Table of Content

10 June 2024, Volume 32 Issue 6

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Preparation of tea stem catechins and their staining and functional modification of silk fabrics

FANG Jiaojiao, ZHAO Peihong, ZHAO Yitao, DENG Shuyi, CHEN Xin , CAO Hongmei,

2024, 32(6):  1-8. 

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As a major tea-producing country, China produces a huge amount of tea stems every year. In order to improve the current situation of tea stems being abandoned, increase the utilization of tea stems, and solve the waste of resources caused by discarded tea stems, the paper investigated the dyeing and function of tea stem pigments. In this paper, catechins were extracted from Tieguanyin tea stems, and LC-MS, UV-visible spectrophotometer, Fourier transform infrared and other instruments were used to identify and analyze the structure of the tea stem extracts. Then, the extract was used to dye silk. The dyeing pH value, dyeing temperature and dyeing time were used as variables, and the Integ value of silk was used as an indicator to explore the optimal dyeing process. Finally, by using the best process for direct dyeing and Al3+ as a pre-mordant dyeing method, the Tieguanyin tea stem extract, Tieguanyin extract and green tea extract were used as dyes to compare the differences in color fastness and functional finishing for dyeing silk between the tea stem extract and tea leaf extracts. The results indicate that LC-MS characterization shows that the Tieguanyin tea stem extract has the same retention time and fragment ion peak as the catechin standard monomer. At the same time, the UV absorption spectrum shows that the extract has strong absorption at 280 nm and has structure of flavanols. The Fourier transform infrared spectrum also shows that the extract contains the same function group as catechins. Therefore, the main component of the Tieguanyin tea stem extract has been determined to be catechins. Under the condition that the catechins dye dosage is 10% (o.w.f) and the liquor ratio is 1:50, the dyeing time is 70 minutes, the dyeing temperature is 80 °C, and the dyeing pH value is 7.5, the Integ value of the silk can reach over 21. The color fastness of silk dyed with Tieguanyin tea stem catechins is the same as those dyed with Tieguanyin catechins and alpine green tea catechins, which can meet the basic requirements of clothing. The UPF values of the silk directly dyed with the three dyes extracted from different sources are 168.84, 150.58, and 150.20 respectively. The UPF values of the silk after mordant dyeing are all more than 230. The Tieguanyin tea stem catechin is slightly higher than the other two catechins extracted from tea. After direct dyeing, the antioxidant properties of the three catechins are 67%, 64%, and 77% respectively. The high mountain green tea catechin is higher than the Tieguanyin tea stem catechins and Tieguanyin catechins, and it is still demonstrated to have the highest antioxidant property after mordant dyeing. In conclusion, although the Tieguanyin tea stem catechin doesn't have the best antioxidant properties, it has satisfactory dyeing effect and functional results as a natural pigment obtained from tea wastes, so it has good application value.

Optimisation of the dyeing process of oak bowl seeds by response surface methodology (RSM)

GE liwen, LI yonggu, YAO Mingyi, SU Miao, ZHAO Feng,

2024, 32(6):  9-17. 

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Before the advent of synthetic dyes, natural dyes had a long history of use and wre very widely used in the world. Black is one of the five normative colors in China. There has been a great demand for successive dynasties, so the black natural dyes are indispensable in China's dyeing history. Oak acorn is one of the most important sources of brown and black dye in China, which is the fruit of Quercus acutissima. Its main component is tannin. Many ancient books, such as Compendium of Materia Medica, Be Capable of General Affairs, and T'ien-kung k'ai-wu, recorded the dyeing process related to oak acorn. With the advent of synthetic dyes, the use of natural dyes fell silent for a long time. However, natural dyeing has regained popularity in recent years due to contemporary consumer interest in environmentally friendly printing and dyeing, as well as the discovery of the many benefits of using natural dyes derived from plants and animals.
In order to explore a faster, more efficient and scientific dyeing process of oak acorn, Response Surface Methodology (RSM) was used to optimize the oak acorn dyeing process, with ferrous sulfate as the mordant, K/S value and Integ value as the response value. In this study, the factors influencing the dyeing process, such as dyeing temperature, dye concentration, mordanting temperature, mordant concentration, dyeing time, mordanting time, and pH, were investigated using the Plackett-Berman experiment to screen the significant influencing factors on oak acorn dyeing. Factors with P-values higher than 0.05 were considered as non-significant. Based on the P-value, the factor of dyeing temperature was found to be the most influential factor on the color depth of oak acorn dyeing, followed by dye concentration and mordanting temperature. After the significant factors were clarified, the response surface methodology (RSM) was carried out using the central composite design (CCD) method. Then, the response surface results were obtained and the response surface model was analyzed, based on which the interaction between oak acorn dyeing results and each dyeing factor was analyzed. Based on the above, K/S value and Integ value as the response value, the optimization model of the oak acorn dyeing process was established and the differences of the obtained response surface models were compared. It was found that the optimal oak acorn dyeing process - the dyeing temperature was 82.9 ℃, the dye concentration was 200% (owf), and the mordanting temperature was 53.5 ℃. The dyeing results showed that increasing the dye concentration and dyeing temperature can improve the K/S and Integ values of acorn-dyed silk, but the mordanting temperature should not exceed 60 ℃. The results of RSM experiments showed that the value of Integ is more suitable as the response value of natural dye oak acorn seed dyeing, which can more accurately reflect the change of color depth, and the validation results are in line with the predicted values, which indicates that the model is reasonable in design, stable and reliable. In addition, the color fastness results of silk showed that the dyed silk fabrics had good resistance to washing, rubbing and sunlight, which were all above grade 3.
The experiments showed that RSM provides a simple and reliable method to optimize the oak acorn dyeing process. It also provides a reference for the subsequent deconstruction of the dyeing methods recorded in ancient documents. In addition, when the dye composition was analyzed in this study, it was found that its up-dyeing components were divided into ellagic acid. Therefore, the experimental design of this study may have important reference significance for the process optimization of tannin-based natural dyes containing ellagic acid.


