Selected Mechanical Properties of Glue-Laminated Timber Produced from Locally Repaired Timber

Abstract

This study aimed to evaluate the mechanical properties determined in a 4-point bending test of beams made of lumber from which knots had been locally removed and the resulting loss replaced with sound wood. Three sets of beams were prepared, which differed in the number of layers/lamellas and the position of the lamellas from which edge knots were removed. All the lamellas used in the tests were subjected to a modulus of elasticity assessment. In addition to the distribution of defects, it determined the position of a given piece in the beam structure. The tests showed that high mechanical properties could characterise the beams produced in this way, i.e., a modulus of elasticity close to 12 kN/mm2 and a strength above 40 N/mm2, if the lamellas without knots were located below the outer tension lamella. Significantly better results were obtained when PUR glue was used in the inserts rather than MUF. In this case, beams with an improved outer lamella in the tension zone using semi-circular inserts glued with PUR glue had an average strength of 34.6 N/mm2.

The Displacements Study of Birch Veneer Layers from Composition of Plywood during Water Jet Cutting Using the Finite Element Method (FEA)

“…Shanmugam and Masood [ 14 ] developed a predictive model correlating the kerf taper angle with the process variables. Using an analytical and graphical optimization technique based on analysis of variance (ANOVA) [ 15 ], the optimum cutting parameters were identified, and the effects of the combined cutting parameters were studied [ 12 ]. Additionally, the ANOVA method has been used in the optimization of the jet-cutting process by many authors in order to increase the dimensional accuracy and improve the quality of the obtained surfaces.…”