Risa 3d deflection limits
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When members are used solely for structural purposes such as in upholstered furniture, however, they often may be engineered exactly to meet specified strength requirements.
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The principal task of the designer in such cases is to verify that each member can safely carry the forces imposed upon it without exceeding the allowable stress design values. In many types of furniture, members may be deliberately oversized so that no attempt is made to determine the optimum or most efficient size for each member. This process provides a methodical way of designing a piece of furniture to meet any specified service condition. In the methodology of furniture engineering once forces and moments these acting to the ends of each member have been analyzed, the internal stresses in these members can be calculated and by comparing their magnitudes with the allowable design stresses for the material used, it can be seen whether or not each of the members has been safely designed. The section size and geometries of members that integrate the furniture frames should be designed rationally and they should carry the acceptable loads probably imposed upon them in service. However, some researchers have shown interest in this field ( Gustafsson 1997).
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As far as known, no manufacturer or designer applies static analyses to determine the internal forces inside the wooden members of a furniture body.
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The design of furniture almost rests on traditional experiences in handcraft manufacturing. However, it is becoming increasingly important because of various reasons such as consumer demands for more reliable furniture, government pressures for warranties of furniture, increasing needs for material economics, among others. Until recently, the engineering design received little attention. The first one requires esthetic design that is, the artistic development of the furniture structure, the design of the second is necessary for the use/functionality of the furniture such that the furniture structure is planned to have the capability of its intended functionality, and the last can be obtained by an engineering design that is, the furniture can safely resist the loads imposed upon it in its service life and manufactured with minimum cost. The design of the new furniture should satisfy three main criteria such that it should have an aesthetic looking, functional, durable and also feasible. Keywords: Acceptable design loads chair strength cyclic loading finite element analysis furniture engineering design structural analysis wooden. In the case of pine chairs they could meet the medium service for front to back and back to front loading, while light service for backrest loading. Depending on allowable design loads by American Library Association chairs constructed of beech could meet the medium service for front to back and back to front loading, while heavy service for backrest loading. As a result, it was concluded that finite element method analyses achieve reasonable estimates for strength performances and failure behaviors of chairs. Additionally, specimens were analyzed as structures by using the finite element method in order to obtain axial, shear, and bending stresses acting on each member under loadings and compare these values with design stresses. Chairs were tested under 3 cyclic loading directions namely, front to back, back to front, and backrest according to American Library Association (ALA) specifications, and obtained loading performances of chairs were crosschecked with allowable design load levels. Totally, 30 real size chairs were constructed and assembled with polyvinyl acetate adhesive. Tests were carried out to investigate the cyclic loading performance of chairs constructed of Scotch pine ( Pinus sylvestris) and Oriental beech ( Fagus orientalis).