Реферат: Balsawood Structure Design Essay Research Paper 1

glued joints simply because the material had compressed to form a sort

of socket for the joint. Although it is doubtful that this would be a

part of the design, it is important to take this in to consideration in

the design, and hopefully take advantage of this type of behavior.

The use of plywood-style pieces of balsa was not tested, but it needs

to be considered. Where the load and stresses are known it would be

best to form the plys in a unidirectional grain orientation, where the

strongest orientation is used. However, where the stresses are unknown

it would be better to use a criss-cross pattern in the balsa plys to

produce a strong, general purpose material in these regions.

Now to discuss the initial design. Figure 7 shows a basic design. The

grain representations are accurate for the lower portion. However, in

the top section where the arch is horizontal, and the load will be

applied, this section will be in bending and therefore requires a

horizontal grain. (This inaccuracy is due to limitations in the graphics

package used for the figure.) Note that the bottom support piece is

thick at the ends to encourage the self forming joints previous

discussed, and since the bottom piece is believed to be subject to

tension, the middle section is made thinner to cut down on material

weight.

The loading cap will need to be constrained so it will not slide down

the side of the structure, so added material needs to be place in those

points. In testing prototypes, the effects of the grain orientation

needs to be observed. In the top most sections, strictly horizontal

grains will be used, but as the arch curves to a vertical orientation,

vertically oriented grains need to be used. This gradual change in

grain will be possible with plywood style layering of the balsa.

Until further testing of prototypes is possible, this is all of the

relevant information available. Ideally, a structure such as this one