Identification of pomegranate peel plant dye and its dyed cashmere fiber

GUI Zuwen, HE Jianfeng, XU Haoning, CHEN Shenghang, YU Zhicheng, HOU Zhanchang, CHEN Chao

2024, 32(6):  18-27. 

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In recent years, the international community has paid close attention to global environmental issues, and the concept of sustainable development has gradually become the theme of social development. With the popularization of the concept of ecology, health and environmental protection, the application of natural dyes in textiles has been paid more and more attention. At present, plant dyes are one of the most important sources of natural dyes. A variety of plant dyes have been applied in textiles. Pomegranate peel, as a renewable resource, is one of the common plant dyes and has been widely used in the field of ecological textile dyeing. However, there is no corresponding identification method and standard for pomegranate peel plant dyes on the market. In order to improve the lack of plant dyeing standard system, it is necessary to establish the identification method and standard of pomegranate peel plant dyes.
In order to improve the lack of plant dyeing standard system and establish the identification method and standard of pomegranate peel plant dyes, this paper studies the identification of pomegranate peel plant dyes and their dyed cashmere fibers. Firstly, the pomegranate peel plant dyes were tested by ultraviolet spectrophotometer to determine the markers for identifying pomegranate peel plant dyes. Then, the standard substance, pomegranate peel plant dye and its dyed cashmere fiber extract were detected by ultraviolet spectrophotometer and liquid chromatography-mass spectrometry in negative ion mode. By comparing the retention time and mass spectrum of the dye, the dyed cashmere fiber extract and the standard substance, and combining with the characteristic peaks contained in its ultraviolet-visible absorption spectrum, a perfect identification standard system was established to identify whether the dye and cashmere fiber were pure pomegranate peel plant dye and its dyed cashmere fiber.
The experimental results show that punicalagin and ellagic acid can be used as markers to identify pomegranate peel plant dyes and their dyed cashmere fibers. The quasi-molecular ion peak m/z 300.9862 was detected in the mass spectrometry of pomegranate peel plant dyes, and the retention time was 1.02 min. The quasi-molecular ion peaks m/z 300.9896 and 300.9868 were detected in the mass spectrometry of direct dyeing and ferrous sulfate post-mordanting cashmere fiber extract, and the retention time was 1.02 min and 1.04 min, respectively. Both of them were similar to the peak time of ellagic acid standard at 1.02 min. In the range of ±2.5 % deviation allowed by the standard, combined with the fact that the UV-visible absorption spectrum only contained gallic acid at 277 nm and ellagic acid at 255 and 357 nm, it could be determined that the dye and its dyed cashmere fiber were pure pomegranate peel plant dyes.
At present, although a variety of identification methods and standards for plant dyes have been established, there is still a lack of standard systems for some plant dyes in the market, and consumers cannot verify the conformity of products from the standards. Therefore, in order to enable consumers to purchase satisfactory plant dye products, identifying the corresponding plant dyes and their dyed fabrics is still the top priority in the development of plant dyes.


The latest research progress of lignin flame retardants

LIU Yia, LIU Yuanjuna, b, c, ZHAO Xiaominga, b, c, LIU Yanyan

2024, 32(6):  28-40. 

