Influence of the number of layers on the strength of beech laminated elements in the three-point flexural test

A chair is a piece of furniture whose elements are loaded with relatively high forces. The strength of these elements is vital for the safety of using this type of furniture. The research aims to test the chair material system made of beech wood. The authors analyzed laminated elements with 9, 11, and 13 layers of veneers. The veneers were 1.23 mm thick, with perpendicular fiber directions in adjacent layers, and bonded with 220 g/m2 of PVAc adhesive. The moisture content of the elements was 6 ± 1%. A three-point bending flexural test was performed to determine the stress-strain response of the tested three variants. A complementary numerical analysis allowed a more precise comparison of the three analyzed laminated elements variants. It was confirmed that all variants exceed the desired minimal values in chair support design. Moreover, the average strength values for tested laminated elements, differing in the number of veneers, were sufficient even with a reduced number of veneer layers. The experiments and numerical analysis results confirmed the usability of the three tested types of beech laminated elements to be used as highly loaded chair elements.