白桦材12个弹性常数的研究

该文结合木材的正交各向异性特征论述了木材的柔度系数与其工程弹性常数的关系 ,并采用电测法测试了白桦木材的 1 2个弹性常数 .试验结果表明 ,木材作为多孔性材料 ,粘贴应变片时 ,涂胶量不能过多或过少 .涂胶量过多则胶层太厚影响应变片性能 ;过少则粘贴不牢 ,不能准确传递应变 .木材作为正交各向异性材料 ,弹性常数间存在一定的相互联系 ,满足马克斯韦尔定理 ,该试验测定的试验数据基本满足这些联系 .从数据结果的检测来看 ,白桦弹性常数的测量是准确可靠的 ,证明电测法这一测试手段可行 .就剪切弹性模量的测试结果看 ,抗弯弹性模量的倒数与高和跨度之比的平方的线性回归相关系数较高 ,均大于 0 95 .这说明应用三点弯曲试验方法测试的剪切弹性模量值是可靠的

Study on twelve elastic constant values of Betula platyphylla Suk.wood

Elastic constants are needed to describe the elastic behavior of wood and should be taken as an important design parameter for wood based composite materials and structural materials. This paper clarifies the relationships between compliance coefficients and engineering elastic constants combined with orthotropic nature of wood, and twelve elastic constants of Betula platyphylla Suk. were measured by electrical strain gages. Wood as an orthotropic material, the moduli of elasticity and poisson's ratios are related by Maxwell's theory. The results from experiment show that the elastic constants of Betula platyphylla Suk. measured by electrical strain gages are precise and consistent with the relations. Based on the results of shear modulus G TL , G LR , a high linear correlation coefficient (>0 95) between the reciprocal of elastic modulus MOE -1 and the square of the depth to length ratio (h/l) 2 shows the obtained shear modulus values reliable by three_point bending experiment. Elastic constant measurement provides necessary parameters for studying fracture property and will provide a reference to study wood mechanical properties.