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        無(wú)紡布的粘彈性泊松比

        2023-06-20 13:44:49夏騰騰葛陳勇李健李紅光李勇
        現(xiàn)代紡織技術(shù) 2023年2期
        關(guān)鍵詞:粘彈性泊松比無(wú)紡布

        夏騰騰 葛陳勇 李健 李紅光 李勇

        摘要:為了研究無(wú)紡布的粘彈性力學(xué)行為,精確計(jì)算其粘彈性泊松比。以粘彈性力學(xué)理論為基礎(chǔ),結(jié)合Laplace變換和蠕變應(yīng)力條件,推導(dǎo)了由橫向應(yīng)變和松弛模量計(jì)算粘彈性泊松比的精確表達(dá)式。由蠕變實(shí)驗(yàn)和松弛實(shí)驗(yàn)數(shù)據(jù),獲得了無(wú)紡布橫向應(yīng)變和松弛模量隨時(shí)間變化的Prony級(jí)數(shù),并利用1stOpt軟件模擬了無(wú)紡布的粘彈性泊松比時(shí)變曲線。結(jié)果表明:在蠕變條件下,隨著載荷作用時(shí)間增加,無(wú)紡布泊松比逐漸增大并趨近于0.25。該方法可有效獲得無(wú)紡布的粘彈性泊松比,為其后續(xù)生產(chǎn)加工所涉及的力學(xué)指標(biāo)計(jì)算提供參考值。

        關(guān)鍵詞:無(wú)紡布;泊松比;粘彈性;蠕變;松弛

        中圖分類號(hào):TS171

        文獻(xiàn)標(biāo)志碼:A

        文章編號(hào):1009-265X(2023)02-0107-05

        泊松比是衡量材料力學(xué)性能的重要指標(biāo)之一,其精確表達(dá)和測(cè)定對(duì)相關(guān)研究工作極為重要[1-2]。部分學(xué)者對(duì)針織物、機(jī)織物、無(wú)紡布等的泊松比做了研究[3-5],但多將織物作為彈性材料考慮,即認(rèn)為泊松比為常數(shù)。粘彈性材料的泊松比一般表現(xiàn)出與溫度和時(shí)間的相關(guān)性,若假定為常數(shù),會(huì)使得其相關(guān)應(yīng)力分析和強(qiáng)度計(jì)算產(chǎn)生較大誤差[6]。隨著紡織產(chǎn)業(yè)發(fā)展,無(wú)紡布產(chǎn)量和使用量逐年增加,對(duì)于無(wú)紡布力學(xué)性能的研究也逐漸被重視。通過(guò)拉伸測(cè)試發(fā)現(xiàn),無(wú)紡布具有典型的粘彈性屬性。作為材料的基本力學(xué)參數(shù)之一,無(wú)紡布粘彈性泊松比的精確測(cè)定必不可少。

        目前,關(guān)于材料粘彈性泊松比的研究較多,但針對(duì)紡織材料的研究尚未見(jiàn)到。Lakes等[7]對(duì)線性粘彈性固體中的泊松比進(jìn)行了理論分析,發(fā)現(xiàn)粘彈性泊松比與加載時(shí)間呈函數(shù)關(guān)系,但并不一定隨時(shí)間單調(diào)增大。鄭健等[8]采用遺傳積分形式表達(dá)粘彈性泊松比,結(jié)合蠕變實(shí)驗(yàn)條件,推導(dǎo)并計(jì)算了固體推進(jìn)劑的粘彈性泊松比。申志彬等[9]提出了一種基于數(shù)字圖像法的固體推進(jìn)劑泊松比高精度測(cè)量方法,研制相應(yīng)的測(cè)試系統(tǒng)并測(cè)定了HTPB推進(jìn)劑的粘彈性泊松比。Hoshino 等[6]提出利用二維數(shù)字圖像法直接測(cè)量動(dòng)態(tài)粘彈性實(shí)驗(yàn)中的泊松比的方法,并通過(guò)測(cè)試環(huán)氧樹(shù)脂的材料特性進(jìn)行了驗(yàn)證。

