首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Fabric or foam sheet moulding is an important manufacturing technique for the apparel industry, in particular for bra production. It is the most economical and convenient method to seamlessly form a garment part into a specified 3D shape. This paper proposes an example-based method for designing moulded bra cups. In this study, a total of 10 typical moulded bra cup specimens were scanned using the Steinbichler Comet white light scanner. Parameterization based remeshing and registration algorithm was used to characterize the 3D shapes of the convex surface of the scanned bra cups. Using an example-based method, virtual master moulds were constructed based on the 3D surfaces of the investigated bra cups after eliminating the style lines and size differences. Then a new bra cup design can be developed from the master mould, either by drawing the style lines in the virtual environment or using scissors to cut the moulded plastic shot along the desired style lines. Different sizes can also be made by grading the wire frame model in 3D manner. The present method will provide a scientific tool for the product development of new bra cups which was conventionally very time-consuming and ineffective.  相似文献   

2.
Seamless knitting, as a new technology, has a great potential in the development of lingerie products. Bra knitting using seamless knitting technology is a difficult engineering problem due to the lack of knowledge on how to achieve proper underband tension and cup strain for optimal comfort and shape. In this study, we aim at identifying the key knitting parameters and experimentally investigating their relationships with the knitted bra tension. The knitting parameters under investigation were loop density, elastic yarn tension, cover yarn tension and nylon yarn tension. Factorial experimental design was used to explore the most significant factors affecting the underband tension and cup strain of seamless knitted bra. The results show that the loop density and elastic yarn tension were the two main factors affecting the underband tension. The cup strain was mainly affected by the loop density. Empirical prediction equations have been established to estimate the underband tension and cup strain from knitting parameters.  相似文献   

3.
Softwood kraft lignin (SKL)-based water-blown flexible polyurethane foams were prepared using SKL as a crosslinking agent and a hard segment polyol. Polyethylene glycol (PEG) as a soft segment diol and 2,4-toluene diisocyanate (TDI) were used. While increasing hard segment content caused the increase in crosslink density in foams, the foams became more and more viscous with increasing hard segment content due to the distinctive phase heterogeneity in foams. In this case, the contributiveness of the filler-like behaviors of separated hard segments always overtook the crosslinking effects derived from SKL in terms of overall viscoelasticity, thus the resultant viscometric properties such as tanδ max and hysteresis loss increased as hard segment content increased. Furthermore, increasing M n,PEG caused the severer microphase separation and intensified the filler effects in foams, thus the foams became more viscous with increasing M n,PEG. The 25 % and 65 % CFD values and Young’s moduli of foams increased with increasing hard segment content due to the increase in crosslink density for foams, and the properties also increased with increasing foam density. Most of foams showed the support factors in the range of 2–3, which are suitable values for cushioning use. Even though the microscopic deformation behaviors in foams are irrelevant to foam density, the cyclic compressive tests showed that the higher foam density possess the better shape recovery performances.  相似文献   

4.
The fiber-reinforced syntactic foam is a type of lightweight materials. In this paper, hollow glass microspheres/epoxy syntactic foams reinforced by carbon fibers are prepared. Carbon fibers of five mass fractions are used to obtain five types of reinforced syntactic foams. The effect of the fiber content and soaking corrosion on the flexural properties of syntactic foams are investigated. The results of soaking test show that the moisture rate in distilled water is greater than that in seawater. The flexural test results show that the flexural strength of syntactic foams increases obviously by adding fibers. The maximum value increases 25.5 % than that of composites without adding fibers when fiber-mass fraction is 5 %. Soaking corrosion reduces the flexural properties of the syntactic foams. The flexural strengths of syntactic foams immersed in water and seawater with 5 % fiber-mass fraction decrease 34.4 % and 37.5 % respectively. The main reasons of the flexural strength reduction of syntactic foams with soaking corrosion are discussed.  相似文献   

