非破壞性檢測技術應用於南方松木材彈性模數之探討

Application of Nondestructive testing to evaluate modulus of elasticity of Southern pine (Pinus spp.) wood

木材之抗彎彈性模數表示木材在受力後之應力與應變之關係，其值也是木材在機械分等中的主要依據，為了快速而有效的進行木材等級區分，本研究主要利用3種非破壞檢測技術（超音波法、應力波法、打音法）探討其應用於評估不同斷面尺寸木材抗彎彈性模數之適用性。結果指出，本次南方松木材製品之抗彎彈性模數可分為L50級~L200級，以3種非破壞檢測技術所得之音速值與動彈性模數評估南方松木材製品之抗彎彈性模數時，其r 2 值分別為0.53~0.55與0.69~0.72，而進一步以多變項線性迴歸分析更能建立較佳之預測模型，其ra 2 值0.719~0.893，其中，又以考量動彈性模數與厚度因子之模式2較佳。 Modulus of elasticity (MOE) is a kind of relationship between stress and strain of wood under a given force, the value is also the key indicator in structural lumber grading system. For rapidly, effectively and accurately grading wood, Southern pine lumber were evaluated nondestructively with three nondestructive testings, including ultrasonic wave , stress wave and tap tone methods. Then the results were compared with the static MOE determined by static bending test. The experimental results indicated that L50 to L200 grades of Southern pine lumber were found after E-grading. Additionally, three nondestructive testings predicted the MOE of Southern pine lumber with linear regression, the r 2 value were ranged from 0.53~0.55 and 0.69~0.72 for velocity (V) and dynamic MOE (DMOE), respectively. Compared to simple linear regression models, the well relationships were found, the ra 2 value ranging from 0.719~0.893, after the multiple linear regression analyzed. Among these models, the model 2 which combined the DMOE and thickness factors was suggested.