        基于粘彈性力學(xué)理論,本文建立了粘彈性泊松比表達(dá)式,結(jié)合蠕變實(shí)驗(yàn)和松弛實(shí)驗(yàn)測(cè)定材料拉伸指標(biāo),精確計(jì)算了無(wú)紡布粘彈性泊松比,以期為紡織材料的泊松比測(cè)定提供參考。

        1粘彈性泊松比計(jì)算

        常規(guī)彈性泊松比v定義為:

        v=-εx/εy(1)

        式中:εx為材料橫向應(yīng)變;εy為材料縱向應(yīng)變。

        無(wú)紡布具有典型的粘彈性屬性,在載荷作用下會(huì)產(chǎn)生松弛或蠕變,且橫向應(yīng)變響應(yīng)εx(t)滯后于縱向變形歷史εy(t) [10-11]。因此,直接由拉伸過(guò)程實(shí)測(cè)值εx(t)、εy(t)計(jì)算,無(wú)法得到精確泊松比v(t)。

        基于彈性-粘彈性對(duì)應(yīng)原理,在恒定載荷拉伸作用下,粘彈性時(shí)域泊松比v(t)為:

        v(t)=-εx(t)/εy(t)(2)

        粘彈性泊松比v(t),表征在拉伸靜載作用下橫向應(yīng)變?chǔ)舩(t)對(duì)縱向應(yīng)變?chǔ)舮(t)的響應(yīng),是橫向變形的一個(gè)記憶函數(shù)[12]。

        對(duì)于線性粘彈性材料,定義Laplace變換域內(nèi)的泊松比v(s)為:

        v(s)=-εx(s)/εy(s)(3)

        式中:縱向應(yīng)變?chǔ)舮(s)=σy(s)/E(s);蠕變實(shí)驗(yàn)中,縱向拉伸應(yīng)力σy(s)=σ0/s;符號(hào)上的“-”表示Laplace變換算符。

        則式(3)可寫(xiě)為:

        v(s)=-εx(s)sE(s)/σ0(4)

        式中:σ0為蠕變拉伸應(yīng)力;E為拉伸松弛模量。

        利用卷積定理,對(duì)式(4)求Laplace逆變換,得:

        v(t)=-1σ0∫t0E(t-τ)εx(τ)dτ(5)

        利用式(5),可由εx(t)和E(t)的實(shí)驗(yàn)值求得粘彈性泊松比v(t)的精確值,是間接測(cè)試粘彈性泊松比的理論基礎(chǔ)。

        令εx(t)、E(t)為Prony級(jí)數(shù)形式,如下:

        εx(t)=εxe+∑mi=1εxiexp(-t/τi)

        E(t)=Ee+∑nj=1Ejexp(-t/τj)(6)

        式中:m、n為Prony級(jí)數(shù)的階數(shù);εxe為最終應(yīng)變;εxi為各階應(yīng)變量;τi為各階蠕變時(shí)間;Ee為平衡模量;Ej為各階松弛模量;τj為各階松弛時(shí)間。

        將式(6)代入式(5)并整理,即得材料蠕變的粘彈性泊松比精確表達(dá)式:

        v(t)=-1σ0[Ee∑mi=1εxi(exp(-t/τi)-1)+

        ∑mi=1∑nj=1εxiEjτjτj-τi(exp(-t/τi))-exp(-t/τj))](7)

        2實(shí)驗(yàn)

        2.1實(shí)驗(yàn)材料

        本研究選用佳聯(lián)達(dá)無(wú)紡布有限公司生產(chǎn)的聚丙烯(PP)熔噴無(wú)紡布(以下簡(jiǎn)稱無(wú)紡布),纖維間接觸形式為點(diǎn)粘合,幅寬143 mm、厚度0.305 mm、平方米質(zhì)量30 g/m2。

        考慮試樣厚度較小,忽略無(wú)紡布厚度方向應(yīng)力及應(yīng)變分量,僅討論無(wú)紡布的二維平面泊松比[4]。因所選無(wú)紡布內(nèi)部纖維不存在經(jīng)緯取向,本文認(rèn)定其為平面各向同性材料。

        參考標(biāo)準(zhǔn)GB/T 24218.3—2010《紡織品 非織造布試驗(yàn)方法 第3部分:斷裂強(qiáng)力和斷裂伸長(zhǎng)率的測(cè)定(條樣法)》,并根據(jù)實(shí)際情況進(jìn)行相關(guān)實(shí)驗(yàn)設(shè)置。

