The in-plane tensile behaviors of bi-axial warp-knitted(BWK) composites under quasi-static and high strain rates loading were experimentally analyzed in this article. The tensile tests were conducted along warp direct...The in-plane tensile behaviors of bi-axial warp-knitted(BWK) composites under quasi-static and high strain rates loading were experimentally analyzed in this article. The tensile tests were conducted along warp direction( 0°) and weft direction( 90°) at quasi-static rate of 0. 001 s^(-1) and high strain rates ranging from 1 450 to 2 540 s^(-1),respectively. It is found that the significant strain rate sensitivity can be observed in the stress-strain curves of BWK composites. The fracture morphologies of BWK composites demonstrate that the tensile failure modes are shear failure and fiber breakage under the quasi-static testing condition while interface failure and fibers pullout are at high strain rates.展开更多
In this study, 3D computer modeling of simple warp-knitted structures is achieved based on 3D model of warp-knitted loops. Firstly, according to the studying on the geometric structure of warp-knitted loops, Goktepe＇...In this study, 3D computer modeling of simple warp-knitted structures is achieved based on 3D model of warp-knitted loops. Firstly, according to the studying on the geometric structure of warp-knitted loops, Goktepe＇s 3D solid yarn model is developed, and the dimensions of the warp-knitted loops are obtained; then 3D models of stitch defined by eleven given points and in-lay defined by five given points are built with the method of Non-Uniform Rational B-Spline （NURBS） curves and surfaces. Secondly, according to the chain notations of warp-knitted structures, the loop＇s shape can be decided, and with the 3D models the loops can be connected freely and smoothly in some special warp-knitted structures, such as miss-lapping and two- course in-lay. At last, with the tools of Visual C ＋＋ and OpenGL, computer 3D simulation of two-bar warp-knitted fabrics is successfully realized, taking the factor of fabric light and materials into 3D structural model.展开更多
This paper reports the evolution of textile structure and mechanical properties of vascular prosthesis in the level of the whole prosthesis and the constituent filaments with respect to the manufacturing process. The ...This paper reports the evolution of textile structure and mechanical properties of vascular prosthesis in the level of the whole prosthesis and the constituent filaments with respect to the manufacturing process. The tubular wall of the prosthesis is divided circumferentially into three zones; basic line (BL), remeshing line ( RL) and guide line ( GL). Some heterogeneity has been observed on the tubular wall in terms of stitch structure of the prosthesis and linear density of the constituent filaments. The breaking position of the prosthesis under circumferential tensile localizes preferentially in remeshing line that is the weakest zone by warp knitting with double needle bed. Furthermore, the statistical differences of the mechanical properties of the filaments of zone RL, GL and BL have been confirmed too. It is predictable that the deterioration of prosthesis, under physiological loads (periodical pulse blood pressure etc.), could happen firstly in the weaker zone in vivo.展开更多
A new geometric model of Multiaxial Warp-Knitted (MWK) performs, which is based on the experimental observations and analysis of basic stitch, is developed to relate the geometric parameters and process variables. The...A new geometric model of Multiaxial Warp-Knitted (MWK) performs, which is based on the experimental observations and analysis of basic stitch, is developed to relate the geometric parameters and process variables. The fiber volume fraction and fibre orientation of MWK reinforced composites are described in terms of structural and processing parameters in the model. And this model provides a basis for the prediction of mechanical behavior of the MWK reinforced composites.展开更多
