The typical micro-knitting structure of knitted fabric,which makes it very different from woven fabric,is described.The tensile tests of knitted fabric are reported.The deformations of the micro-knitting structures ar...The typical micro-knitting structure of knitted fabric,which makes it very different from woven fabric,is described.The tensile tests of knitted fabric are reported.The deformations of the micro-knitting structures are carefully studied.The study indicates that when a knitted fabric sheet is subjected to a tension along w-direction an extra compressive stress field inside loop in c-direction is induced.The extra stress field is also determined through analysis.Finally,a micro-mechanical model of knitted fabric is proposed.This work paves the way for the simulations of buckling modes of a knitted fabric sheet as are observed in experiments.展开更多
该文利用有限元辅助测试(Finite element Aided Testing,FAT)方法测得了四种工程材料的等效全程单轴本构关系,基于此全程本构关系对拉伸过程中漏斗试样的应力三轴度演化进行了有限元分析,并同基于Bridgman应力修正后的单轴本构关系得到...该文利用有限元辅助测试(Finite element Aided Testing,FAT)方法测得了四种工程材料的等效全程单轴本构关系,基于此全程本构关系对拉伸过程中漏斗试样的应力三轴度演化进行了有限元分析,并同基于Bridgman应力修正后的单轴本构关系得到的漏斗试样漏斗根部截面中心处应力三轴度计算公式结果进行了比较。得到了四种材料的等效全程单轴本构关系、破断应变、破断应力和漏斗根部截面上应力三轴度分布随截面中心Von-Mises等效应变的变化规律。同时基于三轴度理论还讨论了漏斗型试样的拉伸破断机理以及断口的形貌。展开更多
A series of elastomers , based on NBR , polysiloxanes （PS） were prepared and characterized by tensile tests, thermogravimetry （ TG ） and differential scanning calorimetry （ DSC ）. Two kinds of vulcanizing agent,...A series of elastomers , based on NBR , polysiloxanes （PS） were prepared and characterized by tensile tests, thermogravimetry （ TG ） and differential scanning calorimetry （ DSC ）. Two kinds of vulcanizing agent, DMDBH （2,5-dimethyl- 2,5-di （ t- butyl perory ） hexane ） and DCP （ dicumylperoxide ） were used to investigate the influence of different vulcanizing agents on properties of PS/ NBR. The addition of PS to NBR was found to improve the thermal stability and decrease the tensile strength of NBR. The tensile strength decreased conshterably while the elongation at break increased obviously with the increase of PS content. The series using DMDBH as vulcanizing agent showed a higher tensile strength and elongation at break than the series using DCP as vulcanizing agent. Simultaneity the thermal stability increased with the increase of PS content.展开更多
The effect of mechanical cyclings on the stress-strain(S-S) curves was studied systematically using tensile tests over a wide temperature range. Two-stage yielding was observed in the temperature range between Ms and ...The effect of mechanical cyclings on the stress-strain(S-S) curves was studied systematically using tensile tests over a wide temperature range. Two-stage yielding was observed in the temperature range between Ms and the ultimate temperature to induce martensite, denoted by Md. The first stage was confirmed to be associated with stress-induced martensite(SIM) and the second stage was associated with the yielding of SIM. When the samples were mechanically cycled between Ms and Md, a stress-softening phenomenon was observed. The cyclings made the martensite amount increase, critical stress σc of SIM decrease according to exponential law, and the entropy(also enthalpy) of the parent to martensite transformation also decrease. The variations of SIM relative amount were determined by recording the changes of electrical resistances in the course of tension.展开更多
The purpose of the current work is the development and application of a new identification method of material parameters of elastoplastic damage constitutive model under large strains. A relationship relating the intr...The purpose of the current work is the development and application of a new identification method of material parameters of elastoplastic damage constitutive model under large strains. A relationship relating the intrinsic and extrinsic parameters of a reference material is built and transformed in equivalence relation. Extrinsic parameters concern the shape of their experimental tensile force/elongation curve, however, intrinsic parameters deal with Swift hardening law coupled with an isotropic damage variable. The relationship is carried out from a statistical characterization of a material reference (standard-steel E24). It based on multiple linear regression of a data set obtained according to a full factor design of numerical simulations of mechanical tensile tests. All materials satisfying this equivalence relation belong to the same equivalence class. This is motivated by observing that gathered materials must behave somewhat like the reference material. The material parameters can be immediately identified by only one task by running the found relationship. The current method facilitates the identification procedure and offers a substantial savings in CPU time. However it just needs only one simulation for the identification of similar behavior instead of the few hundred required when using other methods.展开更多
The article used new experimental equipment for effective testing of adhesion coatings on the sheets. Testing was performed in jig by bending roller with selected radius. In the context of experiments a multi-jet syst...The article used new experimental equipment for effective testing of adhesion coatings on the sheets. Testing was performed in jig by bending roller with selected radius. In the context of experiments a multi-jet system was used. The aim of my previous publications and even this article is to achieve that by using of multi-jet plasma system, samples were achieved that will not be damaged coating after the bending. Specific coats on the sheets have been optimized composition of the plasma so that its result was the maximum adhesion of the coating to the steel base of samples. Results of experiments are presented in article. The article focuses on the tensile test and the result of the tensile test. All important values of tensile tests are published in this article. For example: elongation A<sub>50</sub>, A<sub>g</sub>, tensile strength R<sub>m</sub>, and yield strength R<sub>p0.2</sub>. Results with values of tensile tests are also presented in this article. Selected coated steel samples were photographed in the clamped in jig on the tension device. Group selected samples were divided by the applied coating. First, the basecoat, the final coat and coat were treated with a multi-jet plasma system. From a previous publication graphs show the dependence of the strength on elongation of a sample. Further research will be focused on selected coated samples, where samples are etched onto the surface of a network and are bent in a special jig in range bending radius R11 to R35. After bending, the samples are examined at a special optical device and are evaluated deformation circles in straight and bent part of the samples.展开更多
基金The key scientific and technological project of Shandong province (2009GG10009039)The commercialization project of research findings of Shandong provinceNational public service sectors (Agriculture) research project (200903053)
基金The project supported by the National Natural Science Foundation of China(10272079)
文摘The typical micro-knitting structure of knitted fabric,which makes it very different from woven fabric,is described.The tensile tests of knitted fabric are reported.The deformations of the micro-knitting structures are carefully studied.The study indicates that when a knitted fabric sheet is subjected to a tension along w-direction an extra compressive stress field inside loop in c-direction is induced.The extra stress field is also determined through analysis.Finally,a micro-mechanical model of knitted fabric is proposed.This work paves the way for the simulations of buckling modes of a knitted fabric sheet as are observed in experiments.
