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Determination of the impact of creeping of furniture joints on their rigidity

The study presents research results on the effect of creeping on changes in the rigidity of selected joints used in constructions of upholstered furniture, expressed as the substitute modulus of elasticity Ez. The modulus was calculated analytically for this purpose using the Maxwell–Mohr constitutive equation. | Turkish Journal of Agriculture and Forestry http://journals.tubitak.gov.tr/agriculture/ Research Article Turk J Agric For (2013) 37: 802-811 © TÜBİTAK doi:10.3906/tar-1206-8 Determination of the impact of creeping of furniture joints on their rigidity Jerzy SMARDZEWSKI, Robert KŁOS, Beata FABISIAK* Department of Furniture Design, Faculty of Wood Technology, Poznan University of Life Sciences, Poland Received: 04.06.2012 Accepted: 14.12.2012 Published Online: 23.09.2013 Printed: 23.10.2013 Abstract: The study presents research results on the effect of creeping on changes in the rigidity of selected joints used in constructions of upholstered furniture, expressed as the substitute modulus of elasticity Ez. The modulus was calculated analytically for this purpose using the Maxwell–Mohr constitutive equation. In addition, actual runs of creeping curves were determined and a theoretical model well describing the obtained results was selected. Simultaneously, a detailed statistical analysis was carried out. It was found that creeping exerted a significant impact on the mechanical quality of the examined joints by reducing their substitute modulus of elasticity by 11%– 16%. This modulus can be employed in numerical calculations using the finite elements method. Key words: Creeping, furniture joint, rigidity, substitute modulus of elasticity 1. Introduction The phenomenon of material creeping can be observed in all known construction materials and its intensity depends, to a considerable extent, on material structure and the value and duration of the applied loads, among other factors. The creeping process leads to the destruction of material, and its course may be divided into 3 phases. The first is characterised by decreasing velocity of deformations over time. The second phase develops at the constant velocity of deformations, whereas in the third phase, an increasing velocity of deformations leading to the destruction of material can be observed (Dietrich .