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Lignin is currently the second largest resource of biomass materials in the plant world. However, due to the complexity of the molecular structure of lignin, its thermal stability is relatively poor, and it does not contain flame retardant elements such as phosphorus and nitrogen. The direct use of lignin as a flame retardant shows limited effectiveness in enhancing the flame retardancy of materials, hindering its market prospects as a high-end flame retardant material. Physical synergy and chemical grafting treatment can improve the inherent defects of lignin fibers, resulting in low smoke release, low heat release rate, high flame retardancy and high thermal stability. At the same time, this treatment can better maintain the original performance of the fuel, such as softness, air permeability and so on. However, the traditional flame retardant preparation process involves the use of toxic substances, such as halogens and metals, resulting in processing difficulties. Finally, it tends to decompose easily at high temperatures, diminishing its flame retardant effectiveness. Safety problems seriously restrict the sustainable development of traditional flame retardants. In summary, the use of lignin flame retardant materials is the most environmentally friendly and easy-to-implement improvement method in the flame retardant industry.
Usually, lignin is compounded with other flame retardants, or flame retardant elements or groups are introduced into the chemical structure of lignin by chemical modification. In physical synergy, lignin can be used as a charring agent to make the char layer of the flame retardant material more compact after combustion. In composite flame retardant materials, the content of lignin has a certain impact on the flame retardant effect. As the lignin content increases, the limiting oxygen index of the combustible material rises, the total smoke production and the total heat release rate decrease. Chemical grafting modification can be roughly divided into nitrogen and phosphorus modification, nitrogen and phosphorus modification containing metal ions, organic silicon modification and nano modification. Among them, nitrogen and phosphorus modification is widely used. In terms of flame retardancy, most chemically modified lignin flame retardants can improve thermal stability and reduce smoke generation. In terms of flame retardancy, most chemically modified lignin flame retardants can improve thermal stability and reduce smoke generation. In the nitrogen and phosphorus modified lignin flame retardant, the phosphorus element plays a role in promoting the formation of carbon in the composite, making it form a dense carbon layer and flame retardant in the condensed phase. During the combustion process, nitrogen forms ammonia to dilute air, achieving the purpose of high efficiency flame retardant in the gas phase flame retardant mechanism. The introduction of metal ions can further improve the performance of nitrogen and phosphorus modified lignin flame retardant. Silicone lignin flame retardant has good heat resistance, oxidation resistance and smoke suppression. The introduction of organosilicon contributes to the formation of a uniform and dense carbon layer, aiding in the reduction of carbon emissions. The nano-modified lignin flame retardant, due to the presence of nanoscale, exhibits a higher specific surface area, facilitating contact with the material surface and enhancing flame retardant effectiveness. At the same time, the dispersion of lignin nanoparticles in the material can form a gas phase barrier effect, slow down the combustion spread and improve the flame retardancy.
Through physical synergy and chemical grafting modification, the flame retardant effect of lignin is improved. There are problems in the use of traditional flame retardants. Such as, high toxicity, serious environmental pollution and high energy consumption. These problems seriously restrict the sustainable development of flame retardant industry. The preparation of lignin flame retardant is an effective way to improve environmental protection and flame retardancy. Lignin flame retardants can carbonize combustibles at high temperatures to produce porous carbon materials and release some harmless gases. As a result, lignin flame retardant is more environmentally friendly and efficient. Therefore, lignin flame retardant become a research hotspot for the sustainable development of flame retardant industry.


Numerical simulation of fiber surface deposition characteristics of viscous particles in different cross-sectional shapes

LIU Qianqiana, YOU Jianming, WANG Yan, SUN Chenglei, JIRI Militky, DANA Kremenakova, YAO Jumingb, ZHU Guocheng,

2024, 32(6):  41-51. 

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Numerous researchers focus on the simulation of factors affecting particle deposition and agglomeration within the fiber, while few researchers have paid attention to the changes in the coefficient of rolling friction between the particles on particle deposition and agglomeration. To simplify the process of calculating the fiber filtration media model is also limited to the circular regular arrangement of the fiber model, and if the fiber model and the actual filter media have a lower degree of conformity, the difference between the simulation results and the actual test results will be larger.
In this paper, by observing and analyzing the surface morphology and structural characteristics of polyester fibers with round, triangular and cruciform cross sections, a three-dimensional fiber model with a fiber diameter of 5 μm, an SVF of 9%, and randomly distributed cross sections of round and triangular fibers in space was established by using Digimat fiber modeling software. Based on the CFD-DEM coupling method, the JKR contact model was introduced under the laminar flow field to analyze the changes of the filtration mechanism of the particles during the motion process, the influence of the changes of the rolling friction coefficient between the particles on the deposition characteristics of the viscous particles inside the fibers with different cross-sectional shapes, and the influence of the fiber cross-sectional shapes on the particles trapping efficiency.
The filtration mechanism of particles in the process of time-varying movement changes, and in the early stage of filtration, the number of particles produced is small, mainly relying on the fiber itself to capture particles, while surface filtration plays a dominant role; in the late stage of filtration, most of the particles are accumulated in the windward side of the fiber to form a cluster of dendritic particles, and the filtration mechanism changes to a portion of the capture by the fiber itself, with the other portion of the dendritic particles being deposited in the fiber cluster. The other part is captured by the dendritic particles that have been deposited on the fibers, which is captured by the filter cake formed by the fiber, i.e. "dust filtering dust". When the inter-particle rolling friction coefficient is less than 0.05, the inter-particle adhesion is small, the relative sliding between the particles increases, and the particles adhering to the windward side of the fiber force chain structure are in a non-straightened state; when the inter-particle rolling friction coefficient is greater than 0.05, the inter-particle rolling damping force will increase with the rolling friction coefficient, and then the inter-particle chain of force is more stable, the resistance of the bending performance is greatly increased, and the chain of force structure tends to be longer and straighter, reducing the particles' resistance to bending due to the rolling friction coefficient, reducing the chance of particles falling due to collision, and increasing the number of inter-particle adhesion. The increase of inter-particle rolling friction will increase the inter-particle normal elastic force and adhesion force, the inter-particle interaction is more close, and the number of mutually adhesive particles will also increase; in the three cross-sectional shape fiber model, the number of fibers trapping the viscous particles as a whole increases with the increase of the coefficient of inter-particle rolling friction. At the early stage of filtration, the rolling friction coefficient has less influence on the number of captured particles because the number of released particles is small and the chance of collision between particles is small. With the filtration and the increase of the number of released particles, the collision rate between particles becomes larger, the rolling damping between particles with large rolling friction coefficient increases, the force chain structure formed between particles is more stable, the increase of the normal force makes it more difficult for particles to slip after collision, and the more number of particles adheres to the particles; the number of particles captured is larger than the number of circular and triangular cross-section fibers because of the raised and groove structure of the surface of the cross-shaped fibers, and the specific surface area of triangular cross-section fibers is larger than the number of particles captured by the cross-shaped fibers. The specific surface area of fibers with triangular cross-section is larger than that of fibers with circular cross-section, and the number of particles captured is higher than that of fibers with circular cross-section.


