies including micromorphology in thin sections and submicroscopic studies under a scanning electron microscope. The complex approach of investigation at macro-, micro-, and submicroscopic levels found that most of carbonate pedofeatures are secondary and multiphase. Many of them are related to cryogenic features. The general trend was of decreasing carbonate content in the older paleosols except for increased content in the 1st and 3rd paleosols. Most of carbonate morphologies are similar in the modern soil and paleosols, but pseudomycelium was found only in the modern Chernozem, while soft masses and impregnations are associated with the paleosols. Detailed study on carbonate attributes revealed their specific features in the modern soil and in paleosols. Veins have dissolution features under the modern environment and seem to reprecipitate in form of pseudomycelium. Coatings in paleosols at a depth of the 1st paleosol include specific fine tubes. Powdery soft masses and impregnations in the paleosols are strongly related to cryogenic fissures and paleopermafrost level. Under SEM they consist of tiny crystals, much smaller than in regular soft masses. Several types of hard concretions were identified:rounded, irregular and platy. Small concretions in the modern Chernozem have similar morphology and similar 14C-age as the rounded concretions of the upper paleosols. They are expected to represent the same generation of concretions. Platy concretions fill the bottom part of the large fissures. The 14C-age of hard concretions varies from 3310±80 yrs. B.P in the 1st paleosol up to 20 400 yrs. B.P. in the 3rd. As a result we found the reflection of several wet-dry and cold-warm stages in carbonate morphologies and distributions. High variability of carbonates at macro-, micro- and submicroscopic levels indicates several generations and multiphase formation of carbonate pedofeatures in the loess-paleosol pedocomplex. Carbonate pedofeatures in the examined pedocomplex are more informative for the study of late Pleistocene and Holocene climatic cycles rather than characterization of a single paleosol.展开更多
基金The authors gratefully acknowledge the financial support of the National High-Tech Research and Development of China （No. 2004AA404260）；the Science Foundation for Distingguished Young Scholars of Heilongjiang Province （No. JC-05-11） ；the Program for New Century Excellent Talents in University （No. NCET-04-0322）.
文摘From the viewpoint of production engineering, microforming is considered as an effective process to fabricate various microparts. Several key problems in microforming processes were investigated. A new microforming apparatus with a high stiffness piezoelectric actuator as the punch driver was developed to produce microparts.To improve the forming abilities and locate the billets, a floating microdie was designed. The size effects of the billets and die cavities on the microforming abilities were studied with upsetting and coining tests, respectively.And the isothermal microforming process of microgears was performed with the developed microforming apparatus. Several analysis methods were used to evaluate the forming quality of the microparts.
基金Project supported by Development Program of Local Science Park by the ULSAN Metropolitan City and the MEST(Ministry of Education,Science and Technology)Project supported by Basic Science Research Program,the National Research Foundation of Korea(2011-0026072)
文摘The mechanical behavior of superplastic 5083 aluminum alloy during microforming process was investigated by finite element analysis.A micro V-groove die was modeled to analyze the effects of forming time,load and temperature on the microformability of the 5083 aluminum alloy.First,the microformability of the 5083 aluminum alloy was estimated using a microformability index.The simulation results show that the microformability increases with the forming load,time and temperature increasing.Superplasticity of the 5083 aluminum alloy during microforming using the V-groove die was also investigated in terms of the effective strain rate.The results show that the superplasticity of the 5083 aluminum alloy occurs in a specific part of the material for a specific period during the microforming process depending on the forming conditions and the microformability index.
