激光测距方法测量结构材的顺纹抗拉弹性模量

该文以经过120 d、温度90℃条件下窑干干燥处理的56根日本柳杉人工林结构材(110 mm×55 mm×2 500 mm)作为测试试件，介绍了一种利用激光测距系统测量顺纹抗拉弹性模量的方法. 首先将试件含水率调至15%，在抗拉试验开始前采用纵向基频振动方法 (FFT) 得到试件的动态弹性模量(Efr)，再利用由激光测距仪、数据采集器和计算机处理系统组成的激光测距系统，测定了顺纹抗拉弹性模量（Et），最后破坏试件完成顺纹抗拉强度（σt）的测定. 对Efr、Et和σt相互关系的比较分析表明，Et的平均值比FFT方法得到的Efr的平均值小78% (0.63　GPa)；Et与Efr具有很好的相关性，相关系数R为0971，在0.001水平上呈显著相关；Et和σt的相关系数R为0727，也在0.001水平上呈显著相关. 足尺试件的顺纹抗拉测试结果表明，激光测距方法可以准确地测量结构材在顺纹受拉时发生的拉伸变形，从而得到可靠的抗拉弹性模量试验结果.  

Application of a laser measurement method in measuring the modulus of elasticity in tension parallel to grain of Cryptomeria japonica D. Don structural lumber

The objective of this paper is to introduce a laser measurement method to obtain the modulus of elasticity (MOE) in tension parallel to grain of structural lumber. Fifty six pieces of Cryptomeria japonica D. Don plantation lumber (110 mm×55 mm×2 500 mm), dried at 90℃ temperature in kiln for 120 days, were selected as the testing specimens. After adjusting the moisture content to 15%, the dynamic MOE (E_fr) of all pieces was measured based on longitudinal vibration in fundamental frequency (FFT). A laser measurement system consisting of laser meter for tensile deformation, data logger and computer analyzer was then applied to measure tension MOE (E_t) of lumber. Meanwhile, tension strength (σ_t) of lumber was obtained when pieces were in failure at maximum load. The results indicated that the average E_t was 7.8% (0.63　GPa) less than E_fr. Statistical linear regression analyses revealed that useful relationship was evident among E_t, E_fr and σt (P<0.001). The correlation coefficient was 0.971 between E_t and E_fr, and 0.727 between E_t and σ_t. The tensile testing results demonstrated that the laser measurement method could be used to obtain precise tensile deformation for reliable MOE in tension parallel to grain of structural lumber