Prediction of suture strength of high-strength suture anchors based on modified Weibull model

LI Xinya, WANG Ning, LU Jiahao, ZHANG Peng, XIA Zhaopeng, HOU Lei

2024, 32(6):  52-60. 

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Suture anchors play a pivotal role in securely affixing soft tissue to the skeletal framework, having emerged as indispensable tools in the realm of orthopedic surgery. The genesis of suture anchors, comprised initially of metallic screws and sutures, traces back over three decades. In the pursuit of augmenting the tensile strength of these suture anchors, a plethora of variants have been conceived, encompassing metallic suture anchors, biodegradable suture anchors, bio-stable suture anchors, bio-composite suture anchors, and all-suture anchors. The quintessential suture anchor necessitates the provision of substantial mechanical stability to ensure the resolute fixation of soft tissue upon osseous substrates. Within the realm of suture anchors, it is noteworthy that improvements in the anchoring component have mitigated suture rupture as a primary cause of surgical failure in orthopedics. Thus, augmenting suture tensile strength represents the crux of the contemporary challenge. This investigation delves into the fabrication of high-strength suture anchor sutures and scrutinizes their mechanical properties. Leveraging a braiding methodology, we have manufactured high-tensile suture anchor sutures, further prognosticating the rupture strength of suture anchor sutures via both two-parameter Weibull model and modified Weibull model, thereby mitigating risks associated with the utilization of suture anchors.
In this experimental endeavor, 8.3 tex UHMWPE fibers were adopted as the primary raw material,  and a braiding technique was employed to engender single-layer braided sutures as well as axially-reinforced double-layer braided sutures. To scrutinize their mechanical properties, we selected varying intervals of 8, 16, 24, 32, 40, and 48 mm to test the tensile strength of individual fibers, opted for 50 and 200 mm intervals for assessing the tensile strength of 8.3 tex filaments, and relied upon a 200 mm interval for gauging the tensile strength of single-layer braided sutures and axially-reinforced double-layer braided sutures. Concurrently, the diameter of fibers and the angular displacement between fibers within the sutures were subjected to meticulous measurement. Subsequently, both the two-parameter Weibull model and the modified Weibull model were employed to characterize the tensile strength of individual fibers, 8.3 tex filament, and single-layer braided sutures.
The findings unveiled that the fracture strength of single-layer braided sutures stood at 299.8 N, whereas axially-reinforced double-layer braided sutures exhibited an impressive fracture strength soaring to 393.0 N. Regrettably, when utilizing the two-parameter Weibull model to prognosticate the rupture strength of 8.3 tex filament and single-layer braided sutures, substantial disparities from actual values were noted, with all predictions falling outside the 95% confidence interval of the observed values and an accuracy rate of less than 5%. Conversely, the forecasts derived from the modified Weibull model consistently fell within the 95% confidence interval of the actual values, attesting to their superior accuracy.
This study's manufactured high-tensile suture anchor sutures evince superior tensile strength when juxtaposed with analogous medical sutures. The axially-reinforced double-layer braided sutures, in particular, attain a formidable rupture strength of 393.0 N. Whether it pertains to the prediction of the tensile strength of 8.3 tex filament or single-layer braided sutures, the modified Weibull model's prognostications surpass the accuracy of those rendered by the two-parameter Weibull model. Furthermore, by employing the modified Weibull model, it becomes possible to predict the tensile strength from individual fibers to filaments and subsequently to yarns. This achievement establishes a solid theoretical foundation for future research in medical suture structural design and mechanical performance analysis.


Design of shedding mechanisms guided by coupler curves

ZHAN Kuihuaa, ZHU Jiacheng, BAI Lunb

2024, 32(6):  61-69. 

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The loom shedding mechanism is designed to achieve the heald frame motion that includes three periods of opening, pause and closing. To ensure the easiest passage of weft carrier, the pause period is an important condition for most looms' shed-forming device. However, due to the lack of pause in heald frame motion, the traditional linkage shedding mechanisms have become difficult to adapt to the technological requirements for modern high-speed and wide-width looms, and cam shedding mechanisms are becoming more widely used.
This study introduces the concept of special coupler curve guidance and applies the principle that coupler curves with Ball's point or circling-point can make the follower pause to improve the previous design approaches of shedding mechanism. Specifically, because the coupler curves with Ball's point or circling-point have long approximate straight-lines or circular arcs, they can enable the heald frame as a follower to perform linear reciprocating movement with dwells at the limit positions by reasonable design.
In this paper, we proposed two novel linkage shedding mechanisms guided by the symmetric coupler curves with two Ball's points and two circling-points (hereafter called shedding mechanism I and shedding mechanism II). The symmetric coupler curve with two Ball's points was obtained by a graphical method based on the inverted inflexion circles, while the symmetric coupler curve with double circling points and equal curvature ratios was obtained by the analytic method based on Euler-Savary's theory of curvature of point trajectory. In shedding mechanisms I and II, the length ratios of the crank, coupler, rocker and frame were 1:2:2:2.76 and 1:2:2:2.3, with the position-angles of the coupler-points of 62.49°and 49.15°, respectively, and the lengths of the connecting rods adjacent to the rockers were equal to that of the couplers. Shedding mechanism I was connected to the frame's pushing rod to directly drive the heald frame, and shedding mechanism II drives the heald frame through a composite component composed of the connecting rod, swing-rod and frame's pushing rod.
The results of the heald frame motion show that: (1) both shedding mechanism I and II can make the heald frames pause at two limit positions, with dwell times of around 150° as well as 40°and 200° (loom's main shaft angle), respectively, indicating that there is a long shed dwell time; (2) the velocities and accelerations of the heald frames at two limit positions are both 0, indicating that the motions of the heald frames are stable, without flexible impact.
In conclusion, the proposed new linkage-type shedding mechanisms meet the requirements of loom shedding motion. Our study fully demonstrates application prospects of coupler curve guidance mechanisms in textile machinery, and the replacement of high pair with low pair will create conditions for the development of low-cost looms.


