3种无损检测技术评估足尺规格材的静态弹性模量

首先利用横向振动、纵向基频振动和超声波3种无损检测法获得天然林樟子松Pinus sylvestris var.mongolica足尺规格材（38 mm×89 mm×4 000 mm）和人工林杉木Cunninghamia lanceolata足尺规格材（45 mm×90 mm×2 500 mm）动态弹性模量,同时根据D198-99（American Society for Testing and Materials）标准测试了其静态弹性模量;进而通过探讨动态与静态弹性模量之间的相互关系。研究结果表明,无论对哪种木材的规格材,利用上述3种无损检测方法获得动态弹性模量（Etv,Efr,Eusw）与静态弹性模量（Etru）平均值之间的关系为：Eusw〉Efr〉Etru〉Etv;动态弹性模量与静态弹性模量之间的线性相关极显著,表明这3种无损检测方法均可以用于评估规格材的静态弹性性质;从设备的方便、可靠和易操作等方面综合考虑,利用纵向基频振动法来评估规格材的静态弹性模量,其预测效果更为理想;天然林樟子松和人工林杉木比较而言,动静态弹性模量线性相关决定系数前者大于后者,即预测天然林樟子松规格材效果更好。

Evaluation of modulus of elasticity for dimension lumber by three nondestructive techniques

Dynamic bending modulus of elasticity of Mongolia scotch pine （Pinus sylvestris var. mongollca） full dimension lumber （38 mm × 89 mm × 4 000 mm） and Chinese fir （Cunninghamia lanceolata） plantation dimension lumber （45 mm × 90 mm × 2 500 mm） were tested by three non-destructive techniques, i. e. transverse vibration method, longitudinal fundamental frequency vibration method and ultrasonic wave method. At the same time, the static modulus elasticity of the above specimens were tested according to ASTM D198- 99. The results showed that the value of dynamic and static modulus of elasticity followed the sequence as the following,Eusw〉Efr〉Etru〉Etv, the relationship between dynamic and static modulus of elasticity concerning the three methods was significant at 0. 01 level, indicating that all the three nondestructive methods could be used to predict the bending properties of dimension lumber. Furthermore, considering the operation of the equipment, longitudinal fundamental frequency vibration technique was the most accurate, convenient, reliable, easy and practical method. It was also found that the coefficient of determination （R2） obtained by using the three nondestructive techniques for Chinese fir plantation full dimension lumber was lower than that of Mongolia scotch pine full dimension lumber, estimating the static modulus elasticity of Mongolia scotch pine was more accurate than that of plantation Chinese fir. [ Ch, 6 fig. 1 tab. 17 ref. ]