Development of Dynamic Portable Graders for Structural Lumber Using Tapping Method

本计画之目的在于发展一种可携式动态分级机，用于结构材强度之非破坏性评估.开发了以下系统：（1）由快速傅立叶变换（FFT）频谱分析仪和16位个人计算机组成的自动高速系统，（2）由计数器LSI和逻辑IC组成的袖珍杨氏模量测试仪，（3）由16位个人计算机和商用A/D转换器板组成的自动系统，（4）由袖珍计算机和商用A/D转换板组成的系统.自动化系统的现场应用测试：将使用FFT频谱分析仪的自动化系统运送到木材米尔斯和森林侧原木场，以检查适用性并获得传统日本木屋的2X 4木材（S-P-F）和杉和扁柏结构木材的物理参数数据。在结构木材的情况下，最大测量速度为每小时100件木材。测量的速率决定步骤是通过人工操作更换样本。对于原木，应改进重量测量。3.采用传递矩阵法对变截面梁的弯曲振动理论进行了数值分析，将弯曲振动技术应用于原木。研究结果为等截面梁振动理论的应用提供了可能.利用现场试验中存储的结构木材物理性质知识库，对结构木材强度无损预测算法进行了检验。研究了用共振频率和多元回归模型预测莫伊的方法。

The object of this project was directed to the development of the portable dynamic graders which are used for the non-destructive strength evaluation of structural lumber.1. The following systems were developed : (1) An automated high-speed system which was composed of an Fast Fourier Transformation (FFT) spectrum analyzer and a 16-bit personal computer, (2) A pocket Young's-modulus tester which was composed of a counter LSI and logic ICs, (3) An automated system which was composed of a 16-bit personal computer and a commercial A/D converter board, and (4) A system which was composed of a pocket computer and a commercial A/D converter board.2. In situ application test of the automated system : The automated system using a FFT spectrum analyzer was transported to lumber mills and a forest-side log yard in order to examine the applicability and to obtain the data on the physical parameters of 2X4 lumber (S-P-F) and structural lumber of sugi and hinoki for the traditional Japanese wooden house. The maximum measuring speed was 100 pieces of lumber per an hour in the case of structural lumber. The rate-determining step of the measurement was the changing of specimens by human handling. In the case of logs, the weight measurement should be improved.3. Numerical analysis of the flexural vibration theory of tapered beam was made to adopt the flexural vibration technique to logs by using the transfer matrix method. The results made the application of the vibration theory of the beam with homogeneous cross-section possible.4. Knowledge base of the physical properties of structural timbers which was stored during in situ test was use to examine the algorism of the non-destructive strength prediction of structural timber. MOE prediction by the resonance frequency and the multiple regression model were studied.