        2.2蠕變實(shí)驗(yàn)

        試樣上下端用夾具夾持,懸掛并施加縱向載荷。試樣尺寸為300 mm×70 mm,夾持距離200 mm。為避免卷邊影響,測(cè)量位置距邊緣10 mm,即測(cè)量寬度為50 mm。為使無(wú)紡布不發(fā)生結(jié)構(gòu)破壞且橫向應(yīng)變可測(cè)量,確定縱向載荷為0.239 MPa(由下端夾具和砝碼共同施加,夾具20.7 g,砝碼500 g),載荷瞬時(shí)施加并持續(xù)12 h。實(shí)驗(yàn)示意如圖1(a)所示。測(cè)量并記錄試樣中部最窄處的寬度隨蠕變時(shí)間變化情況,進(jìn)行5次實(shí)驗(yàn)并取平均值,計(jì)算得到布料中部橫向應(yīng)變?chǔ)舩′??紤]布料在較小載荷作用下存在輕微頸縮現(xiàn)象,以0.5εx′作為等效橫向應(yīng)變?chǔ)舩,得到εx-t曲線。

        2.3松弛實(shí)驗(yàn)

        儀器設(shè)備采用YT010-1000型土工布綜合強(qiáng)力試驗(yàn)機(jī),試樣尺寸為300 mm×50 mm,夾持距離200 mm。本實(shí)驗(yàn)數(shù)據(jù)處理采用基于Prony級(jí)數(shù)的數(shù)據(jù)擬合法[13],該方法綜合考慮了松弛實(shí)驗(yàn)加載階段和松弛階段,初始應(yīng)變和加載速度對(duì)計(jì)算結(jié)果無(wú)影響,考慮實(shí)驗(yàn)效率且避免沖擊載荷,確定拉伸速度20 mm/min。考慮無(wú)紡布不發(fā)生結(jié)構(gòu)破壞且應(yīng)力可測(cè)量,拉伸試樣至0.05縱向應(yīng)變后停止,保持拉伸狀態(tài)12 h。實(shí)驗(yàn)示意如圖1(b)所示。記錄拉力值隨松弛時(shí)間變化情況,進(jìn)行5次實(shí)驗(yàn)并取平均值,計(jì)算拉伸應(yīng)力σ,得到σ-t曲線。

        3結(jié)果與分析

        3.1蠕變實(shí)驗(yàn)結(jié)果

        通過(guò)蠕變實(shí)驗(yàn),得到無(wú)紡布蠕變過(guò)程等效橫向應(yīng)變隨時(shí)間變化關(guān)系,如圖2所示。

        由圖2可知,載荷施加瞬間,試樣產(chǎn)生約0.023的等效橫向應(yīng)變,該階段應(yīng)變主要由纖維及纖維網(wǎng)的彈性變形引起。其后,隨著蠕變時(shí)間的增加,橫向應(yīng)變逐漸增大并趨近于定值,該階段應(yīng)變歸因于無(wú)紡布內(nèi)部纖維間的粘結(jié)點(diǎn)逐步剝離和滑移。

        采用Levenberg-Marquardt優(yōu)化算法[14],擬合蠕變階段(瞬時(shí)應(yīng)變之后)實(shí)驗(yàn)曲線,得到無(wú)紡布等效橫向應(yīng)變?chǔ)舩(t)的6階Prony級(jí)數(shù)表達(dá)式:

        εx(t)=εxe+∑m=6i=1εxiexp(-t/τi)=-0.03491+

        0.00202e-t/11759.96575+0.007e-t/11031.19268+

        0.00183e-t/204.64279+0.00012e-t/444.43763+

        0.00077e-t/30.03434+0.00013e-t/0.10405

        (8)

        3.2松弛實(shí)驗(yàn)結(jié)果

        通過(guò)松弛實(shí)驗(yàn),得到無(wú)紡布應(yīng)力松弛過(guò)程縱向應(yīng)力隨時(shí)間變化關(guān)系,如圖3所示。