Design of multi-head computer embroidery machines with a statically indeterminate beam

XUAN Haifeng, ZHANG Rongrong , LIN Feng , LÜ Rong, LI Jianmin, YUANYAN Haohan

2024, 32(6):  70-79. 

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Computer embroidery machines are the main member of the decorative sewing machine industry. They are widely used in the sewing of all kinds of decorative patterns, such as the production of clothing signs and decorative patterns, enjoying a very important position in the textile and garment industry.
The multi-head embroidery machine frame features a large-span crossbeam structure, and its machine head incorporates an eccentric cam mechanism. Operating at high speeds, this setup frequently produces significant vibrations, thereby impacting the quality and production output of embroidered products. In response to the vibration challenges associated with the crossbeam in the multi-head embroidery machine, the concept of statically indeterminate crossbeam frame of multi-head computer embroidery machine was put forward through multi-body dynamic analysis and finite element analysis. By installing semi-cylindrical balance blocks on both sides of the machine head, the inertia force of the machine head's movement was reduced, and internal excitations were minimized. The design concept of a statically indeterminate beam was employed to strengthen the constraints on the crossbeam, reduce its amplitude and improve the vibration cycle. The vibration conditions of the crossbeam were analyzed and solved through a combination of ADAMS dynamic analysis and ANSYS transient dynamic analysis. For the force situation of the large-span embroidery machine crossbeam, theoretical calculation methods for maximum displacement and nodal vibration amplitude were employed and the consistency between finite element methods and theoretical calculation methods was verified. By utilizing ADAMS software, optimal design dimensions and installation angles for the balance block were obtained, significantly reducing the impact of the machine head movement on the crossbeam. The design concept of employing a statically indeterminate beam and the theoretical analysis results proposed in the design are applicable to various optimization scenarios with similar multiple loads and large spans. This approach is intended to mitigate vibration issues in crossbeams.
The result showed that compared with various frame vibration reduction schemes in the market, the statically indeterminate beam proposed in this paper can obviously optimize the vibration amplitude and vibration period, which help the cross beam to get rid of the periodic impact caused by the head operation, thus greatly reducing the vibration problem of the long-span cross beam of the multi-head embroidery machine under the high-speed operation. This study has certain significance for improving the process accuracy of embroidery machine under high speed operation. 


Finite element analysis of mechanical properties of weft plain knitted fabrics

WANG Xuhuia, JIANG Wenbina, WANG Jinfenga, b

2024, 32(6):  80-88. 

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To solve the problem of time-consuming and labor-intensive prediction of the mechanical properties and appearance effects of fabrics by enterprises through weft knitted plain weave and sampling, a method using ABAQUS finite element analysis to predict the mechanical properties of fabrics was proposed. Firstly, the yarn and fabric were photographed by using the Axio Cam Erc 5S Zeiss polarizing microscope at different zoom angles to obtain the geometric parameters of the fabric coil. 19 feature points of the coil for three times of NURBS curve fitting were selected, the coil center curve was obtained, and the obtained geometric parameters were used to establish a fabric model. According to GB/T 3916-2013 "Textiles—Yarns from Packages—Determination of Single-end Breaking Force and Elongation at Break Using Constant Rate of Extension(CRE) Tester", GB/T 3923.1-2013 "Textiles—Tensile Properties of Fabrics—Part 1: Determination of Maximum Force and Elongation at Maximum Force Using the Strip Method", and GB/T 19976-2005 "Textiles—Determination of Bursting Strength—Steel Ball Method", tensile and breaking tests were conducted on fabrics. Then, ABAQUS was used to perform finite element analysis and simulation on the constructed fabric model.
The accuracy of the model is a prerequisite for the ideal results of finite element analysis. The similarity between the model and the fabric was measured by measuring the coordinates of 19 feature points. Firstly, the ABAQUS finite element analysis simulation results and experimental results of a single yarn were compared to analyze whether the material properties of the yarn are accurate. The comparison in Fig. 11 (b) proves the correctness of yarn material properties. Yarns are defined as a nonlinear elastic-plastic material, and material properties are determined by the tensile properties of the yarn, as shown in Tab. 2. Under the premise of national testing standards, finite element models with different seed sizes and friction coefficients were analyzed and simulated. It was found that when the seed size was 0.1 and the friction coefficient was 0.25, the difference rate between the simulated and experimental values was the smallest. In the finite element analysis, a seed size of 0.1 and a friction coefficient of 0.25 were selected to simulate longitudinal stretching and bursting of the fabric. By comparing the experimental values with the simulated values, as shown in Fig.12 (b) and (d), it is found that the maximum difference rate is 4.76%, the minimum difference rate is 0.29%, and the difference rates are all less than 5%. This indicates the feasibility of ABAQUS finite element analysis of fabrics’ mechanical properties.
After comparing the finite element analysis simulation and actual experimental results of five different fabrics, it has been proven that finite element analysis is not only applicable to engineering structural problems, but also to complex interwoven fabrics. The use of ABAQUS finite element analysis simulation can provide some auxiliary functions for enterprise sampling and weaving, which can further reduce the cost and time of enterprises.