5.
Biodegradable foams made from potato starch and natural fibres were obtained by extrusion. The effects of varying origins of these fibres on foam properties were studied, as well the relationships between their properties and the foam microstructure. The addition of fibres increased the expansion index and led to a significant reduction in water adsorption of starch foams, generally improving foam properties. The mechanical properties of the foams were affected by both relative humidity (RH) of storage and foam formulation. In general, as the RH increased, the foam strength decreased. The formulation presenting the best mechanical properties contained 10 wt% hemp fibre and had a maximal resistance of 4.14 MPa and a modulus of 228 MPa, corresponding to a more compact and dense microstructure.  相似文献   

6.
Seamless knitting for making bras is a novel approach. The fitting evaluation of these products remains unknown and there is limited knowledge about the effects of knitting parameters on the bra tension. This study developed 3 styles of seamless knitted bras with various loop length and elastic yarn tension based on a 22 full factorial experimental design with one additional centre level. Therefore, a total of 3 × 5= 15 new seamless bra samples have been knitted. The skin pressure exerted by the new bras was compared with 4 commercial bras including 2 “cut and sewn” wired bras and 2 seamless knitted bras. Six women subjects of breast size 75B* in our newly developed breast sizing system were invited to wear all the bra samples. The skin pressure exerted by the bra was measured by the Novel pliance-X pressure sensors on 11 body positions. The results indicated that newly developed seamless bras showed lower pressure than the commercial bras, but had a considerably higher pressure at the cup base point. The new seamless bras with the largest loop length presented the lowest pressure values. Furthermore, empirical equations were established to predict 2 critical pressure points at “apex” and “side bottom band” from two major knitting parameters. This study provides the new knowledge of seamless knitted bra fitting and the resulted bra pressure, as well as some guidelines for seamless knitted product design and manufacturing.  相似文献   

7.
Background odors produced by plants in the environment can interfere with the response of insects to a point-releasing attractant, especially when their compositions overlap. In this study, a series of binary choice tests was conducted in a wind tunnel to investigate whether background odors emitted from cherry, blueberry, blackberry, or raspberry fruits would affect the level of Drosophila suzukii (Matsumura) attraction to its symbiotic yeast, Hanseniaspora uvarum (Niehaus) (Saccharomycetales: Saccharomycetaceae). Whether an increase in the intensity of background odors would affect the attractiveness of H. uvarum to D. suzukii was also investigated, either by increasing the number of cherry or raspberry fruit per cup or by increasing the number of fruit cups surrounding the cup baited with the yeast. In wind tunnel assays, background fruit odors interfering with D. suzukii attraction to the yeast varied among fruit types. Raspberry odor inhibited the attractiveness of H. uvarum to the fly the most, followed by blackberry odor, whereas cherry and blueberry odors had no significant impact on the attraction. An increase in the intensity of odors by adding more cherry or raspberry fruit per cup did not increase the impact of fruit odor on the attraction; however, adding more raspberry cups around H. uvarum linearly decreased its attractiveness, suggesting that background host fruit abundance and likely increase in host odor may influence D. suzukii attraction to yeast odor depending on host species.  相似文献   

8.
Polyurethane foams were produced by using a homogenizer as a mixing equipment. Effects of stirring speed on the foam structure were investigated with SEM observations. Variation of the bubble size, density of the foam, compressive strength, and thermal conductivity were studied. A hybrid foam consisting of polyurethane foam and commercial polystyrene foam is produced. Mechanical and thermal properties of the hybrid foam were compared with those of pure polyurethane foam. Advancement of flow front during mold filling was observed by using a digital camcorder. Four types of mold geometry were used for mold filling experiments. Flow during mold filling was analyzed by using a two-dimensional control volume finite element method. Variation of foam density with respect to time was experimentally measured. Creeping flow, uniform density, uniform conversion, and uniform temperature were assumed for the numerical simulation. It was assumed for the numerical analysis that the cavity has thin planar geometry and the viscosity is constant. The theoretical predictions were compared with the experimental results and showed good agreement.  相似文献   

