Studies on the nondestructive test of wood and its application to the grading system

一个有效的无损检测是非常必要的，以发展木结构建筑中的结构构件（锯材或木基材料）的分级系统。本研究以木材为研究对象，探讨了木材强度分级体系作为检测手段的可能性和条件，主要研究结果如下：（1）采用静载弯曲、动载弯曲、应力波和声分析等无损检测手段，对木材试件进行了莫伊测试。并采用声发射测试和图像分析方法对木材缺陷进行了检测。这些试验的数据将用于保守目视检查。(2)在实际应用中，各种方法都有其局限性，将这些方法结合起来进行木材结构性分级是非常有效的。(3)材料的含水率对无损检测值有很大的影响。为此，提出了一种含水率的预测方法.该系统可以根据木材的重量和体积计算出木材的含水率。(4)通过各林业科研单位提供的大量莫伊和MOR数据，探讨了莫伊和莫尔之间的关系。然后，从可靠度理论的角度对这种关系进行了分析，并将其应用到强度分级系统中。

An effective nondestructive test is strongly necessary to develop the grading system of the structural members (sawn lumber or wood-based materials) in the wood construction. In this study, several kinds of nondestructive tests were applied to the wooden materials to investigate the possibilities and the conditions as the testing method for the strength grading system.Results of the study are summarized as follows ; (1) Static bending by dead load, dynamic bending, stress wave and sound analysis tests were considered as nondestructive testing methods to get MOE of the specimen. Also, acoustic emission tests and image analysis method were taken up to inspect the defect of wood. The data from these tests will serve for the conservative visual inspection. (2) Every methods have their own limitations in the practical application to the structural grading of wood and the combination of these test methods seemed to be very effective. (3) Moisture content of the material has a great effect on the value of nondestructive test. So, a prediction method of moisture content was proposed. Moisture content can be calculated from the weight and the volume of wood by this system. (4) A plenty of data of MOE and MOR were provided from each forestry institutes, and the relationship between MOE and MOR was investigated. And then, this relation was analyzed in the way of reliability theory for its application to the strength grading system.