Fabric image classification algorithm based on improved 3E-LDA

JIN Wenzhe, LÜ Wentao, GUO Qing, XU Yuzhen, YU Runze

2024, 32(6):  89-96. 

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Textiles are one of the three physical elements of clothing. In recent years, with the development of computer technology, the classification and recognition of fabric images and intelligent manufacturing have played a very important role in the textile field. In the process of production, traditional manual detection methods are still widely used for fabric defect detection, which is time-consuming and laborious, and the efficiency is very low. It is easy to cause false detection and missed detection due to fatigue, and it will also affect the quality and price of textiles. Therefore, the use of digital image processing technology to complete the recognition and classification of fabric images has become a hot issue in recent years.
Relying on machine vision, spots, pits, scratches, color differences and defects on the fabric surface can be detected. Linear discriminant analysis (LDA) is a supervised dimensionality reduction and classification algorithm that can effectively classify fabric images. LDA classifies by calculating the optimal discriminant matrix to minimize the intra-class distance and maximize the inter-class distance. However, LDA is sensitive to outliers, ignores local geometric information and small sample size (SSS), which affects the classification accuracy. The 3E-LDA (three enhancements to linear discriminant analysis) algorithm improves the above three problems on the basis of LDA and improves the classification accuracy. However, when the number of training samples is smaller than the data dimension, it will reduce the model's resolution ability and ultimately affect the classification accuracy.
A fabric image classification algorithm based on improved 3E-LDA, called I3E-LDA algorithm (Improved 3E-LDA), was proposed to address the problem of reduced model resolution caused by training samples being smaller than the data dimension. Firstly, the nonparametric weighted feature extraction (NWFE) method was used to regularize the intra-class scatter matrix, and then the goal combination method was used to introduce equilibrium parameters to regularize the objective function, so as to weaken the influence of outliers and noise, retain more discriminative feature data, and rely on these feature data to better classify fabric images. It is necessary to combine the improved null space learning method to solve the singularity and small sample problems of intra-class scatter matrices and improve classification efficiency, and to train and test on the Alibaba Tianchi fabric dataset and pattern fabric images to distinguish between normal and abnormal patterns (defect images). The experimental results show that the I3E-LDA algorithm effectively achieves fabric image classification, and improves classification accuracy for a small number of training samples (20%-40% of the samples are used for training).


Production effort investment strategy in the apparel supply chain based on online reviews

XU Linga, WAN Yanhongb, ZHANG Kea, ZHONG Shaojuna

2024, 32(6):  97-107. 

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With the gradual enhancement of e-commerce platforms' product review system, consumers are increasingly inclined to rely on other buyers' reviews as a determining factor for their purchasing decisions. In recent years, online sales in the clothing industry have exhibited a noticeable upward trend compared to offline physical stores. When purchasing clothes offline, consumers can genuinely assess the quality of clothing products. However, when buying clothes online, it is challenging to gain direct and authentic experiences solely through merchants' provided images. Other buyers' reviews serve as crucial references for consumers to comprehend clothing products. To mitigate the impact of negative reviews on consumers' purchase intentions, garment manufacturers strive to enhance product quality and value by improving production efforts, thereby offering customers an enhanced purchasing experience and garnering more positive reviews that ultimately influence potential consumers' buying intentions. In the real market scenario, there exists a conflict of interests between garment manufacturers and e-commerce platforms. While e-commerce platforms may not bear the costs associated with production efforts directly, they aspire for garment manufacturers to improve these efforts in order to increase the proportion of positive reviews. This undoubtedly undermines garment manufacturers' interests and diminishes their willingness to invest in production endeavors while also adversely affects both parties involved. Consequently, finding ways to coordinate e-commerce platforms and garment manufacturers towards achieving an ideal state where production efforts are optimized and simultaneously all participants' interests within the supply chain are enhanced has become a pivotal issue faced by contemporary enterprises.
The study aimed to explore how each participant in the apparel supply chain develops relevant strategies under the dual influences of production efforts and online reviews. Considering that the production efforts of apparel manufacturers will affect online reviews, and thus have an impact on the purchasing decisions of potential consumers, this study introduced the combination contract of "cost sharing + revenue sharing" to coordinate the interests between garment manufacturers and e-commerce platforms in the apparel supply chain composed of a single garment manufacturer, a single e-commerce platform and consumers, and explores the coordination effect of contract parameters on the apparel supply chain.
This study constructed an apparel supply chain model composed of a garment manufacturer, an e-commerce platform and consumers. In the centralized decision-making and decentralized decision-making models, the production efforts of the garment manufacturer, online reviews, retail price and supply chain profits were analyzed, and the apparel supply chain was coordinated through the combination contract of "cost sharing + revenue sharing". Through the model and numerical analysis, it is found that there is a unique optimal decision, whether it is a centralized decision or a decentralized decision. The supply chain profit and production effort of a centralized decision are better than those of a decentralized decision. Through the combination of contracts, the garment manufacturer and e-commerce platform can obtain higher profits, while consumers can also get higher quality products and better shopping experience at the same price; when consumers prefer more production efforts, the garment manufacturer will increase the production efforts of products in order to expand the sales market and make up for the increased costs caused by the production efforts by increasing the wholesale price, while the e-commerce platform will also increase the retail price of clothes in order to maintain profits.