9.
Tannin-based rigid foams are networked structures obtained by polycondensations of polyflavonoid tannins and furfuryl alcohol. They present a wide range of characteristics. Thus, there is the need to characterise the different kinds of tannin foams to better understand their physical behaviour and their chemical composition. Mimosa tannin, pine tannin and quebracho tannin bark extracts were used as building blocks. Foams modified by the addition of hydroxymethylated lignin, polyurethane and an industrial surfactant were also characterised. Water absorption, compression resistance, direct flame behaviour and foam cells dimensions were measured for each foam sample. The foams were characterised also by 13C NMR analysis. Tannin-based rigid foams appear suitable for a wide range of applications.  相似文献   

10.
Expanded polystyrene (EPS) foams are widely used to provide protection to merchandise during shipping and handling. The disposal of EPS foams, however, causes pollution to the environment. Starch based loose fill packaging foams are commercially available to replace the EPS foams. Starch foams dissolve readily in water, and do not possess satisfactory physical and mechanical properties. To improve the functional properties and water resistance of starch foams, regular (25% amylose) and waxy corn starches blended with Mater-Bi® ZF03U (MBI) were extruded into loose-fill packaging foams using a co-rotating twin screw extruder. MBI contents of 10, 25 and 40% and starch moisture contents of 19, 22 and 25% (d.b.) were used. Waxy starch produced foam with greater radial expansion and lower unit and bulk densities than regular starch. Higher levels of MBI reduced radial expansion and increased unit and bulk densities. Foam made with regular starch had a lower water solubility index than foam made with waxy starch. The addition of MBI improved the water solubility. Higher starch moisture contents increased foam water solubility indices. Foams made from both types of starch possessed acceptable mechanical properties. Regular starch produced more rigid foams than the waxy starch as indicated by the higher compressibility values based on both single-piece and bulk samples. Moisture content affected the compressibilities. Higher moisture contents produced more rigid foams. The spring indices of bulk samples were excellent (>95%) for all MBI contents.  相似文献   

11.
Albumin-based rigid and elastic foams were prepared by mechanically beating water solutions of the protein mixed with formaldehyde and camphor. The resulting foams were cross-linked in a traditional or in a microwave oven. Formaldehyde was used as hardener of the protein and camphor as a plasticizer. Thermal conductivity was tested and found to be acceptable for thermal insulation but did not appear to be influenced by variations in foam density. Scanning electron microscopy of the different formulations showed some differences in cells structure. Formulations of different water content, formaldehyde hardener content, camphor content and oven curing time were tested. Within certain limits (a) increases in water proportion rendered the foam more elastic, (b) higher formaldehyde content increased foam rigidity and strength up to a value beyond which no further increase occurred, (c) the amount of camphor influences markedly the compression strength and foam elasticity/plasticity, (d) curing time improving foam strength up to 5 min in microwave curing, without any further effect for longer heating times. Only addition of glycerol, yielded truly soft elastic foams.  相似文献   

12.
In this study, nonwoven fabrics were developed for the replacement of polyurethane foams in car interiors, in particular, cushioning materials for car seats. Polyethylene terephthalate (PET) hollow fibers and two types of bicomponent binder fibers were used to manufacture automotive nonwovens by carding processes and then post-bonding processes, such as needle punching or thermal bonding. The physical and mechanical properties of nonwovens were thoroughly investigated with respect to the effects of binder fibers and bonding processes. The tensile strength and elongation for nonwovens were found to be significantly improved by combined needle punching and thermal bonding processes. In addition, the nonwoven cushioning materials were characterized in terms of hardness, support factors, and compressive and ball rebound resilience. The nonwovens showed greater hardness than the flexible PU foam. However, support factors over 2.8 for the nonwovens indicated improved seating comfort, along with better seating characteristics of greater resilience and air permeability in comparison with the PU foam.  相似文献   

