劍麻切割應(yīng)力力學(xué)性能

張琪琪等

摘要：以成熟的、生長(zhǎng)狀況相似的劍麻（Agave sisalana Perr. ex Engelm.）葉片為研究對(duì)象，利用WD-200B微機(jī)控制電子萬(wàn)能試驗(yàn)機(jī)，采用單因素試驗(yàn)法測(cè)得不同影響因素下最大切割應(yīng)力，并分析了切割速度、切割部位、切割葉面、切割方式、切割角度、含水率對(duì)切割應(yīng)力的影響。結(jié)果表明，切割劍麻主要影響因素有切割角度、切割方式以及切割葉面部位。在100 mm/min速度下切割收集的劍麻根部的側(cè)面部位，側(cè)切較正切和背切的剪切應(yīng)力小為0.521 MPa； 在250 mm/min速度下取不同含水率最高時(shí)應(yīng)力最小為0.476 MPa；取側(cè)面部位削切的角度為30°～45°區(qū)間內(nèi)，應(yīng)力區(qū)間為0.330～0.352 MPa。該結(jié)果為劍麻的收割機(jī)械研制時(shí)切割位置、切割時(shí)間、切割器及刀具的設(shè)計(jì)、電動(dòng)機(jī)功率的選取等方面提供數(shù)據(jù)支持。

關(guān)鍵詞：劍麻（Agave sisalana Perr. ex Engelm.）；切割應(yīng)力；力學(xué)性能

中圖分類(lèi)號(hào)：S225 文獻(xiàn)標(biāo)識(shí)碼：A 文章編號(hào)：0439-8114（2015）16-4044-05

DOI：10.14088/j.cnki.issn0439-8114.2015.16.055

Mechanical Properties of Sisal Cutting Stress

ZHANG Qi-qi， LAI Wen-yu， WANG Tao

（School of Mechanical and Electrical Engineering， Hainan University， Haikou 570100， China）

Abstract： Studying the mechanical properties of Sisal leaf gives basic idea of Sisal harvester design and development. To analyze the properties of Sisal leaf shear stress under different stress conditions， we took cutting speed，leaf height，cutting position of leaf surface，cutting mode，cutting angle and moisture content as factors. Mature Sisal leaves with identical growing condition as the research object was chose. Using computer control electronic universal testing machine， the maximum shear stress was supposed to be measured and the effect was analyzed through single-factor controlled experiment. The results showed that the main factors affecting cutting sisal were cutting angle，cutting mode and cutting position of leaf surface. The lower part of the fresh leaves with the highest moisture content was chose. The shear stress was measured in three different parts of sisal leaf —the side，front and the back part. The stress at the side was minimum， which was 0.521 MPa with lower part of the Sisal leave edge being cut. The stress was 0.476 MPa under maximum moisture content. If the cutting angle towards the side part lay within range of 35°～40°，the corresponding stress varied from 0.330 to 0.352 Mpa. The analytical results offered the experimental data required for sisal harvester technology development.

Key words：Agave sisalana Perr. ex Engelm.；cutting stress；mechanical properties

劍麻（Agave sisalana Perr. ex Engelm.）是極具特色的熱帶經(jīng)濟(jì)作物，隸屬于龍舌蘭科，原產(chǎn)地是墨西哥尤卡坦半島，現(xiàn)主要種植于南美洲、非洲、亞洲等地。劍麻在中國(guó)的面積和產(chǎn)量分別處于世界第5位和第2位，單位面積產(chǎn)量也是世界平均水平的4倍以上，居世界第1位[1]。目前，我國(guó)劍麻加工原材料需求量大，每年進(jìn)口的數(shù)量仍呈現(xiàn)增加趨勢(shì)。劍麻莖粗而短，葉片無(wú)葉柄，硬而狹長(zhǎng)，呈放射狀展開(kāi)，且葉片強(qiáng)度較大，因此劍麻葉片的收割十分困難。而國(guó)內(nèi)的劍麻生產(chǎn)機(jī)械化和自動(dòng)化水平很低，基本上仍是由人工完成的，收割勞動(dòng)強(qiáng)度大，勞動(dòng)成本高，越來(lái)越難找到割葉操作工人是劍麻產(chǎn)業(yè)發(fā)展的瓶頸，因此實(shí)現(xiàn)機(jī)械化收割劍麻葉片是當(dāng)前急需解決的技術(shù)難題[2，3]。切割劍麻的切割器及其刀片的研制就成為機(jī)械收割劍麻的關(guān)鍵，劍麻切割力學(xué)特性研究對(duì)切割器及刀片的設(shè)計(jì)研制極為重要。國(guó)內(nèi)外學(xué)者對(duì)于農(nóng)作物的秸稈進(jìn)行了大量的力學(xué)性能研究，高欣[4]對(duì)不同種類(lèi)、不同節(jié)間、不同加載速度的玉米秸稈進(jìn)行了拉伸、彎曲、剪切的力學(xué)試驗(yàn)；潘紅瑋等[5]研究了不同預(yù)處理后劍麻纖維的性能特點(diǎn)；張西良等[6]對(duì)黃瓜藤秸稈力學(xué)特性進(jìn)行了研究；Holt等[7]研究了農(nóng)業(yè)纖維棉力學(xué)性能。然而，國(guó)內(nèi)外關(guān)于劍麻的力學(xué)性能研究較少，本研究對(duì)劍麻的力學(xué)性能進(jìn)行深入分析與討論，利用單因素試驗(yàn)分析了劍麻的力學(xué)性能和理化性能指標(biāo)的相關(guān)性，為相關(guān)配套收割機(jī)械的切割器、切割刀片、動(dòng)力裝置的功率匹配等設(shè)計(jì)研制提供可靠的參考，為進(jìn)一步設(shè)計(jì)劍麻收割機(jī)械等相關(guān)的農(nóng)業(yè)機(jī)械設(shè)備提供充足的理論數(shù)據(jù)支持。