本文選題：纖維隨機(jī)排列 + 纖維幾何特征�。� 參考：《東華大學(xué)》2017年博士論文

【摘要】：纖維性能對成紗質(zhì)量的影響一直是紡織領(lǐng)域的經(jīng)典課題之一。其中,纖維在紗條中的排列狀態(tài)不僅影響著紡紗過程,也直接決定了紗或線的條干均勻度、斷裂強(qiáng)力等性能,從而對后續(xù)織造工藝和最終紡織品的質(zhì)量產(chǎn)生影響。纖維在紗條中的隨機(jī)排列很大程度上取決于纖維的幾何特征(長度、細(xì)度)。因此,模擬纖維在紗條中隨機(jī)排列將有助于從理論上認(rèn)識纖維幾何特征對成紗質(zhì)量的影響機(jī)理,這對于原料配置的優(yōu)化、紡紗工藝的改進(jìn)、優(yōu)質(zhì)紗線的生產(chǎn)都具有指導(dǎo)意義。本研究從模擬纖維在紗條中的隨機(jī)排列出發(fā),探討纖維的長度和細(xì)度對成紗條干極限不勻(或稱為理論不勻)的綜合影響。然后根據(jù)此模擬建立單紗斷裂強(qiáng)力的計算方法,并據(jù)此分析單紗斷裂強(qiáng)力的影響因素。單紗拉伸斷裂過程中斷裂截面上的纖維可能會發(fā)生斷裂或者滑脫,這取決于臨界滑脫長度。臨界滑脫長度的求解不僅與纖維性質(zhì)有關(guān),還取決于單紗的加捻。單紗的加捻程度還決定了斷裂纖維和滑脫纖維對單紗斷裂強(qiáng)力的實際貢獻(xiàn)。本研究采用模擬方法建立了計算的理論模型,并對理論計算值采用實驗和文獻(xiàn)數(shù)據(jù)驗證分析。由于纖維頭端位置以及長度、細(xì)度指標(biāo)具有隨機(jī)性,在模擬纖維排列時采用Monte Carlo的方法對這些隨機(jī)變量進(jìn)行生成,使其能夠與實際相符合。關(guān)于成紗性能的分析和臨界滑脫長度的推導(dǎo)還采用了幾何概率方法。為便于模擬和計算,本研究未考慮紡紗過程中機(jī)械因素以及纖維形態(tài)(或彎鉤)對成紗質(zhì)量的影響。論文按照研究內(nèi)容共分為五章,其中各章的主要工作如下:論文的第一章介紹了研究的背景,并在文獻(xiàn)綜述中著重介紹了國內(nèi)外關(guān)于纖維在紗條中隨機(jī)分布、成紗條干不勻和斷裂強(qiáng)力的理論研究模型,并介紹了這些研究中所存在的問題。論文的第二章首先基于纖維左頭端沿紗軸方向呈均勻分布的假設(shè),模擬了纖維在紗條中隨機(jī)排列,模擬紗條的條干極限不勻是通過計算從紗條截取的各子片段中包含所有纖維總重量的不勻來表示。以單紗8mm片段極限不勻的計算為例,若僅考慮纖維長度因素的影響,計算結(jié)果表明,單紗的條干極限不勻隨著纖維長度的增加而增加,并最終趨于穩(wěn)定,這與suh的理論和紡紗實測值的趨勢是一致的。對于不等長纖維紗,其條干極限不勻僅與平均纖維長度有關(guān),與纖維長度本身所服從的分布類型無關(guān)。若進(jìn)一步考慮纖維細(xì)度的影響,模擬計算結(jié)果表明考慮纖維細(xì)度分布時計算得到的條干極限不勻率高于未考慮纖維細(xì)度分布時的計算結(jié)果。其中纖維細(xì)度不勻越大,兩者之間的差異也越大,考慮纖維細(xì)度分布時計算的極限不勻值更趨近于實測值,這說明纖維細(xì)度分布對紗條極限不勻的影響是顯著的。將纖維長度和細(xì)度各指標(biāo)對條干極限不勻的影響進(jìn)行綜合分析,得到它們的影響程度順序為:平均纖維細(xì)度纖維細(xì)度不勻平均纖維長度纖維長度不勻。纖維在紗條中隨機(jī)排列的模擬是對紗條條干均勻度的直觀反映,從而為進(jìn)一步研究成紗的實際不勻以及成紗斷裂強(qiáng)力等性質(zhì)提供了可行的方法。論文的第三章根據(jù)纖維在單紗中的隨機(jī)排列提出了單紗斷裂強(qiáng)力的模擬計算方法。其中單紗斷裂中纖維發(fā)生的斷裂或滑脫取決于臨界滑脫長度,發(fā)生斷裂的纖維對單紗強(qiáng)力的貢獻(xiàn)為其本身斷裂強(qiáng)力,發(fā)生滑脫的纖維對單紗強(qiáng)力的貢獻(xiàn)為其平均滑脫摩擦力,它們的貢獻(xiàn)之和就為單紗的斷裂強(qiáng)力。據(jù)此可計算模擬單紗中各個截面可能發(fā)生斷裂時的強(qiáng)力,其中的最小值就為整個單紗的斷裂強(qiáng)力。從模擬計算結(jié)果可以看出,當(dāng)纖維長度增加或臨界滑脫長度減小時,發(fā)生斷裂的纖維數(shù)目增多,發(fā)生滑脫的纖維數(shù)目減少,因而單紗的斷裂強(qiáng)力就呈增加趨勢,這是與紡紗實測值的趨勢是一致的。而對于不等長纖維紗,其斷裂強(qiáng)力還與纖維長度本身的分布形式有關(guān)。此外,模擬單紗片段長度越長,單紗斷裂強(qiáng)力的計算值也越低,這也是與前人得到的理論和實驗結(jié)論相一致。由于考慮了單紗截面纖維根數(shù)的變異,采用纖維在單紗中隨機(jī)排列的模擬計算成紗斷裂強(qiáng)力更加合理可靠,它能夠直觀反映纖維長度對成紗強(qiáng)力的影響,也能夠直觀反映單紗中出現(xiàn)的弱節(jié),因此它可以用于單紗斷裂強(qiáng)力的預(yù)測。論文的第四章基于單紗結(jié)構(gòu)的假設(shè),探討了臨界滑脫長度的近似計算方法,并對第三章單紗斷裂強(qiáng)力的模擬計算方法進(jìn)行了修正。臨界滑脫長度的近似表達(dá)式不僅考慮了纖維的力學(xué)性能,還考慮了單紗加捻的影響。計算結(jié)果表明臨界滑脫長度隨著捻系數(shù)的增加而下降。由于單紗加捻造成纖維斷裂強(qiáng)力的損失,因此發(fā)生斷裂的纖維和發(fā)生滑脫纖維對單紗強(qiáng)力的貢獻(xiàn)需要進(jìn)一步的修正,并將其代入第三章提出的單紗斷裂強(qiáng)力模擬計算方法中進(jìn)行強(qiáng)力計算。從模擬計算結(jié)果可以看出,單紗斷裂強(qiáng)力的模擬計算值隨著捻系數(shù)的增加先上升至最高值而后發(fā)生下降,這是與實測值的變化趨勢是一致的。低于臨界捻系數(shù)時,臨界滑脫長度的下降使發(fā)生滑脫的纖維根數(shù)減小,且發(fā)生斷裂的纖維增多,這導(dǎo)致單紗強(qiáng)力隨捻系數(shù)的增加而上升。而在高于臨界捻系數(shù)時,纖維因強(qiáng)力損失過大導(dǎo)致其有效強(qiáng)力的劇烈降低,并且纖維有效強(qiáng)力沿紗軸方向上的分力也大大減小,這將最終導(dǎo)致單紗強(qiáng)力的下降。此外,對于等長纖維,各纖維指標(biāo)對單紗斷裂強(qiáng)力的影響程度順序為:纖維細(xì)度纖維強(qiáng)力纖維長度。臨界滑脫長度的求解和單紗斷裂強(qiáng)力的計算能夠揭示單紗隨捻系數(shù)變化的斷裂機(jī)理,它是合理且符合實際的。論文的第五章是對本論文的主要貢獻(xiàn)和不足之處進(jìn)行了總結(jié),并且提出了本課題未來的研究方向。綜上所述,本研究通過模擬纖維在紗條中的隨機(jī)排列,對成紗條干極限不勻和斷裂強(qiáng)力分別進(jìn)行了計算,其能夠較為直觀地揭示了纖維的幾何特征對成紗質(zhì)量的影響機(jī)理,為纖維原料的配置、紡紗工藝的優(yōu)化及成紗性能的預(yù)測提供了理論依據(jù)。
[Abstract]:The effect of fiber properties on yarn quality has always been one of the classic topics in the textile field. The arrangement of fiber in yarn not only affects the spinning process, but also directly determines the evenness of yarn or thread, breaking strength and so on, thus affecting the quality of subsequent weaving and final textiles. Fiber is in yarn bar. The random arrangement of the medium depends largely on the geometric characteristics (length, fineness) of the fiber. Therefore, the random arrangement of the simulated fibers in the yarn will help to understand the mechanism of the influence of the geometric characteristics of the fiber on the yarn quality in theory, which is of guiding significance to the optimization of the configuration of the raw materials, the improvement of the spinning technology and the production