农业工程学报
農業工程學報
농업공정학보
Transactions of the Chinese Society of Agricultural Engineering
2015年
20期
26-33
,共8页
沈成%李显旺%田昆鹏%张彬%黄继承%陈巧敏
瀋成%李顯旺%田昆鵬%張彬%黃繼承%陳巧敏
침성%리현왕%전곤붕%장빈%황계승%진교민
模型%复合材料%弹性%苎麻%茎秆
模型%複閤材料%彈性%苧痳%莖稈
모형%복합재료%탄성%저마%경간
models%composite materials%elasticity%ramie%stalk
为了提供苎麻收割、剥制机械研究设计的力学参数及理论基础,论文对苎麻茎秆的几何形状进行假定,运用复合材料力学理论建立苎麻茎秆力学模型,利用微机控制万能试验机对苎麻茎秆各向(轴向、径向)及各组分(木质部、韧皮部和茎秆整体)进行拉伸、压缩、弯曲等力学试验,获得力学参数数据,并通过数据的分析计算获得苎麻茎秆力学模型的全部弹性参数.同时,试验结果表明,苎麻茎秆在轴向拉伸中表现更多为木质部的承载作用,其韧皮部与木质部的粘附力不能阻止韧皮部沿木质部表层滑移;苎麻茎秆径向弹性参数测量值和通过各组分弹性参数值计算获得的计算值接近,苎麻茎秆径向符合复合材料的特性.
為瞭提供苧痳收割、剝製機械研究設計的力學參數及理論基礎,論文對苧痳莖稈的幾何形狀進行假定,運用複閤材料力學理論建立苧痳莖稈力學模型,利用微機控製萬能試驗機對苧痳莖稈各嚮(軸嚮、徑嚮)及各組分(木質部、韌皮部和莖稈整體)進行拉伸、壓縮、彎麯等力學試驗,穫得力學參數數據,併通過數據的分析計算穫得苧痳莖稈力學模型的全部彈性參數.同時,試驗結果錶明,苧痳莖稈在軸嚮拉伸中錶現更多為木質部的承載作用,其韌皮部與木質部的粘附力不能阻止韌皮部沿木質部錶層滑移;苧痳莖稈徑嚮彈性參數測量值和通過各組分彈性參數值計算穫得的計算值接近,苧痳莖稈徑嚮符閤複閤材料的特性.
위료제공저마수할、박제궤계연구설계적역학삼수급이론기출,논문대저마경간적궤하형상진행가정,운용복합재료역학이론건립저마경간역학모형,이용미궤공제만능시험궤대저마경간각향(축향、경향)급각조분(목질부、인피부화경간정체)진행랍신、압축、만곡등역학시험,획득역학삼수수거,병통과수거적분석계산획득저마경간역학모형적전부탄성삼수.동시,시험결과표명,저마경간재축향랍신중표현경다위목질부적승재작용,기인피부여목질부적점부력불능조지인피부연목질부표층활이;저마경간경향탄성삼수측량치화통과각조분탄성삼수치계산획득적계산치접근,저마경간경향부합복합재료적특성.
Mechanical cutting and fiber peeling are important parts in the ramie production process, and its working process is the process of interaction between rigid body (machine) and flexible body (ramie stalk). To make the developed harvester and peeling machine to meet the working requirement of high quality, efficiency and low consumption, the premise is to get mechanical characteristic parameters of crop, to have a fundamental understanding of ramie harvesting and fiber peeling mechanism. Based on this, in order to provide the mechanical parameters and theoretical basis for the research on cutting and peeling ramie, experimental analysis on the mechanical model of ramie stalk has been made in the paper. The crop object for experimental analysis was the third crop of Zhongzhu No.1 planted in Xianning Ramie Comprehensive Experiment Station of China Agricultural Research System (Bast fiber crops), the acquisition time was on November 2nd, 2013, and the test was conducted in Nanjing Research Institute for Agricultural Mechanization, Ministry of Agriculture, during November 5th to 15th, 2013. During the experimental research process, the geometric model for ramie stalk was assumed firstly. The cross section of ramie stalk was similar to the circle, which could be respectively divided into central medulla, xylem, phloem and green husk layer. The mechanical property in the central medulla and green husk layer might be ignored. The paper abstracted and simplified the geometrical shape, and presumed that the cross section was round with certain diameter. The material, diameter and wall thickness dimension of each fraction were even. After ignoring the central medulla and green husk layer, the geometrical shape of ramie was assumed as hollow pipe, made up of different kinds of materials including xylem and phloem. Secondly, composite mechanical theory was employed to construct mechanical model of ramie stalk. Elastic parameters that should be obtained from experiment were decided according to the assumption of ramie geometrical shape and experimental equipment conditions, as well as the calculation formula of each elastic parameter. Thirdly, PC-controlled universal testing machine was applied to make mechanical test, such as tensile, compressive and bending, to ramie stalk from each direction (axial direction and radial direction) and to each part (xylem, phloem and the whole stalk), to acquire mechanical parameter data. The universal testing machine used in the experiment was WDW-10 PC-controlled electronic universal testing machine with test power range 5 kN, and the accuracy of its force sensor and displacement sensor were both maintained within ±0.1%. In tensile test, xylem, phloem and stalk samples were 20 groups of rectangle samples about 80 mm long, 6-7 mm wide, material thickness thick. Plate fixture was used, and the clamped position was covered by gauze for protection. Pre-tightening force when starting was less than 5 N, test loading rate was 5 mm/min. Then, axial tensile stress-strain curve of each sample group was obtained. In compressive test, xylem, phloem and stalk samples were 10 groups of rectangle samples about 10- 11 mm long, 5-6 mm wide, material thickness thick. Compressive test briquetting was used. Thus, radial comprehensive stress-strain curve of each sample group was obtained. In bending test, xylem and stalk samples were 10 groups of samples with the length of about 120 mm. The sample cross section was tube-shape, and external and inner diameter was decided by material conditions. Sample was placed between the support and pressure head of three-point bending test fixture. Span of the support was 80 mm, pre-tightening force when starting was less than 5 N, and test loading rate was 5 mm/min. Radial bending force-deformation curve was obtained. At last, all elastic parameters of ramie stalk mechanical model were obtained with analysis of test data. The radial compressive elasticity modulus were 9.73 MPa (stalk), 10.34 MPa (xylem) and 8.03 MPa (phloem); the axis tensile elasticity modulus were 466.17 MPa (stalk), 320.92 MPa (xylem) and 2409.22 MPa (phloem); the radial bending shear modulus were 39.77 MPa (stalk), 69.02 MPa (xylem) and 33.80 MPa (phloem), the axis torsional shear modulus were 3.74 MPa (stalk), 3.98 MPa (xylem) and 3.09 MPa (phloem), the Poisson's ratios of plane XZ of each parts was assumed to 0.3, and the Poisson's ratios of plane XZ and the Poisson's ratios of plane XZ were equal, the values were <0.0269 (stalk), <0.0451 (xylem) and <0.0043 (phloem). Meanwhile, the test results of paper showed that the axial tension of ramie stalk played the load-bearing role much more in the xylem, and the adhesive force in the phloem and xylem was incapable to prevent the phloem from sliding along the surface of xylem; the measurement value of elastic parameter in the radial direction of ramie stalk was closed to the calculated value gained by calculating the elastic parameters of each fraction, and the radial direction of ramie stalk could match the characteristics of composite materials. In conclusion, the assumption of the composite model adopted in the experiment is reasonable, and experimental analysis results can be applied into subsequent related researches.
