Research On Testing Methods Of Glued Laminated Timber With Glue Line Defects

The introduction of modern timber structure and the concept of "energy conservation and environmental protection" have made the increasingly extensive application of glulam. In order to guarantee the bearing capacity and durability of wooden bridges and buildings, we should firstly ensure the quality of wood components. The quality of glued wood components depends on the selection of lumber as well as the quality of the agglutination. We have selected the Id Sing-an larch for raw materials to make three-layer glue laminated constructions. With the laminated wood as test object, the experimental study has been tested by using the method of ultrasonic wave and stress wave. The main research contents are as follows:1. Through artificial simulation of single and double glue line defects, using the ultrasonic method to test research, then the slope(PSD)、the wave velocity(V) and amplitude(A) namely PSD-V-A comprehensive criterion has been presented in this paper.The PSD-V-A comprehensive criterion is used to distinguish the position、 boundary and severity of the glue line defect. Through mapping the PSD-V-A curve, the transformation law between glue line defects and the related parameters has been studied;2. Stress wave method is used to do the contrast test, the accuracy and the differences and similarities of measured results between the ultrasonic wave and stress wave would be studied in this paper;3. In order to make up for the inadequacy residing in the wave velocity and amplitude analysis, the ultrasonic test signal would be analyzed in frequency spectrum and wavelet by using the MATLAB software to further understand the detail information of wave signal in this paper.