两种无损检测法评估人工林杉木抗弯性质

Evaluation of Bending Properties of Chinese Fir Plantation by Two Nondestructive Testing Methods

用超声波法和纵向共振法分别测量了气干人工林杉木无疵小试样的动态弹性模量(E_(us),E_(fr)),根据GB 1936.2—2009和GB 1936.1—2009分别测量了其静态抗弯弹性模量(E_(st))和抗弯强度(σ),分析了动态弹性模量和静态抗弯弹性模量之间的差异,研究了抗弯性质(E_(st),σ)与动态弹性模量、密度(ρ)之间的关系.结果表明:E_(us),E_(fr)平均值皆比E_(st)平均值大,E_(fr)与E_(st)在0.05水平下差异不显著,E_(us)与E_(st),E_(us)与E_(fr)均在0.05水平下差异显著;E_(st),σ与E_(us),E_(fr),ρ之间各自的相关性均在0.001水平下显著;σ与E_(us),σ与E_(fr)之间相关性低于σ与ρ之间的相关性,而E_(st)与E_(us),E_(st)与E_(fr)之间的相关性高于E_(st)与ρ之间的相关性;综合利用动态弹性模量和密度预测人工林杉木抗弯性质比单独用动态弹性模量或密度预测的效果好.

Two nondestructive testing（NDT） methods namely ultrasonic wave and longitudinal resonance methods were used to determinate the dynamic modulus of elasticity Eus and Efr of air-dried small clear specimen of Chinese fir （Cunninghamia lanceolata） plantation. The bending properties including static bending modulus of elasticity（Est） and bending strength （σ） were also measured in accordance with GB 1936.2--2009 and GB 1936. 1--2009. The difference and correlation of each method were also analyzed. The results indicate that the average values of both Eus and Efr are greater than Est. The difference of Efr and Est is not significant at the level of 0.05, while the difference of Eos and Est,, Eus and Efr, are significant at the level of 0.05 by variance analysis. The correlation of Est, a and Eus ,Efr ,p are significant at the level of 0. 001. The correlations of a and Eus ,σ and Efr are lower than that of a and p whereas the correlations of Est and Eus,Estand Efr are higher than that of Efr and p. The effect of predicting the bending properties by combining dynamic modulus of elasticity and density is better than that by only using dynamic modulus of elasticity or density.