Improving the strength and durability of panel-based cabinet furniture
The primary objective of this study was to improve existing engineering designs of bookcases so that structurally sound and durable panel-based cabinets can be produced from wood composite materials at reasonable cost. Methods of improving the quality and robustness of composite based furniture were investigated. A total of eighteen bookcases were constructed and tested: Three cases each were constructed to determine (a) the actual reduction of deflection of the front edge of a shelf as a function of reinforcement of the back edge, (b) to evaluate the contribution of intermediate support to prevent undue bowing of the sides, and (c) to investigate the effect of front frames on side deflection: The remaining six cases were used to investigate the effect of joint rigidity on shelf deflection at mid-span. Bookcases were subjected to a creep test under a uniformly distributed load for either six months or three months. The study showed that the amount a shelf deflects depends upon material thickness and type, stiffness, method of reinforcing the shelves, and rigidity of the ends of the shelves. Creep deflection was found to correlate with the bending stiffness of the wood composite panels. In fastening the shelves to the sides of the case, the longer the screw length, the lower the shelf deflection values obtained. Highest creep deflection resulted in the greatest amount of irrecoverable deflection. Results of this study supported the design convention of doubling the elastic deflection to account for creep effects in the usage of panel products. The highest resistance to creep was exhibited by the MDF panels. The results of the study showed that the performance of existing designs can be improved by attaching the shelves to the back of the case with screws, making the ends of the shelves rigid, increasing panel thickness or using a board with higher MOE values. When properly supported, 5/8-inch thick particleboard shelves perform well and provide a very economical way to produce a bookcase. Outward side deflection of the bookcases can be significantly reduced by attaching of a front frame to the open face of the bookcase or some type of support at mid-height.
Eckelman, Purdue University.
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