Реферат: Balsawood Structure Design Essay Research Paper 1

constructed to test the principles discussed in this report. The goal

of this report is to combine the results from testing and experience to

produce a working preliminary design.

2. Material Testing

All standard testing was performed on the Applied Test System located in

room XXXXXXXXXXXXXX. The goal of this section is to determine the

material strengths of balsa, and how balsa responds to different

loading. Before testing, the basic structure of balsa needs to be

considered. Wood grain is composed of bundles of thin tubular

components or fibers which are naturally formed together. When loaded

parallel to this grain, the fibers exhibit the greatest strength. When

loaded perpendicular to the grain, the fibers pull apart easily, and the

material exhibits the least strength.

Generally, for design considerations, the weakest orientation should be

tested. However, testing procedure called for testing of the material

in the greatest strength orientations; torsion and compression, parallel

to the grain, and bending with the shear forces perpendicular to the

grain. Testing the materials for their “best direction” characteristics

can produce results that are not representative of real behavior. To

expect uniform stress distributions and to predict the exact locations

of stresses prior to testing prototypes is generally not a good idea.

However the values obtained from these tests can give a general idea of

where the structure may fail, and will display basic properties of the

material.

Tension Test

In tension testing, it is important to have samples shaped like the one

in Figure 1, or the material may break at the ends where the clamps are

applied to the material. Failure was defined to occur when the specimen

broke in the center area, and not near the clamps. The machine records