农业工程学报2017，Vol.33Issue(18)：51-58,8.DOI:10.11975/j.issn.1002-6819.2017.18.007
棉秆挤压剥皮剪切力学特性试验
Peeling and shearing mechanical performance test of cotton stalks in extrusion state
摘要
Abstract
Cotton stalks have a high lignified degree.The fiber configurations and physical-mechanical properties of cotton stalks are closest to wood,and it is an ideal substitute for wood.Cotton stalk scrimber is a new artificial material,and it is a new way of cotton stalk material utilization.Defibering and peeling are important processes for preparation of cotton stalk scrimber.For a long time,cotton stalk peeling is used by manual separation of phloem and xylem,this method is inefficient and becomes a bottleneck restricting the development of cotton stalk material industry.In order to study defibering and peeling method and equipment of cotton stalk scrimber material,peeling force test was done using homemade test-bed.The test-bed is composed of traction mechanism,framework and peeling force detecting device,and it can press vertically and peel horizontally cotton samples.The length of harvested cotton stalks was from 100 to 130 cm,chosen cotton stalks with no pests whose stem was straight,and root diameter was between 13 and 14.99 mm as the test materials.The total length of the sample was 35 mm.Some phloem was retained to form the test area.The axial is in the stalk length direction,and the tangential is in the perpendicular direction of stalk length.The cotton stalk samples were fixed on the rack in the axial and tangential direction.The direction of loading disk and skin parts was lined up properly.Load weight in the end of the loading disk.Apply positive pressure on the skin part of the sample.Then the traction mechanism was started,the clamp moved in the frame of the table at the speed of 1 mm per minutes.Force sensor installed on the dead plate and loading disk was connected by a wire rope.The xylem of cotton stalk samples was subjected to traction,and phloem to peeling force in the horizontal direction.The two forces were the same size and the opposite directions,thus shearing action was brought in the bonding interface between xylem and phloem.The wire rope was tensioned gradually in the experiment,thus the peeling force was steadily increasing until phloem peeling off the sample,and then the peeling force plunged.The force sensor recorded the changes of peeling force from the beginning of the experiment to the separation of the phloem and xylem.Peeling shear strength was the ratio of maximum peeling force recorded by force sensor to cotton stalk sample peeling area.In order to test the peeling shear strength,center combination experiment was done on the three factors:Water content,sampling position and loading strength.Single factor experiment was made on skin attachment length.And the water softening cotton stalk and fresh cotton stalk were compared.The results showed that the sampling location and the loading strength had significant influence (P＜0.01) on axial and tangential peeling shear strength.The effect of water content on axial and tangential peeling shear strength was not significant (P＞0.05).Improving the moisture content can reduce peeling difficulty,but the effect is limited.The interaction between the three factors was not marked (P＞0.05).Loading strength,sampling location and water content have a strong to weak influence on peeling shear strength.Tangential peeling was more highly active and lower consume than axial peeling,and it was a more reasonable operation mode.The axial peeling shear strength of fresh cotton stalk is greater than the tangential strength,this feature is consistent with the water softening cotton stalk,fresh stalks are easy to peel compared with the water softening ones,and the effectiveness of peering was high for a timely peeling after harvest.Our research offers a reference for the design of the equipment for defibering and peeling of cotton stalk.关键词
农业机械/力学特性/水分/棉秆/取样部位/加载强度/剥皮剪切强度Key words
agricultural machinery/mechanical properties/moisture/cotton stalks/sampling location/loading strength/peeling shear strength分类
农业科技引用本文复制引用
史诺,郭康权,范宇杰,刘宝选,袁新璐..棉秆挤压剥皮剪切力学特性试验[J].农业工程学报,2017,33(18):51-58,8.基金项目
陕西省13115工程技术研究中心项目(2011HBGC-03) （2011HBGC-03）