Mining the industry chain link relationship of clothing enterprises based on the industry chain map

FANG Zhijian, CHENG Yu, Jin Yao, TANG Zhechong, XU Jinying

2024, 32(6):  108-115. 

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The construction of the clothing industry chain map has become a focal area and a key strategy for the digital upgrade of China's clothing industry. Serving as a vital tool, the clothing industry chain map helps enterprises and researchers better understand and grasp the structure, relationships, and dynamics of the entire industry chain.
This study aims to use digital technology to visually present the entire clothing industry chain, enhancing efficiency, reducing costs, optimizing resource allocation, and ultimately boosting the competitiveness and market position of enterprises.In the clothing industry chain map, determining which industry chain point a company belongs to and understanding the relationships among various enterprises is crucial for industry investment, resource optimization, improved production efficiency, and reduced costs. However, traditional methods of enterprise linkage often involve manual examination of company names, business scopes, and product information, leading to time-consuming and inefficient processes with suboptimal results. Therefore, researching automatic linkage algorithms for clothing enterprises is of practical significance and theoretical value in optimizing the clothing industry chain map.Current research efforts are primarily focused on text information mining and machine learning methods. However, limited research has been conducted on how to use the enterprise profiles and industrial chain map for automatic linkage in the industry chain. This study addresses this gap by collecting enterprise information, extracting keywords, establishing an enterprise information database, and proposing an automatic linkage algorithm based on the CoSENT model. The algorithm utilizes the CoSENT model to calculate the similarity between enterprise keywords and industry chain points, filters matching results through custom rules, assesses the relevance between keywords and points, and achieves automatic linkage in the industry chain for enterprises. Leveraging machine learning technology, this approach provides a more feasible solution for handling vast amounts of information related to clothing enterprises.
Experimental results demonstrate that the proposed algorithm significantly outperforms other traditional algorithms on the F1-Measure metric. Compared to the Jaccard method, the accuracy of this algorithm improved by 14%; compared to the Word2Vec method, it improved by 10.5%; and compared to the SBERT method, it improved by 2.5%. This substantial enhancement elevates the accuracy and efficiency of enterprise linkage, providing robust support and guidance for optimizing the clothing industry chain map. Future research directions include collecting more enterprise information to build richer enterprise profiles, further enhancing linkage efficiency. This study offers a practical solution for the digital upgrade and optimization of the clothing industry chain.


Recent advances in wave absorbers based on flexible electromagnetic metamaterials with different structures

JIAO Xinyua, ZHANG Fuyong, LIU Yuanjuna, b, c, ZHAO Xiaoming

2024, 32(6):  116-128. 

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With the advancement of science and technology, electromagnetic protective materials are no longer confined to traditional flexible electromagnetic shielding materials. The emergence of electromagnetic metamaterial functional devices has enabled effective manipulation of electromagnetic waves. In the fabrication of metamaterial absorbers, a majority of them are constructed as three-layer structures on rigid substrates. Flexible metamaterials not only enable the conformal wrapping of objects but also contribute to the electromagnetic properties of materials.
Traditional metamaterial structures consist of three layers, namely, a metal-dielectric-metal structure. The top layer is used for providing impedance matching, the middle layer attenuates electromagnetic waves through absorption, and the bottom layer is employed to block transmitted waves. Researchers have designed and prepared flexible absorbing materials that achieve efficient absorption at specific frequencies and within a wide frequency range, with polyimide (PI) being a commonly used flexible medium. Researchers replaced the metal resonator in the top layer of the absorbing material with a resistive film to optimize impedance matching. Studying flexible electromagnetic metamaterial absorbing materials with different material combinations is crucial for addressing complex electromagnetic wave environments and coping with multi-frequency band communication systems.
Subsequently, researchers began to design flexible electromagnetic metamaterial absorbing materials based on structures with more than three layers. The materials mainly achieve absorption at different frequencies by combining the electromagnetic characteristics of multiple layers, thus providing a broader absorption spectrum. Among them, flexible electromagnetic metamaterial absorbing materials based on indium tin oxide (ITO) not only achieve high absorption rates, but also maintain good optical transparency. This type of structure has greater design flexibility and resonance intensity. Therefore, such materials can achieve precise and extensive impedance matching, demonstrating broadband absorption characteristics.
Compared to planar structures, flexible electromagnetic metamaterial absorbing materials based on three-dimensional structures have significant potential applications. These materials can absorb electromagnetic waves in multiple frequency bands simultaneously and adapt to surfaces of various shapes and curvatures to meet various engineering and design requirements.
In general, the research scope of flexible electromagnetic metamaterial absorbers is extensive, involving diverse fabrication techniques employing multiple structures. The optimization and enhancement of electromagnetic performance are achieved through meticulously layered designs. In-depth exploration and practical experimentation in the aforementioned research directions may potentially offer novel insights and methodologies for the preparation and application of flexible electromagnetic metamaterial absorbers. The future applications of flexible metamaterial absorbers are expected to continually expand across various domains.


