Реферат: Balsawood Structure Design Essay Research Paper 1

glue and has an obvious best solution. It is assumed that the results

would be similar for testing in shear.

Sample specimens were broken in two, and then glued back together, see

Figure 4. Next, the specimen were tested under tension to determine

which glue was the strongest. Three glues were tested, 3M Super

Strength Adhesive, Carpenter?s Wood Glue, and standard Epoxy.

Figure 4: Glue Test Specimen

Table 4: Glue Testing Results

Ironically, the cheap Carpenters? Wood Glue is the best glue to use.

Both the Wood Glue and the Epoxy both were stronger then the actual

wood, and the wood broke before the glued joint did. The so called, 3M

Super Strength Adhesive proved to give the worst results, and gave off a

noxious smell both in application and in failure. Since price is also

an important design consideration, and drying time is not of the utmost

importance, the Carpenters? Wood Glue was used in joint testing, and

will most likely be used in the final design. Another factor that

wasn?t considered is that the Wood Glue is also easy to sand, which

makes shaping the final design much easier.

4. Joint Testing

At first, basic joint testing was done, three different connections were

glued together using carpenters? wood glue as shown in Figure 5 and

loaded until failure of either the joint or the material.

Figure 5: Joints Tested

The finger joint (Figure 5-c) was the only of the above joints found to

fail before the actual wood. This is simply a continuation of the glue

test. The finger joint is likely to have failed because it has the most

area under shear force and as stated earlier, glue is weaker in shear

than in normal stress. Thus a more advanced form of joint testing was

needed.