Stiffness Analysis of Wood Chair Frame

Abstract

This paper presents a stiffness analysis of a statically indeterminate wood-chair side-frame. Numerical calculations are carried out with a 'linear elastic model' for orthotropic materials. The mathematical model is solved by a 'finite element method'. The matrix analysis of structure is carried out by a 'direct stiffness method'. The frame joints are assumed to be ideally rigid and also as semi-rigid. Horizontal displacement of the top point of the back post is calculated for the most frequently used type of loading for the structure. The results of the calculation indicate that chair side frame becomes stiffer as the position of the stretcher is lowered and/or the stretcher cross section is increased. The results revealed that stiffness of joints in a frame had a considerable impact on the structure deflection. A satisfactory agreement was found between the numerical results and the results obtained by direct stiffness method.

Construction of Wood-Based Lamella for Increased Load on Seating Furniture

“…The second direction deals with furniture design and construction using numerical and analytical methods. The finite element method (FEM) used to estimate or determine the load capacity of individual joint dimensions is the most often used method [73][74][75][76][77][78].…”

Verification of Orthotropic Model of Wood

“…This study examines orthotropic conditions for different species of wood and verifies the wood constants given in the reference material. When all elastic constants are given [7,10,11,12,15,16,21,22,23,29,31,33,39] it is sufficient see whether condition (2.9) is met ( Table 1, Table 2) because if eigenvalues are positive, the compliance matrix is positive-definite. For incomplete data [4,15,22] the conditions (2.7) are reviewed ( Table 3).…”

“…Black Walnut [15,22], Oak [4] and Beech [4] were found to show orthotropic behavior. If the accuracy of calculation terms of the compliance matrices are reduced, Spruce [4] and Maple [11] can also be assumed to be orthotropic. The elastic constants for Pine in [21] were calculated using the orthotropic material model, assuming the symmetry of the compliance matrix.…”

“…Based on the orthotropic model, three principal orthogonal directions of elasticity for wood, i.e., longitudinal (L), tangential (T) and radial (R) are determined. In some papers [11,24,37,38], mostly in numerical simulation, nine independent elastic constants such as three elastic moduli ( , , ), three transverse elastic moduli ( , , ) and three Poisson's ratios ( , , ) are defined. In experimental studies [10,12,17,23,27,29,31,33,39]…”

Experimental Analysis of New Furniture Joints

“…Both types of loads are impossible to determine precisely, due to unknown values of the forces exerted by assembly, depending on the manufacturing technology of joined sub-assemblies (precision of production, variable strength properties of wood materials - (Sydor and Wieloch 2009)), as well as the adopted assembly conditions and method. The value of the operational loads to be applied depend on incompletely known factors: operation mode, ambient conditions (temperature and humidity), and the method of furniture storage and transport (Eckelman et al 1988;Eckelman 1999;Çolakoğlu and Apay 2012;Hajdarević and Busuladžić 2015;Smardzewski 2015).…”