Based On The Piezoelectric Acceleration Sensor Wood Instrument For Nondestructive Testing Research

Our country is not only a big timber production country, but also a large timber consumption country. In recent years, with the forest resources reducing rapidly, the available timber resources has been shrinking rapidly. Under the condition of limited timber resources, improving the utilization rate is equal to increase the total amount of available wood. So it is a main priority to take a nondestructive test on the wood on-line to improve the timber utilization rate scientifically and reasonably. This topic focuses on the present development situation and production requirements of the domestic and the foreign, taking electronic technology, computer control technology and the stress wave of nondestructive detection method to identify the wood internal defects, aiming to find the internal defects of wood to cut reasonably and improve the utilization rate.This article mainly research content includes:(1) The selection of log nondestructive testing method. Aiming at the development history and research status of nondestructive test technology at home and abroad. Finally, this paper selects the technology of stress wave nondestructive testing to test the log internal defects after comparing and selecting.(2) The design of the detection circuit. take charge(stress wave) type acceleration sensor to receive close stress signal, and take the current acceleration(stress wave) sensor to receive the remote stress signal, through the respective measurement circuit and signal processing circuit, transform the time difference produced by the stress wave signal of sensor into 0~5 v square wave signals to supply for single chip to collect and process. The width of the square wave pulse is on behalf of the time that the stress wave spreads in the internal log, and the time describes the length material and defect of the log.(3) The design of the intelligent control system.By contrast, the performance of the various types of single-chip microcomputer chose the suitable main controller, the design with MSP430F149 as the core of the stress wave velocity test system.(4) In terms of the system software design, PC with TreeWin software combined with the data storage technology, serial communication technology at the same time, realizes to receive, process and store the date of the lower machine, and bring out the defects two-dimensional image in the wood internal. And by detecting the defects in the log, taking advantage of the matlab software to simulate the defects and then do some analysis from the two sides, and the re-emergence of the measuring precision of the instrument is determined. The software of single chip processor, MSP430F149 MCU as the core of C programming language is used in the stress wave detection system, is implemented under the machine data collection, and the data communication with PC.This topic in the research of wood nondestructive testing system, can realize measuring elastic modulus of wood, and detect the wood internal defects position, can achieve optimal material optimum use of wood, thus reduce the more limited felling of forestry resources, protection of forestry resources. The system has real-time, accuracy, and can quickly measure the elastic modulus of wood, connecting with the upper machine of internal defects in present 3 d stereogram, provide reliable theory basis for the reasonable cutting wood.