Based on classic theory of elastic rod,the warp-knitted loop geometry in plane is independent of yarn properties,while there is a certain gap between the geometrical model and the actual fabrics.According to this prob...Based on classic theory of elastic rod,the warp-knitted loop geometry in plane is independent of yarn properties,while there is a certain gap between the geometrical model and the actual fabrics.According to this problem,further analysis of loop geometry is done based on the theory of elastic rod with theoretical calculation and experiments.The theoretical analysis found that the distance between the contacted points at the loop root affected the loop geometry,and the distance was affected by the ratio of bending rigidity and the friction between yarns.The experiments,forming simple loop by taking the yarn as an elastic rod,found that the bending rigidity affected the loop geometry.Then the relationships between warp-knitted loop geometry in plane of metallic fabrics and wires properties were studied.The results show that metallic fabrics are more suitable for the theory of elastic rod;the friction and bending rigidity of wire yarns affect the loop geometry in plane.Also,the elongation of yarn affects the loop geometry in the actual warp-knitted fabric.展开更多
A flexible electronic shogging system was presented based on rotary type servo motor, which aimed to improve the dynamic response of the shogging drive and decrease the impact of the guide bar during the higher speed ...A flexible electronic shogging system was presented based on rotary type servo motor, which aimed to improve the dynamic response of the shogging drive and decrease the impact of the guide bar during the higher speed running of warp.knitting machine. In this system, the speed control mode, faster response servo motor, no-flat modified trapezoid motion law, and its electronic cam were chosen; the realization standard and method were also introduced in details. The speed response curves of loaded motor indicated that the system could satisfy the technology requirements of high-speed warp- knitting machine which run at the speed of 1 000 r/min in the experiments, and the vibration curves showed that the guide bar had weaker mechanical impact and higher dynamic response characteristics. The results indicated that the flexible electronic shogging system designed following the previous step was successful, and the design principle of the electronic shngging was testified validly.展开更多
Products made by Raschel Jacquard(RSJ)high-speed jacquard warp knitting machine are used in ornament and apparel fabrics.However,most products are produced according to the existing samples.The capability of creative ...Products made by Raschel Jacquard(RSJ)high-speed jacquard warp knitting machine are used in ornament and apparel fabrics.However,most products are produced according to the existing samples.The capability of creative design is not enough at home.In this paper,based on the basic features,the knitting methods and the working principles of warp knitting jacquard machines,the rules for manufacturing jacquard products are summarized.The article provides the new thoughts for the development of fabrics,such as the pattern design,changing the cams,power-net and a special technology of without pillar,which were obtained from the practices in a factory.展开更多
The special lapping requirements were pointed out and the safe range to fix the guide eyes on the circular guide unit was determined by means of Locus Formulas of Warp sections in lapping movement, which were carried ...The special lapping requirements were pointed out and the safe range to fix the guide eyes on the circular guide unit was determined by means of Locus Formulas of Warp sections in lapping movement, which were carried out on installing prototype machine. Based on the calculations of the force components acting on lapping points, the positions of the guide eyes in chain overlapping could be used to determine the safe range that could meet the requirements for tricot overlapping. The safe range can ensure the successful lapping and the multi-guide unit designing in circular warp-knitting machines.展开更多
The tensile property of bi-axial warp knitted fabrics is tested and compared with that of the plain weave fabric. The results show that there are obvious differences between the tensile property of a bi-axial warp kni...The tensile property of bi-axial warp knitted fabrics is tested and compared with that of the plain weave fabric. The results show that there are obvious differences between the tensile property of a bi-axial warp knitted fabric and that of a plain weave fabric.The former can give fuller play to the property of a high modulus yarn than the latter. The tensile strength of a bi-axial warp knitted fabric is linear with the number of yarns in the direction of force.展开更多
