Study And Application For Lumber Testing System Based On Simply Supported Beam Vibration Principle

Nondestructive testing (NDT) and nondestructive evaluation (NDE) are essential processes in evaluating the performance of structural lumber and improving the utilization of our limited forest resources. In this study, a vibration-based measurement system was developed for nondestructively measuring the modulus of elasticity (MOE) of structural lumber. The applicability and validity of a simply-supported beam vibration theory were examined under various boundary conditions. The effects of shear deformation and torsion moment on beam vibration were discussed through a theoretical analysis.As the major task of the study, a lumber testing system that combined the traditional vibration measurement and advanced virtual instrument (VI) technology was developed and verified through laboratory experiments. The testing system developed includes both hardware and software can measure the fundamental natural frequency of a piece of lumber, and compute the dynamic modulus of elasticity accordingly.The system features modular and hierarchical design that greatly improved the data acquisition, data process/analysis, data storage, and data display. It can achieve better testing results compared with the traditional vibration approach. This is the first NDT system developed in China that can be used to evaluate lumber property for stress rating purpose.This development work has practical implication to the wood industry in China. It provides an effective means for lumber producers to evaluate the lumber quality during the manufacturing process, improve the production efficiency, and maximize the use of limited wood resources.