文摘Peculiar properties of morphological structures of organelle membranes were studied by fluorescent confocal microscopy. The list of objects in our experiments was represented by mitochondria, chloroplasts and vacuoles. During this study, identification of lipid microinclusions having the form of such lipid-protein structural microformations as lipid-protein microdomains, vesicles and membrane tubular structures (cytoplasmic transvacuolar strands and nanotubes) located in organelle membranes or bound up with them was conducted. Such membrane probes as laurdan, DPH, ANS and bis-ANS were used. Comparison of fluorescence intensity of these membrane probes was conducted. This investigation of the morphological properties of lipid-protein structural microformations was accompanied with analysis of 1) the phase state and 2) dynamics of microviscosity variations in the membrane elements of isolated plant cell organelles. Distributions of laurdan fluorescence generalized polarization (GP) values for the membrane on the whole and for the intensively fluorescing membrane segments were obtained. It was discovered that the microviscosity of intensively fluorescing membrane segments essentially differed from the microviscosity of the rest part of the membrane. In conclusion, some results of the study of peculiar properties of lipid-protein structural microformations related to the structure of organelle membranes and the discoveries made in this investigation are discussed.
文摘Research on microforming of fine-grained superplastic Zn-AI22 alloy was carried out in this paper by means of superplastic forming. With the selected material, microformability tests have been carried out with the specially developed evaluation method by using two kinds of stainless steel dies. With these dies, micro-extrusion tests have been carried out and the characteristics of microformability of the material have been clarified. Effects of processing parameters and die structure on forming have been analyzed. SEM and metallographic microscope have been used to analyze the formed specimens. Through analysis of flow lines of the formed specimen, behavior of material could be understood well.
基金The authors would like to acknowledge the funding support to this research from the projects of ZE1W and BBAT from The Hong Kong Polytechnic University,the National Natural Science Foundation of China(NSFC)(Grant No.51835011)the General Research Fund(GRF)(Grant No.15223520).
文摘As one of the indispensable actuating components in micro-systems,the shafted microgear is in great production demand.Microforming is a manufacturing process to produce microgears to meet the needs.Due to the small geometrical size,there are uncertain process performance and product quality issues in this production process.In this study,the shafted microgears were fabricated in two different scaling factors with four grain sizes using a progressively extrusion-blanking method.To explore the unknown of the process,grain-based modeling was proposed and employed to simulate the entire forming process.The results show that when the grains are large,the anisotropy of single grains has an obvious size effect on the forming behavior and process performance;and the produced geometries and surface quality are worsened;and the deformation load is decreased.Five deformation zones were identified in the microstructures with different hardness and distributions of stress and strain.The simulation by using the proposed model successfully predicted the formation of zones and revealed the inhomogeneous deformation in the forming process.The undesirable geometries of microgears including material unfilling,burr and inclination were observed on the shaft and teeth of gear,and the inclination size is increased obviously with grain size.To avoid the formation of inclination and material unfilling,the punch was redesigned,and a die insert was added to constraint the bottom surface of the gear teeth.The new products had then the better forming quality.
基金support provided by Boeing India to Indian Institute of Technology Kanpur,IndiaTEQIP funding from Government of India provided to G.B.Pant Institute of Engineering&Technology Pauri-Garhwal India
文摘This paper reports a novel micro-blast driven manufacturing process for micro-forming of Aluminum foils. The micro-blast is realized by using a nanoenergetic material system comprising of Bi_2O_3 microrods and aluminum particles. There is an enhanced need of forming of thin aluminum foil structures in small regions from point of view of drug packaging etc. The process developed caters to this need by using a single shot forming process using a micro-blast source. The micro-blast that is generated from an energetic composite system is made highly tunable by modulating the peak pressure generated through the blasting process and their impact in micro-forming of thin aluminum foils is observed through parametric studies. The engineering challenge involved in these experiments is to tune the blast pressure properties in order to address the forming of thin metal sheets with limiting boundary values as defined by the failure criteria. A variety of characterization techniques related to a thorough analysis of the synthesized material viz. X-ray diffraction(XRD), Scanning Electron Microscopy(SEM) etc, are used to tune the functional properties like gauge blast pressure etc, of material system. We have found a material system that can generate a maximum peak pressure of 73.8 MPa with pressurization rate of 2460 GPas^(-1) and that is able to accomplish micro-forming on thin metal foils(around 0.3 mm thickness). Experimental investigations demonstrate that tunabilty aspect of the energetic composites when exercised can enable variant processes such as embossing, coining, drilling etc. which may be of significant utility to drug packaging industries. A proper mathematical modeling of the forming process and critical process parameters therein have also been detailed.