The effect of courtyards as microclimate modifiers on the sustainability of traditional houses in a region with 13Wks mesoclimate in Iran was explored. The principle behind traditional Iranian courtyards was investiga...The effect of courtyards as microclimate modifiers on the sustainability of traditional houses in a region with 13Wks mesoclimate in Iran was explored. The principle behind traditional Iranian courtyards was investigated to identify the most intluential physical-environmental character- istics that can effectively improve energy efficiency in contemporary residential buildings. A field study was performed to analyze various physical elements of six valuable traditional courtyard houses located in a region with BWks mesodimate in Iran. These elements included the orientation, extension, rotation angle, dimensions, and proportions of enclosed and open spaces, as well as physical bodies （opaque waUs）, transparent surfaces （openings）, and natural elements （water and soil）. Results showed that most of the studied Iranian courtyards were particularly designed to enable orientation, dimension, and proportion to act as microdimate modifiers. All survey-based data were sumrnarized and integrated to propose a physical- environmental design model for courtyards as a useful energy-efficient strategy for contem- porary sustainable housing in a region with BWks mesoctimate. The proposed model can be generalized to all design cases located in areas with similar climatic conditions.展开更多
基金National Natural Science Foundations of China(Nos.11272087,11572085)Financial Supports from Foundation for the Fok Ying-Tong Education Foundation of China(No.141070)the Fundamental Research Funds for the Central Universities of China(No.170310103)
文摘The in-plane tensile behaviors of bi-axial warp-knitted(BWK) composites under quasi-static and high strain rates loading were experimentally analyzed in this article. The tensile tests were conducted along warp direction( 0°) and weft direction( 90°) at quasi-static rate of 0. 001 s^(-1) and high strain rates ranging from 1 450 to 2 540 s^(-1),respectively. It is found that the significant strain rate sensitivity can be observed in the stress-strain curves of BWK composites. The fracture morphologies of BWK composites demonstrate that the tensile failure modes are shear failure and fiber breakage under the quasi-static testing condition while interface failure and fibers pullout are at high strain rates.
文摘In this study, 3D computer modeling of simple warp-knitted structures is achieved based on 3D model of warp-knitted loops. Firstly, according to the studying on the geometric structure of warp-knitted loops, Goktepe＇s 3D solid yarn model is developed, and the dimensions of the warp-knitted loops are obtained; then 3D models of stitch defined by eleven given points and in-lay defined by five given points are built with the method of Non-Uniform Rational B-Spline （NURBS） curves and surfaces. Secondly, according to the chain notations of warp-knitted structures, the loop＇s shape can be decided, and with the 3D models the loops can be connected freely and smoothly in some special warp-knitted structures, such as miss-lapping and two- course in-lay. At last, with the tools of Visual C ＋＋ and OpenGL, computer 3D simulation of two-bar warp-knitted fabrics is successfully realized, taking the factor of fabric light and materials into 3D structural model.
基金Funded by the Shanghai Post Doctoral Foundation Overseas Returned Scholars' Foundation of Education Ministry the Shanghai Key Discipline Project
文摘This paper reports the evolution of textile structure and mechanical properties of vascular prosthesis in the level of the whole prosthesis and the constituent filaments with respect to the manufacturing process. The tubular wall of the prosthesis is divided circumferentially into three zones; basic line (BL), remeshing line ( RL) and guide line ( GL). Some heterogeneity has been observed on the tubular wall in terms of stitch structure of the prosthesis and linear density of the constituent filaments. The breaking position of the prosthesis under circumferential tensile localizes preferentially in remeshing line that is the weakest zone by warp knitting with double needle bed. Furthermore, the statistical differences of the mechanical properties of the filaments of zone RL, GL and BL have been confirmed too. It is predictable that the deterioration of prosthesis, under physiological loads (periodical pulse blood pressure etc.), could happen firstly in the weaker zone in vivo.
文摘A new geometric model of Multiaxial Warp-Knitted (MWK) performs, which is based on the experimental observations and analysis of basic stitch, is developed to relate the geometric parameters and process variables. The fiber volume fraction and fibre orientation of MWK reinforced composites are described in terms of structural and processing parameters in the model. And this model provides a basis for the prediction of mechanical behavior of the MWK reinforced composites.
