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

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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.