基金Supported by National Natural Science Foundation of China(Grant Nos.51975398,51974196)Research Project Supported by Shanxi Scholarship Council of China(Grant No.2020-037).
文摘In the present work,austenitic stainless steel(ASS)304 foils with a thickness of 50μm were first annealed at temperatures ranging from 700 to 1100℃for 1 h to obtain different microstructural characteristics.Then the effects of microstructural characteristics on the formability of ASS 304 foils and the quality of drawn cups using micro deep drawing(MDD)were studied,and the mechanism involved was discussed.The results show that the as-received ASS 304 foil has a poor formability and cannot be used to form a cup using MDD.Serious wrinkling problem occurs on the drawn cup,and the height profile distribution on the mouth and the symmetry of the drawn cup is quite non-uniform when the annealing temperature is 700℃.At annealing temperatures of 900 and 950℃,the drawn cups are both characterized with very few wrinkles,and the distribution of height profile,symmetry and mouth thickness are uniform on the mouths of the drawn cups.The wrinkling becomes increasingly significant with a further increase of annealing temperature from 950 to 1100℃.The optimal annealing temperatures obtained in this study are 900 and 950℃for reducing the generation of wrinkling,and therefore improving the quality of drawn cups.With non-optimized microstructure,the distribution of the compressive stress in the circumferential direction of the drawn foils becomes inhomogeneous,which is thought to be the cause of the occurrence of localized deformation till wrinkling during MDD.
基金supported by Russian Foundation for Basic Research (grants No 07-04-01146 and 06-05-65203)
文摘Carbonate pedofeatures were studied in details in a loess-paleosol pedocomplex near Kursk, in the central part of the European Plain. The soils studied included a modern Chernozem and five Pleistocene paleosols. Carbonate morphologies and distributions were described in the field. Various morphologies were sampled for further studies including micromorphology in thin sections and submicroscopic studies under a scanning electron microscope. The complex approach of investigation at macro-, micro-, and submicroscopic levels found that most of carbonate pedofeatures are secondary and multiphase. Many of them are related to cryogenic features. The general trend was of decreasing carbonate content in the older paleosols except for increased content in the 1st and 3rd paleosols. Most of carbonate morphologies are similar in the modern soil and paleosols, but pseudomycelium was found only in the modern Chernozem, while soft masses and impregnations are associated with the paleosols. Detailed study on carbonate attributes revealed their specific features in the modern soil and in paleosols. Veins have dissolution features under the modern environment and seem to reprecipitate in form of pseudomycelium. Coatings in paleosols at a depth of the 1st paleosol include specific fine tubes. Powdery soft masses and impregnations in the paleosols are strongly related to cryogenic fissures and paleopermafrost level. Under SEM they consist of tiny crystals, much smaller than in regular soft masses. Several types of hard concretions were identified:rounded, irregular and platy. Small concretions in the modern Chernozem have similar morphology and similar 14C-age as the rounded concretions of the upper paleosols. They are expected to represent the same generation of concretions. Platy concretions fill the bottom part of the large fissures. The 14C-age of hard concretions varies from 3310±80 yrs. B.P in the 1st paleosol up to 20 400 yrs. B.P. in the 3rd. As a result we found the reflection of several wet-dry and cold-warm stages in carbonate morphologies and distributions. High variability of carbonates at macro-, micro- and submicroscopic levels indicates several generations and multiphase formation of carbonate pedofeatures in the loess-paleosol pedocomplex. Carbonate pedofeatures in the examined pedocomplex are more informative for the study of late Pleistocene and Holocene climatic cycles rather than characterization of a single paleosol.