13.
中国城乡居民茶叶消费对比研究   总被引：3，自引：0，他引：3  
管曦  杨江帆 《茶叶科学》2015,35(4):397-403
基于CHNS 2011年的数据,本文利用Double hurdle模型,从参与消费和消费多少两个角度对比分析了中国城乡居民的茶叶消费。结果表明,中国城乡居民中分别有2.61亿和1.67亿的饮茶者,日均饮茶量分别为3.19杯和2.81杯,城乡的茶叶消费普及率分别达到46.5%和33.0%,城镇居民和农村居民的茶叶消费收入弹性分别为11.19%和7.9%。城镇居民参与茶叶消费受年龄和收入影响,农村居民参与茶叶消费受收入和家庭规模影响,城乡居民中男性消费者的饮茶量更多,在茶叶消费量的影响上,年龄、收入、家庭规模和受教育程度对城乡居民茶叶消费量具有显著的正向影响。推动中国国内茶叶消费的政策建议是考虑政策的适用性、加快提升城乡居民收入和准确寻找缝隙市场。  相似文献   

14.
盐胁迫下海马齿叶肉细胞超微结构观察   总被引：1，自引：1，他引：0  
通过透射电镜,在超显微结构水平上对淡水和海水栽培的海马齿(Sesuvium portulacastrumL.)植物叶肉细胞结构进行了比较。结果显示:海水栽培的海马齿叶肉细胞质膜明显向内折叠,出现大量大小、形状各异的质膜突起,以及质膜片层;而淡水栽培的海马齿叶肉细胞质膜向内折叠不明显,质膜突起少见。相对于淡水栽培,海水栽培的海马齿植物叶肉细胞叶绿体变小、数量增多;形状变短,由肾形、梭形或弓形变成椭圆形或一端膨大的不规则形状;叶绿体基粒片层结构清晰完整,垛叠程度增加,叶绿体没有受到明显伤害;叶绿体中淀粉粒数量增多,体积变大,淀粉粒表面出现皱褶,形状由长椭圆型变成短椭圆形或不规则形状,电子密度变低;叶绿体上脂质体增多且体积变大。线粒体数量增加,但体积变小;形状由圆球状或棒状变成椭圆体状;线粒体内膜向内折叠所形成的嵴清晰,但海水栽培的海马齿叶肉细胞线粒体外膜模糊,受到轻微伤害。  相似文献   

15.
In the present work polyurethane foams containing variable concentrations of nano-sized clay and esparto wool were prepared and studied, with the objective of developing new multi-scalar rigid foams. The addition of montmorillonite clay favoured foaming and the formation of finer and homogeneous cellular structures, resulting in foams with compressive elastic moduli and collapse stresses lower than that of the polyurethane foams. Nevertheless, a comparative analysis versus the foams’ relative density demonstrated that both properties follow one single trend for the two materials. The combination of esparto and montmorillonite further reduced the cell size of foams, at the same time promoting higher open cell contents, resulting in the foams with the lowest mechanical properties. Although no important differences in thermal conductivity were found with adding montmorillonite, its value decreasing with reducing the relative density, the incorporation of esparto led to higher thermal conductivities, independently of the relative density. The combination of esparto and montmorillonite resulted in foams with thermal conductivities halfway between the esparto-reinforced and the montmorillonite-reinforced foams, related to a higher open cell content.  相似文献   

16.
刘龙  王胜  屈哲  杨晨  张润锴  余永昌 《大豆科学》2019,38(2):291-297
小区大豆播种机田间作业时不同品种大豆需要人工换种,为解决换种效率低的问题,研究设计一种新型的自动转盘式小区大豆播种机自动供种装置。整个供种装置采用转盘式的圆形种盘与种杯组合的方式,使用PLC控制工作过程,完成小区大豆播种机播种过程中的自动换种。该自动供种装置包括机械部分和电控部分,其中机械部分由种杯、种盘、底座、安装支架等组成。试验对种杯进行了理论分析及结构设计,对电控部分进行了硬件选型及参数确定,并设计直流步进电机的控制软件。通过该自动供种装置进行室内台架试验,结果表明:种杯的偏移量合格率最大为99.6%,种子无破碎供种合格率最大为99.836%,具有较好的准确性和可靠性,符合小区播种机上种的农艺要求。  相似文献   

