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Safety Info

• Safety glasses are required at all times while equipment is turned on.   Not only are safety glasses a good precaution, they prepare students for industry where they are also required.

• Dial calipers
• Instron 4400R testing machine or Instron 4485 testing machine
• Dial gage

[excel data sheets] right-click, save target as

procedure for compression parallel to grain

Before testing

1. Select two 2" x 2" x 8" specimens (one dry and one wet) for the parallel to the grain test.
2. Record any significant defects in the specimens.
3. Measure cross sectional area and length.
4. Attach the strainometer to the specimen and measure the gage length prior to placing it in the testing machine.

1. Verify load application speed of 0.02 inches/minute.
2. Place the specimen in the machine and apply a small holding load (under 100lb).
3. Zero the extension (GL Reset) used to measure deformation and zero the strainometer gage.
4. Record load and strainometer gage reading at 0.002 inch increments of deformation (labeled extension on the test machine).
5. Continue loading until a peak load is reached or, if no peak is reached, until the load approaches a constant value.
6. Repeat to test the wet specimen.

Before testing

1. Select and label (pencil works best) two 2" x 2" x 5" specimens (one dry and one wet).
2. Record any significant defects in the specimens.
3. Place the bearing plate on top of the specimen at the center of the specimen. Make sure the plate is perpendicular to the specimen, and preferably against a radial surface, if possible
4. Measure all dimensions of both specimens accurately, including area to be loaded.

On the Instron 4400R Machine

1. Verify load application rate of 0.02 inch/minute.
2. Place the specimen in the machine and apply a small holding load (under 100lb).
3. Zero the extension (GL Reset) used to measure deformation.
4. Record the load at 0.002 inch increments of deformation (labeled extension on the test machine).
5. Continue loading until failure, or just beyond 0.1 inch deformation, which we consider to be "failure by excessive deformation."
6. To determine the moisture content, weigh the specimen after testing, and place in the oven for drying. (It can be assumed that the parallel test specimens have the same moisture content)

Someone will have to come back tomorrow to weigh the two dried specimens!

compression parallel to grain

1. Plot a stress-strain curve for both the dry and wet specimens. Use the original cross sectional area when computing the stresses.
2. Compute the maximum compressive stress parallel to the grain and the modulus of elasticity for both the dry and wet specimens.

compression perpendicular to grain

1. Plot a stress versus deformation curve for both the dry and the wet specimens
   
2. Compute the following for both the dry and the wet specimens:

1. compressive stress at proportional limit
2. maximum compressive stress (at 0.1" deformation typically)
3. moisture content