FORECASTING DURABILITY OF WOOD COMPOSITES BASED ON ACCELERATED TESTS

Abstract

Long-term strength and durability tests are long and laborious, therefore new accelerated test methods are constantly being offered. The aim of this study is to develop a method for predicting durability based on data obtained from standard short-term tests for bending strength. The forecasting method is based on the kinetic concept of the strength of solids. The experiments were carried out on samples of structural chipboards based on urea-formaldehyde resin. The significance level for the tensile strength and time to failure in the studied temperature range from 273 to 353 °K, as well as for the loading speed from 0.81 to 98.25 mm/min, was less than 0.05, which indicates that the influence temperatures and strain rates are statistically significant. The results showed that temperature had a more significant effect on the tensile strength than the strain rate. At the same time, their effect on the time to failure is almost the same. Studies have confirmed the hypothesis of a non-linear reaction of wood composites to external thermo-moisture-force effects. The reason for the nonlinearity is the result of the interaction of variable factors with each other, but this requires special further study. The created technique allows to significantly reduce the time required for testing. The data presented in the work allow us to verify the proposed mathematical model that describes the change in the long-term strength of composite materials on wood fillers (wood composites), as well as assess the influence of external factors on the strength characteristics of the composite during production and operation.

Keywords

• wood boards
• durability prediction
• durability indicators
• accelerated tests