of high quality yarns. Based on the random arrangement of simulated fiber in yarn bar, the effect of length and fineness of fiber on the limit unevenness of yarn evenness (or theory unevenness) is discussed. Then, the calculation method of breaking strength of single yarn is established according to this simulation, and the influence factors of single yarn fracture strength are analyzed. The fiber on the section may break or slip, which depends on the length of the critical slipping. The calculation of the critical slipping length is not only related to the properties of the fibers, but also depends on the twisting of the single yarn. The twist degree of the single yarn also determines the actual contribution of the broken fiber and the slipping fiber to the breaking strength of the single yarn. The theoretical model is calculated, and the theoretical calculation values are tested and analyzed by the literature data. Due to the randomness of the end position and length of the fiber head and the fineness index, the Monte Carlo method is used to generate these random variables in the simulation of the fiber arrangement, so that it can be in conformity with the actual phase. In order to facilitate the simulation and calculation, the effect of mechanical factors and fiber form (or hook) on yarn quality is not considered in this study. The main work of this paper is divided into five chapters. The main work of each chapter is as follows: the first chapter of the paper introduces the background of the study and is used in the first chapter of the paper. In the literature review, the theoretical research model about the random distribution of fiber in yarn and the unsymmetry breaking strength of yarn evenness and breaking strength is introduced in the literature, and the problems in these studies are introduced. The second chapter of the paper is based on the assumption that the left end of the fiber is uniformly distributed in the direction of the yarn axis, and the random arrangement of the fiber in the yarn bar is simulated. The unevenness of the dry limit of a simulated yarn is expressed by calculating the unevenness of the total weight of all the fibers in each fragment intercepted from the yarn. Taking the calculation of the limit unevenness of the single yarn 8mm fragment as an example, if only the influence of the fiber length factor is considered, the calculation results show that the dry limit of the single yarn increases with the increase of fiber length. It is consistent with the trend of the Suh theory and the measured value of spinning. For unequal length fiber yarn, the dry limit of the yarn is only related to the average fiber length, and is independent of the distribution type of fiber length itself. If further consideration of the fiber fineness, the simulation results show that the fiber fineness distribution is considered. The ultimate unevenness of the strip is higher than that of the calculation of the fiber fineness distribution. The greater the fiber fineness is, the greater the difference between the two. The limit unevenness calculated by the fiber fineness distribution is closer to the measured value, which shows that the fiber fineness distribution has a significant effect on the limit unevenness of the yarn. The influence of fiber length and fineness on the ultimate unevenness of the strip is analyzed synthetically, and the order of their influence is as follows: the average fiber length of average fiber fineness is not uniform. The simulation of the random arrangement of fiber in the yarn is a direct reflection of the evenness of the yarn evenness, thus further research is made. In the third chapter of the paper, the fracture strength of single yarn is calculated according to the random arrangement of fiber in single yarn. The fracture or slipping of fiber in single yarn fracture depends on the length of critical slipping and the strength of broken fiber to single yarn. The contribution of the fibers to the strength