        由圖3可知,初始松弛階段,試樣應(yīng)力下降較為劇烈,說(shuō)明該無(wú)紡布具有較強(qiáng)的松弛特性,該階段應(yīng)力變化主要由纖維伸直及滑移引起。隨后,應(yīng)力下降趨勢(shì)逐漸放緩,并趨近于定值,該階段應(yīng)力變化歸因于伸直后纖維的應(yīng)力松弛。

        采用基于Prony級(jí)數(shù)的數(shù)據(jù)擬合法和Levenberg-Marquardt優(yōu)化算法,擬合松弛階段實(shí)驗(yàn)曲線,得到無(wú)紡布松弛模量E(t)的6階Prony級(jí)數(shù)表達(dá)式:

        E(t)=Ee+∑n=6j=1Ejexp(-t/τj)=4.42628+

        1.09253e-t/32028.50978+0.73885e-t/282.31417+

        0.58798e-t/3771.29624+1.60838e-t/57.29553+

        0.52102e-t/1346.1015+7.18362e-t/7.14774

        (9)

        3.3粘彈性泊松比計(jì)算結(jié)果與分析

        在已知無(wú)紡布橫向應(yīng)變?chǔ)舩(t)和松弛模量E(t)的6階Prony級(jí)數(shù)(相關(guān)系數(shù)R均大于0.999)后,將其擬合參數(shù)代入式(7),使用1stOpt軟件編制計(jì)算程序,計(jì)算步長(zhǎng)為t=1 s。依據(jù)計(jì)算結(jié)果,使用Origin軟件繪制式(7)曲線,得到無(wú)紡布在蠕變條件下的泊松比隨時(shí)間變化關(guān)系,如圖4所示。

        由圖4可知,無(wú)紡布的粘彈性泊松比具有明顯的時(shí)間效應(yīng)。在蠕變過(guò)程中,隨著載荷作用時(shí)間的增加,無(wú)紡布泊松比逐漸增大并趨近于定值。在初始時(shí)段,泊松比由0迅速增大至0.08左右,呈“階躍”性變化;之后變化趨勢(shì)逐漸放緩,直至趨近于0.25。由此,可將0.08作為無(wú)紡布初始粘彈性泊松比,則泊松比為隨時(shí)間從0.08逐漸趨近于0.25的值。本文所得無(wú)紡布粘彈性泊松比在正常泊松比范圍(0~0.5)內(nèi),且符合絕大部分材料泊松比約為1/3的情況[15]。泊松比趨近值(v=0.25),與高曉平[3]所得聚丙烯熱粘合無(wú)紡布(點(diǎn)粘合)彈性泊松比結(jié)果相近,存在差異可能是由于布料規(guī)格、生產(chǎn)工藝等不同,但仍具有一定參考價(jià)值。

        4結(jié)論

        粘彈性材料泊松比不能簡(jiǎn)單假定為常數(shù),而是一個(gè)與時(shí)間相關(guān)的函數(shù)。基于無(wú)紡布的粘彈性屬性,本文推導(dǎo)了橫向應(yīng)變?chǔ)舩(t)和松弛模量E(t)等效計(jì)算泊松比的方法。以Prony級(jí)數(shù)擬合蠕變實(shí)驗(yàn)和松弛實(shí)驗(yàn)數(shù)據(jù)得到εx(t)、E(t),再經(jīng)1stOpt軟件計(jì)算得到了無(wú)紡布泊松比與時(shí)間的關(guān)系,發(fā)現(xiàn)無(wú)紡布泊松比逐漸增大并趨近于0.25。所得結(jié)果符合常規(guī)泊松比范圍,且與相關(guān)研究吻合較好。本文所述方法,可較為簡(jiǎn)便地計(jì)算無(wú)紡布等紡織材料的粘彈性泊松比,為其后續(xù)生產(chǎn)加工所涉及的力學(xué)指標(biāo)計(jì)算提供參考值。

        參考文獻(xiàn):

        [1]MOTT P H, DORGAN J R, ROLAND C M. The bulk modulus and Poisson's ratio of "incompressible" materials[J]. Journal of Sound and Vibration, 2008, 312(4/5): 572-575.

        [2]高光發(fā),李永池,王道榮,等.多功能布泊松比的實(shí)驗(yàn)研究[J].力學(xué)與實(shí)踐,2010,32(5):62-66.