17.
This study proposes a combination for reciprocal reinforcement between warp knitting spacer fabrics and PU foams. PET/Kevlar nonwoven fabrics are made with an 80:20 ratio and an incorporation of various needle-punching speed of 100, 150, 200, 250, and 300 needles/min. Ascribing to having an optimal bursting strength, sound absorption coefficient, and limited oxygen index (LOI), the PET/Kevlar nonwoven fabric that is made by 200 needles/min are selected to be combined with a glass-fiber fabric by applying needle punch in order to form a surface layer. Next, warp knitting spacer fabrics and the nonwoven fabrics are laminated, followed by being combined with polyurethane (PU) foam that are featured with different densities of 200, 210, 220, 230, and 240 kg/m3 in order to form spacer fabric/PU foam composites with multiple functions. The composites are then tested with a drop-weight test, a compression test, a bursting strength test, a sound absorption test, and a horizontal burning test. The test results indicate that all spacer fabric/PU foam composites reach a horizontal burning level of HF1, and their sound absorption coefficients at 2500-4000 Hz also suggest a satisfactory sound absorption. In particular, the optimal residual stress and compressive strength are present when the composites contain 210 kg/m3 PU foam. Similarly, the optimal bursting strength of the composites occurs when they are composed of 230 kg/m3 PU foam. The spacer fabric/PU foam composites are proven to have high strengths, sound absorption, and fire retardant, and thus have promising potentials for use as construction materials and light weight composite planks.  相似文献   

18.
A field design using a decagonal geometric shape is described which enables twenty small plots, each 0.08 ha in size, to be evaluated under communal grazing condilions. The decagonal design was compared with a conventional design using botanical composition and plant density as discriminating parameters. The results showed that communal grazing in the decagonal design gave similar botanical composition and plant density as the conventional design. Since less materials per treatment were used in the decagonal design, it offers a means of minimizing costs in preliminary screening experiments. However, since animal production cannot be monitored under communal grazing the most successful treatments would have to be further evaluated using the conventional approach.  相似文献   

19.
Polyurethane (PU) foam was combined with protein drug-loaded pH-sensitive alginate-bentonite hydrogel for wound dressings. Alginate is a linear copolymer composed of 1–4-linked β-D-mannuronic acid (M) and its c-5-epimer α-Lguluronic acid (G). The amount of (M) and (G) and their sequential distribution are varied depending on the alginate source. Soluble sodium alginate can become a hydrogel when cross-linked with divalent cations and has widespread applications in the food, drink, pharmaceutical and bioengineering industries. Recently, it has been also proposed as a biomaterial for drug delivery systems. Bentonites are the natural inorganic polymers consisting of a large proportion of expandable clay minerals with a three-layer structure such as montmorillonite, beidellite, nontronite, etc. They are important adjutants and supports for medical products, and they have many useful physicochemical, mechanical, and biological properties such as absence of toxicity, indifference to other raw materials, sorption, swelling, and complex formation properties. Alginate-bentonite hydrogels were prepared at concentration ratios of 10/0, 7/3, 5/5, 3/7. PU foams were prepared using hydrophilic polyols. We investigated the controlled release of a protein drug from PU foam combined with alginate-bentonite hydrogel at different pH values of 4.2, 5.2, 7.2, 8.2. The mechanical properties and cytotoxicity tests of this foam were also studied.  相似文献   

20.
A protein isolate from rapeseed was exhaustively modified by acetylation, succinylation and phosphorylation. Changes in protein solubility, adsorption kinetics, surface pressure and surface potential of monolayer, wetting and foaming properties due to chemical modification were studied. Chemical modification distinctly increased the solubility of the rapeseed protein in the alkaline pH range. Acylation increased the reduction of the surface tension. An overall improved pressure transformation and increase in surface potential in monolayer after modification was observed whereby the highest changes were achieved after succinylation. The wettability with water of protein coated hydrophobic glass substrates could be improved by succinylation and phosphorylation. Chemical modification increased the foam capacity and foam expansion of the protein. A higher foam stability was only measured after acetylation and phosphorylation. Adsorption kinetics and surface potential could be related well to the properties of protein films on hydrophobic substrates as well as in foams.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号