落叶松指接规格材弹性模量的研究

Study on MOE of Larch Finger Jointed Dimension Lumber

研究指接、锯材等级对兴安落叶松结构用指接材弹性模量的影响,分析不同检测方法评估落叶松指接规格材弹性模量的可靠性。以落叶松锯材为原料,根据纵向基频振动(FFT)测试结果将其分为M_E12、M_E14、M_E16、M_E18四组,制备截面为40 mm×90 mm的规格材和指接规格材;分别利用纵向基频振动(FFT)、横向振动(TV)、机械应力分等级(MSR)测试评估指接材的静态弹性模量。结果表明:落叶松规格材和指接规格材是一种高弹性模量的锯材,其平均弹性模量大于SPF目测二级规格材的弹性模量;分级后,不同等级指接材弹性模量差异显著;指接加工降低中低等级锯材的弹性模量,但不影响高等级锯材的弹性模量;利用MSR测试结果评估指接材的弹性模量效果最佳,但其设备复杂,结合FFT设备的优点,推荐工厂使用FFT在线检测落叶松指接规格材的弹性模量。

This paper studies the impact of finger jointed processing and lumber's grade on modulus of elasticity(MOE)of Larix gemelini finger jointed lumber,and analyzes the reliability of using different Nondestructive Testing(NDT)methods to evaluate the MOE of finger jointed lumber.The dynamic and static MOE of finger and non finger jointed larch lumber with 40 mm×90 mm cross-section grouped by dynamic MOE were measured by methods of Fast Fourier Transform-longitudinal vibration(FFT),transverse vibration(TV),mechanical stress rating machine(MSR)and mechanical experimental machine.The dynamic and static MOE get in testing were analyzed.The results show that:(1)Larix gmelin lumber and finger jointed lumber are a kind of wood of high MOE compared to SPF in visualⅡgrade;the MOE of lumber in different groups are different significantly;(2)The finger jointed processing has a negative impact on MOE of lumber in low and mid grades,but it has no significant impact on high grade lumber's MOE.The lumber should be graded before finger jointed processing to reduce the negative effect of the processing on the lumber;(3)FFT method is suggested to be used in online testing of larch lumber in manufactory in consideration of the advantage of facilities of FFT.