of the single yarn is the strength of the single yarn. The contribution of the fibers to the strength of single yarn is the breaking strength of the single yarn. According to this, the strength of each section in the single yarn may be calculated. The minimum value is the breaking strength of the whole single yarn. It can be seen that when the length of fiber increases or the length of critical slipping decreases, the number of broken fibers increases and the number of slipping fibers decreases, so the breaking strength of the single yarn increases, which is consistent with the trend measured by the spinning yarn, and the breaking strength of unequal length fiber yarn is also with the fiber length itself. In addition, the longer the length of the single yarn fragment, the lower the calculated value of single yarn breaking strength, which is in accordance with the theoretical and experimental conclusions obtained by the predecessors. Considering the variation of the fiber root number of single yarn cross section, it is more reasonable and reliable to calculate the breaking strength of yarn by random arrangement of fiber in single yarn. It can directly reflect the influence of fiber length on yarn strength and can also directly reflect the weak joints appearing in single yarn. Therefore, it can be used to predict the breaking strength of single yarn. The fourth chapter of the paper discusses the approximate calculation method of critical slip length based on the assumption of single yarn structure, and the simulation calculation method of breaking strength of single yarn in third chapters is entered. The approximate expression of the critical slipping length not only takes into account the mechanical properties of the fibers, but also considers the effect of the single yarn twisting. The calculation results show that the critical slipping length decreases with the increase of the twist factor. The fiber and the slipping fiber are produced to the single yarn because of the loss of the breaking strength of the fiber. The strength of the contribution needs further correction, and it is replaced in the third chapter of the single yarn fracture strength simulation calculation method to carry out strength calculation. From the simulation results, it can be seen that the simulation calculation value of single yarn breaking strength first rises to the highest value with the increase of the twist factor and then drops, which is the change trend with the measured value. It is the same. When the critical twist factor is lower, the decrease of the critical slipping length makes the number of slipping fibers decrease and the broken fibers increase, which leads to the increase of the strength of the single yarn with the increase of the twist factor. The strength of the strength along the axis of the yarn will be greatly reduced, which will eventually lead to a decrease in the strength of the single yarn. In addition, the order of the influence of the fiber index to the breaking strength of the single yarn is: the length of the fiber strength fiber, the calculation of the critical slipping length and the calculation of the single yarn breaking strength can reveal the single yarn with the twist system. The fifth chapter of the paper is a summary of the main contributions and shortcomings of this paper, and the future research direction of this subject is put forward. In summary, this study is based on the random arrangement of simulated fibers in the yarn, and the strength of the yarn evenness is not uniform and breaking strength respectively. The calculation has been carried out to reveal the influence mechanism of the geometric characteristics of the fiber on the yarn quality, which provides a theoretical basis for the configuration of fiber materials, the optimization of spinning technology and the prediction of yarn properties.
【學(xué)位授予單位】：東華大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TS104.1

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