Eng. Rodica SAVA

Study of Physical, Mechanical and Technological Characteristics of Thin Plywood (1÷3mm) made from Indigenous Wood Species

SCIENTIFIC COORDINATOR: Prof.dr.eng. Virgiliu ISTRATE

PhD thesis asserted at “Transilvania” University of Brasov – Faculty of Wood Industry, January 2005

This Phd-thesis has pursued the comparative study of physical, mechanical and technological characteristics of a certain cathegory of plywood, which is not produced at industrial scale in our country, namely thin plywood (thickness 1÷3mm), made of beech, birch, alder and lime wood.

Since te characteristics of this kind of boards are different from te characteristics of standard ones, several studies have been performed:

1. teoretical study concerning te influence of wood characteristics upon te properties of plywood;
2. teoretical study concerning determination methods of these characteristics, with a focus on nondestructive methods; within this context, an original contribution must be emphasized, namely te elaboration of a method for nondestructive evaluation of te dynamic modulus of elasticity (MOE), based on the propagation of oscillations in an acoustic field (18÷20000Hz).
3. FEM analysis of the behaviour of a plywood structure to bending, as an application example for this non-distructive method

Additionally, an original device for the determination of MOE by this method has been conceived and built. The experimental results were processed by means of a computer program in C-Builder.

After making the correlations between the values obtained by classical methods and the ones obtained by the proposed method, specific manufacturing parameters could be established for the processing of thin plywood panels and their influence on the physical, mechanical and technological properties of this special plywood type.

The theoretical studies have been completed with a large experimental research, so that finally, conclusions verifiable from both points of view could be drawn.

The thesis also presents in detail the proposed fabrication technology, emphasizing the novelty elements introduced within, such as the densification by compressing the veneers, by means of an originally conceived method. The discussions concerning the obtained results motivate the technological modifications undertaken.