气干和饱水状态下毛竹4种力学性质的比较

Comparative on Four Mechanical Properties of Bamboo under Air-Dried and Saturated State

以毛竹为研究对象,测试不同年龄毛竹顺纹抗剪强度、顺纹抗压强度、弯曲模量和顺纹拉伸弹性模量在气干状态(北京,含水率8%)和饱水状态下之间的差异,由此探索竹材力学性能的含水率依赖特性。结果表明:上述4种力学性能指标对含水率变化的敏感程度不同,顺纹抗剪强度和顺纹抗压强度受含水率的影响程度最大,弯曲模量次之,顺纹拉伸弹性模量最小;4种力学性能指标对含水率变化的敏感程度均随着竹龄的增大而降低,但是受影响的程度不同,其中顺纹抗压强度从气干到饱水态的降幅受竹龄的影响最小,最大和最小降幅之间的差值只有3.6%,顺纹剪切强度和顺纹拉伸模量次之,弯曲模量最大,差值为14.77%。

No research has been focused on comparing the moisture dependence of different mechanical properties of bamboo until now. In the present paper,four kinds of mechanical properties of bamboo with four ages were tested both under air-dried（Beijing,MC 8%） and saturated state to explore the different moisture dependence of them. The results show that the four mechanical properties of bamboo exhibited different sensitivity to moisture change. Compressive and shearing strength parallel to gain are most significantly affected by moisture content,then is bending modulus and followed by longitudinal tensile modulus. Furthermore,the sensitivity of the above mechanical properties to moisture change was all reduced with the increase of bamboo ages（from 0. 5 year to 4. 5 year） but at different speed,among which the decreasing ratio of compressive strength parallel from air-dried to saturated state is only 3. 6%,then was shearing strength and tensile modulus followed by bending modulus with a maximum value of 14. 77% .