基金Young and Middle-aged Teacher's Education and Research of Fujian Province,China(No.JA15405)the Excellent Academic Leaders Project of Shanghai Municipal Science and Technology Commission,China(No.12XD1400400)+2 种基金the Natural Science Foundation of Shanghai Municipal Science and Technology Commission,China(No.13ZR1400500)the Fundamental Research Funds for the Central Universities,China(No.13D110126)National Innovation Experiment Program for University Students,China(No.131025501)
文摘Based on classic theory of elastic rod,the warp-knitted loop geometry in plane is independent of yarn properties,while there is a certain gap between the geometrical model and the actual fabrics.According to this problem,further analysis of loop geometry is done based on the theory of elastic rod with theoretical calculation and experiments.The theoretical analysis found that the distance between the contacted points at the loop root affected the loop geometry,and the distance was affected by the ratio of bending rigidity and the friction between yarns.The experiments,forming simple loop by taking the yarn as an elastic rod,found that the bending rigidity affected the loop geometry.Then the relationships between warp-knitted loop geometry in plane of metallic fabrics and wires properties were studied.The results show that metallic fabrics are more suitable for the theory of elastic rod;the friction and bending rigidity of wire yarns affect the loop geometry in plane.Also,the elongation of yarn affects the loop geometry in the actual warp-knitted fabric.
基金National Science and Technology Support Program,China(No.2012BAF13B03)China Textile Industry Association Technology Guidance Program(No.2011067)Jiangnan University Independent Research Funding Plan,China(No.JUSRP211A04)
文摘A flexible electronic shogging system was presented based on rotary type servo motor, which aimed to improve the dynamic response of the shogging drive and decrease the impact of the guide bar during the higher speed running of warp.knitting machine. In this system, the speed control mode, faster response servo motor, no-flat modified trapezoid motion law, and its electronic cam were chosen; the realization standard and method were also introduced in details. The speed response curves of loaded motor indicated that the system could satisfy the technology requirements of high-speed warp- knitting machine which run at the speed of 1 000 r/min in the experiments, and the vibration curves showed that the guide bar had weaker mechanical impact and higher dynamic response characteristics. The results indicated that the flexible electronic shogging system designed following the previous step was successful, and the design principle of the electronic shngging was testified validly.
文摘Products made by Raschel Jacquard(RSJ)high-speed jacquard warp knitting machine are used in ornament and apparel fabrics.However,most products are produced according to the existing samples.The capability of creative design is not enough at home.In this paper,based on the basic features,the knitting methods and the working principles of warp knitting jacquard machines,the rules for manufacturing jacquard products are summarized.The article provides the new thoughts for the development of fabrics,such as the pattern design,changing the cams,power-net and a special technology of without pillar,which were obtained from the practices in a factory.
文摘The special lapping requirements were pointed out and the safe range to fix the guide eyes on the circular guide unit was determined by means of Locus Formulas of Warp sections in lapping movement, which were carried out on installing prototype machine. Based on the calculations of the force components acting on lapping points, the positions of the guide eyes in chain overlapping could be used to determine the safe range that could meet the requirements for tricot overlapping. The safe range can ensure the successful lapping and the multi-guide unit designing in circular warp-knitting machines.
文摘The tensile property of bi-axial warp knitted fabrics is tested and compared with that of the plain weave fabric. The results show that there are obvious differences between the tensile property of a bi-axial warp knitted fabric and that of a plain weave fabric.The former can give fuller play to the property of a high modulus yarn than the latter. The tensile strength of a bi-axial warp knitted fabric is linear with the number of yarns in the direction of force.
文摘The effect of courtyards as microclimate modifiers on the sustainability of traditional houses in a region with 13Wks mesoclimate in Iran was explored. The principle behind traditional Iranian courtyards was investigated to identify the most intluential physical-environmental character- istics that can effectively improve energy efficiency in contemporary residential buildings. A field study was performed to analyze various physical elements of six valuable traditional courtyard houses located in a region with BWks mesodimate in Iran. These elements included the orientation, extension, rotation angle, dimensions, and proportions of enclosed and open spaces, as well as physical bodies （opaque waUs）, transparent surfaces （openings）, and natural elements （water and soil）. Results showed that most of the studied Iranian courtyards were particularly designed to enable orientation, dimension, and proportion to act as microdimate modifiers. All survey-based data were sumrnarized and integrated to propose a physical- environmental design model for courtyards as a useful energy-efficient strategy for contem- porary sustainable housing in a region with BWks mesoctimate. The proposed model can be generalized to all design cases located in areas with similar climatic conditions.
