| 摘要: |
| 以内蒙古干旱半干旱沙区固沙先锋树种沙柳(Salix psammophila)枝条为对象，研究其冬季休眠期抗拉、抗剪与抗弯力学特性，分析枝条长度、直径及其化学组分等对其力学特性的影响，为丰富植物固沙能力的评估指标体系，也为沙柳平茬机具的研制提供生物力学依据。结果显示:在测试径级0.5~2.5 mm时，沙柳枝条的极限抗拉力为14.05~52.02 N、抗剪力为16.26~80.04 N、抗弯力为1.02~3.54 N，均随着直径的增大而增大，应力直径递增函数不同；极限抗拉强度为8.96~66.19 MPa、抗剪强度为8.04~39.87 MPa、抗弯强度为1 566.46~46.71 MPa，均随直径的增大而减小，应力强度-直径递减函数不同。表明直径是影响枝条力学特性的重要影响因子。随着枝条长度的增长，其抗弯强度呈增大的趋势，而抗拉强度和抗剪强度无明显的变化规律；沙柳枝条极限抗拉力均值36.19±3.29 N>抗剪力均值 50.04±4.54 N，枝条极限抗拉强度均值31.01±2.81 MPa>抗剪强度均值16.98±1.54 MPa，说明枝条易破坏外力类型为剪切力。沙柳枝条抗拉强度、剪切强度和抗弯强度与纤维素、半纤维素含量呈显著(P<0.05)和极显著(P<0.01)正相关，与木质素含量呈显著正相关(P<0.05)。试验结果表明影响枝条抗拉、抗剪和抗弯强度的因素中纤维素和半纤维素起主要作用，其次是木质素含量。 |
| 关键词: 沙柳 枝条 力学特性 抗拉强度 抗剪强度 纤维素 |
| DOI：10.11841/j.issn.1007-4333.2021.11.08 |
| 投稿时间：2020-02-18 |
| 基金项目:国家自然科学基金项目(41867011)；内蒙古自然科学基金项目(2021MS04011) |
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| Mechanical properties of the branches of Salix psammophila and its influencing factors |
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WANG Zhengxian1,Gerile1*,CUI Tianmin1,HAO Xuting1,ZHANG Yongliang1,SIqin2
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| (1.College of Desert Control Science and Engineering, Inner Mongolia Agricultural University, Hohhot 010011, China;2.College of Grassland and Resources and Environment, Inner Mongolia Agricultural University, Hohhot 010011, China) |
| Abstract: |
| The aim of this study was to provide a biomechanical basis for the enrichment of evaluation index system of the sand-fixing ability of plant and the development of sand willow stubble machines. The branches of Salix psammophila, a pioneer tree species for sand fixation in the arid and semi-arid desert areas of Inner Mongolia, was taken as study object, and the mechanical properties of its tensile, shear and flexural properties during winter dormancy were studied. The effects of the length, diameter and chemical composition of the branches on their mechanical properties were analyzed. The results show that the ultimate tensile strength was(14. 05-52. 02 N), shear strength(16. 26-80. 04 N)and flexural strength(1. 02-3. 54 N)of the branchesin the test diameter range within the range of 0. 5-2. 5 mm. With the increase of the branch diameter, the stress-diameter increasing function is different. The ultimate tensile strength(8. 96-66. 19 MPa), shear strength(8. 04-39. 87 MPa)and bending strength(1 566. 46-46. 71 MPa)increased with the decreasing of diameter. The stress intensity-diameter decreasing function was different. It shows that diameter is an important factor affecting the mechanical properties of branches. As the length of the branches grows, the flexural strength tends to increase, while the tensile strength and shear strength have no obvious changes. The average ultimate tensile strength of the branches of S. sylvestris is(36. 19±3. 29 N)is stronger than the average shear strength of(50. 04±4. 54 N), and the average ultimate tensile strength of the branches is(31. 01 MPa±2. 81 MPa), which is stronger than the average shear strength of(16. 98±1. 54 MPa), indicating that the branch is easily damaged by the external force type of shear force. The tensile strength, shear strength and flexural strength of Salix branches are significantly(P<0. 05)and extremely significant(P<0. 01)positively correlated with cellulose and hemicellulose content, and were significantly positively correlated with lignin content(P<0. 05). In conclusion, the tensile, shear and flexural strength of the branches play a major role in which cellulose and hemicellulose followed by the lignin content. |
| Key words: Salix psammophila branche mechanical property tensile strength shear strength cellulose |