        GAO Guangfa, LI Yongchi, WANG Daorong, et al. Experi-mental study on Poisson's ratio of multi-function clothes[J]. Mechanics in Engineering, 2010, 32(5): 62-66.

        [3]高曉平,宋欽杰.基于圖像處理技術(shù)的非織造土工布的泊松比測(cè)試[J].產(chǎn)業(yè)用紡織品,2014,32(12):35-38.

        GAO Xiaoping, SONG Qinjie. Measurement of Poisson's ratio of nonwoven geotextilebased on image processing tech-nology[J]. Technical Textiles, 2014, 32(12): 35-38.

        [4]楊可,王朝暉.基于數(shù)字圖像相關(guān)法的針織物泊松比測(cè)定[J].毛紡科技,2021,49(1):1-6.

        YANG Ke, WANG Zhaohui. Measurement of Poisson's ratio of knitted fabrics based on digitalimage correlation method[J]. Wool Textile Journal, 2021, 49(1): 1-6.

        [5]盧業(yè)虎,戴曉群.基于雙向拉伸法的織物泊松比測(cè)定[J].紡織學(xué)報(bào),2009,30(9):25-28.

        LU Yehu, DAI Xiaoqun. Calculation of fabrics Poisson ratio based on biaxial extension[J]. Journal of Textile Research, 2009, 30(9): 25-28.

        [6]HOSHINO Y, TAMAI K, ZHANG Y, et al. Direct measurement and master curve construction of viscoelastic Poisson's ratio with digital image correlation[J]. Strain, 2018, 54(6): e12294.

        [7]LAKES R S, WINEMAN A. On Poisson's ratio in linearly viscoelastic solids[J]. Journal of Elasticity, 2006, 85(1): 45-63.

        [8]鄭健,張建彬,周長(zhǎng)省,等.蠕變?cè)囼?yàn)下固體推進(jìn)劑泊松比研究[J].南京理工大學(xué)學(xué)報(bào),2014,38(5):593-596.

        ZHENG Jian, ZHANG Jianbin, ZHOU Changsheng, et al. Study on Poisson's ratio of solid propellant using creep test[J]. Journal of Nanjing University of Science and Technology, 2014, 38(5): 593-596.

        [9]申志彬,鄧斌,潘兵.推進(jìn)劑粘彈性泊松比測(cè)試的數(shù)字圖像相關(guān)方法[J].固體火箭技術(shù),2016,39(4):513-518.

        SHEN Zhibin, DENG Bin, PAN Bing. Digital image correlation method for measuringviscoelastic Poisson's ratio of propellant[J]. Journal of Solid Rocket Technology, 2016, 39(4): 513-518.

        [10]單桂芳,楊偉,馮建民,等.材料泊松比測(cè)試方法的研究進(jìn)展[J].材料導(dǎo)報(bào),2006,20(3):15-20.

        SHAN Guifang, YANG Wei, FENG Jianmin, et al. Advances in test methods for Poisson's ratio of materials[J]. Materials Reports, 2006,20(3): 15-20.

        [11]李馭骉,李海濱.粘彈性藥柱泊松比的實(shí)驗(yàn)研究[J].新型工業(yè)化,2016,6(4):16-21.

        LI Yubiao, LI Haibin. Experimental Study on Poisson's ratio of viscoelastic grain[J]. The Journal of New Indus-trialization, 2016, 6(4): 16-21.

        [12]趙伯華.粘彈性泊松比與動(dòng)態(tài)復(fù)數(shù)泊松比的研究[J].推進(jìn)技術(shù),1995,16(3):1-7.

        ZHAO Bohua. An investigation on viscoelastic Poisson's ratio and dynamic complex Poisson's ratio[J]. Journal of Propulsion Technology, 1995, 16(3): 1-7.

        [13]許進(jìn)升,鞠玉濤,鄭健,等.復(fù)合固體推進(jìn)劑松弛模量的獲取方法[J].火炸藥學(xué)報(bào),2011,34(5):58-62.

        XU Jinsheng, JU Yutao, ZHENG Jian, et al. Acquisition of the relaxation modulus of Composite solid propellant[J]. Chinese Journal of Explosives & Propellants, 2011, 34(5): 58-62.