文摘该文利用有限元辅助测试(Finite element Aided Testing,FAT)方法测得了四种工程材料的等效全程单轴本构关系,基于此全程本构关系对拉伸过程中漏斗试样的应力三轴度演化进行了有限元分析,并同基于Bridgman应力修正后的单轴本构关系得到的漏斗试样漏斗根部截面中心处应力三轴度计算公式结果进行了比较。得到了四种材料的等效全程单轴本构关系、破断应变、破断应力和漏斗根部截面上应力三轴度分布随截面中心Von-Mises等效应变的变化规律。同时基于三轴度理论还讨论了漏斗型试样的拉伸破断机理以及断口的形貌。
基金Funded by the Defense Pre-research Project of the"EleventhFive-Year-Plan"of China(51312040404)
文摘A series of elastomers , based on NBR , polysiloxanes （PS） were prepared and characterized by tensile tests, thermogravimetry （ TG ） and differential scanning calorimetry （ DSC ）. Two kinds of vulcanizing agent, DMDBH （2,5-dimethyl- 2,5-di （ t- butyl perory ） hexane ） and DCP （ dicumylperoxide ） were used to investigate the influence of different vulcanizing agents on properties of PS/ NBR. The addition of PS to NBR was found to improve the thermal stability and decrease the tensile strength of NBR. The tensile strength decreased conshterably while the elongation at break increased obviously with the increase of PS content. The series using DMDBH as vulcanizing agent showed a higher tensile strength and elongation at break than the series using DCP as vulcanizing agent. Simultaneity the thermal stability increased with the increase of PS content.
文摘The effect of mechanical cyclings on the stress-strain(S-S) curves was studied systematically using tensile tests over a wide temperature range. Two-stage yielding was observed in the temperature range between Ms and the ultimate temperature to induce martensite, denoted by Md. The first stage was confirmed to be associated with stress-induced martensite(SIM) and the second stage was associated with the yielding of SIM. When the samples were mechanically cycled between Ms and Md, a stress-softening phenomenon was observed. The cyclings made the martensite amount increase, critical stress σc of SIM decrease according to exponential law, and the entropy(also enthalpy) of the parent to martensite transformation also decrease. The variations of SIM relative amount were determined by recording the changes of electrical resistances in the course of tension.
文摘The purpose of the current work is the development and application of a new identification method of material parameters of elastoplastic damage constitutive model under large strains. A relationship relating the intrinsic and extrinsic parameters of a reference material is built and transformed in equivalence relation. Extrinsic parameters concern the shape of their experimental tensile force/elongation curve, however, intrinsic parameters deal with Swift hardening law coupled with an isotropic damage variable. The relationship is carried out from a statistical characterization of a material reference (standard-steel E24). It based on multiple linear regression of a data set obtained according to a full factor design of numerical simulations of mechanical tensile tests. All materials satisfying this equivalence relation belong to the same equivalence class. This is motivated by observing that gathered materials must behave somewhat like the reference material. The material parameters can be immediately identified by only one task by running the found relationship. The current method facilitates the identification procedure and offers a substantial savings in CPU time. However it just needs only one simulation for the identification of similar behavior instead of the few hundred required when using other methods.
文摘The article used new experimental equipment for effective testing of adhesion coatings on the sheets. Testing was performed in jig by bending roller with selected radius. In the context of experiments a multi-jet system was used. The aim of my previous publications and even this article is to achieve that by using of multi-jet plasma system, samples were achieved that will not be damaged coating after the bending. Specific coats on the sheets have been optimized composition of the plasma so that its result was the maximum adhesion of the coating to the steel base of samples. Results of experiments are presented in article. The article focuses on the tensile test and the result of the tensile test. All important values of tensile tests are published in this article. For example: elongation A<sub>50</sub>, A<sub>g</sub>, tensile strength R<sub>m</sub>, and yield strength R<sub>p0.2</sub>. Results with values of tensile tests are also presented in this article. Selected coated steel samples were photographed in the clamped in jig on the tension device. Group selected samples were divided by the applied coating. First, the basecoat, the final coat and coat were treated with a multi-jet plasma system. From a previous publication graphs show the dependence of the strength on elongation of a sample. Further research will be focused on selected coated samples, where samples are etched onto the surface of a network and are bent in a special jig in range bending radius R11 to R35. After bending, the samples are examined at a special optical device and are evaluated deformation circles in straight and bent part of the samples.
