Ukrainian Journal of Forest and Wood Science

The most common method for automated nondestructive testing of materials and products is the ultrasonic method. The method is fairly accurate, allows to automate the process of plywood internal defects detecting. Measurement results can be used for selective sorting of plywood and for automated adjustment of plywood production processes. However, ultrasonic method has several disadvantages, namely this method requires a fairly stable environmental conditions (temperature, plywood surface quality, absence of convective air currents, etc.), which complicates the design of the measuring installation, implementation of method is relatively expensive.In this regard, the goal was to create a system for automated detection of internal defects of plywood, which would exclude all the disadvantages, described above. The work is basedon the free oscillations method. The method is basedon measuring of the properties of vibrational process that occurs in the plywood after short-term impact. The studied area of plywood surface is affected by the short-term strike. Strike raises mechanical oscillationsin the plate of plywood and can be converted into electrical signal using piezoelectric transducer. The form of output electrical signals at the piezoelectric transducer depends on the properties of the plywood.

plywood, flaw detection, the method of free oscillations, bundle, area, depth, the place of occurrence of the defect