        [14]李虎,周國(guó)發(fā).模內(nèi)微裝配成型二次充填熔體應(yīng)力松弛特性研究[J].塑料工業(yè),2019,47(11):59-62.

        LI Hu, ZHOU Guofa. Study on stress relaxation characte-ristics of secondary injection meltfor in-micro mold assembly[J]. China Plastics Industry, 2019, 47(11): 59-62.

        [15]ALDERSON K L, FITZGERALD A, EVANS K E. The strain dependent indentation resilience of auxetic microporous polyethylene[J]. Journal of Materials Science, 2000, 35(16): 4039-4047.

        Viscoelastic Poisson's ratio of nonwovens

        XIA Tengteng1,2, GE Chenyong3, LI Jian1,2, LI Hongguang4, LI Yong1,2

        (1.The Mechanical Engineering College, Tarim University, Alaer 843300, China;

        2.The Key Laboratory of Colleges & Universities under the Department of Education of Xinjiang Uygur Autonomous Region, Alaer 843300, China;

        3.Alaer Fiber Inspection Institute, Alaer 843300, China;

        4.Alar City Zhongtai Textile Technology Co., Ltd., Alaer 843300, China)

        Abstract: The nonwoven is widely used in many industries and occupies a large proportion in the textile industry for its excellent performance, low cost and diversified types,. With the utilization of nonwovens in various industries, the output and usage have increased year by year. Therefore, in order to promote the use of nonwovens, it is necessary to study the mechanical properties of nonwovens. It can be found from the tensile test curve that all kinds of nonwovens have typical viscoelastic properties. Poisson's ratio, as one of the important indexes to measure the mechanical properties of materials, has been concerned and studied by many scholars, and some of them have studied the viscoelastic Poisson's ratio of materials. However, most studies focus on the viscoelastic Poisson's ratio of solid propellants, epoxy resins, and other materials. The research on textile materials has not been reported, but it has great research value.

        The conventional polypropylene (PP) melt-blown nonwoven was selected as the object, the viscoelastic mechanical behavior of the nonwoven was tested, and its viscoelastic Poisson's ratio was accurately calculated. Based on the theory of viscoelastic mechanics, combined with Laplace transform and creep stress conditions, the exact expression of viscoelastic Poisson's ratio was calculated by transverse strain (under creep conditions) and relaxation modulus. The internal fibers of nonwovens are disordered and thin, so they can be regarded as isotropic materials (ignoring the stress and strain in the thickness direction), and only the two-dimensional planar Poisson's ratio is studied. The creep and relaxation experiments of nonwovens were carried out according to the standard GB/T 23218.3—2010, and the curves of transverse strain and relaxation modulus were obtained and fitted into the 6th-order Prony series. The Prony series of transverse strain and relaxation modulus were substituted into the expression of viscoelastic Poisson's ratio, and the time-varying curve of viscoelastic Poisson's ratio of nonwovens under creep condition was calculated by using 1stOpt software. In this study, the calculation method of viscoelastic Poisson's ratio was introduced into textile materials, and the viscoelastic Poisson's ratio of the selected nonwoven was analyzed and measured. It is found that as the loading time increases, the viscoelastic Poisson's ratio of the material gradually increases and tends to be constant. The viscoelastic Poisson's ratio approach value of the nonwoven selected in this paper is close to 0.25, which is in line with the Poisson's ratio range of conventional materials and is close to the value of conventional elastic Poisson's ratio in related research.

        The method can effectively determine the viscoelastic Poisson's ratio of nonwovens, with simple operation and reliable results, which can provide reference for the determination of Poisson's ratio of other textile materials.. The accurate determination of viscoelastic Poisson's ratio also provides a reference value for the calculation of mechanical indexes involved in the subsequent production and processing of textile materials.

        Keywords: nonwoven; Poisson's ratio; viscoelasticity; creep; relaxation; time-varying curve

        收稿日期:20220630

        網(wǎng)絡(luò)出版日期:20220914

        基金項(xiàng)目:兵團(tuán)財(cái)政科技計(jì)劃項(xiàng)目(2021BB022)

        作者簡(jiǎn)介:夏騰騰(1998—),男,甘肅天水人,碩士研究生,主要從事材料性能研究與應(yīng)用方面的研究。

        通信作者:葛陳勇,E-mail:329439500@qq.com

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