Application of finite element analysis technology in the field of fabric mechanical properties

LI Denggao a, LIU Chengxiaa, b

2024, 32(6):  129-141. 

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The mechanical properties of fabrics have always been an important research content in the field of textiles and clothing, but the three-dimensional structure of fabrics is complex, and many factors such as fiber, yarn, organizational structure and composite materials will affect the mechanical properties of fabrics. The traditional mechanical experimental methods are often costly, and it is difficult for researchers to observe the changes at the meso level. With the rapid development of computer and software technology, the finite element analysis technology shows more and more potential, and has become an important means of mechanical property research in the field of textile and clothing. This paper first described the construction methods of fabric finite element models by some scholars at present. The geometric model construction methods are divided into two categories. One is based on the experimental data to generate the model, and the fabric finite element model is constructed by collecting the experimental image information. This method is suitable for fabric local modeling, and can obtain fine and real fabric structure. The other is based on the physical or geometric generation model, that is, using the actual physical weaving process or geometric parameters to construct the three-dimensional structure of the fabric, and this method is easier to construct periodic boundary conditions. The constitutive model of fabric materials is a key step in constructing finite element models. This paper introduces continuous models, discrete models, and semi-discrete models respectively. The continuous models have the fastest calculation speed, but cannot reflect the internal characteristics of the fabric. By contrast, the discrete models can express the state of yarns or fibers, but the computational cost is high. The semi-discrete models combine the advantages and disadvantages of both. At present, most finite element analysis can be done with finite element software. For several commonly used finite element analysis software, this paper introduced their application fields, advantages and disadvantages. In this paper, the current status of finite element research on the mechanical properties of fabrics is roughly divided into four fields: tensility, bullet proofness, tearing and bending. At present, there are more studies in the two fields of tensility and bullet proofness, and the research materials are mainly woven fabrics. Although finite element technology plays an important role in the simulation of fabric mechanical properties, there are also some shortcomings, such as the lack of model accuracy, the difficulty of determining material parameters, and the difficulty of setting boundary conditions, which affect the accuracy of simulation results. In view of these shortcomings, this paper put forward four suggestions for the follow-up development of finite element in the field of fabric mechanics. First, it is necessary to apply multi-scale analysis methods, and research feature changes at a more microscopic level while ensuring computational efficiency. Second, it is necessary to develop a higher precision textile tester to obtain more accurate material parameters.  Third, it is necessary to fit the actual environment and carry out multi physical field coupling simulation. Fourth, it is necessary to combine other numerical methods to solve complex problems. It is believed that the finite element technology will play a more important role in the simulation of fabric mechanical properties in the future.

Development status and prospect of outdoor tent materials

YUAN Shengchao, LIANG Huifang, DAI Guoli, MO Fanbo, LUO Yi, YE Xiangyu, WANG Chenglong, ZHU Feichao,

2024, 32(6):  142-150. 

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Tents act as temporary shelters in outdoor activities to protect the safety of users. Tent cloth is the main body of the tent, and different tent materials can endow the tent with different functions to cope with different use scenarios. This paper reviewed the development history of tent materials, and summarized the latest progress in the field of tent materials in the past ten years, with focus on the development and practical application of functional civil and military tent materials. 
At present, the tent materials on the market are mainly synthetic fiber composite materials, and on the basis of meeting the basic performance requirements of wind and rain and cold resistance, consumers pay more attention to the multi-functional tents, for example, tents that can maintain the humidity of the tent waterproof permeable materials. Thermal insulation materials reduce heat transfer between internal and external temperatures through thermal insulation, reflective materials and ventilation design, so that the temperature inside the tent is kept within a suitable range; radiative cooling materials achieve no energy consumption cooling through radiative heat transfer; inflatable tents are light and easy to carry and set up. Made of environmentally friendly materials, biodegradable and recyclable bio-based tents are hot spots in the field of civilian tents. Military tents play an essential and key role in military operations, providing the necessary infrastructure and support for the army, and providing comprehensive protection for high-intensity military activities. Compared with civilian tent materials, military tent materials have more special performance requirements in terms of functionality, such as infrared stealth materials to reduce detection risks, electromagnetic shielding materials to protect communication privacy, bio-resistant tents to protect against biochemical threats, and solar-powered tents for sustainable energy supply are all hot spots in research. 
With the continuous improvement of the level of textile and material science and technology, as well as the further development of outdoor leisure industry, the outdoor tent material market at home and abroad has broad prospects for development. At present, in terms of the research, development, and production of civil and military tent materials, Europe, the United States and other developed countries are in a leading position, while in terms of processing and application, domestic research units and enterprises only stay in the laboratory or theoretical application range, and industrial processing means and large quantities of application effects still need to be further developed and verified. In the future, outdoor tents will tend to be lightweight, intelligent, multi-functional,green, and sustainable.