Research Progress Report 325 January, 1968
Computer Analysis of Member Stresses in Chair Side Frames
C. A. Eckelman and F. E. Goodrick
Department of Forestry and Conservation

Introduction
Furniture design has long been held to be an art rather than a science, but science nonetheless has an important role to play. Other fields of structural endeavor have also begun as art but have embraced scientific principles embodied in structural theory and procedures as these have been developed and become available. Most structures were first built on a trial and error basis. Some failed whereas others remained sound. Destructive testing was first introduced to eliminate weak designs. A heavily loaded wagon, for example was often pulled across a bridge before the bridge was declared safe for public use. Later, as structural theory was developed and became available, the integrity and strength of a structure could be determined theoretically before it was built and costly mistakes could thereby be avoided. Structural theory as it is embodied in the subject matter of structural mechanics has entered slowly into furniture design. Although numerous existing methods of structural analysis are applicable, their widespread use and acceptance have been hampered because there are too few people in the furniture industry trained to use them and also because the analyses are often involved and time consuming. Until recently these two factors necessarily limited the
engineering design of furniture. The analysis of even the simplest three dimensional frame, for example, may require the solution of 30 to 40 equations. Such a task is impractical by hand, and would require weeks if attempted. But just as important, furniture design truly is an art as well as a science, and although there are undoubtedly designers trained both as artists and engineers, it is not reasonable to expect all furniture designers to be trained in structural mechanics. Consequently, before the advantages resulting from structural analyses can be realized, analytical methods must first be put into a form in which they can be utilized by a greater part of the furniture industry.

The introduction and widespread use of the modern digital computer is helping to remove these obstacles. Once properly programmed, a modern high speed computer can carry out an entire structural analysis in seconds that would take hours by hand. Because of its speed the computer may also be used as a powerful research tool to investigate and evaluate any number of structural parameters. An example of this aspect of design was given in another paper (Eckelman, 1966) in which the most advantageous structural position of a stretcher in a chair frame was theoretically determined. Furthermore,

PURDUE UNIVERSITY • Agricultural Experiment Station • Lafayette, Indiana