桂桑优12和农桑14号草本式栽培桑枝条力学特性研究

Study on the Mechanical Characteristics of Mulberry Branches of Guisangyou 12 and Nongsang 14 in Herbaceous Cultivation

针对草本式栽培桑树枝条收割过程中桑条的损伤问题,文中以桂桑优12和农桑14号草本式栽培桑树枝条为研究对象,利用电热干燥箱测量试验桑条含水率,并利用万能试验机对不同取样位置桑条和木质部进行剪切、压缩和弯曲力学特性试验。桑树同一品种、不同取样位置,桑条含水率有显著差异(P<0.05),桑条的剪切、压缩和弯曲力学特性有显著差异(P<0.05);而木质部轴向压缩弹性模量无显著差异(P>0.05),木质部的剪切和径向压缩弹性模量有显著差异(P<0.05)。桂桑优12和农桑14号两个桑树品种桑条的抗压力大于木质部(P<0.05);而木质部的剪切强度、抗压强度和压缩弹性模量大于桑条(P<0.05)。桂桑优12桑条的剪切和压缩力学特性均大于农桑14号(P<0.05)。桂桑优12桑条的弯曲力大于农桑14号(P<0.05)。桂桑优12桑条的抗弯强度和弯曲弹性模量均小于农桑14号(P<0.05)。试验结果表明,桂桑优12桑条和农桑14号桑条的含水率自上而下呈递减规律,桑条和木质部的剪切、压缩和弯曲力学特性(除木质部轴向压缩弹性模量)自上而下呈递增规律。该研究结果可为草本式栽培桑树枝条收割装置的设计与优化提供参数依据。

To solve the problem of damage to the mulberry branches in the harvesting process,branches of Guisangyou 12 and Nongsang 12 from herbaceous cultivation were taken as the research objects.The moisture content of the test mulberry branches was measured by an electric drying oven.The shear,compression and bending tests were carried out on mulberry branches and their woody parts at different sampling locations using a universal testing machine.As for the same mulberry variety at different sampling locations,there was a significant difference in moisture content of mulberry branches(P<0.05),and there were significant differences in shear,compression and bending mechanical characteristics(P<0.05).There was no significant difference in axial compressive elastic modulus of xylem(P>0.05),and there were significant differences in the shear and radial compressive modulus of elasticity of the xylem(P<0.05).The stress resistance of mulberry branches of Guisangyou 12 and Nongsang 14 was higher than that of the xylem,and there was a significant difference between them(P<0.05);The shear strength,compressive strength and compressive elastic modulus of the xylem of Guisangyou 12 and Nongsang 14 were significantly higher than those of mulberry branches(P<0.05).The shear and compression mechanical parameters of Guisangyou 12 were significantly higher than those of Nongsang 14(P<0.05).The bending force of Guisangyou 12 was significantly higher than that of Nongsang 14(P<0.05).The flexural strength and flexural modulus of elasticity of Guisangyou 12 were significantly lower than those of Nongsang 14(P<0.05).The results showed that the moisture content of the mulberry branches of Guisangyou 12 and Nongsang 14 decreased from top to bottom,and the mechanical properties in shear,compression and bending of the mulberry branches and xylem(except for the axial compressive modulus of elasticity of the xylem)showed an increasing pattern from top to bottom.The research results can provide a parameter basis for the design and optimization of herbaceous mulberry branch harvesting devices.