成熟期巨菌草底部茎秆力学特性试验

陈文滔　方兵　梁晓　叶大鹏

摘要：研究巨菌草（Pennisetum sinese Roxb）茎秆力学特性及其变化规律是建立巨菌草茎秆材料力学模型与本构关系的重要基础。利用SNAS微机控制电子万能材料试验仪对成熟期巨菌草底部茎秆进行顺纹拉伸、压缩、弯曲试验，获得其在试验条件下的应力-应变曲线，并进行分析。试验选取的巨菌草底部茎秆平均含水率为75%，测得的巨菌草底部茎秆顺纹拉伸最大抗拉强度的平均值为93.2 MPa，弹性模量平均值为593.8 MPa；顺纹压缩最大抗压强度平均值为10.1 MPa，弹性模量平均值为126.4 MPa；顺纹弯曲最大抗弯强度平均值为11.3 MPa，弹性模量平均值为610.5 MPa。表明巨菌草茎秆的拉伸破坏应力参数与苜蓿（Medicago L.）、毛竹[Phyllostachys heterocycla （Carr.） Mitford cv. Pubescens Mazel ex H.de Leh.]相近，而壓缩与弯曲破坏应力参数却远小于芦竹（Arundo donax L.）。因此，所获成熟期巨菌草底部茎秆力学特性参数，可为巨菌草机械切割设备的设计提供理论指导和基础技术参数。

关键词：巨菌草（Pennisetum sinese Roxb）；茎秆；力学特性；强度；弹性模量

中图分类号：S233.75 文献标识码：A 文章编号：0439-8114（2016）08-2031-04

DOI：10.14088/j.cnki.issn0439-8114.2016.08.028

Abstract： The research on the variation of mechanical properties of Pennisetum sinese Roxb stalks is important foundation for the establishment of material mechanics model and constitutive relation of P. sinese stalk. Stretching test， compressing test and bending test on the bottom stalks of maturity P. sinese were carried out by using the SNAS computer-controlled electronic universal testing instrument， and the experimental data were analyzed in form of stress-strain curves. The stalks with an average moisture content of 75% were used as meterial. The results showed that the average maximum of pulling resistance intensity along veins is 93.2 MPa； and the modulus of elasticity is 593.8 MPa. The average maximum of stress resistance intensity along veins is 10.1 MPa； and the modulus of elasticity is 126.4 MPa. The average maximum of bend resistance intensity along veins is 11.3 MPa； and modulus of elasticity is 610.5 MPa. The results also indicated that the tensile breaking stress parameters of the P. sinese is similar to Medicago L. and Phyllostachys heterocycla （Carr.） Mitford cv. Pubescens Mazel ex H.de Leh.， but is far less than the compression and bend breaking stress parameters of Arundo donax L. Therefore， the parameters of mechanical properties of the mature bottom stalk of P. sinese can provide theoretical background and basic technical parameters of the guidance for the designing of the Pennisetum sp. mechanical cutting machines.

Key words： Pennisetum sinese Roxb； stalk； mechanical properties； strength； elastic modulus

巨菌草（Pennisetum sinese Roxb）是多年生直立丛生型植物，属于被子植物门单子叶植物纲禾本科狼尾草属，分布于热带、亚热带、温带地区，能耐受短期的干旱，但不耐涝，具有较强的分蘖能力[1]。其外观似芦竹（Arundo donax L.），植株高大，最高可达7.08 m，抗逆性强，茎粗可达3.5 cm，产量高，粗蛋白和糖分含量高，根系发达。从1983年引进中国后，经过20多年的人工培育，已形成适合国内气候土壤环境的高产优质草种。同时，以草为原料栽培食用菌也可以有效解决“菌林矛盾”。巨菌草的茎秆木质纤维可作为生物能源与工业原料，从2008年开始已应用于生物质发电、纤维板生产、制造燃料乙醇等新能源用途[2]，其潜在的经济价值巨大。……